INTRODUCTION TO FOOD PROCESSING & PRESERVATION

WORLD FOOD PROBLEMS - Need for more effective and more widely used methods of Food processing & preservation

1. Dietary Inadequacies - Undernutrition or malnutrition of large part of word’s population - Possible reasons: technical, economic, political, cultural, religious, along with a large measure of unconcern. - The problem could be at least temporarily solved by adequate processing/ preservation, proper distribution and willing consumption

2. Long-term solutions a. Control of Population growth b. Increased Supply of Foods - By devoting a greater portion of the earth’s surface for food production - By increasing the yield per acre - By developing new sources of food - By greater exploitation of sea foods.

c. Decreased food wastage It is a critical factor affecting the world’ supply of food. Urbanization: intensifies greatly food wastage in some areas of the world (moves consumer further away from food production and increases the time between harvest and consumption). Moreover, the systems for distributing and preserving food have generally not improved.

Food wastage occurs through: - Contamination - Consumption by pests - Inefficient utilization It is a major cause of food wastage. It occurs: (a) when nutritious portions of food are not fully utilized for human consumption and (b) When food tissues are harvested or slaughtered at maturities that provide a less than optimum combination of yield and quality.

- Spoilage Spoilage is also a major cause of food wastage Table1: Classification of essentially unmodified foods according to degree of perishability

Table 1. Perishability of Essentially Unmodified Foods Degree of perishability (storage life at room temperature) Water contentType of product Highly perishable (1-7 days) Medium to highAnimal tissues: meats, poultry, seafood Plant tissues: soft, juicy fruits and vegetables with rapid respiration, e.g., berries, peaches, spinach, immature or leafy vegetables Milk Moderately perishable (1 to several weeks) MediumPlant tissues: root crops, mature apples, and pears Eggs Slightly perishable (1 year or more) LowPlant tissues: food grains, beans (dry), peas (dry), nuts

Causes of spoilage: microorganism growth, contamination, normal respiration, water loss, sprouting, autolysis, various chemical reactions, physiological disorders, mechanical damage. Spoilage can be prevented by: immediate consumption or effective processing and/or preservation

FOOD PRESERVATION

Aim of commercial food preservation : to prevent undesirable changes in the wholesomeness, nutritive value, or sensory quality of food by economical methods, which: control growth of microorganisms, reduce undesirable chemical, physical and physiological changes, and prevent contamination

Food Preservation methods: a) Chemical (addition of various substances or exposure of food to chemicals) b) Biological (alcoholic or acidic fermentations) c) Physical: the most extensively used methods in developed countries. They include: - Temporary increase of product’s energy (heating, irradiation) - Controlled product’s temperature reduction (chilling, freezing) - Controlled water content reduction (concentration, air dehydration, freeze drying) - Use of protective packages

Physical methods of Food Preservation - The greatest concern (during preservation of moderately or highly perishable foods): inhibition of growth or death of microorganisms. - This can be achieved by physical methods of preservation. - Some of these methods completely stop growth of m/o but none of them can completely stop chemical and physical changes. - The most successful methods on preventing microorganism growth cause undesirable changes on the sensory and nutritional features of foods. - Thus, food preservation techniques need to be improved in order to decrease the disadvantages while maintaining the advantages.

Constraints (restrictions) -The problems of energy and resources consumption in the industrialized nations and the impact of the environment. -The discharges of food plants must now be carefully monitored. -Most of energy is derived from nonrenewable sources (since natural resources are no longer abundant, costs of energy are rapidly increased). -Large annual increase in energy consumption (part of this increase is due to increases in population but most is due to markedly increased energy per calorie of food output).

In summary: - Food processing industries in industrialized countries face tremendous new restrictions, which often differ in degree or kind from those prevailing in underdeveloped countries. - Thus, Food Scientists are confronted with novel challenges that cannot be met without a complete knowledge of the principles underlying the various methods of food processing and preservation.