Unit 3: Food Preservation
Table of Contents
Basic Concepts of Food and Nutrition
- Food: Any substance, usually composed of carbohydrates, fats, proteins, and water, that can be eaten or drunk by an animal or human for nutrition or pleasure.
- Nutrition: The science of food and its relationship to health. It involves the study of nutrients, their action, interaction, and balance in relation to health and disease.
- Nutrients: Chemical components in food that are essential for the body to provide energy, build and repair tissues, and regulate life processes.
- Malnutrition: An imbalanced nutritional status resulting from a deficiency or excess of one or more nutrients (e.g., undernutrition or obesity).
- Health: A state of complete physical, mental, and social well-being, not merely the absence of disease. Good nutrition is a cornerstone of good health.
Classification of Food and Nutrients
Classification of Food
Foods can be classified in several ways:
- By Origin: Plant-based (cereals, fruits) vs. Animal-based (meat, dairy).
- By Chemical Composition: Carbohydrates (rice), Proteins (pulses), Fats (oils), Vitamins & Minerals (vegetables).
- By Function:
- Energy-giving: Carbohydrates, Fats.
- Body-building: Proteins.
- Protective/Regulating: Vitamins, Minerals.
Classification of Nutrients
- Macronutrients: Needed in large quantities.
- Carbohydrates: Main source of energy.
- Proteins: For growth, repair, and enzymes.
- Fats (Lipids): Stored energy, insulation, hormone production.
- Micronutrients: Needed in small quantities.
- Vitamins: For metabolic regulation (e.g., A, B, C, D).
- Minerals: For structure and regulation (e.g., Ca, Fe, I).
- Water: Essential for all bodily functions.
Food Preservation: Principles and Methods
Definition, Objectives, and Principles
- Definition: The science of treating and handling food to stop or greatly slow down spoilage (loss of quality, edibility, or nutritive value) caused by microorganisms or chemical changes.
- Objectives:
- To prevent microbial spoilage.
- To increase the shelf-life of food.
- To retain the nutritional value, texture, and flavor.
- To make seasonal foods available year-round.
- Principles:
- Asepsis: Preventing contamination (keeping microbes out).
- Inhibiting Microbes: Slowing or stopping the growth of microbes (e.g., by refrigeration, drying, or adding acid/sugar).
- Killing Microbes: Destroying microorganisms (e.g., by heating/canning, irradiation).
Different Methods of Food Preservation
- Refrigeration/Freezing: Low temperature slows down microbial growth and enzyme activity.
- Canning (Heating): Food is sealed in cans and heated to high temperatures (Pasteurization or Sterilization) to kill microbes.
- Drying/Dehydration: Removing water (lowering water activity) inhibits microbial growth. (e.g., dried fruit, milk powder).
- Use of Sugar (Sugaring): High sugar concentration (as in jams) draws water out of microbes by osmosis, killing them.
- Use of Salt (Salting/Curing): High salt concentration (as in pickles, cured meat) acts by osmosis, just like sugar.
- Use of Acid (Pickling): Low pH (high acidity) (e.g., using vinegar) inhibits the growth of most microbes.
- Smoking: The smoke contains chemicals (like formaldehyde) that act as preservatives and the heat dries the food.
- Chemical Preservatives: Using food additives (see Unit 4).
Preserved Products
This section covers common food products made using preservation techniques.
| Product | Type/Composition/Manufacture | Nutritional Aspects/Uses |
|---|---|---|
| Jam | Made from fruit pulp, sugar, and pectin. Boiled to a thick consistency. | High in sugar (energy), source of fruit fiber. Used as a spread. |
| Jelly | Made from fruit juice (strained, no pulp), sugar, and pectin. Boiled to a clear, firm gel. | High in sugar, but less fiber than jam. Used as a spread. |
| Marmalade | A jelly-like product that contains suspended slices of citrus fruit peel (e.g., orange). | Similar to jam/jelly, but with added fiber and flavor from the peel. |
| Sauces | Thick liquid (e.g., tomato sauce, soy sauce) made from fruits/vegetables, often with vinegar, spices, and sugar. | Used as a condiment to add flavor, moisture, and appeal to food. |
| Pickles | Preserved in a high-acid (vinegar) or high-salt (brine) solution. Can be fermented. | Low in calories, can be a source of probiotics (if fermented). High in sodium. |
| Squashes | Concentrated syrup made from fruit juice, sugar, and water. Must be diluted to drink. | Source of sugar (energy). Nutritional value depends on fruit juice content. |
| Syrups | A thick, viscous liquid consisting primarily of a solution of sugar in water. (e.g., maple syrup, corn syrup). | Used as a sweetener, topping. Very high in calories from sugar. |
Food Standards
These are quality marks and regulatory bodies in India to ensure the quality and safety of food products.
- ISI Mark: (Indian Standards Institution, now under BIS - Bureau of Indian Standards). A standard of quality for industrial products, including some food processing equipment and additives.
- Agmark: (Agricultural Mark). A certification mark for agricultural products, assuring they conform to a grade standard. (e.g., for spices, ghee, flour).
- FPO Mark: (Fruit Products Order). A mandatory mark for processed fruit products (jams, juices, pickles) to ensure quality and hygiene.
- MPO Mark: (Meat Food Products Order). A mandatory mark for processed meat and fish products.
- PFA: (Prevention of Food Adulteration Act, 1954). The former primary law in India to prevent the adulteration of food.
- FSSAI: (Food Safety and Standards Authority of India, 2006). The modern, overarching authority that has replaced the PFA and FPO/MPO. FSSAI is now the single reference point for all food safety standards and regulations in India.