CONVENIENCE FOODS

Introduction

Today the term “Convenience Foods” is widely used. This is probably due to the rapid progress in food technology over the past decade.

Considerable amounts of convenience foods are now used in all levels of catering packaged and graded specially for the industry. This varies from individual types of food to complete meals.

The term “convenience foods”, strictly translated, refers to any type of food, where some stage of preparation has been completed beforehand.

Processes               

The following are some of the facts and methods used at present, undoubtedly further progress in new developments will bring forth many more.

Accelerated Freeze Drying (AFD): By using high-vacuum techniques it is possible to produce specific conditions of temperature and pressure which create ideal conditions for the dehydration of food without the collapse of cells. Foodstuffs so treated have gently improved texture retention and rehydration potentialities. Example: Peas, cauliflower etc.

Additives: Non-nutritive substances added to food (generally in small quantities) to improve its appearance, flavor, texture and storage properties. Example: Sodium benzoate, citric acid, acetic acid, vinegar etc.

Aseptic Canning: A newer development is canning designed for those products adversely affected by heat within sealed containers. Products like fruit juices are sterilized, then placed into sterile cans under microbe free conditions.

“Boil-in-the-bag” Ready Food: A convenience entrée or vegetable commodity. Portioned items are packaged in special plastic bags, sealed, and then frozen. To reconstitute, the unopened bag is dropped into boiling water for a predetermined period.

Dehydration: A method of preserving food by reducing the moisture content to such a level that microbe cannot grow and reproduce. The methods used depend on the food, but popular techniques include tunnel, roller and spray-drying. Nutritionally the products lose little value, but the texture, especially in fruit and vegetables, is suspect. Newer methods (dehydro-freezing, freeze dehydration and quick dehydration) are overcoming this problem. A large variety of foods is now available, e.g. pulses and leaf vegetables.

Dehydro-freezing: A method of preservation where the moisture content of certain foods is reduced by 70 percent, then quick frozen. Because the cells do not collapse, the product has good texture retention. Product must be stored in a frozen state.

Freezer Bum: In any frozen storage room there is a steady removal of moisture from unprotected foods which may result in unpleasant irreversible changes to the color, texture, flavor and nutritive values.

Freezing: Foods freeze over a wide range of temperatures although their individual freezing points are unidentifiable. Because of the high water content in many foods, they freeze at temperatures between 320F and 250F. Quick-freezing has been defined as the process whereby food passes through this zone of maximum ice crystal formation (250F-320F) in 30 minutes or less. This ensures that minimum damage is done to the cell structure.

“Free-flowing” Products: Many quick-freezing methods (e.g. Fluidized bed and flash freezing) produce commodities that have no surface frost, and therefore do not adhere in the pack. Advantageous where thawed appearance is important, e.g. fruit.

Instant-freezing: Method of preservation using liquid nitrous oxide at 1280F below zero. By gently flushing foods through with nitrogen, freezing is almost instantaneous, producing very tiny ice crystals so important for good texture retention.

Irradiation: A novel method of preservation, as it produces a raw sterile article with only a slight rise in temperature. The reaction depends on the absorption of energy by food stuffs from a material or machine producing radiation. Nutritionally there is little lost, and the dangers from radiation are negligible.

Preservation: Stored food tends to deteriorate under the influence of its own enzymes, chemical action and through the growth and reproduction of micro-organisms. The techniques developed for preservation aim to retard these reactions or destroy the cause of deterioration. Methods include: refrigeration, quick freezing, canning, sterilization, pasteurization, irradiation and the addition of various chemicals.

Spray Dying: A method of dehydrating food by spraying slurry of the commodity into a hot-air chamber, which dries the material immediately forming a powder. Good rehydration properties and nutrient retention in milk, dried soups and instant coffees.

Sublimation: Under certain conditions of temperature and pressure it is possible for water to change from ice to vapour without becoming a liquid at any time. This allows food to be dehydrated without the collapse of tissues, giving products with excellent texture and rehydration characteristics.

Hope you liked this blog!                 

This article is written by Dr. Bimal Chhajer (Heart Cure Specialist)