Food Production and Preservation for Food Security in Nigeria PDF

MODULE EIGHT FOOD PRODUCTION AND PRESERVATION FOR FOOD SECURITY: THE PLACE OF COOPERATIVES IN NIGERIA 1Omotesho, A.O., 2Joseph, J.K., 1Muhammad-Lawal, A. and 2Kayode, R.M.O. 1Departmentof Agricultural Economics and Farm Management, , University of Il...

MODULE EIGHT FOOD PRODUCTION AND PRESERVATION FOR FOOD SECURITY: THE PLACE OF COOPERATIVES IN NIGERIA 1Omotesho, A.O., 2Joseph, J.K., 1Muhammad-Lawal, A. and 2Kayode, R.M.O. 1Departmentof Agricultural Economics and Farm Management, , University of Ilorin, Ilorin, Nigeria 2Department of Home Economics and Food Science, University of Ilorin, Ilorin, Nigeria Introduction Food is necessary for health, growth and normal functions of living organisms. It is the material that enables man to grow and reproduce himself (Lapedes, 1977). Essentially food is a mixture of chemicals which could be separated into different components having different functions in the body. One of the greatest world major problems today is how to eliminate hunger and food insecurity. This challenge is greatest in the developing countries where people starve for lack of adequate food and nourishment. Learning Outcomes By the end of this module, you should be able to: i. Analyze food and explain the meaning of food security and insecurity. ii. Discuss food access, food utilization and the effects of food insecurity on livelihoods. iii. Highlight five of the constraints militating against adequate supply of high-quality food to consumers. iv. Enunciate the principles and applications of different methods of food preservation. v. Clearly explain the solutions to food insecurity. vi. Itemize the role of cooperatives in mobilising resource-poor, small-scale farmers in agricultural production for a sustainable food security i. Discuss the role of cooperatives in mobilising resource-poor, small-scale farmers in agricultural Production and food security. Main Body Introduction This module highlights the importance of food security, the constraints militating against getting enough high-quality food to the consumers, and methods of food preservation. Besides, the chapter looks at the role of cooperatives in mobilising resource-poor, small-scale farmers in agricultural production and food security. This module is divided into six units as follows: Unit 1 Issues of Food Security Unit 2 Food Preservation Unit 3 Cooperatives in Nigeria Unit 1: Contents 1.0 Introduction 2.0 Learning Outcomes 3.0 Main Contents 3.1 Issues of Food Security 3. 2 Solutions to Food Insecurity 4.0 Summary 5.0 Self-Assessment Questions 6.0 Tutor Marked Assessment 7.0 Further Reading 1.0 Introduction The unit discusses the issues of food security and enunciates the solutions to food security. 2.0 Learning Outcomes By the end of this unit, you should be able to: i. Highlight 5 importance of food security ii. Discuss the constraints militating against getting enough high-quality food to the Consumers 3.0 Main Content 3.1 Issues of Food Security Food security has been described as an important aspect in any consideration of wealth and economic sustainability of a nation. It is generally defined as a situation that exists when all people, at all times, have physical, social and economic access to sufficient, safe and nutritious food that meets their dietary needs and food preferences for an active and healthy life (FAO, 2002). Important aspects to be considered in food security issues include the availability of foodstuff, the quality of the diet, the stability of supplies over time and space, and access to food produced (Honfoga & van den Boom, 2003). It is recommended that an individual should consume between 65-86g crude protein per day out of which 35g (40%) must be from animal products. Although there is variation in the estimate of the food insecure people all over the world, available statistics show that a large proportion of the world population have the problem of food insecurity. It was observed that more than eight hundred million people were food insecure (Wiebe, 2003; FAO, 2005). According to a World Food Program estimate, hunger affects one out of seven people on the planet. Food insecurity is a particularly serious issue in many low-income countries. For instance, sub- Saharan Africa and South Asia stand out as the two developing-country regions where the prevalence of human malnutrition remains high. The largest absolute numbers of undernourished people are in Asia, while the largest proportion of the population that is undernourished is in Africa, south of the Sahara. In terms of proportionality, this was estimated at 34 percent in Africa and 23 percent in South Asia. (FAO, 1998). Though nutrition insecurity is generally being reduced worldwide, the problem is actually growing worse in Africa. This is due to increasing population growth and poor progress in efforts directed at reducing food insecurity in many countries on the continent (Benson, 2004). With an estimate of sixty thousand people majority of whom are children dying each day of hunger, food insecurity is considered a common phenomenon in Africa. The majority of the deaths related to food insecurity are reported to occur in sub-Saharan Africa. In virtually all rural sub-Saharan Africa, fluctuation in food security has become a fact of life that majority of the people have to contend with (Milich, 1997). In sub-Saharan Africa, the total number of hungry people increases each year. Given that food deficits are projected to rise, the problem probably will only get worse (Trueblood & Shapouri, 2002; Paarlberg, 2002). In view of its global dimension, the international community has placed the