Food And Nutrition: Meaning Of Food Purchasing, Food Processing And Food Preservation (Food Processing Methods)

Meaning Of Food Purchasing, Processing, Preservation And Food Safety.


This the process of procurement of food by means of a financial transaction. Food Purchasing Is obtain food in exchange for money or its equivalence; to buy food, food may be purchased in raw, cooked or processed forms.


This is the transformation of raw ingredients, by physical or chemical means into other forms of the food.

It involves activities such as mincing, liquefaction, emulsification, cooking (such as boiling, broiling, grilling), pickling and preservation, canning or jarring.

These activities or a combination thereof, result in the manufacture of ready-to-cook or precooked food products like confectionery, instant foods, flavored and health drinks, pickles, jams, canned foods, purees, jellies, powders and mixes, sauces, etc.


This involves preventing the growth of bacteria, fungi (such as yeast) or any other micro-organisms,as well as retarding the oxidation of fats that cause rancidity (spoilage of fat).

Food Preservation can also include processes that inhibit visual deterioration, such as the enzymatic browning (reaction in apples after they are cut), which can occur during food preparation.


Food safety is a scientific discipline describing handling, preparation and storage of food in ways that prevent food-borne illness. It involves a number of routines that should be followed to avoid potentially severe health hazards. Food safety goes through these processes:

i. Prevent contamination of food with pathogens which can spread from people, pets, and pests.

ii. Separate raw and cooked foods to prevent contaminating the cooked foods.

iii. Cook foods for the appropriate length of time and at the appropriate temperature to kill pathogens.

iv. Store food at the proper temperature.

v. Use safe water and cooking materials.

Perishable And Non-Perishable Foods:

i. Perishable Foods

These are those foods that can spoil easily. They do not keep long because of their moisture content.

Examples of Perishable Foods Are: Fresh fish, meat, vegetable, fruits, and tomatoes.

ii. Non-Perishable Foods

Non-perishable foods are those foods that do not spoil easily. They can be kept, for a long time if stored properly.

Examples of non-perishable foods are: rice, beans, flour, yam, sugar and cereals.

Food Processing Methods

Food Processing Methods have been developed over the centuries and are adopted apparently to make the food products more attractive in flavor, appearance, taste and consistency. Besides, these aspects of consumer preferences, several of the methods aim at:

i. Making the food safe and wholesome

ii. Conserving available food for later use by increasing its availability.

iii. Increasing the shelf or storage life of the food.

The Common Household Method Of Food Processing Are:

iv. Milling

v. Germination and Malting.

vi. Cooking.

vii. Fermentation.

i. Milling: In Milling, the coarse, fibrous bran or seed coat of grains are removed. This may result in significant nutrient losses, particularly the B-Vitamins And Minerals.

The extent of the losses depends upon the degree of milling and distribution pattern of nutrient in the grain.

However, milling makes grains easier to cook and digest. Milles grains are less likely to deteriorate on the storage.

ii. Germination and Malting: This involves soaking food in water over night. This is followed by germination and sprouting of the grains (Especially Legumes) and then dried.

During germination, several enzymes systems become active and bring about profound changes in the nutritive value of the pulse’s. For Instance, Vitamin C And Folic acid which are particularly absent in dried Legume seed increase in significant amount after germination, consequently availability of iron in germinated grains Improve significantly.

iii. Cooking: Cooking In boiling water or by steam pressure is yet another common household practice of food processing. Cooking Improves the quality of diet, Improves taste, and makes inedible food edible or make food more digestible.

Cooking also kills micro organisms In food. Cooking of some foods removes undesirable compounds such as anti-nutrients e.g trypsin inhibitors in soybeans.

iv. Fermentation: Fermentation in food processing is the conversion of carbohydrates (Plant Foods) to alcohols and carbon-dioxide, or organic acid using yeast, bacteria or a combination thereof, under anaerobic (no oxygen) condition.

This implies that the action of micro organisms is desirable and the processes can be used to produce alcoholic beverages such as wine and beer. Fermentation is also employes In the leavening of bread and Production of yoghurt.

Food Fermentation has been said to serve some purpose. These include:

i. Enrichment of diets through the development of a diversity of flavours, aromas and textures in Foods.

ii. Preservation of food through lactic acid, alcohol, acetic acid fermentation.

iii. Elimination of anti-nutrients in Foods such as phytase in grains, nuts, seeds and legumes.

iv. A decrease in cooking time.