Bioprocess Fermentation Chap 3 PDF

Chap 3: DESIGNING FOOD PRODUCTS USING BIOPROCESS FAT 3103 TS DR MARYANA MOHAMAD NOR WEEK 3  WEEK 2 RECAPP Types of control systems Batching and continous Automatic process control...

Chap 3: DESIGNING FOOD PRODUCTS USING BIOPROCESS FAT 3103 TS DR MARYANA MOHAMAD NOR WEEK 3  WEEK 2 RECAPP Types of control systems Batching and continous Automatic process control Advantage vs disadvantages Components 2  Course online To understand fermentation process of various foods 3.1. 1Concept of fermentation and bioprocess 3.1.2Classification of fermented food products (dairy / meat /marine) – animal-based 3.2. Classification food fermentation (plant/ vegetable) –plant-based 3.3. Enzyme classification and technology PART 1……. Definition: 1. BIOPROCESS Food is produced using biological processe. Food- grade microorganisms are used to produce different types of fermented food using raw materials from animal/ plat (its called ‘starter culture’), such as fermentation, enzymatic reactions, and microbial activity, to transform raw materials into consumable food products or enhance their properties. 2. FERMENTATION The conversion of carbohydrates to alcohol or organic acids using microorganisms (yeasts or bacteria) under anaerobic conditions. glucose → ethanol + carbon dioxide 3.1.1 Concept of fermentation and bioprocess Fermentation USING ACETOBACTER ACETIC ACID FERMENTATION PRODUCE ALCOHOL USING LACTOBACILLUS Factors Affecting Fermentation Factors that control the growth and activity of microorganisms in food fermentations are: Carbon and nitrogen sources, and any specific nutrients required by individual microorganisms Substrate pH Moisture content Incubation temperature Redox potential Stage of growth of microorganisms Presence of other competing microorganisms 3.1.2 Classification of fermented food products (dairy / meat /marine)  A. Dairy Product Manufacturing (cultured butter, buttermilk, cheese and yogurt) The most common is cow’s milk and foods produced from cow’s milk, such as butter, yogurt, sour cream, and cheese Milk from other animals such as goats, sheep, and buffaloes are used in various cheeses Dairy products are extremely versatile and used throughout the kitchen Nutrition Dairy products are high in vitamins, minerals, and protein Milk is fortified with vitamins A and D Does contain cholesterol FUNCTION OF STARTER CULTURES To acidify the milk → promoting coagulation of the curd (in cheese production) Functions To modify the texture & flavor of the cheese during ripening  Traditionally… Cheese was a way of preserving the nutrients of milk. Cheese Is the fresh or ripened product obtained after coagulation and whey separation of milk, cream or partly skimmed milk, buttermilk or mixture of these products. Cheese  Treatment of the milk Additives incorporated Inoculation and milk ripening Coagulation Enzymes added Acid Added Heat acid processing Curd treatment Cheese ripening How is it made??  Is a semi solid fermented milk product! Ingredients include…milk and bacteria! Can be served Mixed with fruits Soft Frozen Yogurt  Buttermilk is a by-product of the butter industry and Can be condensed, dried, or mixed with skim milk Has a higher fat content than milk! Buttermilk  Butter is essentially the fat of milk! It is usually made from sweet cream and is salted. Butter is made of 80 to 82% Fat 15.6 to 17.6% Water 1.2% Salt 1.2 Proteins, Calcium, Phosphorus Butter Microbes involved in manufacture of fermented dairy products All cheese images courtesy of Wisconsin Cheese Mart  LAB USES : TRANSFORMED MILK TO VALUE ADDED FERMENTED FOODS Milk Inoculate with Inoculate with Inoculate with Lactococcus lactis + Lactobacillus bulgaricus Lactococcus cremoris + Lactococcus cremoris + Streptococcus Lactococcus lactis subsp. thermophilus diacetylactis Press curd to Stop fermentation remove whey Stir fruit or other by cooling to 5ºC flavoring into the (prevent Ripen Package coagulated milk coagulation) (may (fresh involve cheese) salting) Package Package (yogurt) (buttermilk) Package (e.g. cheddar)  Yogurt, cheese & buttermilk cannot be made without the participation of a specific group of Gram +ve bacteria → lactic acid bacteria (LAB) Relatively acid tolerant – Lack pathogenicity – have a long can survive & grow in history of safe use in foods & do not acidic environment as low cause disease & do not give danger to as pH3 human health Can ferment lactose & Because of pH-lowering other carbohydrates Characteristics of fermentation products & into lactic acid – enough LAB due to the common lactic acid accumulates production of bacteriocins →casein in the milk (compounds that inhibit coagulates, resulting in other bacteria) – growth of improve the flavor of a semisolid product LAB in milk extends the dairy products – e.g shelf life of the milk & diacetyl that gives increases protection buttermilk its against pathogenic characteristic flavor is bacteria produced by Lactococcus cremoris  LAB USES : TRANSFORMED MILK TO VALUE ADDED FERMENTED FOODS Milk Inoculate with Inoculate with Inoculate with Lactococcus lactis + Lactobacillus bulgaricus Lactococcus cremoris + Lactococcus cremoris + Streptococcus Lactococcus lactis subsp. thermophilus diacetylactis Press curd to Stop fermentation remove whey Stir fruit or other by cooling to 5ºC flavoring into the (prevent Ripen Package coagulated milk coagulation) (may (fresh involve cheese) salting) Package Package (yogurt) (buttermilk) Package (e.g. cheddar) B. FERMENTATION PROCESS OF MEAT PRODUCTS TYPES OF MEAT PRODUCTS Semi dry Quickly fermented Dry Sausages Summer Sausage Slow fermentation Cervelats Metwursts Salami Bolognas (U.S.) Pepperoni Thuringer Genoa Salami (beef / Both types include pork) soft and hard Hard Salami  Increase demand (improvement in flavour, taste, aroma, colour) More tender (soft) Long storage life (enzyme (acidulation) activity beneficial protease) effect of fermented meat products Safer from Less dangerous & pathogenic cooking time High microorganisms nutritional (starter culture) value (peptides, amino acid)  FERMENTED MEAT RAW MEAT  Starter Cultures Used in quick Improves safety fermenting (semi-dry) and quality of product products Quicker than waiting for Used by large “house flora” to Mixture of manufacturers develop bacteria added to immediately start fermentation The main effects of starter micro-organisms on flavor and taste of fermented meats are formation of lactic acid reduction of nitrate protein degradation by mould proteases degradation of peptides and amino acids formed by meat proteases transformation of compounds from 29 breakdown of lipids  SAUSAGE Most traditional Asian meat products are fermented for : - extension of their shelf-life - flavour and taste. The typical characteristic of most products is the utilization of sugar as an ingredient. Sausage products must have a water activity reading below 0.85 and a pH under 5.3 to be shelf stable 31 ADDITION OF STARTER CULTURE In fermented food products: affect fermentation by desired ADDITION OF NaCl organisms (starter and/or wild), preservation qualities (retardation of spoilage organisms) ACID PRODUCED texture taste ADDITION OF NITRITE/NITRATE color SUGAR PRESENT SODIUM NITRITE SODIUM NITRATE (NaNO3) (NaNO2) added during manufacture curing agent Excessive nitrate adds a particular reduction will take place, flavor to the resulting in overly high sausage. concentrations of nitrite responsible for the pink The excessive of nitrite, in the colour (such as bologna and presence of the lactic acid, ham). cause severe oxidation of the meat pigment (myoglobin), producing a green pigment inhibits the growth of the (oxymyoglobin) pathogen Clostridium botulinum This form greening of cured meats - nitrite burn The sample on the left has the desired cohesiveness and colour. The sample on the right was made with an excess of nitrate NaCl The inhibitory effect of NaCl mainly due to its role as an Aw- lowering agents SUGAR Provide food for starter cultures Introduction of more sugar leads to; lower the pH value & stronger the acidification in meat Also helps to offset the sourly & tangy flavour of fastand medium-fermented sausages.  