Food Preservation Methods: Fresh, Processed & More
Food Preservation Methods
Types of Food Based on Preservation
Fresh foods: Those for which no process has been implemented for further treatment or conservation, or to transform their appearance.
Perishable foods: These provide the taste for immediate consumption, or a short, very limited conservation time.
Non-perishable food: Dry consistency, lasting much longer. Presented in clean, unbroken containers, with adequate circulating air, they should be stored in remote locations without moisture and odors.
Processed food: Undergoes all activities that occur from the preparation of raw materials to their final destination.
Conditioned food: Gain control of the various physical, chemical, or biological reactions that take place in food.
Physical Methods of Preservation
Freezing, sterilization, and vacuum packaging are methods that prolong the life of foods by keeping their nutritional qualities, maintaining their aroma, flavor, color, and texture.
Heat Treatment
The aim is to ensure the destruction of all living microorganisms that can impair food quality or injure the consumer’s health.
- Steaming: Steam is performed with water or hot water, at a temperature of 85-95°C for 5 minutes. The objective is to facilitate subsequent processes.
- Pasteurization: Takes place mainly at temperatures below 100°C, between 65 and 75°C, for 20 to 30 minutes. It is then rapidly cooled to 4°C.
- Sterilization: A temperature of 115-120°C is applied for 10 minutes.
Application of Cold
- Cooling: Temperatures between 0 and 4°C. Foods are kept in refrigeration.
- Freezing: -18°C. The process must be done quickly to prevent the formation of ice crystals in the food.
Reduction of Water Content
- Desiccation: Reducing the water content in food.
- Dehydration: Reducing the water content of food by the action of artificial heat. May be partial or total.
- Lyophilization (Freeze-drying): Reducing the water content of foodstuffs by a process.
Other Methods
- Irradiation: The application of radiation to food under strict control, prolonging the life of a product.
- Protective Atmosphere: Packaging that substitutes the atmosphere surrounding the food with another specifically prepared for each product.
Chemical and Biological Methods of Conservation
Curing, smoking, pickling, and salting are techniques that amend certain nutritional and organoleptic properties of the food.
- Salting: Consists of adding common salt to inhibit the growth of degrading microorganisms and enzyme systems. It can be done by adding salt directly to food or with a saline solution (e.g., anchovies, cod).
- Curing: A method with a great tradition that uses, besides common salt, curing salts. It should be tightly controlled by health legislation to avoid adverse effects.
- Smoking: The food is subjected to the smoke of burning low-resin materials or smoke fragrances.
- Pickling: Performed with vegetables to which vinegar is added. This reduces the food’s pH, preventing the development of microorganisms.
- Marinating: Performed with animal foods that are subject to the action of vinegar. The food’s pH is reduced.
- Addition of Sugar: Allows food to be protected against microbial proliferation. This process is carried out in making condensed milk, preserves, etc.
Biological Methods
- Vinegar: Wine obtained from bacteria that produce acetic acid fermentation.
- Yogurt: Obtained from milk and soy.
- Alcoholic Beverages: Fermented or other alcoholic products from grains rich in carbohydrates.