Genotypic variability in the composition of soluble protein from rice bran – Opportunities for nutrition

Protein is an essential macronutrient, but current sources of protein will not meet future demand. It is necessary to explore alternative sources of protein to reduce reliance on animal protein and meet the needs of a growing base of non-meat consumers such as protein sources that are non-allergenic and plant-based. The protein in rice ran is a potential option but little is known about the differences in protein content and composition and how to maximise the protein for extraction. This study identified the genotypic variability in rice bran protein and identified the milling conditions leading to maximum protein recovery from bran. This study investigated bran from 8 different rice varieties. Each sample was milled at 6 different time points (15- to 90 s). The results showed that the highest total protein and albumin was at 15 and 30-seconds of milling. In contrast, at later milling times, the proportion of glutelin and prolamin fractions, and of starch increased. Moreover, there was clear genotypic variability for protein content, the amount of soluble protein, and the amino acid composition of protein, indicating that breeding programs seeking to maximise the value of the bran are able to select for high con- centrations of soluble protein. Utilising protein from rice bran is an excellent opportunity to add value to waste stream.