Most of the metabolically active proteins, mostly enzymes, in oats are in the water-soluble albumin fraction. Among the enzymes, presence of proteases, maltase, a-amylase, lichenase, phenoxyacetic acid hydroxylase, phosphatase, tyrosinase, and lipases were reported. Also proteinase inhibitors which are considered to be anti-nutritional are present. Albumins contain high levels of lysine, in fact, the highest among the cereal albumins and they contain the lowest levels of glutamine-glutamic acid among the other oat proteins. Their high levels of lysine indicate that albumins are located around the embryo as lysine is mostly found in the embryo.
Table 1. Oat protein fractions according to Osborne protein solubility1
1Table remodelled from references Klose & Arendt 2011, Ma & Harwalkar 1984, Robert 1985
*shows wide differences depending on the cultivar and growth conditions (climate, soil quality etc.)
Nutritional quality of oat proteins
When compared with amino acid requirements for children, oats exceed the requirements for all essential amino acids except lysine and threonine (Table 2). However, they fall short when compared with egg and milk proteins. Nutritional value of oat protein products can be improved by supplementation of lysine, threonine and methionine.
1Table remodelled from reference Peterson 2011
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