NUFS100 Topic 3 Microbes in Food PDF
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University of Alberta
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Summary
This document provides a detailed overview of microbes, their growth factors, and types, including viruses, bacteria, yeasts, and molds. It explores the factors influencing microbial growth, such as pH, temperature, time, and oxygen, along with different types of microbes and their roles in foodborne illnesses.
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Microbes + growth factors in foods Main factors encouraging growth - Optimum external factors - Nutrient availability - Plant and animals support growth of microorganisms - pH - Pathogens can...
Microbes + growth factors in foods Main factors encouraging growth - Optimum external factors - Nutrient availability - Plant and animals support growth of microorganisms - pH - Pathogens can grow at pH between 4.6-9.0 - Foods dont exceed over pH of 7 (food is mostly acidic) - Temp - Danger zone encourages rapid growth of bacteria - Time - Double every 20 mins - Oxygen - Obligate aerobes - Surface growth - Microaerophilic - Prefer limited oxygen - Indifferent - Does not need and can live with or without - Facultative anaerobe - Grows in oxygen and can survive without - Obligate anaerobes - No oxygen plz - Aw - Microbes grow in a range between 0.6-0.85 - Exponential growth Types of microbes - Viruses - Food transports viruses between hosts - Remain in undercooked/raw food - HAV - Obligate pathogen (ONLYin human cells) - Found in human faeces - Found in contaminated raw/undercooked shellfish, fresh produce, and infected premade food - Heat and disinfectant resistant - Prevented by vaccination - Can cause liver disease - Norovirus - Found in contaminated raw shellfish, oysters, fresh produce, infected premade items - pread through contaminated surfaces (last for days to weeks) S - Very contagious - Can cause acute gastroenteritis, vomiting, diarrhea, stomach pain, stomach flu - Bacteria - Main source of foodborne disease - Spoilage AND pathogenic - Can be beneficial (probiotics) - Harsh conditions - Bacterial spores develop in response to unfavorable growth conditions - Vegetative bacteria are replaced by pseudodominant spores - Only germinate into vegetative state when conditions become favourable - Highly resistant: Thermoduric and acid-resistant - Therefore require longer processing time or higher heat - Most common bacterias are non spore forming pathogens (ie. ecoli, listeria, staphylococcus - Yeats - Spoilage organism - Fermentation - Cultures into bread, wine, bear, etc - Molds (fungi) - Grows in a structure calledmycelium - Replicate through spores calledconidiaand is visibleat the top replicating filament calledhyphae - Conidiasare dispersed through the air - Rhizoidshelp anchor the hyphae to food source - Most arespoilageorganisms - Can cause allergic reactions, respiratory problems, and health consequences - Produce poisonous substance calledmycotoxins - Parasites - Common types - Protozoan parasites: single cells eukaryotes - CRYPTOSPORIDIUM: obligate parasite causes gastrointestinal infections - Transmitted through water contaminated with feces - Obligate parasite protozoa are obligated to invade a species to use as host - Not commonly foodborne - Parasitic worms - TRICHINELLA SPIRALI: causes trichinosis in humans - Cause by consumption of undercooked/raw meat (esp pork) - Can be found in infected animals - eat must be cooked to an internal temperature of 68 to M kill it - Mostly found in raw/undercooked meat or seafood or raw fruits/vegetables - Transmitted by water or soil or through human contact (esp unhygienic practices) Microbial food spoilage - isible: mold V - Not visible: bacteria - Sometimes visible: yeast - Types of foodborne illness - Foodinfections - Ingestion of living pathogenic bacteria - Multiply in hosts organsafterconsumption - Ie. salmonella, listeria - Foodintoxications - Toxins arepre-formedby pathogenic microbes in food - Toxins may remain after cooking - Ie. clostridium b, staphylococcus, bacillus - Toxin-mediated infections - Caused by ingestion of large number of live pathogens - Release toxins in gastrointestinal tracts - Ex. clostridium p. Ecoli H7 - Top pathogens in canada - Norovirus - Highly contagious and causes gastroenteritis - Listeria monocytogenes - Causes listeriosis - Resistant to heat, salt, nitrite, low temp, acidity - Come from: smoked fish, raw milk, soft cheese. Premade meats, leafy greens - Salmonella - Causes gastroenteritis - Can form biofilms - Ecoli - Lives in cattles and other poultry - Causes kidney failure and bloody diarrhea - Staphylococcus - Produces toxin that cannot be destroyed by cooking - Campylobacter - Associated with IBS and reactive arthritis HACCP - Hazard, analysis, and critical control points - Globally applied food safety system Microbes in food - Foodborne illness from home - Cross-contamination - Inadequate cooking/cooling of foods - Inadequate reheating of leftovers - Food left too long at room temperature - Bacteria multiply rapidly within the danger zone (4-60c) - Food is not thaw at room temperature because of bacterial growth - Done in the fridge, cold water, or microwave - Germ study - 20% of foodborne illness comes from home - Germiest place is the refrigerator water dispenser GMP - ood manufacturing practices G - Hygiene - Prevent cc - Identification and control - SOPs PRPs - P rereq program - Foundation for HACCP to ensure that basic conditions essential for maintaining hygienic and safe environment in food are met CFIA - Responsible for food recalls PHAC - Responsible for surveillance of foodborne illnesses in canada Food fermentations and probiotics Fermentation - Process - Production of acid by the addition of nonpathogenic bacteria - Discouraged growth of pathogenic and spoilage organisms - Benefits - Preservation and distinct quality attributes of food - Fermentation products - Lactic acid, co2, ethanol - Types of fermentation - natural/wild/spontaneous fermentation is used in home/traditional fermentation - Microbe is indigenous to the food - Starter cultures - Used by food industry fermentations - Results in consistent product - Controlled microbial growth - Uses starter cultures - Encouraged to grow in controlled conditions Probiotics - Live bacteria that is beneficial for digestive health Prebiotics - Carbs as food for probiotics - Delivered as spores Gut microbiome - Microorganisms that live in your intestines - Gut health influences mental health, cardiovascular health, sleep physiology, weight management