Lactic Acid Bacteria (LAB) Gram- positive, catalase- Organisms positive cocci that (GCC) Ferment Molds Pediococcus sp. Yeast Approved By USDA Functions As Commercial Cultures For Meat Fermentation Acidity Pediococcus Flavour Lactobacillus plantarum Texture Micrococcus Colour  Pediococcus Cultures can be classified produces antimicrobial inhibit into following groups; Staph. Aureus, Salmonella, C. botulinum & yeast Colour Surface Lactic acid Bio-protective fixing & coverage producing flavour cultures cultures cultures (producing forming (yeast & (fermentation) cultures bacteriocins) molds)  C. FERMENTED FISH Fermented fishery products widespread in parts of Asia, which contribute more protein in human diet. Traditionally, fermented fish known as the act of preservation of fresh fish using these three types of preservation : SALTING, SMOKING and SUN-DRYING. Depending on the proportion of salt added, the products can also be classified into high salt (more than 20% of total weight), low salt (6 to 8%) and no salt products SMOKING FISH SMOKING FISH SUN-DRYING SUN-DRYING SALTED-FISH  Non-traditional fermented fish -produced using bacteria starter cultures. For example: Thai fermented fish : Plaa-som using Lactobacillus plantarum & Pedah-siam using Pediococcus acidophilus West-Africa : Lanhoiun using Bacillus licheniformis and Bacillus subtilis  Types of fermented fish products: 1. Products in which the fish retain substantially their original form or preserved as large chunks. cured mackerel Examples: pedah siam (Thailand), makassar (Indonesia), buro (Philippines), Colombo cured mackerel (India) BURO  Products in which fish are reduced to a paste. Examples: ngapi (Burma), prahoc (Kampuchea), belachan (Malaysia), trassi (Indonesia), bagoong (Philippines) prahoc Ngapi  Products in which fish are reduced to a liquid. Examples: budu (Malaysia), patis (Philippines), nuoc-mam (Vietnam), nampla (Thailand) patis nampla DESCRIPTIONS OF THE FERMENTATION IN FISH SAUCE Nuoc-Mam : The fish species used : Stolephorus, Engraulis, Dorosoma and Decapterus and Cupeoids @ shrimp. -Whole fish are kneaded lightly by hand, mixed with salt (4 parts of salt : 6 parts fish) ferment for few months. -After 3 days, the blood pickle (nuoc-boi) is allowed to flow out. -The fish are then trampled by foot until a flat. Then, covered with coconut leaves few days. -The nuoc-boi is then poured back over the fish until a 10 cm liquid layer is formed. -It is then left to mature for 4 months – 1year. After maturation, the pickle is now top quality nuoc-mam & add fresh brine on top of it. PREPARATION OF FISH SAUCES (BUDU) Anchovies (3 parts) Salt (2 parts) Mix thoroughly Ferment in tanks (3-12 months), weight Boil for 2 hours, (added with tamarind, palm sugar, caramel, MSG) Filter/decant Bottle ‘Budu’  DESCRIPTIONS OF THE FERMENTATION IN FISH PASTE Bagoong is reddish in colour with a slightly fishy cheese-like odour. -It can be prepared from genera Stolephorus, Sardinella and Decapterus, and small shrimp. -The fish are washed in clean water, placed in a concrete or wooden vat & mixed with salt (Ratio 1:3). -Then transferred to earthenware jars for 5 days and sealed. The containers then held in the sun for one week -Then the product is then transferred to five gallon cans. & allowed to ferment further between 3 months - 1 year. -The composition is not less than 40% total solids, 12.5% protein and 20-25% sodium chloride. PREPARATION OF SHRIMP PASTE (BELACHAN) Ground shrimp Salt added (4-10 %) Dry under the sun (5-8 hours) Ferment at 30°C, 7 hours Homogenize and dry (5-8hours) Filling into container, leave for 7-90 hours Packing  FERMENTED FISH THAT RETAIN ITS ORIGINAL FORM Makassar, the fish species used are anchovies (Engraulis spp. and Stolephorus spp.). placed in earthenware pots with equal weight of salt.After 3 to 4 days, a red coloured rice product called angkhak is mixed with the fish and salt Angkhak is made up of rice fermented with a mould (Monascus purpureus). Ragi (a Japanese preparation made from yeast and rice flour) is then added with spices After a few days, the mixture becomes red & then packed into glass bottles for distribution The composition of makassar fish includes, 66% moisture, 16% protein, 1% fat and 17% ash.  