Abstract:

In this study, experiments were conducted to examine the effect of different pretreatments on the extraction
efficiency of protein from rice residue using alkaline. The results showed the extraction efficiency of protein was increased
largely compared to that without pretreatment, reaching 84.60% and 80.1%, respectively, when rice residue was soaked
for 180 min in 0.5% citric acid or 0.875 mol/L acetic acid at 25 ℃ before being extracted at 50 ℃ for 27 h with 0.1 mol/L
NaOH. The rice proteins extracted from both pretreated samples were could be effectively separated by sodium dodecyl
sulfate polyacrylamide gel electrophoresis (SDS-PAGE) with 18% separating gel. During the extraction process, rice
proteins were decomposed into fragments mostly having a molecular weight around 9.5 or 4.1 kD, especially around the
smaller molecular weight. Moreover, the rice residue protein obtained with 0.5% citric acid pretreatment had a bright purewhite
color and a smooth and delicate texture.

Key words: rice residue, pretreatment, protein, extraction efficiency, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE)