23: Food and Industrial Microbiology Notes

Food Spoilage and Preservation

• Microbes have always been a factor in food storage and consumption.
• Food spoilage refers to microbial changes that make a product unfit or unpalatable.
• Food contamination (food poisoning) refers to the presence of human pathogens.

Food Preservation Strategies

• Eat fresh food before microbes can spoil it.
• Preserve extra food before microbial spoilage occurs.
• Heat Treatment:
  • Pasteurization: Quick heat to kill most microbes (Louis Pasteur originally experimented with beer, not milk).
  • Sterilization via Heat:
    • Cooking: Kills all microbes.
    • UHT (Ultra-High Temperature) or pressure-cooking (autoclave) for canning.
• Remove Excess Water:
  • Drying, salting, concentrating sugars.
• Use Acids:
  • Vinegar, lactic acid, citric acid.

Food Preservation - Impact of Temperature and pH

• Temperature Effects:
  • The provided graph (Part A) illustrates the relationship between storage temperature and microbial population growth (log₁₀ CFUs/g) over time (days).
  • Lower temperatures (0°C, 2°C, 4°C, 6°C) result in slower microbial growth compared to higher temperatures.
  • A