Saran's Learn Microbiology

  FOOD CONTAMINATION AND FOOD SPOILAGE FOOD CONTAMINATION Source of Contamination How Contamination Occurs Common Microorganisms Green Plants & Fruits Naturally on surface, damaged tissues, during harvesting & transport Molds (Penicillium, Aspergillus), Yeasts, Lactic acid bacteria, Bacillus Animals Skin, hair, intestines, hides, slaughter, milking, egg laying Salmonella, Staphylococcus, Streptococcus, E. coli Soil Contact with soil, unwashed vegetables, root crops, eggs, meat Clostridium, Bacillus, Mucor, Rhizopus, Actinomycetes Water Washing, cleaning, processing, contaminated ice E. coli, Shigella, Salmonella, Vibrio Sewage Leakage, irrigation of crops, water contamination Pathogens – E. coli, Salmonella, Viruses, Parasites Air Dust particles, ...

  FOOD PRESERVATION GENERAL PRINCIPLES OF FOOD PRESERVATION Method Key Concept Mechanism Examples Asepsis Prevent entry of microbes Hygiene, packaging, sealed containers, sterilized equipment Milk packaging, cheese making Removal of Microorganisms Reduce microbial load Filtration, centrifugation, washing, trimming Filtered juices, beer, milk clarification Anaerobic Conditions Absence of oxygen prevents aerobic microbe growth Vacuum packing, CO₂/N₂ flushing, oil layer Canned foods, pickles, vacuum-packed meat HIGH TEMPERATURE PRESERVATION Method Temperature / Condition Effect on Microbes Used In Pasteurization Low-Temperature, Long-Time (or Hold Pasteurization) : 63°C – 30 min/ High-Temperature, Short-Time (or Flash Pasteurization): 72°...