PREPARATION OF SALTED-FISH Wash the fish with clean and fresh water Split the fish into fillet, remove the gill and internal organs Wash again & put in strainer and drain the fish Prepare brine solutions (60kgs of fish : 6.5kgs salt & 5 gallons water) Soak the fish in brine solutions for 1 hour Dry the fish under sun (between 12-15 days in warm weather) HIGH DEGREE OF PROTEOLYSIS ACTIVITY FUNCTION OF MICRORGANISMS IN FERMENTED FISH Lactic Acid Bacteria dominant group of microorganisms in fermented fish Example : Micrococcus spp, Bacillus spp. Leuconostoc, Streptococcus, Lactobacillus, Enterococcus, Aerococcus and Pediococcus spp.  known to such as bacteriocins produce protein Advantage antimicrobial LAB agents (peptides that elicit antimicrobial activity against food spoilage organisms and food borne pathogens, but do synthesis other not affect the producing anti-microbial organisms). compounds (*elicit=cungkil,galak) hydrogen peroxide, reuterin, and reutericyclin. LAB primary role in fermented fish process ferment available carbohydrates & cause the decrease in pH (decrease to pH 4.5 in two days) The decreases of pH & availability of lactic acid act as preservation factor that inhibit pathogenic & spoilage bacteria Breakdown of fish tissue than in sauces Development of aroma, flavour & texture of the products  Fish product fermented by LAB improve Stored for nutritional longer periods free of the fishy odour and taste quality of the (preservations), fish  DEVELOPMENT OF FLAVOUR Ammonia Cheesy (volatile fatty acid, ethanoic, n-buthanoic) Meaty (Volatile constituent- keton.)  ferment available carbohydrates & thereby cause the decrease in pH (decrease to pH 4.5 in two days) The decreases of pH & availability of lactic acid act as preservation factor that inhibit pathogenic & spoilage bacteria the breakdown of fish tissue than in sauces contributes in the development of aroma, flavour & texture of the products PART 2……. 3.2. Classification food fermentation (plant/ vegetable) –plant-based Fermentation of fruits and vegetables can occur “spontaneously” by the natural lactic bacterial surface microflora, such as Lactobacillus spp., Leuconostoc spp., and Pediococcus spp.; however, the use of starter culture such as L. plantarum, L. rhamnosus, L. gasseri, and L. acidophilus provides consistency and reliability of performance Lactic Acid Bacteria Beneficial Effect of Fermented Fruits and Vegetables 1. Enhancing Food Quality and Safety 2. Removal of Antinutrient Compounds 3. Improving the Health Benefits of Humans 4. Biopreservation Vegetables Cucumbers, olives and other vegetables are submerged in 2–6% w/w brine, which inhibits the growth of putrefactive spoilage bacteria. Air is excluded and a naturally occurring sequence of lactic acid bacteria grow in the anaerobic conditions to produce approximately 1% w/w lactic acid. The relative importance of each species depends on the initial cell numbers on the vegetable, the salt content and the pH. PICKLE In some countries, the fermentation of cucumbers is controlled by the addition of acetic acid to prevent growth of spoilage micro-organisms. The brine is then inoculated with either L. plantarum alone or a mixed culture with P. cerevisiae. Nitrogen gas is continuously purged through the vessel to remove carbon dioxide and to prevent splitting of the cucumbers.  