Effect of rice bran protein and cassava starch ratio on physical, mechanical and structural properties of rice bran protein-cassava starch composite film

Abstract

The objective of the present work was to investigate the effect of rice bran protein (RBP) extracted from cold pressed defatted RB and a commercial cassava starch (CS) ratio on physical, mechanical, and structural properties of the composite film. The RBP-CS films were prepared by casting of 5% (w/v) film forming solution with various RBP:CS weight ratios (0:100, 10:90, 20:80 and 30:70) and glycerol (60% w/w of total solid) was used as plasticizer. Results showed that increasing the RBP:CS ratio significantly increased yellowness, redness, opacity, water activity (a_w), thickness (T), and elongation at break (% E) of the films. The increased RBP content resulted in an insignificant decrease of TS (P>0.05) but markedly improved the % E of the RBP-CS composite film (from 6.03 to 39.64%). ATR-FTIR spectra of RBP-CS composite films showed the main interactions between rice bran protein and cassava starch were hydrogen bonds that occurred by protein chain and hydroxyl groups of starch. Thus, a molecular miscibility between these two components was evidenced. The RBP:CS ratio at 20:80 was chosen due to its greatest elongation and desired tensile strength, transparency, and color value.