elimination of famine and hunger on its agenda. The participants at the food summit organised by the Food and Agriculture Organization (FAO) in 1996 pledged to reduce the number of hungry people by half by the year 2015 (World Food Summit WFS, 1996b; FAO, 2005; Meade & Rosen, 2002). Thereafter, the United Nations Rio+20 summit in Brazil in 2012 committed governments to create a set of Sustainable Development Goals (SDGs) that would be integrated into the follow-up to the Millennium Development Goals (MDGs) after their 2015 deadline. Consequently, sustainable food security was adopted as the second goal of the Sustainable Development Goal agenda. This aims at ending hunger and achieving long-term food security including better nutrition through sustainable systems of production, distribution and consumption by the year 2030. Food insecurity and hunger are forerunners to nutritional, health, human and economic development problems. They connote deprivation of basic necessities of life. As such, food security has been considered as a universal indicator of households‟ and individuals‟ personal well-being. The consequences of hunger and malnutrition are adversely affecting the livelihood and well-being of a massive number of people and inhibiting the development of many poor countries (Gebremedhin, 2000). Malnutrition affects one out of every three preschool-age children living in developing countries. This disturbing, yet preventable state of affairs causes untold suffering and presents a major obstacle to the development process. It is associated with more than half of all child deaths worldwide. It is, therefore, the bane of a major waste of resources and loss of productivity which are common occurrences in developing countries. This is because children who are malnourished are less physically and intellectually productive as adults. As such, malnutrition is a violation of the child’s human rights (Smith et. al., 2003). More than 800 million people have too little to eat to meet their daily energy needs. Most of the world’s hungry people live in rural areas and depend on the consumption and sale of natural products for both their income and food. It tends to be concentrated among the landless or among farmers whose plots are too small to provide for their needs. For young children, lack of food can be perilous since it retards their physical and mental development and threatens their very survival. Over 150 million children under five years of age in the developing world are underweight. In sub-Saharan Africa, the number of underweight children increased from 29 million to 37 million between 1990 and 2003 (United Nations, 2005). Furthermore, food insecurity has been identified as the principal cause of increasing and accelerated migration from rural to urban areas in developing countries. Unless this problem is addressed in an appropriate and timely fashion, the political, economic and social stability of many countries and regions may well be seriously affected, perhaps even compromising world peace (FAO, 1996). This is because hunger can provide a fertile ground for conflict, especially when combined with factors such as poverty and difficulty in coping with disasters (United Nations, 2005). 3. 2 Solutions to Food Insecurity The concept of food problem is complex and goes beyond the simplistic idea of a country’s inability to feed its population. Though the issue of serious food and nutrition problem is associated with less developed countries, the main dimensions of the problems in individual countries have however not been subjected to serious analysis. This has encouraged misleading generalisations about the causes, effects and remedies for the problem (Ojo, 1991). The fight against hunger, therefore, demands an integrated set of actions which simultaneously addresses the causes of food insecurity (Committee on World Food Security CFS, 2005). The root problem of inadequate access to food is poverty. This is in the sense of the failure of the economic system to generate sufficient income and distribute it broadly enough to meet households' basic needs. The problem can be addressed by either giving food directly to the poor (non-market distribution of aid); increasing their incomes so that they have greater entitlement to food through the market (given existing marketing costs); and/or reducing the costs of food delivered through markets by fostering technical and institutional innovations in farm-level production and the marketing system (Jayne et.al., 1994). The 1996 World Food Summit reaffirmed that a peaceful, stable and enabling political, social and economic environment is the essential foundation which will enable States to give adequate priority to food security and poverty eradication. Democracy, promotion and protection of all human rights and fundamental freedoms, including the right to development and the full and equal participation of men and women are essential for achieving sustainable food security for all (FAO, 1996). Attaining food security is, therefore, a primary responsibility which rests with individual governments. Access to the components of nutrition security, over and above those required for food security, is also a challenge that must be addressed. Investments in education, sanitation, and access to health care must continue and be increased if the advances required in nutrition security are to be made. Ultimately, the responsibility of ensuring food security for all lies with national governments who have the duty of establishing the conditions and institutions necessary to enable their citizens to have access to the basic requirements of food and nutrition security. The basic