The Optimization of Viscozyme-Assisted Hydrolysis to Enhance Protein Extraction from VD20 Broken Rice: A Response...

This study investigated and optimized the cellulose hydrolysis conditions of VD20 broken rice flour using Viscozyme to enhance protein content and protein recovery efficiency. Four processing variables, including pH (5.0-6.0), temperature (40-60 °C), enzyme concentration (20-40 U/g), and hydrolysis time (34-38 h), were simultaneously evaluated using response surface methodology. The results indicated that temperature, enzyme concentration, and hydrolysis time influenced protein release and recovery, whereas pH had a limited effect within the studied range. All variables exhibited nonlinear effects, with distinct optimal regions beyond which protein extraction efficiency declined. The maximum protein content of approximately 77% was obtained at a pH of 5.56, temperature of about 55 °C, enzyme concentration of 30 U/g, and hydrolysis time of 36 h. In contrast, the highest protein recovery efficiency of approximately 54-55% was achieved at a pH of 5.53-5.57, temperature of about 53 °C, enzyme concentration of about 30 U/g, and hydrolysis time of about 36 h. Simultaneous optimization of both responses identified balanced conditions at a pH of about 5.53, temperature of about 53 °C, enzyme concentration of about 29 U/g, and hydrolysis time of about 36 h, yielding protein content of approximately 76-77% and protein recovery efficiency of about 55%. These findings demonstrate that optimization provides an effective strategy for maximizing protein utilization from VD20 broken rice and support the application of Viscozyme-assisted hydrolysis in the valorization of rice processing by-products.