Fats and oils
Fat is an important component of our diet and serves a number of functions in the body. Fat provides our body with energy. Although we can get energy from other nutrients in our diet, we need some fat as it provides essential fatty acids that our body cannot make. It is also a carrier of the fat- soluble vitamins and is necessary for their absorption. In general, no more than about one third of our energy intake should come from fat as too much fat can be associated with high energy intakes that can lead to weight gain.
· A small amount of fat is an essential part of a healthy, balanced diet.
· Fat helps the body to absorb vitamins A, D and E. These vitamins are fat-soluble, meaning they can only be absorbed with the help of fats.
· Any fat not used by body's cells or to create energy is converted into body fat. Likewise, unused carbohydrate and protein are also converted into body fat.
· All types of fat are high in energy. A gram of fat, whether saturated or unsaturated, provides 9kcal (37kJ) of energy compared with 4kcal (17kJ) for carbohydrate and protein. The fatty acid composition of oil is given in table 5.1.
They have high energy value.
Impart palatability to diet.
Add flavour and texture to the food.
Improve taste and blends well with the food.
Makes the food crispy.
In common usage, it is classified as fats and oils. Fats are solid at room temperature where as oils are liquid at room temperature.
Vegetable oils are produced from oil- containing seed, fruits or nuts by various pressing processes, by solvent extraction and also by combination of these. A seed cake that is relatively high in protein remains, after fat extraction is often used for animal feed.
Plant oils contain a large percent of unsaturated fatty acids and hence have a tendency to become rancid. These unsaturated glycerides in oil can be converted to saturated glycerides by the addition of hydrogen. This process is known as hydrogenation.
Hydrogenated fat is manufactured from vegetable oils by the addition of molecular hydrogen to the double bonds in the unsaturated fatty acids in the presence of nickel.
Unsaturated Fatty Acids are of two types. There are
· MUFA – Mono Unsaturated Fatty Acids
· PUFA – Poly Unsaturated Fatty Acids
Hydrogenated oil in India is known as Vanaspathi. It is manufactured by hydrogenating refined groundnut oil or a mixture of groundnut oil with other edible vegetable oils. Good and Bad Fatty Acids are found in Vanaspathi.
· Margarine is made from vegetable oils like cotton seed oil, soya bean oil, corn oil, groundnut oil, coconut oil and also meat fat.
· Margarine is made from one or more optional fat ingredients churned with cultured pasteurized skimmed milk or whey.
· Margarine is often used as a substitute for butter.