Lipid content in wheat

Lipids represent only 2-3% by weight of wheat grain but they are considered to have significant impacts on flour and dough functionality, by interacting with gluten proteins and starch and by stabilizing gas cells in breadmaking

The endosperm itself comprises two tissues. The outer part is the aleurone layer, which comprises a single layer of cells in wheat. The aleurone cells have thick walls (and hence high dietary fiber), contain storage lipids (i.e., triacylglycerol) and globulin storage proteins, and are rich in minerals, vitamins, and phytochemicals (micronutrients).

Roughly two thirds (66%) of lipids are contained in the germ, 15% are in the bran (particularly in the aleuronic layer), and about 20% are distributed in the endosperm, partly within the starch granules.

Lipid content, lipid classes and fatty acid levels in wheat kernels depend on a set of factors, some of which are genetic, such as species and variety, whereas others depend on the environment and are related to pedoclimatic conditions, agronomic practices and maturity level.

The majority of the lipids in wheat are fatty acid (FA) esters of glycerol, and the remainder include free (unesterified) fatty acids (FFA) and several types of sterol-based lipids and glycosphingolipids.

Traditional methods of lipid analysis such as thin layer chromatography are limited in their ability to identify and quantify specific lipid molecular species. Latest techniques using sensitive mass spectrometry-based high throughput methods have allowed the detailed and systematic characterization of lipids.
Lipid content in wheat

Fat content in oats

With lipid profile of approximately 20 percent saturated fat and 80 percent polyunsaturated and monounsaturated fats oats have a slightly higher fat content than other grains and can go rancid more quickly.

The high fat contents of oats provide soft, chewy, creamy, warming nourishment. To protect the fat from becoming rancid, oats contain a natural antioxidant.

Oats have a fat content in the kernel 2 to 5 times as high as wheat and pericarp contains an active lipase which, unless inactivated, hydrolyses the fat to glycerol and free catty acids primarily, oleic, linolenic and palmitic which produce a bitter flavor.

Lipase activity in the grain is destroyed by a few minutes of steam treatment.  Heat activation is commonly applied to oats for porridge, the process also appearing to stabilize the fat with respect to oxidative rancidity.

In regular oats, fat provides approximately 14% of digestible energy content, a value which will further increased up to approximately 18% in de-hulled and high fat oats.
Fat content in oats

Cereals in Human Nutrition

Cereals are very important part of human diets. The three major species, wheat, maize and rice, account for a large proportion of the calories and protein in human diets.

Cereal grains contain 60% to 70% starch and are excellent energy rich foods for humans. Doctors recommend cereals as the first food to be added to infant diets and evidence from research upholds that healthy diet for adults should have most of its calories in the form of complex carbohydrate such as cereal starch.

Wheat and rice are the most important cereals with regard to human nutrition, and they account for 55% of the total cereal production.

A healthy human diet must also include 20 to 30 g/day of dietary fiber, which can easily achieved by eating whole grain cereal products such as breads, cookies or porridges.

Other components such as proteins and vitamins may be of great significance in human nutrition because of the large contribution of cereals to the diet.

Cereal protein is especially valuable in human diet because it complement amino acids between various plant sources. Cereal protein represents an important component in the diets of people, roughly 16 to 45 g per capita per day. Adult woman requires about 50 g of protein per day, whereas an adult man needs slightly more (about 63g).

In rural areas of poorer countries people may eat more than 500 g of cereal per day, which will provide most of their protein needs (and more than 50% of their total daily energy requirement).

It is also recognized that cereals grain have a low protein concentration and that protein quality is limited by deficiency in some essential amino acids, mainly lysine.

Cereals are an excellent source of fat soluble vitamin E, which is an essential antioxidant. Whole cereal grains contain 20% to 30% of the daily requirements of the minerals selenium, calcium, zinc, and copper.

Cereals in Human Nutrition