General Principles of Food Processing and Preservation

GENERAL PRINCIPLES OF FOOD PROCESSING AND PRESERVATION

Instructor Information

  • Instructor Name: Maristel D. Abelong
  • Institution: Northwest Samar State University
  • Year: 2009

LEARNING OBJECTIVES

  1. Define food processing and food preservation according to the Institute of Food Technologists (IFT).
  2. Differentiate the major classifications of food processing methods:
    • Thermal preservation
    • Non-thermal preservation
    • Non-preservation processes
    • Separation processes
  3. Explain the principles of food preservation, including:
    • Prevention of microbial growth
    • Self-decomposition
    • Chemical reactions
  4. Identify the conditions necessary for microbial growth that lead to food spoilage (FAT TOM).
  5. Describe the different methods of food preservation such as:
    • Chemical methods
    • Biological methods
    • Physical methods
  6. Classify given food processing techniques according to their appropriate category.

FOOD PROCESSING

  • Definition:
    • Food processing involves converting raw ingredients into food products through various methods to create value-added ingredients and processed foods aimed at business-to-business sales, food service establishments, retail outlets, and home consumption (Institute of Food Technologists).
  • Major Classifications of Food Processing Methods:
    • Thermal Preservation
    • Non-Thermal Preservation
    • Non-Preservation Processes
    • Separation Processes

THERMAL PRESERVATION

  • Definition:
    • Processes that employ heat to make food safe for consumption and/or to extend shelf-life by reducing or eliminating microbiological contamination and enzymatic activity.
  • Examples of Thermal Preservation Methods:
    • Cooking/Heating
    • Drying
    • Ultra-high heat
    • Smoking
    • Radiofrequency
    • Canning
    • Heating Treatment
    • Pasteurization
    • Infrared Heating
    • Direct Steam Injection

NON-THERMAL PRESERVATION

  • Definition:
    • Processes that make food safe for consumption and extend shelf life using alternative technologies without heat to reduce/eliminate/inactivate microbial contamination.
  • Examples of Non-Thermal Preservation Methods:
    • High Pressure Processing (HPP)
    • Membrane Filtration
    • Irradiation (e.g., UV-C)
    • Fermentation
    • Aseptic Processing & Acidification
    • Modified Atmosphere
    • Packaging/Storage
    • Freezing

NON-PRESERVATION PROCESSES

  • Definition:
    • Processes that modify the size or state of food products without extending shelf life.
  • Examples of Non-Preservation Processes:
    • Homogenization
    • Cutting/Chopping
    • Emulsification
    • Rolling/Sheeting
    • Shredding
    • Slicing
    • Milling
    • Grinding

SEPARATION PROCESSES

  • Definition:
    • Processes that remove components from food or beverages.
  • Examples of Separation Processes:
    • Centrifugation
    • Sorting
    • Coagulation
    • Thermal Crystallization
    • Concentration & Evaporation
    • Filtration & Separation (including membranes)

PRINCIPLES OF FOOD PRESERVATION

  1. Prevention or Delay of Microbial Decomposition of Food
    • Definition of Asepsis:
      • Keeping out microorganisms by natural or artificial coverings around the food.
      • Natural Barriers: Outermost shells of nuts, skin/peel of fruits and vegetables.
      • Artificial Coverings: Packaging materials like tin cans, plastics, etc.
  2. Prevention or Delay of Self-Decomposition of Food
    • Blanching: A mild heat treatment done before canning, drying, or freezing to inactivate enzymes that can lead to food self-decomposition.
  3. Prevention or Delay of Chemical Reactions
    • Addition of appropriate quantity of antioxidants in food to prevent oxidation and maintain quality.
  4. Prevention of Damage by Insects, Animals, Rodents, and Mechanical Causes
    • Use of fumigants in dried fruits to mitigate damage caused by pests.

METHODS OF FOOD PRESERVATION

CHEMICAL METHODS
  • Principle: Use of chemical preservatives.
  • Examples of Chemical Preservatives:
    • Benzoate
    • Sulfites
    • Sorbic Acid
    • Vitamin C
    • Nitrites
    • Nitrates
BIOLOGICAL METHODS
  • Principle: Use of natural antimicrobials and microorganisms.
  • Examples of Biological Methods:
    • Alcoholic Fermentation
    • Acetic Acid Fermentation
    • Lactic Acid Fermentation
PHYSICAL METHODS
  • Principle: Decrease in temperature or increase in temperature to inhibit microbial growth.
  • Methods of Preservation:
    • Cooling Methods: Refrigeration, freezing
    • High-Temperature Methods: Cooking, pasteurization, sterilization
    • Other Physical Techniques: Dehydro-freezing, carbonation
NON-THERMAL METHODS
  • Principle: Removal of water or lowering water activity.
  • Methods of Preservation:
    • Drying, dehydration, freeze concentration, reverse osmosis, freeze-drying
    • Irradiation techniques such as UV rays and gamma radiations
    • High-pressure processing, pulsed electric fields, microfiltration, aseptic processing and filling

CONDITIONS NECESSARY FOR MICROBIAL GROWTH (FAT TOM)

  • Food: Nutrient source, especially high in carbohydrates and proteins
  • Acid: Optimal pH range (4.6-7.0) for microbial growth
  • Temperature: Danger Zone (5-60°C) for potential spoilage
  • Time: Exposure over 4 hours increases spoilage risk
  • Oxygen: Availability allows aerobic microorganisms to thrive
  • Moisture: Water activity level greater than 0.85 promotes microbial growth.