Fruit canning

Food is preserved by using methods that destroy or hinder the growth of microorganisms, such as molds, yeast and bacteria. These organisms may be present in the soil, on the food, in the air, on equipment or on work surfaces.

Yeasts, molds and bacteria must be destroyed during processing to prevent the food from spoiling. The correct amount of time to process varies with the kind of food. Sufficient heat for a specified length of time kills microorganisms and insures a safe product.

Canning is a method of preserving food by first sealing it in air-tight jars, cans or pouches, and then heating it to a temperature that destroys contaminating microorganisms that can either be of health or spoilage concern because of the danger posed by several spore-forming thermo-resistant microorganisms, such as Clostridium botulinum (the causative agent of botulism).

Canning is also to retain nutrients and optimum quality, preserve fruits and vegetables when at their peak of freshness. All fruit preserved by canning should be heat-processed to attain commercial sterility.

Whereas vegetables and certain other foods require the application of high temperature (240°F, 250°F) or higher for significance lengths of time to attain commercial sterility, most fruits sufficiently acid (PH usually below 4.5) that commercial sterility can be attained by heating the containers in boiling water to the point where all parts of the product reach a temperature of 180°F – 200°F.

After heat sterilization, containers are quickly cooled to prevent overcooking. Containers may be quick cooled by adding water to the cooker under air pressure or by conveying the containers from the cooker to a rotary cooler equipped with a cold-water spray.

Adding syrup to canned fruit helps to retain its flavor, color, and shape. It does not prevent spoilage of these foods.
Fruit canning

Principle of Food Preservation

Principle of Food Preservation
The basic principles of food preservation primary involves the process of inhibiting

• The growth and activity of microorganism

• Activity of endogenous enzymes

• Chemical reactions which may deteriorate the quality of food

• Invasion and spoilage by insects and rodents

In addition, spoilage of food may be caused during mechanical handling, processing, packaging, storing and transportation. Appropriate care has to be exercised to prevent deterioration of quality of food.

Several methods are available for preservation of food based on the above principles, the method include:

• Preventing the accessibility of food to microorganism by asepsis and packaging

• Physical removal of microorganisms from food by filtration or centrifugation

• Hindering the growth and activity of microorganism by use of preservatives, use of low temperatures atmospheric control in packaging and storing of foods and decreasing water activity in foods by drying or evaporation

• Killing the microorganism by use of high temperature and ionizing radiation

• Inactivation of endogenous enzymes by moderate heating

• Inhibition of chemical reaction through the use of chemical additives

• Fermentation of foods to yield more stable or less perishable food product

Food preservation as it is practiced in the industry always involves the use of combination of methods for achieving maximum effectiveness.

Asepsis or preventing the accessibility of food to microorganisms is well exemplified in nature, the protective covering in natural foods such as skins on fruits and vegetables, shells on eggs and nuts and skins and membranes on livestock and fish prevent the attack by microorganisms and maintain the living tissues in healthy condition.

Microbial attack is facilitated only after the death of the animal or when the skin is physically damaged. Packaging of foods and food products in a variety of materials such as metal cans, plastic films pouches, bags or boxes, paper bags or cartons and glass bottles provide effective protection against microbial attack.

Filtration or centrifugation is adopted to physically remove microorganisms particularly in liquid foods such as milk, soft drinks, fruits juices and alcoholic beverages such as wine and beer.
Principle of Food Preservation