Fish Processing Technology in the Tropics PDF

1 FISH PROCESSING TECHNOLOGY IN THE TROPICS J. ESPEJO-HERMES Published in the Philippines by TAWID PUBLICATIONS 102 B. Gonzales St., North Xavier Ville Quezon City, Philippines Telefax No. 426-0578 SECOND PRINTING, 2004 PHILIPPINE COPYRIGHT 1998 BY JASMIN ESPEJO-HERMES Cover sculpture by...

1 FISH PROCESSING TECHNOLOGY IN THE TROPICS J. ESPEJO-HERMES Published in the Philippines by TAWID PUBLICATIONS 102 B. Gonzales St., North Xavier Ville Quezon City, Philippines Telefax No. 426-0578 SECOND PRINTING, 2004 PHILIPPINE COPYRIGHT 1998 BY JASMIN ESPEJO-HERMES Cover sculpture by Manuel D. Baldemor Cover design by Bernadette C. Solina Printing by IJN Katmic Press No part of this book may be reproduced and/or used in any form or by any means - graphic, electronic, or mechanical - without the prior written permission of the publisher and/or author. ISBN 971-91395-7-9  Foreword World fish production is estimated to lag behind demand as a consequence of a faster population growth rate and a growing preference for fish as a health food. The situation makes very critical utilization of the catch, the prevention of its misuse and underutilization. Post-harvest technology is therefore a very important component of every fisheries agenda. This book, Fish Processing Technology in the Tropics, is a most welcome addition to the very few books by Filipino authors on this topic. While scientific principles on which technologies are based are universal, specifics of technologies are usually site dependent. The inclusion of procedures for products found in the tropics makes the book a valuable reference for teachers, students and extension workers. On the other hand, the author’s review of research work on the different processing technologies, especially those undertaken locally, serves the researcher well. Ms. Espejo-Hermes brings to the preparation of this book her years of experience in research and extension work in the University and from consultancy services in some semi- government agencies abroad. Her efforts to put these in writing, thus filling a gap in Philippine fisheries technology are commendable. Leonor M. Santos, Ph. D. College of Fisheries University of the Philippines in the Visayas  Preface The two books, Philippine Handbook on Fish Processing Technology (1980) and Introduction to Minor Fishery Products in the Philippines (1985), were previously written by the author with the primary purpose of providing reference books to fisheries students in the Philippines. Both books were published with limited circulation and were financed by the Department of Science and Technology (then National Science Development Board, afterwards, National Science and Technology Authority). It took more than a decade before these books were complemented with another book for the main reason that the author was out of the country for several years. With the new experiences and insights she gained from living and working abroad (Indonesia, Papua New Guinea, and Germany), she believed that she is in a better position, now, to write a new version of the previous books while she is temporarily back in the country. To date, there is no existing local book that discusses the basics in fish processing, from the field of post-harvesting to marketing and quality assurance of tropical aquatic products. Hence, this book entitled Fish Processing Technology in the Tropics aims (as in the previous books she wrote) to consolidate the current developments and trends in fish processing in tropical countries particularly in the Philippines. Furthermore, this book gives emphasis on the improved processes of manufacturing traditional and new products. The author attempts to present this information in a reasonably balanced and in the most understandable technical language. Majority of the procedures presented for manufactured products have been modified and simplified by the author for better comprehension. The book is intended to serve as a reference book not only to fisheries students, food technologists, and researchers, but to those engaged in fish business and food enthusiasts, as well. The first chapter gives the readers a brief background on the present status of fish processing in the world, in the Philippines, and in other Southeast Asian countries. Basic information on the nutritional importance of aquatic products is also incorporated in this chapter. The chapters on Chilling, Freezing, Salting, Drying, Smoking, Fermentation, Canning, and Additives present updated information on these topics. The chapters on Fish Handling, Minced Fish Processing, Marketing, Packaging, Quality Assurance, and Waste Management provide new and additional insights to the readers. The chapter on Quality Assurance includes the HACCP (Hazard Analysis Critical Control Point) system which is becoming the widely adopted approach to food safety management. This topic will be very useful to those in the industry and to those who are considering starting a business. The last chapter touches on the management of waste produced in fish processing. The author believes that this topic is timely because of the growing problem on waste disposal worldwide. This topic gives the reader basic knowledge on what to do with the waste he will be generating when he becomes involved in fish processing. iii  This book is made possible due to the sincere encouragement and assistance of several persons whom the author wishes to thank: Dr. Leonor M. Santos (the author’s former professor) of the Institute of Fish Processing and Technology, College of Fisheries, University of the Philippines in the Visayas, who painstakingly edited the manuscript and made very valuable comments and suggestions. Ms. Teresita S. Palomares of the Food Processing Division, Department of Science and Technology (DOST); Dr. Dalisay de Guzman-Fernandez of the Philippine Council for Aquatic and Marine Research and Development (PCAMRD-DOST); Dr. Erlinda Banasihan-Panggat of the Institute of Fish Processing and Technology, College of Fisheries, University of the Philippines in the Visayas; Dr. Marco Nemesio E. Montaño of the Marine Science Institute, College of Science, University of the Philippines; Ms. Josefa P. Lucero of the Food Section, Bureau of Food and Drugs (BFAD); Ms. Flor F. Abella and her staff of the Post-Harvest Technology Division, Bureau of Fisheries and Aquatic Resources (BFAR), and many others, for providing the author with useful materials and information. Lastly, the author is thanking her family, relatives and friends, particularly her husband (Dr. Rudolf Hermes), children (Karl-Gerhard and Karin Louise), mother (Mrs. Tarcila Magno-Espejo) and parents-in-law (Mr. and Mrs. Karl-Heinz Hermes), for their moral and spiritual support. Very special thanks is given to her good friends, Ms. Irma Laudencia-Tsuchiya and Ms. Leny Trinidad, who have inspired and instigated her to pursue this endeavor – the author would like to dedicate this book to them. Jasmin Espejo-Hermes, M. Sc. iv  Table of Contents Foreword Preface 1 Introduction 1.1 World Utilization 2 1.1.1 Southeast Asia 2 1.1.2 Philippines 4 1.2 Nutritive Value of Fish 8 1.2.1 Structure of Fish and Fish Muscles 9 1.2.2 Composition of Fish 12 2 Handling of Fresh (Wet) Aquatic Products 2.1 Spoilage of Fresh Aquatic Products 17 2.1.1 Bacteria 17 2.1.2 Enzymes 18 2.1.3 Chemical Spoilage 19 2.2 Hygiene and Sanitation 20 2.2.1 Cleanliness 20 2.2.2 Personal Hygiene 22 2.3 Ways of Preparing Fish 23 2.4 Filleting of Fish 25 2.5 Characteristics of Fresh and Spoiled Aquatic Products 25 2.6 Handling of Fresh Aquatic Products 25 3 Chilling 3.1 Methods of Chilling 31 3.2 Types of Ice 34 3.3 Methods of Storing Iced Fish 36 3.4 Types of Containers 37 3.5 Types of Insulation 41 3.6 Pointers in Handling Chilled Fish 43 4 Freezing 4.1 Types of Freezing 46 4.2 Freezing Systems 46 4.3 Freezing Procedure 47 4.4 Quality Assessment of Frozen Fish 48 4.5 Thawing of Frozen Products 49 4.6 Handling of Frozen Fish 51 4.7 Manufactured Products 52 4.7.1 Boneless Milkfish 52 4.7.2 Freezing of Squids 53 4.8 Technical Problems 54 4.9 Research Notes 55 v 5 Salting 5.1 Salt Quality 58 5.2 Factors Influencing Salt Penetration 59 5.3 Methods of Salting 60 5.4 Salting Procedure 60 5.5 Manufactured Products 61 5.5.1 Kench-Cured Fish (Binoro) 61 5.5.2 Tinabal (Visayan Salted/Fermented Fish) 62 5.5.3 Shrimp Cake (Guinamos) 62 5.5.4 Salted Sea Urchin 63 5.6 Spoilage of Salted Fish 65 5.7 Research Notes 66 6 Drying 6.1 Fundamentals of Drying 68 6.2 Phases of Drying 69 6.3 Types of Dried Fishery Products 70 6.4 Methods of Drying 71 6.5 General Drying Procedure 74 6.6 Manufactured Products 75 6.6.1 Dried in the Round or Whole Fish (Tuyo) 75 6.6.2 Split-Salted Fish (Daeng) 75 6.6.3 Dried Anchovies 76 6.6.4 Fish Jerky 76 6.6.5 Dried Squid 77 6.7 Spoilage and Defects of Dried Fish 77 6.8 Research Notes 78 7 Smoking 7.1 Factors Affecting the Generation of Smoke 82 7.2 Types of Smoking 83 7.3 Types of Smokehouse 85 7.4 Smoking Procedure 90 7.5 Manufactured Products 91 7.5.1 Smoked Sardine (Tinapa) 91 7.5.2 Smoked Soft-Boned Milkfish (Bangus) 92 7.5.3 Tuna Sticks (Katsuobushi) 92 7.6 Spoilage of Smoked Fish 93 7.7 Research Notes 93 8 Fermentation 8.1 Classification of Fermented Products 96 8.2 Methods of Hastening Fermentation 97 8.3 General Procedure (Bagoong and Patis) 98 8.4 Manufactured Products 100 8.4.1 Fermented Fish with Cooked Rice (Burong Isda) 100 8.4.2 Fermented Shrimp with Cooked Rice (Burong Hipon) 101 8.5 Spoilage and Deterioration 102 8.6 Research Notes 102 vi 9 Pickling/Marinating 9.1 Preservative Action of Ingredients 104 9.2 Pickling Procedure 105 9.3 Manufactured Products 107 9.3.1 Pickled Anchovies 107 9.3.2 Marinated Mussels (Tahong) 107 9.3.3 Marinated Fried Mackerel or Sardine 108 9.4 Spoilage of Marinated Products 109 10 Minced Fish