Extraction and evaluation of rice bran protein concentrates

ABIRACHED, C.; BONIFACINO, C.; FRANCO FRAGUAS, E.; CABEZAS, D. M.; PANIZZOLO, L.; WAGNER, J.R.; PALAZOLO, G.G.

Florida

Congreso; 2017 AOCS Annual Meeting; 2017

AOCS (American Oil Chemists' Society)

The defatted rice bran (DRB), which is obtained after extracting oil from rice bran, contains highly digestible,hypoallergenic and high lysine-content proteins. However, it is used for animal feed, fuel or silica source. The aim of this work is to achieve a fullDRB utilization, obtaining concentrates composed by proteins and polysaccharides and thus, with functional properties of both types of macromolecules.The DRB flour (DRB-F) was obtained by DRB sieving (0.355 mm). It was dispersed in distilled water and treated with thermophilic α-amylase andamyloglucosidase until the complete removal of starch. Fiber and proteins were precipitated by addition of ethanol (71% v/v, pH 4.5). The precipitatewas dispersed at pH 8.0 in distilled water and lyophilized to give the concentrate (DRB-C). On DRB-F and DRB-C samples, moisture (drying, 105°C),ash (dry-ashing, 550°C), crude protein (Kjeldahl method, N×6.25), lipids (Soxhlet method), fiber (Protsky method) and starch plus sugars (bydifference) were determined. These latter carbohydrates were efficiently removed from DRB-F (>98%), leading to two-times increase of protein and fibercontents for DRB-C sample (48.0 and 27.0% w/w, respectively). For the concentrate, protein solubility (bicinchoninic acid method) at pH 4.6 and 7.0was near to 10.0%. This low value would be attributed to thermal stabilization made to the rice bran prior to oil extraction which leading to proteinaggregation. Therefore, additional physical and enzymatic treatments must be performed on rice bran or the concentrates to improve the proteinsolubility and their related functional properties.