Other methods of pickling involve different salt concentrations: for example in ‘dry salting’ to make sauerkraut from cabbage, alternate layers of vegetable and granular salt are packed into tanks. Juice is extracted from leaves by the salt to form a brine, and the fermentation follows a similar sequence to that described for cucumber pickles. In each case preservation is achieved by the combination of acid, salt and in some cases pasteurisation. Maize, Cassava and Sorghum In tropical countries, cereals and root crops are fermented to a range of beverages and staple foods. Fermented maize flour is a staple food in many African countries. Maize kernels are soaked for 1–3 days, milled and formed into a dough. Initially Corynebacterium spp. hydrolyse starch and initiate lactic acid production. Aerobacter spp. increase the rate of acid production and S. cerevisiae contributes to the flavour of the product.  As the acidity increases, Lactobacillus spp. predominate and continue acid production. Finally Candida mycoderma outgrows S. cerevisiae and contributes to the final flavour of the fermented dough. It is cooked to form a thick porridge within 1–2 days. The fermentation is therefore used to impart flavour and have a temporary preservative effect. Cassava is grated and the pressed pulp is fermented by Corynebacterium spp., as for maize, to produce lactic and formic acids and to reduce the pH from 5.9 to 4.0. Bread The fermentation and baking of cereal flour alter the texture and flavor of the flour and make it palatable as a staple food. Fermentation has no preservative effect and the main function is to produce carbon dioxide to leaven and condition the dough. Yeast and other micro-organisms (e.g. Lactobacillus spp.) present in the dough also contribute to the flavour of the bread. Carbon dioxide is retained within the loaf when the gluten structure is set by heat above 74°C. The heat treatment and reduction in water activity preserve the bread. 2 types of bread fermenter https://link.springer.com/article/10.1007/s00217-023-04325-7 Key Factors in Bread Fermentation: 1. Yeast Activity: Role of Yeast: Yeast consumes sugars and produces carbon dioxide and alcohol, causing the dough to rise. Types of Yeast: Commonly used types include baker's yeast (Saccharomyces cerevisiae) and sourdough cultures. 2.Temperature: Optimal Range: Typically between 75°F and 85°F (24°C to 29°C) for most yeast activity. Effects: Higher temperatures speed up fermentation, while lower temperatures slow it down. 3. Time: Fermentation Duration: Longer fermentation allows for more flavor development and gluten formation, improving texture and taste. 4. Hydration: Water Content: Affects dough consistency and yeast activity. Higher hydration can lead to more extensive fermentation and open crumb structure. 5. Sugar and Salt: Sugar: Provides food for yeast, enhancing fermentation. Salt: Regulates yeast activity and strengthens gluten structure. 6. pH Levels: Acidity: Lower pH (more acidic) can enhance flavor and inhibit spoilage organisms, especially in sourdough. 7. Flour Type: Protein Content: Higher protein flours provide more gluten, contributing to better structure and rise. Each of these factors interacts to influence the final quality of the bread, Alcoholic Beverages (BEER) the composition of the wort, the strain of yeast (S. cerevisiae, S. carlsbergensis), and the fermentation time and conditions, result in the wide range of beers produced.  Humulus lupulus · 3. Lautering: the beer brewing process that separates the mash into clear liquid wort and residual grain https://www.craftbreweryequipment.com/News_Blog/Beer_Brewing_Tech/Two_main_ferm entation_processes_for_beer_fermentation_2494.html  Key Factors in Beer Fermentation: 1. Yeast Strain: Type: Different strains (e.g., ale yeast vs. lager yeast) produce distinct flavor profiles and fermentation characteristics. 2. Temperature: Control: Critical for flavor development and yeast activity. Ranges: Ales typically ferment between 60°F and 75°F (15°C to 24°C), while lagers ferment at cooler temperatures, around 45°F to 55°F (7°C to 13°C). 3. Fermentation Time: Primary and Secondary: Time impacts flavor complexity and clarity. Longer fermentation can lead to more developed flavors. 4. Oxygen Levels: initial Aeration: Essential for yeast growth before fermentation begins. However, oxygen exposure should be minimized afterward to prevent off-flavors. 