Processing 10.1 Fish Mince 110 10.2 Surimi 111 10.3 Processing of Surimi 112 10.4 Quality Assessment of Surimi 114 10.5 Manufactured Products 115 10.5.1 Fish Balls 115 10.5.2 Fish Burger 116 10.5.3 Surimi-Shrimp Value Added Products 117 10.5.4 Crab Analogue from Big-Head Carp 120 10.6 Research Notes 121 11 Canning 11.1 Classification of Food for Canning 122 11.2 Containers 123 11.3 Packing Methods in Canning 127 11.4 Equipment for Heat Processing 128 11.5 General Procedure for Canning 130 11.6 Manufactured Products 132 11.6.1 Tuna, Adobo Style 133 11.6.2 Milkfish, Salmon Style 134 11.6.3 Roundscad, Sardine Style 135 11.6.4 Indian Sardine in Oil 136 11.6.5 Smoked Mussel in Oil 137 11.6.6 Squid, Adobo Style 138 11.7 Spoilage and Technical Problems 139 11.8 Research Notes 141 12 Additives 12.1 Purpose of Additives 143 12.2 Types of Additives 144 12.3 Additives Permitted in the Philippines 147 12.4 Research Notes 149 13 Minor Aquatic Products 13.1 Seaweeds 152 13.1.1 Nutritive Value of Seaweeds 153 13.1.2 Uses of Seaweeds 155 13.1.3 Manufactured Products 158 vii  13.2 Fish Oils 13.2.1 Composition of Fish Oils 163 13.2.2 Extraction of Fish Oils 164 13.2.3 Uses of Fish Oils 166 13.2.4 Technical Problems in Fish Oil Production 167 13.2.5 Shark Oil Processing 168 13.2.6 Squalene 168 13.3 Shark Fin 13.3.1 Processing 171 13.3.2 Defects in Dried Shark Fins 176 13.4 Jellyfish 13.4.1 Processing 177 13.4.2 Grading of Jellyfish 178 13.4.3 Use of Jellyfish 179 13.5 Fish Protein Concentrate 13.5.1 Types of FPC 180 13.5.2 Methods of FPC Preparation 180 13.5.3 Processing Steps 181 13.5.4 Manufactured Products 184 13.5.5 Quality Problem 188 13.6 Sea Cucumber 13.6.1 Harvesting/Post-Harvest Handling 190 13.6.2 Processing 191 13.7 Fish Meal 13.7.1 Methods of Processing 197 13.7.2 Composition of Fish Meal 198 13.7.3 Nutritional Value 199 13.7.4 Fish Meal in Animal Nutrition 199 13.7.5 Preparation of Fish Meal 200 13.7.6 Problems in Fish Meal Manufacture 202 13.8 Fish Silage 13.8.1 Types of Silage 203 13.8.2 Composition of Fish Silage 203 13.8.3 Uses of Silage 204 13.8.4 Fish Silage Production and Storage 205 13.8.5 Problems in Fish Silage Production 206 13.8.6 Fish Silage Versus Fish Meal 207 13.9 Shells and Shellcraft 13.9.1 Methods of Cleaning and Preserving Shells 209 13.9.2 Shellcraft Making 210 13.9.3 Lime Making 213 14 Marketing of Aquatic Products 14.1 Channel of Distribution 214 14.2 Pricing 217 14.3 Distribution of Aquatic Products 219 14.4 Marketing Practices 220 viii 15 Packaging of Aquatic Products 15.1 Importance and Functions of Packaging 222 15.2 Packaging Materials 223 15.2.1 Wood-Pulp Based Material 224 15.2.2 Plastics 224 15.2.3 Rigid Containers 227 15.3 Packaging Methods 228 15.3.1 Modified Atmosphere Packaging (MAP) 228 15.3.2 Vacuum Packaging 229 15.4 Labeling Requirements 229 15.4.1 Bar Codes 231 15.4.2 Environmental Legislation and Eco-Labeling 231 16 Quality Assurance in Fish Processing 16.1 Intrinsic Quality 233 16.2 Extrinsic (External Quality) 244 16.3 Quality Control and Quality Assurance 245 16.4 Application of Quality Control/ Quality Assurance 245 16.5 Methods of Assessing Quality 247 16.5.1 Sensory Methods 247 16.5.2 Non-Sensory Methods 249 16.6 Quality Assurance and Inspection 252 16.6.1 HACCP (Hazard Analysis Critical Control Point) Concept 252 16.6.2 ISO 9000 (International Standards Organization) 264 16.6.3 Fish Inspection 268 16.7 Grades and Standards 268 16.7.1 Domestic 268 16.7.2 Foreign/Importing Countries 270 17 Waste Management 17.1 Safety of Raw Material 272 17.2 Waste Production 273 17.2.1 Processing Waste 273 17.2.2 Waste from Refrigeration 274 17.2.3 Packaging Waste 275 17.3 Waste Management 275 References 279 Glossary of Terms 293 ix Appendices Appendix A Conversion Table 297 Appendix B Preparation of Brine of Required Strength 298 Appendix C Standards and Grades for Aquatic Products 299 C1 - Grading of Frozen Shrimps/Prawns 299 C2 - Grading of Tuna 300 C3 - Fermented Sauce (Patis) 302 C4 - Carrageenan 304 Appendix D Excerpt from the Official Journal of the 310 European Communities Council Directive (91/493/EEC) Common (English), Scientific, and Local Names of Aquatic Products 329 Index 332 x Fish Processing Technology in the Tropics J. Espejo-Hermes (2004) Chapter 1 Introduction The aquatic resources of a country do not only serve as a source of food but are important economically since they can provide job opportunities, income, and foreign currency for the people and the country, when sustainably utilized. The potential to harvest more products from aquatic environments is now very much limited. Production is decreasing as more and more fisheries are getting heavily or over exploited. At the start of the 1990s, around 69% of the world’s traditional species were fully exploited, overexploited, depleted or in the process of rebuilding due to depletion (FAO, 1995). Simultaneously, the demand for protein world-wide is increasing as the human population grows (Ward, 1996). One means of reducing the shortage between production and demand is to efficiently utilize aquatic resources by the application of effective processing technology to reduce post-harvest losses and wastage. Fish processing technology includes the different processes and techniques employed in the post-harvest handling, processing and marketing of aquatic products from the time of harvesting to final utilization. The application of processing technology in aquatic products is aimed mainly at preventing or delaying spoilage brought about by microorganisms, enzymes, and physical or mechanical means. Developments in fish (processing) technology have gone a long way. In the 1950’s, freezing at sea was the major development in the advanced nations. Bulk chilling in chilled or refrigerated seawater systems on board fishing vessels was also introduced at that time. On-board processing of fish into fillet blocks became an established part of the processing industry. During the 1970’s, meat- bone separators or deboners were brought into the industry, which influenced the promotion of new mince-based products. Likewise, improvements of existing 1 Introduction technologies for surimi and fish analogues manufacture were accomplished. However, from the 1980’s into the 1990’s, no new major technologies have been introduced but only consolidation and anticipated development of current ones. The fish processing industry which once appeared to be entirely different from the rest of the food industry, is becoming more closely associated with it. The industry tends to be more perceptive of the necessity to satisfy consumers and to follow trends in buying and eating patterns. Since the consumer has turned out to be more demanding regarding the safety and quality of fishery products (together with the increased importance put on safety by regulatory authorities), stricter management systems for the quality assurance of fishery products have been introduced in the industry. In general, increased mechanization and automation is taking place in the industry, particularly in production, as a response to different developments such as high wage rates, the manufacture of value added and convenience products, the requirement for accelerated and systematic production processes, and the need for consistent quality (Howgate, 1995). 1.1 World Utilization World trends in the utilization of fish for human consumption are summarized in Table 1. The amount of catch marketed as fresh sharply increased from 1985 to 1993. The increase could be due to farmed fish which was mostly marketed fresh during the period. On the other hand, a gradual decrease in the quantity of frozen fish during these years can be noted. The decrease in the percentage of frozen fish could be due to the withdrawal of factory vessels and freezer trawlers from the former USSR and other East European fleets (Howgate, 1995). The amount of cured fish (salted, dried, or smoked) drastically declined from 17.1% in 1985 to 12.8% in 1993. Meanwhile, the quantity of fish processed in canneries also decreased from 19.1% in 1985 to 17.0% in 1993. The decline in both cases could be attributed to a shift in the fish consumption pattern of the population from cured/canned fish to fresh fish. 1.1.1 Southeast Asia Throughout the Southeast Asian region, traditional methods of fish processing such as drying, salting, fermentation and smoking are still being practiced. However, sophistication and modernization of the processing and preservation technology are gaining recognition in the region. New fisheries 2  Introduction Table 1. Disposition of the Catch, Live Weight Equivalents (1985-1993) 1985 1990 1993 Disposition t x 10-6 %* t x 10-6 %* t x 10-6 %* Marketed fresh 17.1 28.6 22.6 32.1 29.4 37.0 Freezing 21.0 35.2 24.2 34.6 23.9 33.2 Curing 10.2 17.1 10.4 15.2 8.3 12.8 Canning 11.4 19.1 12.6 18.1 11.7 17.0 Total for human consumption 59.7 100.0 69.8 100.0 73.4 100.0 For other purposes 26.6 27.6 28.0 Total world catch 86.3 97.4 101.4 *Of the catch used for human food consumption Adapted from Howgate (1995) products are being developed, and at the same time with increasing income, consumer preference is changing in favor of value-added products such as frozen fillet, fish balls and others. “Ready to heat and eat” fishery products are also becoming in demand. It is expected that the quality of processed fishery products will continue to improve and there will be little distinction between products for domestic and export market. Nevertheless, up to the present, the quality of fresh fish in most domestic markets in the region is far from satisfactory (Ahmad, 1995). Table 2 summarizes the production of selected fishery products in eight Southeast Asian countries. Among the countries, the Philippines produced large quantities of cured fish such as salted dried and smoked products being second only to Indonesia. Dried products are widely available and popular in many Southeast Asian countries; they are commonly described by most countries as salted dried product (Ng et al., 1991). A small quantity of the Philippine fish supply (whether fish or seafood) is converted into chilled or frozen products, compared to Thailand which produced the largest quantity of these products. The high quantity of chilled/ frozen products in Thailand and other countries could be due to better refrigeration facilities (freezing and storage) available in these countries. It has been reported that there is a poor economic performance of fishing ports and ice plants in the Philippines; many are closed and inoperable (FSP, 1996). Furthermore, the poor handling practices in many ports contribute to post-harvest waste and losses. 