determinants of food and nutrition security in any one African country will never be exactly the same as those of another. This is because of the different historical factors, agro-ecological conditions, economic comparative advantages and institutional structures at play in each of the countries. As such, a single detailed policy and action prescription will not enable national governments in different countries to effectively address malnutrition. It must, however, be recognised that all African countries can attain nutrition security if sufficient commitment exists. Political will must be applied and dedicated efforts made to marshal the human, institutional, and material resources necessary for the task (Benson, 2004). For there to be an improvement in food and nutrition security situation of a country, national governments must address a number of issues including the following: i. Enhancing the means to acquire food, whether through cash incomes or access to productive resources. Considering the importance of agriculture as a source of income to rural households, there is a need for improvement in their agricultural production. The effectiveness of on-farm production determines the level of access to food enjoyed by both farmers and the broader population to whom they are linked through the market. Increased food supplies simultaneously increase the income of farming households and reduce the prices people pay for food in the marketplace, both of which enhance nutrition security. Moreover, increases in the production of both food and non-food crops contribute to the broader economy, both in rural areas and in urban manufacturing centres. ii. Improved education for the chain of food handlers, especially, from the producers to the consumers. This is because the knowledge of why and how food spoilage occurs and the agents responsible for spoilage becomes imperative to enable steps to be taken to prevent or minimise it if we must have fresh and wholesome foods that are safe and nutritious for human consumption at all times (Muhammad and Kayode, 2014). The knowledge of food spoilage and preservation is critical in the food chain to achieve nutritional security and enhanced food productivity for economic growth. Furthermore, training will ensure that people can provide themselves and their dependents with nutritionally balanced and hygienically prepared food. iii. Provision of access to sufficient quantities of food items. This may require formulation of policy for sustained, broad-based, economic growth. It is estimated that to end hunger in Sub-Saharan Africa by 2050, a 3.5 percent annual average growth rate in per capita Gross Domestic Product (GDP) is necessary for the region. iv. Direct nutrition interventions to provide food to those suffering from acute hunger and malnutrition and nutrition information and supplements to women of childbearing age and young children are necessary. Such interventions are a vital component of any effort to build the quality of human capital, encourage economic growth, and improve standards of living. v. Provision of clean water, adequate sanitation and effective health services. This is very important for the individuals to benefit from the food consumed. Poor health situation of the individuals may prevent them from having nutrition security. vi. Efforts must be made to open national markets to international trade, both within Africa and globally, as national food availability should not depend upon national food production alone. The nutritional security of the population of a country is enhanced by the degree to which it invests in building the institutional and legal frameworks and physical infrastructure needed to facilitate open, reciprocal and free trade. vii. The issue of gender equity must be addressed, as a close link exists between improved child nutrition and the extent to which women participate in making economic decisions within their households. Greater social equity enhances women’s access to resources thereby increasing the diversity and quantity of food they can provide and improve the level and quality of the care they can give to their dependents. viii. Locally conceived and implemented action has been shown to be the most effective way to improve food and nutrition security. National governments should give broad direction to local efforts and facilitate the success of such efforts through resource allocation, institutional support, and the provision of necessary expertise. ix. Central governments should ensure that budgetary allocations reflect the central importance that food and nutrition security have for the welfare of all people, as well as the immense economic benefits they provide for relatively little cost. In this regard, donor funding should be viewed as a secondary resource and used to complement the resources allocated by governments. x. Dedicated advocacy should be used to inform policymakers at all levels of the critical role that improved nutrition plays in development and poverty alleviation. Without this, it is unlikely the malnourished will receive any attention in any planning and resource allocation decisions made in the democratic, decentralised, bottom-up political systems emerging across Africa. The need to improve food and nutrition security must be communicated effectively and understood widely; its significance for the welfare of all members of society must be recognised. Ultimately, advocacy must build the political will needed to ensure that resources are provided to help individuals and households attain food and nutrition security. 