5.Nutrient Availability: Sugars and Nutrients: Adequate nutrients ensure robust yeast activity and complete fermentation. 6. pH Levels: Acidity: Optimal pH levels support yeast health and influence flavor. Typically, the pH should be around 4.0 to 4.5. WINE  The main acid in most wines is tartaric acid but, in some red wines, malic acid is present in a high concentration. In these, a secondary malo-lactic fermentation by lactic acid bacteria converts malic acid to lactic acid which reduces the acidity and improves the flavour and aroma. Fermentation times in excess of 12 h produce an over-acidified product and it is therefore consumed on the day of preparation. SIX KEY FACTORS AFFECT WINE FERMENTATION 1. TEMPERATURE Fermentation produces heat. The growth rate of yeast, and therefore their ability to consume sugar, doubles for every 10℉ rise in temperature. The warmer the grape juice, the faster the fermentation. 2. PH Yeast grow best at around 5.5 pH. Wines need a pH of ~2.9 – 3.6 to prevent spoilage. Winemakers use cultured yeast strains tolerant of lower pH. 3. SULFUR DIOXIDE (SO2) a warning note ‘Contains Sulfites’ on wine labels in the US. SO2 (pronounced ess-oh-two) acts as a preservative to prevent spoilage. Wineries may add small doses of SO2 at harvest to kill back wild microbes that could cause off- flavors. 4. NITROGEN AND NUTRIENTS In addition to sugar, yeast need nutrients, specifically nitrogen, to help with their lifecycle metabolism. Too little nitrogen can cause hydrogen sulfide (rotten egg smell) to develop as the yeast struggle to survive in the new wine 5. SUGAR Yeast consume sugar and convert it into alcohol. The more sugar available in the grapes, the more food that the yeast can turn into alcohol, and the higher a wine’s final alcohol level. Grapes with very higher levels of sugar levels can take 2-3 months for yeast to ferment – or may never ferment completely. 6 Alkohol Yeast are sensitive to alcohol levels. At about 13% ABV, yeast begin to struggle and die. When a wine is both high sugar and high alcohol, yeast die off, leaving a little sweetness in your wine. Vinegar and Other Food Acids Types of vinegars Vinegars can be categorised based on the substances from which they are produced: (1) those from the juices of fruits, e.g. apples, grapes, oranges, pears, berries, etc.; (2) those from starchy vegetables, e.g. potatoes or sweet potatoes, whose starch must first be hydrolyzed to sugars; (3) those from malted cereals, e.g. barley, rye, wheat, and corn; (4) those from sugars, e.g. syrups, molasses, honey, maple skimm  Fermentation of vinegar The production of vinegar from saccharine materials requires two processes: (1) the fermentation of sugar to ethyl alcohol and (2) the oxidation of alcohol to acetic acid. The first step is an anaerobic fermentation performed by yeasts, either those naturally present in the raw material or, preferable, additional cultures of high-alcohol-producing strains of Saccharomyces cerevisiae var. ellipsoidus. In reality, a sequence of intermediary reactions occur, and minor amounts of additional end products, such as glycerol and acetic acid, are created. In addition, there are trace amounts of chemicals derived from non-sugar molecules, including succinic acid and amyl alcohol. The second stage, alcohol oxidation to acetic acid, is an aerobic reaction carried out by acetic acid bacteria: https://www.shutterstock.com/image-vector/schematic-diagram-cider-vinegar- fermentation-1115913524 https://www.researchgate.net/publication/360769826_Processing_Technologies_and_ Flavor_Analysis_of_Chinese_Cereal_Vinegar_a_Comprehensive_Review/figures?lo=1  Cocoa and Coffee Cocoa and coffee berries contain mucilage around the beans, which is removed by fermentation. Cocoa beans are either heaped or placed in slatted fermentation bins (‘sweat boxes’) and initial fermentation by yeasts (including S. ellipsoideus, Saccharomyces apiculata, Hansenula spp., Kloeckera spp., Debaromyces spp., Schizosaccharomyces spp. and Candida spp.), produces ethanol from sugars in the pulp and raises the temperature in the box. Lactic acid bacteria then predominate in the anaerobic conditions. They reduce the pH and further raise the temperature. Pulp is hydrolysed and solubilised during this period and drains away to allow air to penetrate the bean mass. Ethanol is then oxidised to acetic acid by acetic acid bacteria which also cause the temperature to rise to 45– 60°C, and destroy the yeast population.  