3 Introduction Table 2. Production of Selected Fishery Commodities in Asian Countries in 1992 (Quantity in Metric Tons) Fish Fish Crustaceans Crustaceans, Fish Fresh, Dried, Molluscs Molluscs, and Country Products Chilled or Salted and Fresh, Frozen, Product Preparation* Frozen Smoked Dried, Salted Preparation* Indonesia 194,200 417,520 129,105 55,800 7,060 Malaysia 2,000 7,600 3,800 15,300 4,030 Singapore 13,768 - 4,930 1,649 - Thailand 368,700 58,500 241,150 340,600 109,500 Cambodia - 3,179 81 4,176 - Myanmmar 22,600 62,800 8,100 114,000 - Philippines 9,776 248,867 7,340 74,025 123,082 Vietnam 20,122 9,506 - 154,684 33,795 *Whether or not in airtight container Adapted from Ahmad (1995) 1.1.2 Philippines The Philippines consists of more than 7,000 islands with a coastline of 17,460 km, a continental shelf area of 290,000 km2 and EEZ area (including territorial waters) of 2.5 million km2 (Fig. 1). In addition to marine waters, there are inland waters consisting of freshwater bodies (about 9,000 km2) and brackish water and swamplands (about 5,000 km2). The waters contain more than 2,000 species of fish, molluscs, crustaceans, echinoderms and other aquatic fauna and flora. Table 3. Fish Production (Metric Tons) by Sector, 1991-1995 Sector Year Aquaculture Municipal Commercial Total 1991 692,401 1,146,765 759,815 2,598,981 1992 736,381 1,084,360 804,866 2,625,607 1993 772,082 1,030,274 845,431 2,647,787 1994 791,444 1,009,738 885,446 2,686,628 1995 825,387 987,758 926,887 2,740,032 Adapted from BFAR (1994,1995, 1996) 4  Introduction Fig. 1. Philippine Map 5 Introduction In 1995, the total fish supply of the country was 2.74 million metric tons (Table 3). The municipal or small-scale fishing sector was the largest contributor, 988,000 metric tons, followed by the commercial sector, 927,000 metric tons (BFAR, 1996). The aquaculture sector contributed around 825,000 metric tons. Locally, the important marine fish species are the roundscad, sardines, skipjack tuna and other tuna species, and Indian mackerel. On the other hand, the major aquaculture products are the seaweeds, milkfish, shrimps/prawns and tilapia. In spite of the increase in production (from 2.60 million metric tons in 1991 to 2.74 million metric tons in 1995) the country still had to import 270,213 metric tons to supplement the local demand for fresh fish (Table 4). The main bulk of the imported fresh or frozen or chilled commodity consisted of small pelagics such as sardines and mackerel. These commodities were marketed as “wet” fish or used as raw materials for the canning industry. Table 4. Imports of Fish and Fishery Products, 1993-1995 (Metric Tons) Commodity Quantity 1993 1994 1995 Fresh, Frozen, Chilled 118,991 123,525 132,875 Meals and Feeds 87,595 112,895 127,466 Canned 1,049 2,601 2,466 Salted, Dried, Smoked and Others 27 65 22 Other Commodities 1,233 2,108 7,384 Total 208,895 241,194 270,213 Adapted from BFAR (1996) Imported small pelagics sold in the wet markets compete with domestic products during the lean fishing seasons and this has resulted in calls for protection to keep local producers’ prices high. In 1995, the main sources of sardines and mackerel were the USA and Taiwan. Large quantities of tuna were imported from 1993-1995 and this commodity came mainly from Papua New Guinea and other countries in the Pacific area. Tuna imports went principally to the canning industry. The annual per capita consumption of fish declined from 32.25 kg/year in 1989 to 28.04 kg/year in 1994 (Table 5). The average rate of decline of the per capita fish supply between 1989 and 1994 was -2.42% per year. This could be due to greater differences in the growth rate of the food fish supply and population (FSP, 1996). The food fish supply has not been able to keep up with population 6  Introduction growth since 1991. Another reason for the decline in the per capita consumption of fish could be the change in the consumer preference for fish substitutes such as chicken which became available at more competitive prices. Data on the disposition of catch in the country are disconcerted. Based on estimates, around 6% of the total production are exported as fresh, frozen, canned, dried and other processed products. On the contrary, more than 75% of the total local consumption is utilized as fresh fish followed by 12% as cured (Nambiar, 1991). Processing of fish in the country is still very traditional except for canning and freezing where significant developments have been taking place. Traditionally- prepared products are oftentimes characterized as of low and inconsistent quality due to the use of obsolete processing facilities and age-old processing practices. Salting, drying and smoking are done by various sectors usually operating in strategic places in the country where there is a guaranteed supply of raw materials. The processing level or size of operation ranges from small- to medium- level cottage industry. The industry takes up excess catch which cannot be sold as fresh fish during peak season. In many coastal areas, drying and fermentation are preferred to smoking. About 38% of the total catch are processed into dried fish products. There are approximately 660 drying plants in the country, but only over 400 are registered. In contrast to drying, there are only six regions out of 12 where smoking of fish is practiced (Nambiar, 1991). Limited capital and inadequate infrastructure facilities hamper the development and improvement of the industry. A significant development in drying is the use of artificial dryers in some localities in the country particularly in Cagayan and Palawan. Table 5. Trend in per Capita Fish Supply in the Philippines 1989-1994 Year Fish Supply Population Per Capita Annual Change (t x 10-6) x (10-6) Supply (kg/y) (%) 1989 1.94 60.097 32.25 4.06 1990 1.96 62.049 31.60 -2.01 1991 2.04 63.692 32.06 1.44 1992 2.02 65.339 31.00 -3.30 1993 2.03 66.982 30.35 -2.09 1994 1.95 68.624 28.48 -6.15 Adapted from FSP Report (1996) 7 Introduction The manufacture of fish sauce (patis) and fish paste (bagoong) is an important industry in several regions of the country. The peak of production occurs during the month of April and declines in October. By-catch market excesses like tiny shrimps of Acetes spp. and other species of low market value are absorbed by this industry, consequently reducing losses in resources. A remarkable development in the field is the adoption of fermentation techniques by some processors to shorten the duration of fermentation. Exposure of the covered containers to sunlight or burying of the containers partly in the ground, and the use of artificially produced enzymes such as pepsin have been practiced by some processors. In general, the local industry is beset with many problems which are either industrial, socio-economic, institutional or political in nature. Addressing the majority of these problems would require investment in the purchase of equipment and technology transfer. 1.2 Nutritive Value of Fish Fish provide a very good balance of nutrients. They can compare favorably with meat, eggs, chicken and other protein sources, in both quantity and quality of protein. Fish are presently regarded as a health food because their fish oils consist of fatty acids which are different from those found in other animal fats and vegetable oils. Fish oils contain a unique type of polyunsaturated fatty acids (PUFA), the so- called omega-3 type, which is not found in significant quantities in other common foods. The omega-3 fatty acids have been linked to the low incidence of coronary heart disease in people who consume considerable quantities of fish and fish oils. Most species of fish have a low-calorie, low-fat edge (fish is naturally light) compared with other protein-rich foods, including red meat, pork, and cheese. The lower calorie and fat qualities of fish do not only help keep the body weight down but also lower the chances of developing ailments associated with overweight, including hypertension, diabetes and certain types of cancer. Fish are good sources of vitamins A and B complex, and minerals such as iodine, fluoride, selenium, and zinc. Oysters and mussels have very high levels of iron, higher than red meats. 8  Introduction 1.2.1 Structure of Fish and Fish Muscles Fish refers to cold-blooded vertebrate animals living in water, breathing by means of gills and having limbs represented by fins or rudiments of fins. Fish are commonly divided into classes: Cephalaspidomorphi, jawless fish like lampreys and slime eels; Chondrichthyes, cartilaginous fish like sharks and rays; and Osteichthyes, lungfish and all other bony fish (Huss, 1988). This book will refer to bony fish as teleosts and cartilaginous fish as elasmobranchs. 