4.0 Summary The unit discuss issues of food security, solution to food insecurity and ten (10) issues to be addressed by National Government for there to be an improvement in food and nutrition security situation of a country. Self-Assessment Questions (SAQs) i. Highlight 5 importance of food security ii. Discuss the constraints militating against getting enough high-quality food to the  Consumers 6.0 Tutor Marked Assessment i. What is food? ii. List the six constituents of food iii. List with examples the two classifications of food based on chemical constituents iv. Explain the following terms: food security, food insecurity v. what are the importance of food and the effects of food insecurity on livelihoods? 7.0 Further Reading Africa Conference Brief 1 IFPRI Bretch, P.E. (1980), “Use of Controlled Atmosphere to Retard Deterioration of Produce”, Food Tech, 314:145-149 Buckland, L. and J. Badejo, F.M. (1999). Introduction to Food Science and Technology. Kitams Academic and Industrial Publishers. ISBN 978-34805-3-7. Benson, T. (2004), Assessing Africa’s Food and Nutrition Security Situation 2020 Committee on World Food Security (CFS), Rome, 23 – 26 May 2005. Committee on World Food Security (2005). Report of the 31st Session of the Committee on World Food Security, Rome 23 – 26 May. Diouf, J. (2005), “Towards the World Food Summit and Millennium Development Goal Targets: Food Comes First” Foreword, The State of Food Insecurity in the World 2005, FAO. FAO (1996), World Food Summit, Corporate Document Repository. FAO (1998) “Urgent Action Needed to Combat Hunger as Number of Undernourished in the World Increases” available online @ www.fao.org. Retrieved on 15th December 2005. FAO. 2002. The State of Food Insecurity in the World 2001. Rome. FAO (2005), “FAO Warns World Cannot Afford Hunger”. Frandson, R.D. (1972), Anatomy and Physiology of Farm Animals 2nd edition. Gebremedhin, T. G. (2000), “Problems and Prospects of the World Food Situation” Journal of Agribusiness 18, 2 (Spring 2000): 221- 236. Unit 2 Food Preservation Contents 1.0 Introduction 2.0 Intended Learning Outcomes (Objectives) 3.0 Main Contents 3.1 Food Preservation 4.0 Summary 5.0 Self-Assessment Questions 6.0 Tutor Marked Assessment 7.0 Further Reading 1.0 Introduction Food spoilage is discuss as a major problem facing farmers in Nigeria because of what it does to quality and quantity of food, the unit then dwell into different methods of food preservation. 2.0 Learning Outcomes At the end of this unit, you should be able to: i. Define food spoilage ii. List 5 factors that can cause food spoilage iii. Enunciate the principles and applications of different methods of food preservation. 3.0 Main Contents 3.1 Food Preservation One major issue that is central to the achievement of sustainable food security in Nigeria is a reduction in food spoilage. This is because of its effects on the quantity and quality of food available to the consumer. Spoilage is the adverse changes in the quality of food due to biological reactions. Similarly, the terms deterioration or autolysis could be described as the adverse changes in the quality of food as a result of physical and chemical reactions that occur within the food system (Muhammad & Kayode, 2014). Food spoilage results when the nutritional value, texture, taste of the food are damaged, the food become harmful to people and unsuitable for consumption. On the basis of spoilage, food may be divided into three categories namely perishable foods, semi-perishable foods and stable foods. The inclusion of any food in any of the three categories is based on the level of moisture content of the food as this factor plays a direct prominent role in food spoilage. Food spoilage may be caused by mechanical damage, microbiological activity (bacteria, yeasts, and moulds), autolysis (oxidation reaction and enzymatic activity), insect and rodent attacks, as well as temperature related factors. Food preservation is the act of protecting food from deterioration and decay so that it will be available for future consumption. Preservation of food has been a major anxiety of man over the centuries. Contamination with microorganisms and pests causes considerable losses of foods during storage, transportation and marketing (15% for cereals, 20% for fish and dairy products and up to 40% for fruits and vegetables). Particularly, pathogenic bacteria are an important cause of human suffering and one of the most significant public health problems all over the world. The World Health Organization (WHO) reported that the infectious and parasitic diseases represent the most frequent cause of death worldwide (35%). Any method that will create unfavourable conditions for the factors which are capable of adversely affecting the safety, nutritive value, appearance, texture, flavour, and keeping qualities of raw and processed foods, could be used to preserve foods. Since thousands of food products with different physical, chemical, and biological properties can undergo deterioration from such diverse causes as microbial, natural food enzymes, insects and rodent infestations, heat, cold, light, oxygen and moisture content, food preservation methods differ widely and are optimised for specific products. Numerous processing techniques have been developed to control food spoilage and raise safety. Traditional methods of preserving foods include dehydration, smoking, salting, controlled fermentation (including pickling), and candying; certain spices have also long been used as antiseptics and preservatives. Among the modern processes for food preservation are refrigeration (including freezing), canning, pasteurisation, irradiation, and the addition of chemical preservatives. (a) High-Temperature Treatment The use of heat for the