The combination of heat and up to 2% w/w acetic acid kills the beans. They are then dried to 7% moisture to preserve the product and roasted to produce the characteristic chocolate flavour and aroma. Coffee berries are soaked, pulped and fermented in slatted tanks where microbial and naturally occurring pectic enzymes solubilise the mucilage.  Soy Products Soy sauce and similar products are made by a two- stage fermentation in which one or more fungal species are grown on a mixture of ground cereals and soy beans. Fungal proteases,α-amylases and invertase act on the soy beans to produce a substrate for the second fermentation stage. The fermenting mixture is transferred to brine and the temperature is slowly increased. Acid production by P. soyae lowers the pH to 5.0, and an alcoholic fermentation by S. rouxii takes place. Finally the temperature is gradually returned to 15°C and the characteristic flavour of soy sauce develops over a period of 6 months to 3 years. Bioreactor design Effect of fermentation on foods The mild conditions used in food fermentations produce few of the deleterious changes to nutritional quality and sensory characteristics that are found with many other unit operations. Complex changes to proteins and carbohydrates soften the texture of fermented products. Changes in flavour and aroma are also complex and in general poorly documented. Flavour changes include reduction in sweetness and increase in acidity due to fermentation of sugars to organic acids, an increase in saltiness in some foods (pickles, soy sauce, fish and meat products) due to salt addition and reduction in bitterness of some foods due to the action of de- bittering enzymes.  The aroma of fermented foods is due to a large number of volatile chemical components (for example amines, fatty acids, aldehydes, esters and ketones) and products from interactions of these compounds during fermentation and maturation. The colour of many fermented foods is retained owing to the minimal heat treatment and/or a suitable pH range for pigment stability. Changes in colour may also occur owing to formation of brown pigments by proteolytic activity, degradation of chlorophyll and enzymic browning.  Microbial growth causes complex changes to the nutritive value of fermented foods by changing the composition of proteins, fats and carbohydrates, and by the utilisation or secretion of vitamins. Micro-organisms absorb fatty acids, amino acids, sugars and vitamins from the food. However, in many fermentations, microorganisms also secrete vitamins into the food and improve nutritive value. Micro-organisms also hydrolyse polymeric compounds to produce substrates for cell growth, which may increase the digestibility of proteins and polysaccharides. 3.3 Enzyme Classification and Technology Enzymes in Food Processing 111 Emzyme Def: Enzymes are natural biological protein catalysts that speed up chemical reactions in molecules called substrates, converting them into other more diverse types of molecules. Importance of Enzymes in Food Processing Enzymes are essential for: 1. Producing key changes in functional properties of food 2. Removal of toxic constituents 3. Producing new ingredients 113 Characteristics of Enzymes Characteristics of enzymes that make them suitable to be used in food processing: 1. They are highly specific 2. Act at low temperature (25-45 °C) 3. Do not produce side reactions 114  Example: Production of high-fructose corn syrup and sweeteners; α-amylase glucoamylase