1.2.1.1 Structure of Fish (Bony and Cartilaginous Fish) The structure of a typical bony (teleost) and a cartilaginous (elasmobranch) fish is shown in Fig.2. The main parts of a typical bony fish are: skeleton (consisting of the skull, backbone, rib cage and fin supports) muscle tissues with a small amount of connective tissues and fat, supported by the skeleton skin and fins (often scaly in finfish) viscera (consisting of the alimentary canal and associated organs and the urogenital system) 1.2.1.2 Structure of Fish Muscles The edible portion (amount of edible meat) of a bony fish is about 60% of its whole weight or depending on the anatomy of the animal and, within species, on biological variables such as size and condition. The quantity of recoverable meat will be less than the total amount of flesh and other possibly edible tissues, and will depend both on what is considered palatable and on the technology for recovering it (Howgate, 1995). The fish muscle consists of myotomes (muscular tissue) and lesser amounts of myocommata (connective tissue), and fat found mostly on the lateral portion of the body (Fig. 3). Myotomes These are the layers of muscle cells in fish which are arranged between sheets of connective tissue (myocommata). The unit structure of muscular tissues is the muscle cell. It is long and narrow; hence it is also called a fiber. It may attain a length of 3 cm but its diameter is only 10 to 100 micrometers. The length of the fibers as well as the thickness of the myocommata increases with age. The 9 Introduction Fig. 2. Parts of a Fish myocommata gelatinize when cooked making the myotomes appear in blocks. The myotomes are very conspicuous when raw fish meat is being shredded (Arroyo- Staub, 1982). In many fishes, about 90% of fish muscle is white (light or no pigment) while 10% is red (dark) because of its myoglobin pigment content. The dark muscle is generally situated about the midlateral line of fish. It is believed that the dark muscle essentially functions as a cruising muscle, i.e., for slow continuous motion, 10  Introduction Fig. 3. Structure of Fish Muscle (Source: Arroyo-Staub, 1982) while the light muscle is used as a sprinting muscle for abrupt movements needed for escaping from a predator or for catching prey (Huss, 1988). The chemical composition of the two muscle types differs in many ways. It is noted that there are higher levels of lipids, hemoglobin, glycogen and most vitamins in the dark muscle. The proportion of dark meat to light meat varies with the movement of the fish. Pelagic fish such as herring and mackerel which swim more or less continuously contain up to 48% dark muscle (Love, 1970) while demersal fish which feed on the bottom and only move occasionally have a small amount of dark meat. Fish which are classified as “white” fish are those with negligible amounts of red muscles. Myocommata These are made up of connective tissues which contain mostly the protein collagen. Collagen easily breaks up in hot water. This is the basis for the flaking 11 Introduction off of myotome blocks between the sheets of myocommata during cooking. Fish collagen which is not found as abundantly in fish muscle as compared to red meats of land animals shrinks at 450C while beef collagen at about 640C (Arroyo-Staub, 1982). This is the reason why fish softens faster than red meat during cooking. Bony fish contain about 3% collagen while cartilaginous fish contain about 16%. Collagen in fish is also present in the perimysium and endomysium. Perimysium envelops the muscle bundle while endomysium encloses the muscle cell or fiber (Arroyo-Staub, 1996). Connective tissue protein constitutes 17% of the total protein in mammals. 1.2.2 Composition of Fish The composition of a particular food such as fish is important for the food processor, the nutritionist and the consumer. The components of fish vary greatly from species to species, and also from individual to individual depending on age, sex, environment and season (Table 6). The variations in the chemical constituents of fish are closely associated to feed intake. Fish which feed heavily will at first have a very slight increase in protein then will show a marked and rapid increase in lipids. The greatest change in chemical composition is exhibited by the lipid fraction. Often the variation within a species will show a typical seasonal curve with a minimum about the time of the spawning (Huss, 1988). 1.2.2.1 Protein Proteins are composed of building blocks called amino acids. Most fish contain high quality protein ranging from 16-22%. Fish protein contains the essential amino acids needed for the building and repair of muscles, internal organs, skin, and hair. The essential amino acids such as lysine and methionine are lacking in cereal and root-crop based diets. Lack of protein in the diet lowers the body´s resistance to illness and hinders growth, which is particularly harmful to children. 1.2.2.2 Fat (Lipids) The fat in fish ranges from 0.2-25%, however, in tropical species the amount of fat rarely exceeds 5%. Variation in the proportion of fat is reflected in the percentage of water, since fat and water usually make up around 80% of the flesh. The amount of fat in fish is relatively small compared to pork, beef and chicken meats. Fish lipids differ from mammalian lipids mainly because fish lipids consist of long-chain fatty acids (14-22 carbon atoms) which are highly 12  Introduction Table 6. Proximate Composition of Some Philippine Aquatic Products Percentage Species E.P* Protein Fat Moisture Ash 1. Long-jawed anchovy (dilis) 100 14.1 1.4 79.8 2.8 2. Barramundi (apahap) 55 17.8 0.4 80.7 1.1 3. Threadfin bream (bisugo) 45 19.0 1.5 78.2 1.3 4. Common carp (karpa) 55 17.8 12.6 68.7 0.9 5. Fusilier (dalagang-bukid) 69 21.5 4.7 73.4 1.3 6. Spotted coral grouper (lapu-lapu) 49 14.9 0.4 83.6 1.1 7. Short-bodied mackerel (hasa-hasa) 52 21.6 2.4 74.5 1.5 8. Indian mackerel (alumahan) 62 21.4 2.8 74.6 1.2 9. Spanish mackerel (tanigi) 69 17.6 1.1 79.7 1.6 10. Milkfish (bangus) 65 19.8 6.4 72.8 1.1 11. Fringescale/fimbriated sardinella (tunsoy) 54 20.5 2.7 75.3 1.4 12. Indian sardine (tamban) 52 19.5 4.7 74.2 1.5 13.Shortfin/round scad (galunggong) 49 20.4 2.1 76.8 1.2 14. Red snapper (maya-maya) 44 15.6 0.2 83.2 1.0 15. Mossambique tilapia (tilapia) 46 18.1 3.8 77.2 1.2 16. Frigate tuna (tulingan) 62 24.0 2.6 72.5 1.2 17. Yellowfin tuna (tambakol) 67 23.7 1.4 74.4 2.3 18. Shrimp alamang (alamang) 100 16.6 1.3 78.9 3.2 19. Tiger prawn (sugpo) 63 20.0 0.9 76.6 1.3 20.Green mussel (tahong) 56 13.6 7.5 64.2 3.6 21. Slipper oyster (talaba) 12 5.9 1.7 85.5 1.7 22. Squid (pusit) 96 15.6 1.0 82.2 1.2 23. Octopus (pugita) 94 13.3 0.6 84.9 1.2 24. Blue swimmer crab (alimasag) 34 19.9 0.5 75.5 1.9 25. Mud crab (alimango) 42 18.5 3.2 76.5 1.8 *Edible portion Adapted from FNRI (1997) 13 Introduction unsaturated. The fat of mammals seldom contains more than two double bonds per fatty acid molecule while the depot fats of fish comprise of many fatty acids with five or six double bonds (Stansby and Hall, 1967). Fish fat is rich in high-grade polyunsaturated fatty acids, the so-called omega-3. Two of the seven omega-3 fatty acids, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are not found in beef, pork nor in any vegetables (Fletcher, 1989). Substantial amounts of DHA and EPA are found in the fat components of tuna, mackerel, mullets, and other aquatic products (Table 7). EPA and DHA can prevent heart disease by suppressing the formation of blood clots and can also prevent other diseases. DHA in particular has been reported to be important in the growth and development of the brain (Izumi, 1993; Suzuki, 1993). Fish oils have merits in terms of the effect on human health (Low and Ng, 1992): decrease blood circulatory diseases decrease serum total cholesterol levels increase high density lipoprotein cholesterol which is useful to human health In the Philippines, research on the omega-3 fatty acids has been going on at the Institute of Fisheries Technology, College of Fisheries, University of the Philippines in the Visayas. Omega-3 fatty acids from tuna processing waste (heads, entrails, etc.) are converted into capsules. The percentage yields of omega-3 fatty acids which are recovered from various tuna waste materials were likewise determined (Panggat, 1997; personal communication). 1.2.2.3 Vitamins The amount of vitamins present in fish varies widely from species to species and throughout the year. The red meat of fish is particularly rich in Vitamins A (retinol); B group: B1, (thiamine), B2 (riboflavin) and B12 (cyanocobalamin); and D3 (cholecalciferol). More retinol, thiamine and riboflavin are found in the skin than in the flesh. The guts, particularly the liver, are rich in vitamins A, D3 and Vitamin B3 (niacin). Molluscs and crustaceans are important sources of Vitamin B complex, mainly pyridoxine (Vitamin B6) and niacin (Izumi, 1993). Vitamin A prevents night blindness, promotes growth, and reduces susceptibility to infections, dry skin and dry hair; while the Vitamin B group prevents mental depression, convulsions, irritability, anemia, nerve damage, skin 14  Introduction Table 7. Fatty Acids (EPA, DHA and Cholesterol) Content of Aquatic Food. Aquatic Product Fatty Acid Cholesterol (Species) EPA (mg) DHA (mg) (mg) Barracuda 183* 632* 60* (Sphyraena barracuda) Frigate tuna 203* 520* 75* (Auxis thazard) Mullet 348* 553 49-65 (Mugilidae) Grouper/rockcod 8-41 48-240 37* (Serranidae) Skipjack tuna 78* 310* 49-65 (Katsuwonus pelamis) Snapper 13-42 81-263 37* (Lutjanus spp.) Spanish mackerel 480* 1189* 70-76 (Scomberomorus commerson) Carp 159* 288* 66* (Cyprinus carpio) Clams 21* 34-55 34-55 (Miscellaneous species) Sea urchin 712* 47* 290* (Hemicentrotus pulcherrimus) Octopus 42* 71* 90* (Octopus vulgaris) Crab 54* 42* 42-80 (Scylla serrata) Lobsters 102* 64* 95-350 (Panulirus spp.) Shrimps/prawns 57-589 36-372 152-190 (Miscellaneous species) *Only one value available so no range reported Adapted from Espejo-Hermes and Tumonde (1993) 15 Introduction rashes, tissue degeneration and weight loss. Vitamin D3, a vitamin peculiar to fish, assists in the metabolism of calcium. 