preservation of food has been long in human history and its intensity varies. The heat treatment necessary to destroy the microorganisms or their spores varies with the kind of organism, its state and the medium during heating. The heat resistance of microorganism is usually expressed in terms of their terminal death time which is the time it takes to kill a stated number of organisms including their spores at a chosen temperature at a specified condition. True sterility to ensure total destruction of the most heat-resistant bacteria spores in non-acidic foods may require at least 2500F (1210C) of wet heat for at least 15 minutes treatment. The term commercial sterility refers to a less severe condition that still assures the destruction of both pathogenic and non-pathogenic organisms, as well as organisms that, if present, could grow in the food and produce spoilage under normal conditions of handling and storage. The various methods of high-temperature treatments employed in food processing include: (i) Blanching Blanching is a slight heat treatment, using hot water, steam, gas or high-frequency radiation that is usually applied to fruits and vegetables before canning or freezing. Blanching could be done by the use of hot water (water blanching) at a temperature of 990C for 2-3 minutes by immersing the fruit or vegetable in hot water or steam blanching in which a conveyor containing vegetables or fruits is allowed to pass through a tunnel which is subjected from above and below to jets of steam. There is also microwave blanching which involves the use of heat generated in the food by subjecting it to high-frequency radiation. A recent development in the food processing industries is the use of gas blanching. The advantages of blanching are given as follow: inactivation of enzymes, reduce in tissue gas thus reducing the volume of the food product, improvements of colour and texture of products especially vegetables, removal of adhering dirt’s and slime forming substances on food product and reduction in cooking time of the final product. However, blanching also has drawbacks as follow: It may lead to loss of water-soluble vitamins B and C and leaching of solutes from the food. It may also lead to mushiness of vegetables and fruits if not properly controlled and prolong treatment of vegetables may cause discoloration (Badejo, 1999). (ii) Pasteurization The process is named after the French chemist Louis Pasteur, who devised it in 1865 to inhibit fermentation of wine and milk; it also destroys pathogenic microorganisms and extends the shelf life of a food. Pasteurised products still contain many viable organisms capable of growing and causing spoilage defects. Therefore, pasteurisation is usually combined with another means of preservation such as refrigeration. Thus the ranges of pasteurisation temperature regimes that are practically employed in the food and dairy industries which give almost equal destruction of microorganisms in food include: (i) Low-Temperature Long Time (LTLT): Heat treatment between 63 and 650C for 30 minutes; (ii) High-Temperature Short Time (HTST): Heat treatment between 71.7 and 750C for 15 to 16 seconds; and (iii) Ultra High Temperature (UHT): Heat treatment between 121 and 138 0C (or higher) for 2 to 5 seconds. Heating is done under pressure to produce turbulence and to prevent burning of the milk inside a tubular or on a plate-type heat exchanger. The milk produced is essentially sterile and when packaged under aseptic conditions, may be stored at room temperature for several months. Permanent stability, that is the shelf life of about two years, is obtained with foods that can withstand prolonged heating such as bottled juices. There is a greater loss of flavour from foods that are exposed to a longer time-temperature relationship. Therefore, temporary stability (limited shelf life) is only obtained with some foods where prolonged heating would destroy its quality. These foods such as milk usually require subsequent refrigeration. “High-Temperature Short-Time” (HTST) and “Ultra High Temperature” (UHT) processes have been developed to retain a food’s texture and flavour quality parameters (Ihikoronye & Ngoddy, 1985). (iii) Tyndallization This is a cycle of heat process aimed at destroying the vegetative forms of microbes at a high temperature between 70 – 100 °C followed by cooling to 37 °C by allowing the resistant spores to germinate and finally reheating at a high temperature to destroy the germinated spores. The cycle of heating, cooling and reheating is repeated until the microbial destruction level is satisfactory (Badejo, 1999). (iv) Sterilization Sterilisation is a method of heat treatment that is aimed at removing all microorganisms. Temperature sterilisation could be achieved in two ways, i.e. Low-Temperature Longer time (LTLT) or High-Temperature Shorter Time (HTST). For example, milk and milk products are sterilised at temperatures of 1210C for 5 minutes or 1490C for 6 seconds. Under this process, all pathogenic and toxin-forming organisms (including both vegetative cells and spores) are destroyed, as well as other types of organisms, which if present could grow in the food and cause spoilage under normal handling and storage conditions. To prevent recontamination sterilised products must be packaged in aseptic and hermetically sealed containers such as cans and bottles. Types of commercially sterile processes include canning, bottling, and aseptic processing. Most commercially sterile food products have a shelf life of 2 years or longer. The disadvantage of this process, however, is that high temperatures can diminish product appearance, texture, and nutrient