Comprehensive Notes on Food Deterioration and Preservation

Food Deterioration and Preservation

Types of Food Deterioration

  • Physical Deterioration

    • Adverse changes in sensory properties (taste, texture), nutritional value, safety, and aesthetic appeal.
    • Includes phase separation, undesired drying, loss of structure, and damage due to handling.

  • Chemical Deterioration

    • Undesired chemical reactions, such as enzymatic action and lipid oxidation.
    • Example: Lipoxigenase catalyzes lipid oxidation which can affect food quality.

  • Biological Deterioration

    • Microbial growth leading to food spoilage.
    • Example: Spoilage of milk where pasteurization fails to eliminate all spoilage bacteria, resulting in curdling and souring due to bacterial activity.

Major Causes of Food Deterioration

  1. Microorganism Activity
    • Growth of bacteria, yeasts, and molds causing spoilage and safety issues.
  2. Endogenous Enzyme Activity
    • Reactions within the food itself affecting quality.
    • Example: Polyphenol oxidase catalyzes enzymatic browning in fruits and vegetables.
  3. Infestation by Pests
    • Insects and rodents can contribute to food loss, with significant impact in certain regions.
  4. Improper Temperatures
    • Heat and cold can lead to quality degradation (e.g., chill injury in certain fruits below 10°C).
  5. Moisture Changes
    • Controlled by humidity and packaging; improper moisture levels can lead to spoilage.
  6. Oxygen Reaction
    • Nutrient oxidation (e.g., vitamins A and C) and mold growth.
  7. Light Exposure
    • Induces reactions leading to quality loss, such as oxidation.
  8. Physical Stress
    • Rough handling or damage can accelerate deterioration.
  9. Time
    • Each food product has a specific timeframe for optimal quality.

Controlling Food Deterioration

  • Multiple forms of deterioration can occur simultaneously.
  • Effective preservation methods target all factors to minimize spoilage, vital for:
    • Seasonal produce.
    • Long time/distance between production and consumption.
    • Rapidly deteriorating foods (e.g., strawberries).

Food Preservation Techniques

  • Heating
    • Methods: Blanching, Pasteurization, Canning.
  • Refrigeration and Freezing
  • Dehydration/Drying
  • Acidification
  • Fermentation
  • Smoking
  • Controlled Atmosphere Packaging
  • Chemical Preservation

Technologies for Food Preservation

  • Heating (Thermal Processing)
    • Crucial for initiating shelf-life extension.
  • Freezing
    • Widely used to preserve food while maintaining quality.
  • Dehydration
    • Removes water to inhibit microorganism growth.
  • Acidification
    • Higher acidity extends preservation (e.g., pickling).
  • Fermentation
    • Utilizes microbial growth to change food properties and enhance safety.
  • Smoking
    • Eliminates surface bacteria and generates unique flavors.
  • Controlled Atmosphere
    • Modifies gas composition around the food to extend shelf life.

Chemical Preservatives

  • Definition: Naturally occurring or synthetic substances aimed at preventing microbial growth or chemical changes.
  • Types of Chemical Preservatives
    • Traditional (Salt, Sugar).
    • Acidulants (Benzoic acid, Sorbic acid).
    • Gaseous (SO₂, CO₂).
    • Antioxidants (Vitamin E, Ascorbic acid, BHT).
    • Antimicrobial Peptides (e.g., Nisin).

Emerging Food Processing Technologies

  • Aim to reduce time and energy during processing while preserving quality.
    • Non-thermal methods: Irradiation, high-pressure processing.
    • Novel thermal processes: Microwave heating, ohmic heating.

Relevant Higher-Level Courses

  1. Improving Food Security through Food Science and Technology (FABS 222)
    • Focuses on food quality and safety, post-harvest processing, and nutrition.
  2. Food Additives and Toxicants (FABS 323)
    • Examines various food additives and their safety and toxicity.