1.2.2.4 Minerals Marine aquatic products such as fish, seaweeds, molluscs and crustaceans are the richest natural source of iodine, a mineral needed for proper thyroid function. Iodine has been recently found to play an important role in the mental (brain) development of human beings. Fish also provide respectable amounts of fluorides (protection against tooth cavities) and selenium, which is reported to play a role in preventing heart disease and possibly cancer. Fish are low in sodium and hence a good asset for health-conscious people and those requiring a low sodium diet (Fletcher, 1989). 1.2.2.5 Other Components Fish has a high water or moisture content which ranges from 66-81%. Taurine, a sulphonic amino-acid, is often a major component of nitrogenous extractives mainly from marine invertebrates. This substance is useful in decreasing the total cholesterol value in the blood, helps in the foetal development of the brain and assists in the development of the visual and olfactory bulbs (Izumi, 1993). The carbohydrates in fish are very low, amounting to less than 0.5%. 16 Fish Processing Technology in the Tropics J. Espejo-Hermes (2004) Chapter 2 Handling of Fresh (Wet) Aquatic Products Fish and other aquatic products are among the world’s most perishable commodities. Spoilage in aquatic products begins soon after death. Following the death of fish, the blood circulation stops which results in a series of changes within the muscle. The spoilage of fresh fish is a complicated process for which no single factor is responsible, but, rather, it is a combination of several interrelated processes (Wheaton and Lawson, 1985). These processes result in the breakdown of protein (followed by the formation of hypoxanthine, trimethylamine and other products), the gradual development of undesirable odors and flavors, the softening of the flesh, and the loss of cellular fluid containing fat and protein. 2.1 Spoilage of Fresh Aquatic Products Fresh fish spoilage is mainly bacterial in nature aided by enzymatic activity. Bacterial and enzymatic spoilage are largely temperature dependent; the higher the temperature the faster the rate of spoilage. The rate of spoilage varies from fish to fish and can be summarized as follows: fatty fish spoil faster than lean fish; small-sized fish spoil faster than large fish of the same species; cold-water fish spoil faster than warm-water fish; and round fish spoil faster than flat fish. 2.1.1 Bacteria Bacteria are microscopic one-celled organisms which are found in the environment. The flesh of fish is sterile (free from bacteria) when they are alive but large numbers of bacteria are normally present in the surface slime, on the gills, and in the guts (Ames et al., 1991). The bacterial flora of freshwater fish is significantly different from that of marine species. A big number of mesophilic gram-positive 17 Handling of Fresh (Wet) Aquatic Product bacteria such as Micrococcus, Bacillus and coryneforms are found in freshwater fish while psychrotrophic gram-negative genera such as Pseudomonas, Altero- monas, Moraxella, Acinetobacter, Flavobacterium, Cytophaga and Vibrio are predominant in marine fish (Shewan, 1977; Liston, 1980). Moreover, freshwater cultured species harbor more mesophiles than brackishwater cultured species (Gopakumar, 1990). Bacteria are normally not harmful to healthy living fish since the fish’s natural defense keeps them under control. But as soon as the fish dies, the bacteria and the enzymes they secrete begin to invade the flesh through the skin, through the lining of the body cavity or through any puncture in the body. Bacteria secrete enzymes which break down complex substances in the flesh into simpler substances resulting to spoilage. The rate of microbial spoilage depends upon the number of types of microorganisms present on the fish and the temperature at which the fish is being kept. Reproduction and growth rates of bacteria generally increase at temperatures above 4oC. Some bacteria remain active up to about 60oC (Wheaton and Lawson, 1985). Not all the bacteria present in the fish are responsible for the spoilage of fish. In chilled fish, the most active specific spoilage organisms (SSO) are gram-negative, psychrotrophic rods such as Alteromonas putrefaciens and certain Pseudomonas, Vibrio and Aeromonas (Shewan, 1977). Shewanella putrefaciens is a typical SSO for the aerobic chill spoilage of many fish from temperate waters (Huss, 1994). Bacterial spoilage does not start until the passage of rigor mortis. Rigor mortis is the progressive stiffening of muscle shortly after death. Rigor usually starts from the tail towards the head until the whole body becomes hard and stiff (inflexible). The fish remains rigid for a period ranging from an hour to three days or more depending on the species, size, catching method, handling of fish, temperature, and the physical condition of the fish. Any delay in rigor will therefore prolong the keeping time of the fish. 2.1.2 Enzymes Enzymes are protein substances present in the muscle and in the gut of fish that initiate or speed up chemical reactions. At the death of fish, the normal regulation system ceases to function and the supply of oxygen and energy production stops. The cells begin a new sequence of processes characterized by the breakdown of glycogen (glycolysis) and the degradation of energy-rich compounds (Huss, 1988). 18  Handling of Fresh (Wet) Aquatic Product The enzymes naturally present in the intestines and in the muscle, instead of acting on the food in the gut, begin to act on the gut tissue and the surrounding tissues. The self-breakdown or self-digestion (autolysis) results to the weakening, softening and discoloration of fish tissues. The rate of self-digestion is dependent upon temperature and can be retarded by keeping the fish at low temperature just above the freezing point. Enzymatic activity can be stopped by heating and can be controlled to a large degree by other methods (salting, drying, frying and marinating). 2.1.2.1 Muscle Enzymes and Their Activity The initial autolytic processes in the fish muscle tissue involve the carbohydrates and the nucleotides. For a short duration, the muscle cells proceed with the normal physiological processes but soon the manufacture of adenosine triphosphate (ATP) stops. Rigor mortis develops at low ATP levels. Generally, fish muscles have a relatively low amount of glycogen compared with mammalian muscle and the final post-mortem pH is therefore higher. This renders fish meat more open to microbial attack. Glycogen is degraded either by glycolysis or by direct amylolytic hydrolysis (Tarr, 1966). Since no oxygen is furnished, glycolysis in the post-mortem muscle tissue continues under anaerobic conditions resulting to lactic acid formation. The lactate formed reduces the pH. The post-mortem lowering of pH causes a decline in the water-binding capacity of the proteins since these are brought closer to their isoelectric point. The autolytic changes in the proteins are far less obvious than the changes in nucleotides. Evidence now indicates that lysosomal proteases (cathepsins), which are the main proteases present in fish muscle, play a minor role, in vivo, in starting myofibrillar protein turnover (Goll et al., 1989). 2.1.2.2 Digestive Enzymes and Their Activity Enzymes from the digestive tract play a significant part in the autolysis of whole, ungutted fish. During periods of heavy feeding, the abdomen of some species such as herring and mackerel is vulnerable to tissue degradation and may rupture within a few hours of capture. 2.1.3 Chemical Spoilage Spoilage of fish due to chemical changes mainly occurs during storage in ice or in frozen condition. The oxidative processes in the lipid fraction are purely chemical in nature. However, enzymatic (microbial or tissue enzymes) 19 Handling of Fresh (Wet) Aquatic Product degradation may also play a part. Chemical changes or rancidity of lipids may involve lipid auto-lysis (enzymatic hydrolysis with free fatty acids and glycerol as main products) and auto-oxidation (the reaction of unsaturated lipid with oxygen). Auto-oxidation is generally more prevalent in aquatic products due to their higher degree of unsaturation than in other foods. Oxidative rancidity in fish can result to serious quality problems such as rancid flavors and odors as well as discoloration. Aside from oxidative rancidity, other chemical changes may occur such as denaturation of proteins during frozen storage resulting to tough, dry and fibrous texture. Darkening of the red meat in fresh fish may also occur due to change of myoglobin from bright red to red-brown or dark brown in the cellular tissues. 2.2. Hygiene and Sanitation Hygiene means the science of good health and, in everyday use, it signifies cleanliness and freedom from the risk of infectious diseases (Ng and Low, 1992). Hygiene in foods and food processing indicates good quality as well as the absence of any food poisoning hazard. A hygienically prepared foodstuff should be attractive in appearance, odor and flavor, and should be presented in such a manner that the consumer has every confidence in his purchase. The major cause of spoilage of fish flesh is contamination with bacteria. If the flesh is contaminated with pathogenic (disease-causing) bacteria, it can cause illness or even death in the consuming public. Contamination can be kept to a minimum and the growth of any bacteria that are present is reduced, if fish are kept clean and held at low (chilled) temperature. 