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TAMU FSTC 326 - Food Microbiology Test 1

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I. Microbiology - The study of “small life.”A. Bacteria: Eubacteria,1. Eubacteria – Proteobacteria, Gram-negatives2. ArchaebacteriaB. Viruses1. Virology – study of viruses2. Enteric human pathogenic viruses (e.g., Noroviridae)C. Fungi:Molds,Yeast1. Mycology – study of fungiD. Protozoa – parasitology1. Parasitic protozoa (e.g., Toxoplasma, Cryptosporidium)2. Nematodes, trematodes (e.g., Taenia - tapeworm, Anisakis - sushi, Trichina – cause of trichinosis; consuming undercooked meat)E. OthersII. Bacteria: Small, unicellular organismsA. Structural Characteristics:1. Cell wall & outer membrane2. Unicellular organisms unique from other microbes3. Cytoplasmic space/membrane4. Size: Approximately 0.5-2.0 micrometers (10^-6 m)5. No well-defined nuclear envelope/membrane6. One circular chromosome7. Binary Fission/Geometric Replication8. Asexual reproduction, geometric replicationB. Life Cycle/Phases of Growth: ***** KNOW THESELag phase – beginning of the population when an organism moves into a new area; organism must identify sources of water & chemical nutrientsLog phase – also known as exponential phase; orgs go 10, 100, 1000, etc; very rapid growth to where the organisms can double, triple, etcStationary phase – growth slows down; has defect (spoilage) – spoiled food = a few billion cells in the organismC. Composition1. Water: Primary component of cells (~70%)2. Remainder:a. Proteins, Polypeptidesb. Carbohydrates/Sugars – bacteria import carbohydrates; ferment / utilize monosaccharide (glucose); some can ferment disaccharides (lactose);c. Lipids – energy extraction (as carbon sources) & formation of membrane lipidsd. Minerals – useful to stabilize LPS of bacteriae. Nucleic Acids: DNA, RNA – can be used to classify organisms; plasmid – small circular piece that is useful for inserting genes to have an organism express a protein from, make outer membrane more permeable, naturally occurring, how bacteria share genetic material through horizontal transferIII. Food Microbiology: The Good, Bad, and UglyA. Fermentation: Produces foods not otherwise possible! ;; fermentative microbes = the good; yield energy (ATP); highly controlled spoilage1. Fermentation: controlled, desirable spoilage2. Microbial conversion of food components into other compounds3. Sugars – acids, gases, EtOH4. Proteins – smaller peptides, ammonia, biogenic amine5. Lipids – fatty volatiles (e.g., propionic acid)B. Pathogens: Microbial agents causing disease once consumed or after secretion of toxic substance into food that is consumed ;; the bad; disease-causing1. Infection: invasion and replication in body2. Intoxication: pre-formed toxin consumed3. Toxico-infection: release of toxin by organism during GI tract passage4. Pathogen Types & Examples:a. Bacterial (Listeria monocytogenes, Salmonella (cannot ferment lactose – main difference between this and ecoli, can replicate in epithelial cells particularly in vacuoles), Clostridium botulinum), Staph – enterotoxin; enteric / entero = gut, GI; shigatoxin – protein toxin that will contact your kidneys through your blood stream to inhibit kidney replication which leads to program cell deathb. Fungal (Aspergillus spp., Fusarium spp.)c. Protozoal (Toxoplasma gondii, Giardia lamblia)d. Viral (Noroviruses, Hepatitis A)e. Nematodes/Trematodes (Trichina spiralis)5. Significance of differing pathogen types and disease6. Bacterial, fungal, viral7. Disease syndromes8. Mild gastroenteritis to death9. Parasitic organismsC. Spoilage: Food made undesirable via microbiological/enzymatic breakdown ;; the ugly1. Renders food undesirable to consume2. Uncontrolled fermentation of food3. Breakdown of lipids, proteins4. Fermentation of carbohydrates5. Production of off-flavors, colors, gases, softening of tissue, etc.6. Extent of spoilage based somewhat on extent to which food is made undesirable7. Certain foods desirable to some consumers and completely undesirable to others8. Spoilage of foods can help protect consumer health by preventing consumption of possibly unsafe food9. Subjective process – spoiled to you may be delicacy to anotherIV. Important Historical Figures and Dates in Food Microbiology (pg. 3-8)A. Food Gathering (Pre-8000 BC): Foods typically eaten raw; trial and error on which foods were safe to eat and which were not.1. Many foods eaten raw2. Little / no organized husbandry of animals, plants thought to have occurred3. Some trial / error in food consumption, safetyB. Food Producing/Preserving (To Present): Foods grown and animals, plants domesticated; foods are processed to enhance safety and quality/shelf stability ; advent and early development, mastery of animal, plant husbandry (breeding); use of heat for food preservation (fire, boiling water)1. Boiling2. Brewing of beer (China, 7000 BC)3. Wine (Noah, Genesis 9:20)4. Food storage in cool environments (preservation via reduced temperature storage)5. Animal and plant husbandry/breeding6. Fermentation of milk to cheese7. Use of antimicrobials/salt/fermented acids to preserve foods (e.g., fish, meat)8. Low temperature storage/freezing in snow so it is dehydrated (dried)C. Recent history and accomplishments in food preservation1. 1680 - Antonie van Leeuwenhoek - Identifies microorganisms, doesn’t understand role in food spoilagea. Father of microbiologyb. Discovers microorganisms – calls them “animalcules” (probably yeast cells or some other microbe)c. 1677 – Royal Society of London (first description of what was most likely bacteria)d. Built microscopes on the side; microbiologist wasn’2. 1810 - Nicholas Appert - develops first procedure for canning of foods to preserve foods for Bonaparte’s armya. Confectioner and food preparer, Franceb. Canning process designed to thermally stabilize foods after packagingc. IFT: Nicholas Appert Medal (the food scientist’s Nobel)3. 1860 - Pasteur - Identifies link between microbes and food spoilage; demonstrates thermal processing ability to preserve foodsa. Researched microbial spoilage of foods (beer, wine, beef broths)b. Refuted spontaneous generationc. Early descriptions of lactic and ethanol fermentation by fungi, fermentative bacteria4. 1880 - Commercial refrigeration introduced5. 1910 - Refrigerated transport allowing cross-country shipping of produce6. 1930 - Birdseye release frozen display cases for retail sale7. 1943 - Hamburger irradiationD. Significant pieces of food processing/safety-related legislation1. Ancient


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