quality. Examples of such foods that could be preserved by this method include all forms of cooked food, milk, beer and wine. (b) Low Temperatures Treatment The slowing of biological and chemical activity with decreasing temperature is the principle behind cooling (refrigeration) and freezing preservation. In addition; when water is converted to ice, free water required for its solvent properties by all living systems is removed. Low- temperature treatment prevents the spoilage of food as well as the proliferation of harmful bacteria. Low-temperature treatment involves freezing and refrigeration. (i) Freezing Freezing turns water in food into ice crystals which rupture the microbial cells. Water is unavailable for reactions to occur, and for micro-organisms to grow. Some microbial cells are destroyed during freezing due to denaturation as a result of increased concentration of solute in the frozen food while, others are prevented from multiplying(US History Encyclopedia, 2006). Because not all the diversities of bacteria are killed, however, those that survive reanimate in thawing food and often grow more rapidly than before freezing. In freezing, food temperature is reduced to about (-17°C). However, the freezing compartments of some home refrigerators are not designed to give a temperature of -17°C; the temperature needed for prolonged storage of frozen foods. After we harvest plants or slaughter animals, enzyme reactions can continue and result in undesirable colour, flavour and texture changes in the food. Freezing slows down but does not destroy, enzymes in fruits and vegetables. That is why it is important to stop enzyme activity before freezing. The two methods that can be used are blanching and adding chemical compounds such as ascorbic acid. Fish meat, peas, vegetables and ice-cream are usually preserved using the freezing method. (ii) Refrigeration Refrigeration is the process of lowering the temperature and maintaining it in a given space for the purpose of chilling foods, preserving certain substances, or providing an atmosphere conducive to bodily comfort. Storing perishable foods, furs, pharmaceuticals, or other items under refrigeration is commonly known as cold storage. Chilling slows down microbial activities and chemical changes resulting in spoilage. In chilling, food is kept at 0–4 °C. However, at this temperature range some spoilage microorganisms (psychrophiles) may still be alive and grow slowly, so the food cannot be stored for a long time (US History Encyclopedia, 2006). (c) Controlled Reduction in Moisture Content The presence of adequate water (moisture) allows numerous biochemical and microbial activities in food (Badejo, 1999). Water exists in foods in various forms either as free water or bound water. Water activity can, therefore, be lowered by removing water from food or making water available in the food material. (i) Drying Drying food is a combination of continuous mild heat with air circulation that will carry the moisture off. When sufficient water is removed from foods, microorganisms (bacteria, yeasts, and moulds) will not grow, and many enzymatic and non-enzymatic reactions will cease or be markedly slowed. The process of drying foods removes roughly 80 to 90 percent of the water content of fruits and vegetables. Because drying removes moisture, the food becomes smaller and lighter in weight. When the food is ready for use, the water is added back and the food returns to its original shape. Drying of foods could be achieved using any of the following: air, oven and microwave oven. Dried food items can be kept almost indefinitely, as long as they are not rehydrated. The disadvantages of this preservation method include the time and labour involved in rehydrating the food before eating. Moreover, rehydrated food typically absorbs only about two-thirds of its original water content, making the texture tough and chewy. Examples of food preserved by this process include various dried food products such as fruit, coffee, fish, meat and vegetables. (ii) Dehydration This is a preservative method which involves the substantial reduction of moisture under controlled conditions of temperature humidity and air flow. Dehydration involves the transfer of sufficient heat to food to cause moisture evaporation. It is different from conventional drying because dehydration is a controlled drying process. Foods preserved by dehydration contain considerably lower water activity and less total water than concentrated foods. Dehydration could be in form of convection drying in which food to be dried is placed in contact with a stream of heated air and heat is transferred to the product mainly by convection. Dehydration can also be by direct contact drying in which the food product is placed in direct contact with a hot surface; here heat is transferred through conduction. Radiant heat drying is also another form of dehydration process using the microwave (Ihikoronye & Ngoddy, 1985). Freeze-drying (lyophilization) is also another method of dehydration in which food is frozen first and later sublimation occurs thus effecting drying. Freeze drying ensures retention of shape, size and volatile components of the food. It is however expensive. Examples of food preserved by this process include food products like fruit juices, meat and milk. (iii) Evaporation Evaporation is a type of heat processing operation which involves a reduction in moisture content of food materials to obtain a concentrated product with high total solids. The reduction in total moisture content often reduces the water activity (amount of available water in food) of a food material. Concentrated food product with little or no moisture