2.2.1 Cleanliness Cleanliness is needed at every stage of fish handling and preparation. The word “clean” means the absence of visible dirt or unwanted matter (Ng and Low, 1992), while “cleaning” is the removal of soil, food residues, dirt, grease or other objectionable matter (FAO/WHO, 1983). Cleaning alone, however, will not reduce the number of microbes; hence a further treatment called “sanitation or disinfection” is required. Sanitation is the process of reducing the number of living microorganisms (but not the spores) in the plant to a level judged safe by public health authorities (Ng and Low, 1992). Detergents and disinfectants or sanitizers are used in hygienic cleaning procedures. Detergents loosen and help remove dirt such as fish slime and blood, 20  Handling of Fresh (Wet) Aquatic Product while a sanitizer kills actively growing microbes. Ideal detergents would be characterized by: good wetting capacity ability to remove soil from surfaces power to emulsify capacity to hold material in suspension good rinsing property non-corrosive compatible with other materials quick and complete solubility dissolving action on food solids germicidal action complete water softening power non-toxic economical to use The efficiency of cleaning is affected by factors such as the cleaner, temperature, velocity of force and time. The cleaner must know how to clean, must have a good attitude towards his work and must be physically capable. Temperature has a very important effect during cleaning. Increasing the temperature will decrease the strength of bond between soil and surface, decrease viscosity, increase the solubility of soluble materials and increase chemical reaction rate. Velocity of force, on the other hand, is applicable in the case of “clean-in-place” conditions. The efficiency is, however, less affected by agitation as the physical- chemical potency of the detergent increases. Increasing the time of cleaning, with all other factors remaining constant, can enhance cleaning efficiency. Efficient sanitizers or disinfectants do not basically kill all microorganisms present but reduce their numbers to a level at which they can be reasonably presumed to present no danger to health. No disinfection procedure can exert its full effect unless thorough cleaning has been done before its application. Sanitizers should be selected according to target microorganisms, the type of food being processed and the material making up the food contact surfaces, and less risk to personnel. A good sanitizer or disinfectant must possess the following properties: effective germicide easy to dissolve in water low level of toxicity 21 Handling of Fresh (Wet) Aquatic Product stable in concentrated form does not significantly corrode metal or plastic effective at low concentrations unaffected by water conditions safe to health in both concentrated and diluted form deodorizes compatible with cleaning compounds of low persistence Sanitation or disinfection can be made by physical treatments such as heat, UV irradiation, or by means of chemical compounds. The chemical disinfectants commonly used in the food industry include chlorine and chlorine compounds, iodophors, quaternary ammonium compounds, ampholytic compounds, peracetic acid and hydrogen peroxide (FAO/WHO, 1983; Huss, 1994). All equipment, tools, floors and premises must be kept clean by using detergents and sanitizers. 2.2.2 Personal Hygiene A high degree of personal hygiene of the staff is required in the preparation/ processing of aquatic products. This can be accomplished by providing adequate washing facilities and other paraphernalia such as soap, towel, uniform and others in the fish plant. Good personal hygiene can be practiced through: bathing daily using appropriate deodorants washing hair at least weekly keeping nails clean and trimmed wearing clean uniforms and clean underclothing using a hair net or cap and paper masks over nose and mouth when on duty preparing for work in a systematic fashion so that the individual and his clothing are clean at the time he starts to work Washing of hands is most important in the prevention of contamination in food. Washing of hands must be done with plenty of soapy water to remove surface skin bacteria and other bacteria picked up while handling fish or equipment. Washing of hands must be done regularly after performing the following activities: coughing and sneezing visiting the toilet smoking 22  Handling of Fresh (Wet) Aquatic Product handling equipment and other items handling raw fish handling garbage or soiled materials handling money Adequate supply of clean (chlorinated) water must be available to clean fish, personnel, equipment and others. Cut fish are more susceptible to contamination than whole fish and must be processed, or packaged and chilled immediately. Fish, either whole or cut, must be shielded from direct sunlight, particularly in the tropics where the ambient temperatures are high. Handling of the fish with care must be observed at all times to prevent physical or mechanical damage (cuts, punctures, bruises etc.). 2.3 Ways of Preparing Fish The methods of preparing “wet” whole or round fish either for chilling, freezing or processing vary according to the specific requirements of the user. The following are the most common forms of preparing whole or round fish (fish which has not been gutted or the viscera removed) for most purposes (Fig. 4). Drawn Fish (Gutted). Fish that has been eviscerated or the entrails removed. Dressed Fish. Fish with scales, viscera, fins, head and tail removed. It is ready to cook or prepared particularly to improve presentation. Steaks. These pieces are cross-section slices of a large, dressed fish. A steak is usually 2-3 cm thick. Fillets. The meaty sides of the fish removed from the backbone and ribs of the fish. Fillets are practically boneless. Fillets can be block (butterfly or double), cross-cut fillet, quarter-cut fillet or single fillet. A “butterfly” fillet is formed by both sides of the fish, still joined by the uncut flesh and skin of the belly. Cross-cut fillets are fillets from flat fish (e.g., sole fish) taken from each side as a single piece, while quarter-cut fillets are the flesh from each side taken off in two pieces. A single fillet is just one side of the fish. Single, cross-cut and quarter fillets can be skinless. Sticks and Portions. Sticks and portions are small elongated chunks (rectangles) of uniform size and thickness cut from the meaty portion (fillet) of the fish. 23 Handling of Fresh (Wet) Aquatic Product Fig. 4. Ways of Preparing “Wet” Fish (Source: Espejo, 1980) 24  Handling of Fresh (Wet) Aquatic Product 2.4 Filleting of Fish Fast food restaurants, hotels and food catering houses require fish fillets for the preparation of convenience foods such as battered and breaded fish, fish fingers, burgers and others. The preparation of fillet requires great care and strict conditions of hygiene. The fillet once cut from the body of the fish will be very susceptible to bacterial action on its large exposed surface area. Fish which have been chilled and hence have just passed the rigor (stiffening) condition will be the suitable raw material for filleting. Good quality fillets can also be obtained from frozen thawed fish which have been frozen within two to three days of death (storage being near 0oC). In this case, the fillets produced will not suffer gaping, which is the tendency of fillets to split into fissures. The steps of filleting and skinning of fish (Rogers, 1975) are shown in Figs. 5 and 6. 2.5 Characteristics of Fresh and Spoiled Aquatic Products The freshness quality and the extent of spoilage of aquatic products after harvesting and prior to consumption is generally evaluated by using the human senses (sight, smell and touch). The typical characteristics of fresh and spoiled aquatic products (fish, clams and oysters, shrimps and lobsters, crabs, and squids) are listed in Table 8. 2.6 Handling of Fresh Aquatic Products All aquatic products must be handled with care right after harvest to avoid losses to damage and subsequently to spoilage. Shellfish such as crabs, mussels, clams, oysters and lobsters whenever possible should be alive until processing or cooking. 2.6.1 Fish Fish must be sorted according to species and size without delay and kept at low temperatures. The fish must not be handled frequently. Low temperature, cleanliness, speed, and care are the important factors in maintaining the quality of newly caught fish. This topic is discussed more comprehensively in the Chapters on chilling and quality assurance. 25 Handling of Fresh (Wet) Aquatic Product 1. Lay fish on side. Cut from just behind base of pectoral fin round the back of the head. 2. Cut towards tail along the line of the dorsal fin. The cut should only penetrate as far as the backbone. 3. Cut forward to clear fillet from the ribs. The knife should be held parallel to the rib bones. Cut through the “pin” (small rib) bones. 4. Cut over the edge of the ribs towards the tail, flatten knife onto the backbone after finishing cut- ting over the ribs and remove the fillet. The fillet should be trimmed to remove any belly flap or fin present. Fig. 5. Filleting Procedure 26  Handling of Fresh (Wet) Aquatic Product 5. Turn fish over. Cut just behind the base of pectoral fin and round the back of the head. 6. Cut from tail as close to backbone as possible into the corner at the back of the neck. Note the angle at which the head is held. This keeps the backbone flat on the board. 7. Cut forward parallel to angle of the rib bones, cutting through the “pin” bones and open cut fillet. 8. Cut from behind head over the end of ribs towards tail. The knife should be held at an angle to removeflesh from the center of fish without cutting off fins. On large fish, two cuts may be required if a short-bladed knife is used. Trim fillet to remove any belly flap or fin. 9. Two fillets and carcass. 