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Unformatted text preview: © E.Garcia 2010 FST 1 – Main topics – Lecture 09 Food and Microorganisms ‐ Food Spoilage ‐ Foodborne Illnesses (Pathogens, disease‐causing microorganisms) ‐ Probiotics (“friendly bacteria” ‐ Food Preservation (Fermented products) Probiotics: “Live microorganisms which when administered in adequate amounts confer a health benefit on the host”(World Health Organization, WHO). Ex.: some Lactobacillus and Bifidobacterium Potential health effects: ‐ Help maintain the natural balance of microorganisms in the gut ‐ Resistance to pathogens ‐ Relieve antibiotic induced diarrhea, among others In a broad sense, “food fermentations” refer to changes of food properties caused by living microorganisms (yeasts, molds, bacteria). Processes that depend on growth of microorganisms using carbohydrates as their main source of nutrients. In Biochemistry, fermentation has a more strict definition. Food Fermentation: ‐ one of the oldest food preservation methods ‐ known since the dawn of civilization ‐ earliest records date back to 6000 BC ‐ applied to the preservation of milks, meats, and vegetables ‐ Traditional knowledge transmitted from generation to generation ‐ Originally, small quantities of fermented foods locally produced ‐ By mid 1800s two events affected the way fermented foods were produced: the Industrial Revolution and developments in Microbiology 1850 Louis Pasteur demonstrates that living organisms cause lactic and alcoholic* fermentations. * see Readings Microbiology is “born” Late 1600s Robert Hooke and A. van Leeuwenhoek observed microscopic organisms using a crude microscope. Hooke published a book on the structure of a microscopic fungus (first illustrated book on microscopy). Food Fermentations result in the development of food products with ‐ better keeping qualities than original raw ingredients ‐ desirable/pleasing sensory qualities: taste, smell, texture, carbonation ‐ increased food variety ‐ products can be more nutritious (ex.: ↑ B vitamins); decrease of toxic components (ex.: cyanogens in cassava roots) A large variety of microorganisms participates in food fermentations. A few are widely used: ‐ Yeast: Saccharomyces cerevisiae (Baker’s yeast) ‐ Lactic Acid Bacteria (LAB); such as Lactococcus lactis and Streptococcus thermophilus Examples of fermented foods: Raw material Wheat Cabbage Milk Soybeans Product Microorganism(s) Bread Sauerkraut, Kimchi (Korea) Yogurt Cheese Soy sauce Yeasts & some bacteria Bacteria (LAB) Bacteria (LAB) LAB ; in some cheeses also yeasts and/or molds Mold, yeast, some LAB Readings 1. McGee p.291‐292 (Fermentation and Pickling) 2. McGee p.531‐532 (Yeasts) 3. McGee p. 715‐716 (Yeasts and Alcoholic Fermentation) 4. McGee p. 771‐773 (Vinegar; Acetic Fermentation) 5. McGee p. 44‐45 (Lactic Acid Bacteria) ...
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This note was uploaded on 08/16/2011 for the course FST 001 taught by Professor Charlesf.shoemaker during the Winter '10 term at UC Davis.
- Winter '10