Exercise 2. Read and translate the text. Necessary Nutrients and Disease Fighters in Oils

1) High-quality vegetable oils are the best way to meet your body's daily requirement for fat and fulfill many of the body's nutritional requirements.

Though excess consumption of saturated fat, and the cholesterol found in animal fats, has been associated with heart and arterial disease, some fat is necessary in a daily diet to ensure good health. Current studies suggest that an ideal diet might provide 25 percent of calories from oils and fat.

Fat is needed by the body for absorption of the fat-soluble vitamins A, D and E. Vegetable oils are one of the few sources of the essential fatty acids (EFA), linoleic and linolenic acid. Vegetable oils, especially wheat germ oil, are good sources of vitamin E.

Some oils also contain omega-3 fatty acids that have been shown to protect the body from heart disease and some types of cancer. Flax seed, canola, walnut, and soy oils are good sources of omega-3 fatty acids.

Monounsaturated oils, like olive, peanut, canola, and high-oleic oils also protect the body from heart disease by raising the blood level of HDL, the good cholesterol. Higher levels of HDL prevent plague build-up on arterial walls. Consumption of polyunsaturated oils, like sunflower and soybean oils, lowers levels of the bad cholesterol, LDL, but also of the good, HDL.

2) Oil can be extracted from many raw materials and has many uses but, for small-scale processing, edible oils for domestic cooking are the most important. Oils are also an important ingredient for making soap. The residue of the raw material, after the oil has been extracted, may have a value even higher than the oil itself – for making groundnut cookies for example or other baked products. The by-product of the oil extraction process, known as oil-cake, is also used as animal feed or if there is a substantial surplus, as fertilizer in home gardens. The major edible oils and their uses are:

Oil seeds	Oil content, %	Use
Cotton	15–25	Cooking oil, soap
Niger (Guizotia abyssinica)	38–50	Cooking oil, soap
Sesame	35–50	Cooking oil
Sunflower	25–40	Cooking oil, soap
Rape/mustard	40–45	Cooking oil
Soya beau	23.5	Cooking oil
Nuts
Coconuts	64 (dried copra)	Cooking oil, body and
	35 (fresh nut)	hair cream, soap
Groundnuts	38–50	Cooking oil, soap
Palm kernel nuts	46–57	Cooking oil, body and
		hair cream, soap
Shea nuts	34–44	Cooking oil, soap
Mesocarps
Oil palm	56	Cooking oil, soap

How oil is extracted affects the nutritional quality of the oil because heat, light and oxygen can destroy nutrients.

3) Here are the most commonly used extraction methods:

Expeller pressing is a process that uses mechanical pressure rather than chemicals to extract oil from its source. Friction generates temperatures that may be as high as 185° Fahrenheit depending on the hardness of the seed, gram, bean or nut.

Cold pressing is a term sometimes used for expeller pressing at temperatures below 120° Fahrenheit. The only true cold pressed oil is extra virgin olive oil, the first pressing of olives.

Vacuum extraction is a recently developed vacuum (SpectraVac) expeller process system that extracts oils in a non-oxygen and light-free atmosphere at temperatures as low as 70° Fahrenheit.

Solvent extraction is a process in which oils are extracted chemically with petroleum solvents that destroy the oil's nutritional value.

4) Storage tips

The packaging and storage of oils can affect their quality. Heat, oxygen and light promote rancidity. Unrefined oils should be stored in cool, dark places and unrefined oils that are high in omega-3 fatty acids should be stored in the refrigerator. Natural or unrefined oils will keep from four so six months if stored properly. Refined or heavily processed oils will keep twice as long.

5) A Warning

Aflatoxins are a poisonous group of compounds produced by certain moulds that grow on seeds and nuts. They are poisonous to both human and animals if consumed over prolonged period, causing liver damage, cancer, and death. Aflatoxins are nor destroyed or removed by heating or during processing. The mould can be prevented (thereby preventing the production of Aflatoxins) by drying and storing the crop correctly. All seeds and nuts should be spread out in a single layer and exposed to sunlight for at least two hours. The ultraviolet radiation in the sunlight will help to kill the Aflatoxin chemicals. Seeds and nuts should not be stored until thoroughly dried and then either spread on trays somewhere dry or put in cloth bags (to prevent sweating) and checked regularly to see that no mould is forming.

6) Processing

There are four main stages in the extraction of oil:

1. preparation of the raw material;

2. extraction;

3. clarification;

4. packaging and storage.