27 Handling of Fresh (Wet) Aquatic Product right-hand side of the hinge and then cutting the muscle (Legaspi et al., 1990). Fig. 6. Skinning Fillets 2.6.2 Oysters and Mussels Oysters and mussels should be harvested with care. Farmed mussels possess thin shells and are easily damaged. They must be gathered in clusters to reduce water loss which could shorten their life after harvest. They must be kept damp at all times. The byssus gland which secretes sticky hairs should not be pulled out or the mussel will die within hours. Mussels can be chilled between 2-4oC using a blanket of melting ice (Shoemaker, 1991). Direct contact with ice must be avoided by using a layer of perforated material such as cheesecloth. Oysters, if carefully handled, can survive for one week out of water provided they are kept cool and humid. Holding tanks with recirculating seawater may be used for temporary storage. Live oysters and mussels must be immersed in clean flowing salt water for a number of hours before marketing for purification purposes. When shucking oysters, the shells should be thoroughly cleaned by brushing off the attached dirt before inserting the knife between the shells in the 28  Handling of Fresh (Wet) Aquatic Product Table 8. Sensory Characteristics of Fresh and Spoiled Aquatic Products Aquatic Product Fresh Spoiled 1. Fish Gills Odor - fresh, seaweedy; no - off odor (sour, sulphidy, or unpleasant smell ammoniacal, fecal) Color - bright red - yellowish, grayish or dull brown Eyes - clear, bright (cornea clear - blood shot, cloudy or black) completely white - bulging (convex. protruding) - completely sunken Body Color - normal bright, glossy and - faded or dull color shiny Flesh - firm and elastic; springs back - very soft; finger impression when pressed remains when pressed Scales - adhere strongly - loose 2. Clams and - shell firmly closed when - shell opened Oysters touched; when tapped produces a hard pebble-like sound - bright meat and shell full of - dried up and discolored meat; clear liquor no liquor - fresh, sweet odor - strong off odor (sour, sulphidy, ammoniacal) 3. Shrimps and - fresh, sweet odor; - off odor (sulphidy, Lobsters ammoniacal) - firm flesh and semi- - soft; presence of black spots transparent or blackening 4. Crabs - fresh, seaweedy odor - off odor (sulphidy, ammoniacal, sour) - bright color characteristics of - discolored and presence of the species blackening 5. Squids - fresh, sweet odor - off odor (sulphidy and/or ammoniacal) - creamy-white colored skin; no - discolored; dark spots or dark spots reddish or yellowish skin - transparent quill intact - transparent quill easy to remove 29 Handling of Fresh (Wet) Aquatic Product After shucking, the meat must be washed in cool running water to remove sand and mud, and then packed in containers with chilled water. The shucked oysters must be kept at low temperatures until processing. 2.6.3 Crabs Crabs must not be handled frequently after harvest because they are very delicate. Crabs can be held alive in seawater for a considerable length of time, such as in live wells when on vessels, in floating cages or onshore in tanks. Adequate water circulation or seawater exchange is necessary. For short term storage, crabs can be kept in clean moist bags or boxes but the humidity must be high. Removal of crabs from traps by holding the claws must be avoided to prevent the loss of claws. Crabs shed their claws when they sense their claws are caught. Exposure to high temperature will weaken the crabs. To prevent damage due to fighting during transport, the crabs must be packed closely in wet straw or shavings. 2.6.4 Shrimps Shrimps harvested from the wild and ponds should be cleaned thoroughly and protected from high temperatures. Chilling of shrimps with crushed ice must be done immediately. 2.6.5 Lobsters If possible, lobsters must be landed alive. If harvested alive, they should not be damaged or stressed. They should be protected from direct sunlight and kept moist at all times. They can be kept alive for about 24 hours as long as the humidity is high. Lobsters can be immobilized at temperatures as high as 14oC (Shoemaker, 1991). If dead, lobsters must be beheaded to prevent blackening, and the tails must be washed thoroughly in clean seawater and chilled using crushed ice. 2.6.6 Squids and Cuttlefish Squids and cuttlefish must be cleaned well and stored at low temperatures. Chilling in crushed ice or ice slurry will maintain the freshness of these aquatic products. 2.6.7 Seaweeds Seaweeds that are harvested fresh for local consumption should be washed in clean seawater then packed properly in baskets with banana leaves as covering. 30 Fish Processing Technology in the Tropics J. Espejo-Hermes (2004) Chapter 3 Chilling Fish alone among the major food commodities is subject to virtually no control before harvesting or catching. Since fish is highly perishable, proper handling must start from the moment it is harvested until it reaches the consumer’s table. The fisher, the middleman (wholesaler and retailer) and the consumer all have important roles in keeping fish as fresh as possible. Lowering the temperature (chilling, refrigeration and freezing) is the key factor in maintaining the quality of fresh fish. Chilling is the most common practice in keeping the freshness of fish. Chilling means the reduction of temperature to some point below (-1.1 to -2.2oC) or above (0oC) the freezing point of the fish muscle. Chilling does not stop spoilage but slows it down considerably. 3.1 Methods of Chilling There are several ways of chilling fish, but only the few methods which are relevant in the fishing industry will be discussed here. 3.1.1 Wet Ice (Icing) Icing is by far the most common and useful way of chilling the fish catch. Cooling is effected by the direct contact between the melted ice and the fish. When ice is placed in close contact with the fish, heat is transferred from the warm fish to the ice resulting to the melting of ice; in turn the fish is cooled down by the melted ice. The following considerations must be taken when icing fish:  Sufficient ice must be used to maintain fish temperature at 0oC. For longer trips more ice than fish is needed, more than the usual 1:1 ice: fish ratio. 31 Chilling  The arrangement of ice and fish must be in such a way that accumulated water, blood and slime can be drained easily.  Ice and fish should be placed alternately to avoid localized heating. Fish must be sufficiently surrounded with ice on the sides, top and bottom.  When packing mixed fish, big fish must be placed at the bottom and small fish on top. Fish with delicate skin should be packed on top of fish with scales.  Gutted fish must be filled up with ice in the belly cavity and must be arranged with belly down in a slanting position inside the container. The length of time that iced fish remain in good condition has been investigated extensively. Table 9 summarizes the maximum storage time of chilled aquatic species from warm-water regions. 3.1.2 Chilled Seawater (CSW) or Ice Slurry This is also termed as “slush ice” which is a mixture of seawater and crushed ice used for the chilling of fish catch (Hansen, 1981; 1995). The amount of ice depends on the initial temperature of the water and the fish, the size of the container and the quality of its insulation, and the length of the trip. The advantages of CSW over icing are:  CSW chills fish much faster than wet ice.  Fish in CSW do not suffer from physical damage due to crushing or pressure from other fish.  Fish in CSW are washed in the slurry. In spite of the advantages mentioned above, CSW chilled fish do not necessarily keep longer than wet iced fish. 3.1.3 Other Methods There are other ways of chilling fish such as: Refrigerated Air Air chilling is commonly employed in big commercial boats. Chilled air is circulated by a finned evaporator and fan situated at one end of the fish room. These units are often referred to as air blowers (Merritt, 1969). Fish are packed in 32  Chilling Table 9. Storage Time in Ice (0oC) of Aquatic Species from Tropical Countries Country of Storage Time Aquatic Products (Species) Origin (days) Oil sardine (Sardinella longiceps) India 5-6 Goldstripe sardinella (Sardinella gibbosa) Indonesia 10 Spotted sardinella (Amblygaster sirm) Indonesia 12 Shortfin/round scad (Decapterus macrosoma) Indonesia 10 Indian mackerel (Rastrelliger kanagurta) Indonesia 9-10 Indian mackerel (Rastrelliger kanagurta) India 6 Faughn’s mackerel (Rastrelliger faughni) Philippines 14-15 Threadfin bream (Nemipterus japonicus) India 27 Chinese pomfret (Pampus chinensis) Singapore 16 White pomfret (Pampus argenteus) Singapore 12 Black pomfret (Parastromateus niger) India 7-9 Mullet (Liza subviridis) Philippines 29 Mullet (Valamugil seheli) Philippines 21-22 Mullet (Liza corsula) India 8 Grouper (Epinephelus bleekeri) Singapore 24 Grouper (Epinephelus tauvina) Singapore 28 Sea bass (Lates calcarifer) Singapore 14 Mangrove snapper (Lutjanus argentimaculatus) Singapore 20 Golden snapper (Lutjanus johnii) Singapore 14 Milkfish (Chanos chanos) India 14 Carps (all species) India 18 Catfish (Wallagu atu) India 16-21 Tilapia (Oreochromis niloticus) Philippines 21-27 Tilapia (Oreochromis mossambicus) India 12-13 Tiger prawn (Penaeus monodon) Philippines 17 Squid (Loligo edulis) Philippines 19 Crab (Scylla serrata) India 11 Crab (Portunus pelagicus) India 8 Mussel (Perna viridis) India 8 Black Clam (Villorita cyprinoidis) India 9 Source: Barile et al. (1985); Sumner and Orejana (1985); Reilly et al. (1985); Calanoga (1986); Saluan-Abduhasan (1990); Gopakumar (1990); Low and Ng, 1992 and Reilly et al. (1994) 33 Chilling containers and stacked in the fish hold. This method of chilling is much slower than that of icing and chilled sea water (CSW). The cooling time generally exceeds 24 hours which reflects the slow heat transfer between the chilled air and the stacked cases of fish. Dry Ice Dry ice is solid carbon dioxide. Cooling is effected by the evaporation of the dry ice. Due to its very low temperature (-78.9 oC), dry ice should not be used in direct contact with fish to avoid cold burns (Shoemaker, 1991). This method of chilling is preferred for air shipment of fish as this does not cause leakage. However, the use of dry ice is subject to restrictions because it expands from a solid form into a gas and it may expel oxygen, posing a hazard to the safety of airplanes. Gel Ice Mat Gel ice is made by freezing a water-based gel. The advantage of gel ice is that all water is bound with no chance of water leakage during thawing. Gel mat chilling is suitable for air transport of fish. 3.2 Types of Ice (Fig. 7) The water used for the manufacture of ice must be fit for drinking. Depending on the temperature and length of storage, appreciable numbers of bacteria can build up in the ice. Used ice will be heavily contaminated with spoilage bacteria and must be discarded (Clucas and Johnson, 1990). Spoilage of the fish will be more rapid when old or dirty ice is used. The most common types of ice used in fisheries are the following: 3.2.1 Block Ice Block ice is made by freezing water in forms (cans or moulds) of the desired size. The size of the block produced can vary depending on the requirement. Ice blocks are rarely used directly for cooling fish because of their size and weight. They must be crushed into smaller pieces. Block ice melts slowly but is easy to transport in insulated containers to the villages (Espejo-Hermes, 1993). 