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Food Microbiology, food poisoning and food born diseases notes
- 2. A Brief History ? Early Food Preservation ? 900 AD – “Food Poisoning” Recognized ? 1795-Appert Developed Canning ? 1854-1864-FOOD MICROBIOLOGY BECOMES A SCIENCE
- 3. Why Study Food Microbiology? ? Provide Clean, Safe, Healthful Food to Consumer ? Food Permits Growth ? Control of Microbial Growth ? Prevent Food Spoilage ? Prevent Food-borne Illnesses ? Food Preservation and Production
- 4. Food-Borne Illness ? Estimated burden of food – borne illnesses – $6.9 Billion/Year Cost of FBI ? CDC Estimates – 76 Million Cases of FBI Annually – 325,000 Hospitalizations – 5,000 Deaths
- 5. Common symptoms of food born illnesses ? Nausea ? Vomiting: ? Diarrhea: ? Abdominal cramps: ? Fever ? Headache ? Muscle aches ? Fatigue ? Dehydration ? Other symptoms: chills, weakness, dizziness, and in severe cases, organ damage or neurological symptoms
- 6. Agents of Disease (Foodbourne Pathogens) BACTERIA – E coli – Salmonella spp., – Vibrio cholera, – Bacillus cereus, – Clostridium botulinum, – Listeria monocytogenes, – Staphylococcus aureus VIRUSES – Enteroviruses, – Norwalk virus, – Hepatitis virus PROTOZOA – Giardia lamblia, – Cryptosporidium parvum, – Entamoeba histolyticum, – Cyclospora cayetanesis HELMINTHS – Tapeworms (Beef, Fish and Pork), – Flukes (Fish and Shellfish), – Roundworms and Hookworms
- 7. Public health impact of food born illnesses ? Healthcare Burden: ? Economic Costs: ? Morbidity and Mortality: ? Public Awareness and Concern: This can lead to avoiding certain foods or brands, and increased demand for food safety regulations and oversight. ? Social Disruption: closures of food establishments, ? Long-Term Health Impacts: foodborne bacteria can lead to reactive arthritis, kidney failure, or neurological disorders in susceptible individuals. ? Global Health Security: outbreaks (COVID 19) often crossing international borders through the global food supply chain.
- 8. What Organism Causes the Most Cases of Food-Borne Illness Annually? Campylobacter
- 9. What Organism Causes the Most Deaths Due to Food- Borne Illness? Salmonella
- 10. Intrinsic and Extrinsic Factors ? Intrinsic – pH – Moisture Content – Oxidation-reduction Potential – Nutrient Content – Antimicrobial Constituents – Biological Structures
- 11. pH ? Effects of pH – Enzymes – Nutrients ? Other Environmental Factors – Temperature – Salt – Age ? No known pathogen grows below pH of 4.6 – Clostridium botulinum
- 12. Moisture ? Remove and/or Bind Moisture – Humectants – Dehydration ? Water Activity – Aw ? Most Fresh Foods - Aw > 0.99 0 1 Pure water No water
- 13. Microbial Growth and Aw ? Halophilic 0.75 ? Xerophilic molds 0.61 ? Osmophilic yeasts0.61 ? Lowest Aw for Pathogen Growth – 0.86 – Stapholococcus aureus
- 14. Oxidation- Reduction Potential ? O/R Potential - Eh – “…ease with which the substrate loses or gains electrons.” ? Loss of electrons – oxidized ? Gain of electrons – reduced ? Aerobic ? Anaerobic ? Microaerobic ? Facultative anaerobes
- 15. Others ? Nutrients – Fastidius vs non-fastidious ? Biological Structure ? Antimicrobial Factors – Naturally occurring factors
- 16. Extrinsic Factors ? Temperature ? Relative Humidity ? Gases in the Environment ? Presence of Other Microorganisms
- 17. Temperature ? Microorganisms grow over a wide range of Temperatures ? Psychrotrophs are microorganisms capable of growth at low temperatures, typically between 0°C and 20°C. ? Mesophiles are microorganisms that thrive at moderate temperatures, usually between 20°C and 45°C, including many human pathogens. ? Thermophiles are microorganisms adapted to high temperatures (between 45°C-80°C). often found in hot springs and deep-sea vents. ? Psychroduric - survive at low temperatures but do not necessarily grow or reproduce under such conditions. ? Thermoduric - survive exposure to high temperatures, even though they may not necessarily thrive or grow well under those conditions.
- 18. Other Factors 1. Relative Humidity of Environment – Can change the Aw – Water activity (Aw) is a measure of the amount of water available for microbial growth and chemical reactions within a food product.
- 19. Environmental Gasses ? Oxygen: promotes aerobic microorganisms and spoilage by oxidation. ? Carbon Dioxide. elevated levels can inhibit the growth of aerobic spoilage organisms and slow down enzymatic reactions, However, excessive carbon dioxide levels can also lead to undesirable changes in texture, flavor, and appearance of food products. ? Nitrogen (N2): often used in modified atmosphere packaging to displace oxygen and create an anaerobic environment, which inhibits the growth of aerobic spoilage microorganisms and slows down oxidative reactions. ? Ethylene (C2H4): a natural plant hormone produced by some fruits and vegetables as they ripen. does not cause food spoilage, it can accelerate the ripening and senescence of certain fruits and vegetables, leading to faster deterioration and shorter shelf life if not controlled properly during storage and transportation. ? Sulfur Dioxide used as a preservative in dried fruits and wine to inhibit microbial growth and prevent oxidation. It can also have antimicrobial and antioxidant effects, helping to extend the shelf life of certain food products.
- 20. Presence of Other Microorganisms ? Competitive Exclusion: one species outcompetes another species for nutrients or space, leading to the suppression or elimination of the less competitive species. ? General Microbial Antagonism: inhibition or suppression of microbial growth by one microorganism against another; through production of antimicrobial compounds (bacteriocins), competition for nutrients or space, and alteration of environmental conditions. ? Lactic Acid Antagonism: inhibitory effect exerted by lactic acid bacteria (LAB) against other microorganisms. In fermented products such as yoghurt,
- 21. Other apllications of bacteria in food microbiology ? Microbes that we can exploit ? Bacteria—cheese, yogurt, vinegar, ? Yeasts—bread, beer, liqueurs, wine ? Molds—cheeses ? Bacteria in agriculture Rhizobium spp: ? Nitrogen fixation in root nodules of legumes ? Bacteria used in engineering produce that is resistant to adverse environmental conditions, pests pathogens and spoilage