does not encourage the growth of microbes. Evaporation can also be carried out at a lower temperature using a vacuum evaporator (Badejo, 1999; Muhammad & Kayode, 2014). (d) Smoking The smoke is obtained by burning oak or a similar wood under low breeze/wind at about 93 to 104 °C. Preservative action is provided by such’ bactericidal chemicals in the smoke as formaldehyde (HCHO) and creosote (antiseptic obtained from wood tar), and by the dehydration that occurs in the smokehouse: When foods are smoked they absorb various chemicals from the smoke including formaldehyde, formic acid, ketones, acetaldehydes, aldehydes, waxes, resins, tar and alcohol, among other compounds. Formaldehyde is considered to be the most important antimicrobial compound in wood smoke. It is known that wood smoke is more effective against vegetative cells than bacterial spores and that the rate of germicidal action of the wood smoke varies with the kind of wood employed. The aldehydes cause many microbes to die and the acids lower the pH of the food. Examples of foods preserved by this method include fish, meat, ham and sausage (Badejo, 1999; Muhammad & Kayode, 2014). (e) Sugaring and Salting This is the act of treating food with salt, strong salt solution or strong sugar solution. After adding salt or sugar, the water potential outside the micro-organisms is higher than that inside the micro-organisms. As a result water essential for enzyme action and microbial growth is removed by osmosis; the microbial cannot continue to live. However, a high concentration of salt and sugar may make the foods very salty and sugary respectively. Examples of food preserved by this process include bacon, salted fish, soy sauce, jam, fruits in heavy sugar syrup. (f) Pickling in Vinegar Food is kept in vinegar since microorganisms cannot grow well in low pH value solutions. Vinegar (acetic acid) slows the growth of spoilage bacteria, gives flavour and softens bones. Vinegar, however, is only a temporary preservative, because enzymes continue to act, softening and spoiling the product. Some kind of vinegar such as apple cider vinegar will darken most vegetables and fruits. Examples of foods preserved by this method are sauces, pickled onions and cucumbers (Shephard, 2006). (g) Chemical Preservatives Historically, many toxic substances have been used as food preservatives. Borates, fluorides and various phenols, that serve as antimicrobials, enzyme inhibitors and antioxidants have all been used. However, in the course of time, it became apparent that their efficiency in killing microorganisms was coupled with considerable toxicity to man. Today, the U.S Food and Drug Administration and comparable agencies in various countries vigorously regulate the chemicals that may be added to foods as well as the conditions of their use. There is much pressure to remove chemicals from the food supply, especially where their effects can be achieved by other means. (h) Irradiation This is the act or process of exposing the amount of energy in the form of speed particles or rays for improving food safety, eliminating and reducing organisms that destroy the food products. This is a very mild treatment because a radiation dose of 1 kGy represents the absorption of just enough energy to increase the temperature of the product by 0.36°C. It means that, heating, drying and cooking cause higher nutritional losses. Moreover, heterocyclic ring compounds and carcinogenic aromatic produced during thermal processing of food at high temperatures were not identified in irradiated foods. Ionizing radiation or irradiation is used as a method to destroy enzymes and micro-organisms in food, delay ripening of fruits, and vegetables; inhibit sprouting in bulbs, and tubers; remove insects from grains, cereal products, fresh and dried fruits and vegetables; and destroy bacteria in fresh meats, all with minimal effect on the nutritive value of food (Anon, 1991). Irradiated foods are not radioactive. Radiant energy disappears from the food once it is removed from the source of ionising radiation because the food itself never comes into direct contact with the radiation source. The international bodies including the Food and Agriculture Organization (FAO), the International Atomic Energy Agency (IAEA), WHO and Codex Alimentarius Commission (CAC) investigate projects on food irradiation to verify the safety and quality of different irradiated products. It has shown that irradiation used on alone or in combination with other methods could improve the microbiological safety and extend shelf- life. Furthermore, people are very confused to distinguish irradiated foods from radioactive foods. At no time during the irradiation process does the food come into contact with the radiation source and, it is not possible to induce radioactivity in the food by using gamma rays or electron beams up to 10 MeV. The strength of irradiation source and length of food exposure to the irradiation determine the dose; thus food can be treated at different regimes namely; radurization, radicidation and radappertization to achieve different levels of food treatment success. (i) Canning Canning is the process of preserving food by cooking, sealing it in sterile airtight cans or jars, and boiling the containers to kill or weaken any remaining bacteria as a form of sterilisation (Shephard, 2006). Sterilisation of the food can also be achieved by irradiation. The process was invented (1809) by Nicolas Appert, a French confectioner. Various foods have varying degrees of natural protection against spoilage and may require that the final step occurs in a pressure cooker. High-acid fruits like strawberries require no