34  Chilling 3.2.2 Crushed Ice Crushed ice usually comes from blocks or slabs broken down through mechanical crushers or manually. Crushed ice is irregular in size with sharp edges, which can cause physical damage to the flesh of the fish. 3.2.3 Flake Ice or “Scale” Flake ice is commonly produced from fresh water as thin flakes, formed instantly on cold metallic surfaces such as the inside of a fixed, vertical cylinder. The cylinder wall is kept below -20oC by constant refrigeration. The ice formed is removed from cylinder by “sudden” heating and is collected by a rotary scraper as firm and dry flakes. The flakes fall directly into a storage bin, which is maintained about -6oC (Hansen, 1995; von Rohr, 1995). Flake ice has the advantage of small particles which give good ice-fish contact because of a large surface area. The disadvantages of flake ice are:  It is denser than crushed ice so more flake ice has to be used to achieve the same cooling as crushed ice.  It tends to clump and it melts very rapidly making it less practical for longer transport. 3.2.4 Tube Ice Tube ice is made by freezing water on the inside surface of a tube. Tube ice lasts longer and melts more evenly than other shaped ice and is useful for transporting fish in uninsulated containers. The bulk density is midway between Fig. 7. Types of Ice 35 Chilling that of flake ice and crushed ice; however, due to its cylindrical shape, it is not practical for icing. It can also bruise the fish because of its relatively large size. 3.3 Methods of Storing Iced Fish Bulking, shelfing and boxing are used to store fish with ice (Fig. 8). The choice of storage method will depend on the facilities available and the quantity of the catch. 3.3.1 Bulking In bulking, the ice and the fish are layered to achieve intimate contact, which will ensure the maximum storage life in ice. This method of storing fish is usually utilized in the hold of fishing boats to economize on space (Waterman, 1981). Bulking has disadvantages when a very large volume of fish needs to be stored.  Fish can be physically damaged through the pressure of fish above and the pressure of ice. Fig. 8. Methods of Storing Iced Fish 36  Chilling  Bulked fish are in general of poorer quality than shelved or boxed fish after the same storage time.  The unloading of the catch is difficult which could result to rough handling. 3.3.2 Shelfing Shelfing is applicable to larger species, which are gutted. In this method, the fish is stored in single layers, gut cavity down on a bed of ice; sometimes a little ice is spread on top. This is designed to ensure bleeding through the cut surface of the fish to retard spoilage by chilling. Shelved fish, if well iced on top, are of better or at least of equal quality to bulked fish. The fish can be separated easily into different catches. 3.3.3 Boxing Boxing is the preferred method of storing fish in ice. Fish and ice are layered in specially made boxes. The boxes can easily be moved for transport to market or permanently fixed on board the fishing vessel. Several advantages of boxing:  The segregation of first-caught fish from last-caught fish, small from large, one species from another can be easily achieved.  Handling is kept to a minimum and, with a good boxing practice, fish will not be damaged physically. A disadvantage of boxing in some cases is that the space occupied in storing fish is greater than that for bulking. 3.4 Types of Containers The choice of containers for keeping fish will greatly determine the end quality of the iced product. In the selection of a fish container, the following should be taken into consideration:  insulating properties  proper shape and dimensions for the fishery product concerned  easy to handle, fill and empty  easy to clean and stack securely one on top of the other  constructed from non-poisonous materials  adequate provision for drainage of melt-water 37 Chilling 3.4.1 Plastic Box Plastic is the term used to describe a wide range of materials such as polyethylene (PE) and polypropylene (PP). Plastics are composed of very large molecules (chains or lattices called polymers). Polymers are made up of links or building blocks of distinct molecular structure called monomers. High density polyethylene (HDPE) and polypropylene are widely used in the manufacture of modern day containers (Subasinghe, 1993a). Many containers are made of injection moulded HDPE which resist impact, moisture and chemicals. 3.4.1.1 Polyethylene Polyethylene (PE) is made by subjecting gaseous ethylene monomer to heat and pressure in the presence of a metallic catalyst. PE is classified into low density (0.910 to 0.925 g/cm3), medium density (0.926 to 0.940 g/cm3) and high density. High density polyethylene is divided into type III (density 0.941 to 0.959 g/cm3) and type IV which has a density of 0.960 g/cm3 and above (Wheaton and Lawson, 1985). In general, polyethylene has excellent toughness; it is resistant to chemicals, oil and grease; inert to food; and has extremely low water vapor transmission properties. High density or rigid polyethylene (HDPE) containers have proven to be very useful in the chilling of fish. They are expensive but will last long. Furthermore, these containers can withstand extreme heat or cold and are easy to clean because of their smooth and non-absorbent surface (Fig.9). They are usually built with proper drains. The container can very well retain coldness inside. Fig. 9. Polyethylene Containers 38  Chilling 3.4.1.2 Polypropylene (PP) Polypropylene is a homo-polymer of propylene. It has a low density (around 0.902 g/cm3) and superior processability. It is one of the lightest plastics, has a good resistance to grease and most chemicals, provides a good barrier to water vapor and can withstand high temperatures due to its high softening point (Murray and Gibson, 1971). Polypropylene is more rigid, stronger and lighter than polyethylene. 3.4.1.3 Polystyrene (Styrophore) Polystyrene monomer is polymerized into high molecular weight poly- styrene through a free radical mechanism. Styrene chemically resembles ethylene, except it has a benzene ring attached. Polystyrene resin normally has a density of 1.0 to 1.1 g/cm3. Chemically, polystyrenes are resistant to weak acids and bases, vegetable oils and others. Compounds containing aromatic or chlorinated hydro- carbons attack polystyrene. Polystyrenes are very pervious to water vapor, oxygen and carbon dioxide. Water absorption by polystyrenes is exceptionally low, usually 0.04 to 0.05%. Expanded polystyrene is produced by the addition of a blowing agent and usually a nucleating agent into the resin. When heated, the blowing agent, a low boiling point material such as n-pentane or isopentane, evaporates forming gas pockets in the resin. Nucleating agents assist in controlling the bubble size and consequently the cell size in the foam (Wheaton and Lawson, 1985). Expanded polystyrene is widely adopted due to its distinct properties relative to its density, thickness, cell type and other variables. In general, expanded polystyrene is extremely resistant to bacteria and mold growth, has a very low water absorption, is quite inert, lightweight and nonabrasive, possesses superior cushioning properties and has a low thermal conductivity. During road transport, the weight saving allows either a 10% decrease in load or a 10% increase in fish load on the same van. The lower thermal conductivity prolongs ice life and may eliminate the need for re-icing. Polystyrene boxes are becoming popular locally for transporting fish from the landing place to the market or fish plant. However, the boxes are difficult to clean, do not last long and do not have drainage for melt-water (Fig.10). Further- more, they are difficult to move because they lack hand-grip. The boxes must have additional wooden frames to make them durable and in order to make handling of the containers easier. The containers are difficult to clean especially if the pores are damaged. Dirt is easily accumulated in the damaged pores. 39 Chilling Fig. 10. Polystyrene Containers A modified polystyrene fish container using moulded plastic around it has been produced locally and showed 10-15% better insulating properties than the ordinary polystyrene box (Villadsen et al., 1986). 3.4.2 Galvanized Iron (GI) Sheet Tubs (Bañera) Tubs made from GI sheets (bañera) are conical in shape and so far the most commonly used container by fishers in the Philippines (Fig. 11). These tubs are not provided