The rice bran fermentation conditions for extraction of protein concentrate was enhanced by the use of baker’s
yeast at optimized conditions using response surface methodology (RSM). A central composite design with three
independent variables: fermentation temperature (25 to 35oC), yeast concentration (1 to 5%) and fermentation time
(10 to 24 h) was used to study the response variable (protein yield). Results indicated that the generated regression
model represented the relationship between the independent variables and the responses. Also, all linear terms, two
quadratic terms (fermentation temperature and time) and all interactive terms had significant (p < 0.05) effect on the
protein yield. The optimum conditions for yeast pretreatment of rice bran protein extraction were achieved at 30oC
for 17 h using 3% yeast concentration to obtain a protein yield of 23.37%, which showed no significant difference
(p ≥ 0.05) from the response surface methodology predicted protein yield (23.02%). The use of baker’s yeast in the
fermentation of rice bran for extraction of protein concentrate can be more effectively used to improve the extraction
yield compared to natural fermented (15.43%) and untreated rice bran (10.16%).