glucose isomerase 𝑠𝑡𝑎𝑟𝑐ℎ → 𝑑𝑒𝑥𝑡𝑟𝑖𝑛𝑠 → 𝑔𝑙𝑢𝑐𝑜𝑠𝑒 → 𝑓𝑟𝑢𝑐𝑡𝑜𝑠𝑒 115  Enzymatic production of valuable compounds as additives in foods Enzymatic removal of undesirable compounds Current and potential Enzymes in milk and dairy uses of products (e.g. chymosin) enzymes on an industrial Enzymes in baking scale Enzymes in brewing Enzymes for control of microorganisms 116 Enzymes in Milk and Dairy Products  Enzymes in Milk and Dairy Products BOVINE milk CHYMOSIN Β- Β- contains many (rennet) used in galactosidase- galactosidase enzymes and production of commercial also converts other enzymes several kinds of hydrolysis of whey lactose to are added cheese lactose in milk glucose and during and dairy galactose processing products (for (sweeteners lactose with greater intolerance commercial individuals) demand) 11 8  In the baking world is the unique enzymes found in yeast that speed up the breakdown in starch to produce sugar when activated. During the proofing of dough, this process begins, and then as the dough is heated, it fully activates. The enzyme most commonly used for processes like this and chemical reactions in other baked goods are called amylases. You can find this in almost every dough conditioning solution on the market. Amylase enzymes are most commonly used to produce sugars and certain types of syrups from starch, while protease enzymes are most commonly used to lower the protein level in flours like wheat flour. The baking industry has learned to harness these two enzymes through scientific study and experimentation and to manipulate them to play distinct roles in baking technology. These manipulated enzymes are called conditioning solutions and are often combined with other enzymes and ingredients No Enzyme Functions 1 FUNGAL ALPHA AMYLASE 1. Enhances Fermentation Food grade alpha amylase from a fungal origin Process used specifically in the baking industry. 2. Improves Bread Volume 3. mproves Crumb Texture 2 LIPASE 1. Increases Dough Tolerance Lipase enzymes for the baking industry can 2. Improves Loaf Volume replace chemical based dough improvers. 3. Decreased Stickiness 3 Proteases 1. massive impact on the physical break down proteins into smaller peptides and properties of Gluten amino acids. 2. enzyme softens the dough, 3. assures uniformity of bread dough, 4. controls bread texture, and 5. brings a significant improvement in its flavor. 4 Pentosanases 1. increased volume The water-binding capacity of Pentosanases is 2. offset the negative effects of destroyed by Hemicellulases which in turn results in insoluble Pentosans there in the dough softening. flour. ENZYMES IN BREWING INDUSTRY Sugar formation The majority of sugars used in the brewing process come from starches that are derived from the malted barley used in the mashing process. During the malting process, maltsters trick the barley kernels into thinking it’s time to sprout by soaking them and getting them to spring into action. This germination process loads the grains with the carbohydrates and enzymes necessary to help the grain grow until it comes out of the ground and can start producing energy via photosynthesis. Microbial Enzymes Microorganisms have been used in food fermentation since ancient times and fermentation processes are still applied in the preparation of many of the food items Enzymes Production from Microorganisms The requirements of commercial enzyme production from microorganisms are as follows: micro-organisms must grow well on an inexpensive substrate substrates should be readily available in adequate quantities, with a uniform quality micro-organisms should produce a constant high yield of enzyme in a short time methods for enzyme recovery should be simple and inexpensive the enzyme preparation should be stable 129  Limitations of Enzyme Immobilisation The main limitations are: the higher cost of carriers, equipment and process control changes to the pH profiles and reaction kinetics of enzymes loss of activity (25–60% loss) risk of microbial contamination 130 Conclusion ? 132