Mod. 9.docx

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Food, Nutrition and Health
FNH 200
Nooshin Alizadeh- Pasdar

MODULE 9: Food Preservation with Biotechnology Terms  biotechnology - fermentation, plant and animal breeding, cell and tissue culture, genetic engineering (Health Canada) - utilized microorganisms and cultured animal and plant tissue cells and cell components in production of desired food products  fermentation = anaerobic and aerobic breakdown of carbohydrates and carbohydrate- like materials by microorganisms; fermented foods produced with aid of microorganisms; not genetically engineered  genetic engineering  aerobic, anaerobic  microbial antagonism  antimicrobial agents  starter cultures  rennin = enzyme in gastric juice; causes milk coagulation  chymosin = principle milk-clotting enzyme in bovine rennet extracts  rennet = complex enzymes produced in mammalian stomach; cheese production  cheddaring  curd = fatty part; becomes cheese, whey = watery part of milk  lactid acid bacteria = cheese starter culture  Propionibacterium shermanii = swiss cheese  Streptococcus thermophiles = swiss cheese  Penicillium roquefortii = veined blue cheese  Penicillium camembertii = camembert cheese  Penicillium candidum = camembert cheese Microorganisms in Food Preservation * microorganisms used in fermentation are “good” – beneficial effects in food due to their growth and metabolism in foods * microorganisms sources of enzymes and flavoring ingredient in fermentation  Fermented food products - beverages – wine, beer, sake - dairy products – yogurt, cheese - meat products – salami, prosciutto, bologna - traditional foods – soy sauce, miso, sauerkraut  Ingredients and additives - amino acids - biopolymers - enzymes - vitamins Preservation principle  Encouragement of growth and metabolisms of alcohol and acid-producing microorganisms to suppress growth and metabolic activities of proteolytic, lipolytic, spoilage-causing microorganisms = microbial antagonism  Microorganisms cultured in foods produce end products (acids, alcohols) = antimicrobial agents Benefits of fermentation * fermented foods more nutritious than unfermented; add variety to food supply  Mould fermented foods synthesize vitamin B  Microorganisms liberate nutrients from plants that are normally indigestible  Enhance nutritional value of foods by microbial hydrolysis of cellulosic materials indigestible by humans  Lactic acid bacteria – pickles, olives, vanilla, coffee beans, yogurt  Acetic acid bacteria – oxidize ethanol to acetic acid (vinegar)  Yeasts – alcoholic beverages, breads  Moulds – cheeses, miso, soy sauce Microbial changes in fermented foods  Lactic acid bacteria: lactose, glucose => lactic acid  Yeasts: glucose, other carbs => ethanol  acetic acid bacteria: ethanol => acetic acid  microbial lipases: lipids => free fatty acids, aldehydes, ketones  microbial proteinases: proteins => polypeptides, peptides, free a.a., amines  mould cellulases: cellulose => oligosaccharides, glucose Controlling fermentation in foods 1) acids  add acids or lower pH or encourage growth of acid-producing microorganisms  milk, meat: starter culture lactic acid-producing bacteria  cheese, yogurt, fermented sausages must be refrigerated to delay growth of acid-tolerant psychrotrophic yeasts and moulds 2) alcohol  preservative in sufficient concentrations 3) starter cultures  grown under specific conditions and harvested cells added in specific proportion to food to be fermented 4) temperature  important factor in controlling type of microorganism that grows during fermentation 5) oxygen  may be desirable or undesirable; different requirements for diffe
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