FOOD MICROBIOLOGY

• Seafood is easily perishable.
• Adverse effects from synthetic preservatives.
• Microorganisms are organisms such as bacteria, parasites, viruses, yeasts, and molds that are usually too small to be seen by the naked eye.
• Microorganisms in food come from soil & water, plants/products, utensils/equipment, gastrointestinal tract, food handlers, animal feeds, animal hides, air & dust, and everywhere else.
• Factors affecting microbial growth in food include pH, presence and availability of water, presence of antimicrobial substances, temperature, relative humidity, atmosphere, and more.
• Psychrophiles grow from 1-20°C, examples include Pseudomonas, Flavobacterium, Alcaligenes.
• Psychrotrophic bacteria grow best at 37°C, but can grow at refrigeration (3-7°C), example Listeria monocytogenes.
• Mesophiles have an optimum temperature between 20-40°C, and contain most human pathogens, examples include E. coli, Salmonella, Clostridium botulinum.
• Thermophiles have an optimum temperature above 45°C, example Bacillus stearothermophilus.
• The optimal pH for bacterial growth is 6.0 – 8.0, with disease causing bacteria having a range of 4.6 - 9.5, and spoilage bacteria having a range of 1.5 - 9.5.
• Bacteria can survive in a pH range of 0 - 14, with Vibrio spp., Campylobacter spp., Molds, Yeasts, Lactic Acid Bacteria, Staphylococcus aureus, Salmonella spp., Escherichia coli all growing in specific pH ranges.
• Bacteria can survive in temperatures lower than 5°C/41°F, but will cease to multiply and may be damaged by freezing.
• Listeria monocytogenes cause Listeriosis.
• Microorganisms with a Water Activity (Aw) between 1.0-0.95 are Bacteria.
• Infection occurs when microorganisms are ingested and then cause illness.
• Common foodborne pathogens include E. coli 0157:H7, Salmonella spp., Staphylococcus aureus, Listeria monocytogenes, Campylobacter jejuni, Shigella spp., Norovirus, Rotavirus, Hepatitis A, Cryptosporidium parvum, Giardia lamblia, Cyclospora, and Bacteria.
• Microorganisms with a Water Activity (Aw) between 0.95-0.91 are Bacteria.
• Intoxication occurs when toxins are produced by the pathogen, usually in the food.
• E. coli 0157:H7 causes hemorrhagic colitis.
• Clostridium botulinum cause Botulism.
• Microorganisms with a Water Activity (Aw) between 0.30-0.20 are No microorganisms.
• Spoilage microorganisms cause a food to smell, taste, and look unacceptable.
• Microorganisms with a Water Activity (Aw) between 0.87-0.80 are Molds.
• Water Activity (Aw) is a measure of the ability of water to exist in a material.
• Salmonella spp. cause Salmonellosis.
• Pathogenic, or disease causing, microorganisms can cause illness.
• Fermentation microorganisms produce a desired food product.
• Prevention of foodborne illness includes cooking, avoiding cross-contamination, chilling foods, cleaning, and personal hygiene.
• Illness mechanisms include infection and intoxication.
• Campylobacter jejuni cause Campylobacteriosis.
• Staphylococcus aureus cause Staphyloenterotoxicosis.
• Bacteria can survive in temperatures higher than 57°C/135°F, and will die if heated for a sufficient time.
• Some bacteria can double every 20 minutes under optimal conditions.
• The colder the storage temperature, the longer the potential shelf-life of food.
• Potentially hazardous foods should not remain in the danger zone (10-60°C/50-140°F) for more than 4 hours during the entire food handling process.
• Bacteria are reproduced by division and referred to as “growth”.
• Under optimal conditions, some bacteria can double every 20 minutes.
• Yogurt aids absorption of minerals, especially calcium, due to increased intestinal acidity.
• Other microbes are used to make special breads such as sourdough bread.
• Fermentation in food processing is the conversion of carbohydrates into alcohols, carbon dioxide or organic acids by yeast, bacteria or combinations of both.