Oat grain contains oil from 3% up to 18%, as typical content of oil in most of cultivars is 5-6%. Apart from other cereal grains, oat endosperm contains up to 90% of total grain oil. The highest lipid concentration (15–24%) of any of the groat tissues is in oat germ.
In the aleurone layer and in the embryo the oil bodies occur as individual entities. In the endosperm the oil bodies tend to fuse together during the development of the kernel and in the endosperm of a mature oat kernel oil, starch and protein are thus all attached to each other.
Oat oil consist of neutral lipids and polar lipids. From lipids, 50-60% are neutral lipids which are mainly triacylglycerols which can be mobilized by the action of lipases which release free fatty acids from the oil. Neutral lipids include also diacylglycerols.
Oat contain a relatively high content of total lipids with a high unsaturated fatty acids percentage and a high native lipolytic activity. Oat oil’s main fatty acids are palmitic acid (16:0), oleic acid (18:1) and linoleic acid (18:2), which are shown in table 1. Oat oil polar lipids are phospholipids and glycolipids which can be up to 34%. Polar lipid fraction is shown to be potential oil/water emulsifier. In addition phospholipids are needed for body cells and they act as antioxidants.
Table 1. Main fatty acids in oat oil
According to the Nordic Nutrition Recommendations (Norden 2012) the scientific evidence for the fatty acid composition in the diet is stronger than for the total fat intake with respect to development of chronic diseases such as coronary heart disease, type-2 diabetes, and certain cancers. Also, the dietary sources of major fatty acid categories play an important role in the associations with health. Cis-monounsaturated and cis-polyunsaturated fatty acids should constitute at least two thirds of the total fatty acids in the diet.
Of all cereals, oats have the highest fat content. Oat oil has a high proportion of unsaturated fatty acids, about 80%. Oats contain linoleic acid (18:2 n-6) and alpha-linolenic acid (18:3 n-3) which are necessary fatty acids that the human body is unable to manufacture and which need to be received from the food. Essential fatty acids are needed for normal growth and maintenance of the system.
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