preservatives to can and only a short boiling cycle is required, whereas marginal fruits such as tomatoes require longer boiling time and addition of other acidic elements. Low acid foods, such as vegetables and meats require pressure cooking treatment. Food preserved by canning is at immediate risk of spoilage once the can has been opened. Lack of quality control in the canning process may allow ingress of water or micro- organisms. Most such failures are rapidly detected as decomposition within the can causing gas production and the can could swell or burst. However, there have been examples of poor manufacture due to under processing and poor hygiene practices allowing contamination of canned food by the obligate anaerobe, Clostridium botulinum which produces an acute toxin within the food, leading to severe illness or death (Ihikoronye & Ngoddy, 1985). (j) Fermentation Many foods, such as cheeses, wines, and beers are fermented foods that keep for a long time before spoilage. This is because their production uses specific starter microorganisms that combat spoilage from other less benign organisms. These micro-organisms keep pathogens in check by creating an environment toxic to themselves and other micro-organisms by producing acid or alcohol. The starter micro-organisms, salt, hops, cool storage temperatures, low levels of oxygen and/or other methods are commonly used to create the specific controlled conditions that will support the desirable organisms that produce food fit for human consumption (Ihikoronye & Ngoddy, 1985). (k) Controlled environment Preservation of controlled environment involves controlled atmospheric storage (CAS) and modified atmospheric storage (MAS). CAS and MAS imply the manipulation which may be addition or removal of gases from storage environment to achieve an atmospheric composition condition different from the normal condition. The normal composition of air is 20% oxygen, 79% Nitrogen and 1% carbon dioxide. In MAS this normal gas composition is altered or modified to achieve a reduction in oxygen content while increasing the level of carbon dioxide and nitrogen. Controlled atmospheric storage is a preservation process whereby the gaseous environment is modified to the desired level and controlled at this level within strict limits throughout the storage period (Africa Conference Brief 1980). Gaseous storage atmosphere changes in MAS continuously throughout the storage period since the gaseous composition is not controlled. The idea of MAS and CAS is traced back to the fact that the elevation of carbon dioxide and reduction of oxygen retards catabolic reactions in freshly harvested respiring foods and slows the growth of aerobic spoilage microorganisms. Both MAS and CAS are known to retard physiological processes (respiration and ripening), minimise mechanical injury and microbial infections to maintain optimum quality and extend the shelf-life of food products. Therefore either of the 2 methods is employed in the storage and preservation of fruits and vegetables. Other practices that can delay or prevent food spoilage are as follows: (i) Use of food additives Food additives are natural and synthetic compounds added to food. The use of food additives is justified when it serve at least one of the following purposes: (i) maintenance of nutritional quality (ii) enhancement of keeping quality or storage stability with reduction in food losses (iii) making the food attractive and acceptable to the consumer and at the same time not leading to deception and (iv) as essential aids in food processing. The functional characteristics of chemical food additives are: to supply nutrients, serve as chelating and antifoaming agents, enhance colour, flavour and texture of food, aid in pressure dispensing, ripening and maturation process, and prevention of microbiological spoilage, chemical deterioration, and control of insects and rodents. (ii) Packaging Packaging is a means of providing a correct environmental condition for food and, as such, provides identification, information and sales appeal, protects the food from contamination, moisture gain or loss, flavour loss and odour pickup, the adverse effects of oxygen and light, physical damage, and intentional tampering. Ultimately, a food product’s quality and storage life are determined largely by its package. 4.0 Summary In this unit, we identified the define the food spoilage, identify factors that causes food spoilage , then discussed in depth different ways (both primitive and modern ) of food preservation. 5.0 Self-Assessment Questions (SAQs) i. Define food spoilage ii. List 5 factors that can cause food spoilage iii. Enunciate the principles and applications of different methods of food preservation 6.0 Tutor Marked Assessment (i) differentiate between low and elevated heat treatment of food for preservation 7.0 Further Reading Paarlberg R. (2002), Governance and Food Security in an Age of Globalization A2020 Vision for Food Agriculture, & the Environment 2020 Brief 72 February 2002. Ricketts, E. (1983), Food, Health and You, Macmillan, New York, Washington Shephard, S. (2006). Pickled, Potted, and Canned; How the Art and Science of Food Preserving Changed the World ISBN 9780743255530. Smith, L.C; U. Ramakrishnan; A. Ndiaye; L. Haddad & R. Martorell (2003), The Importance of Women’s Status for Child Nutrition in Developing Countries, Research Report Abstract 131, Trueblood, M. & Shapouri, S. (2002). Food Insecurity in the Least Developed Countries and the International Response AAEA Selected Paper Long Beach, California July 29-31, 2002. United Nations (2005). Millennium Development Goals, United Nations Department of Public Information