Effects of components in the culture solution on peptides accumulation during germination of brown rice

Abstract

In this paper, a growth-promoting culture solution was developed to enhance the accumulation of peptides during brown rice germination. Among 11 variables investigated with Plackett–Burman design, gibberellic acid, NaCl, CuSO₄ and MnSO₄ were selected based on their statistically significant (P < 0.05) and positive effects on peptides content in germinated brown rice. Subsequently, uniform design was used for further optimization of these selected variables to improve the peptides content. By backward regression analysis, a second-order polynomial model was established to identify the relationship between those selected components in culture solution and peptides content, as well as protease activity. The three most effective components are GA₃, NaCl and MnSO₄ and the optimum concentrations were obtained as follows: 55 μmol/L, 6.0 mmol/L and 1.8 mmol/L respectively. An overall 1.90-fold increase in peptides accumulation was achieved in the optimized culture solution (10.53 mg/g) as compared with control (5.53 mg/g), and 2.52-fold increase as compared with ungerminated brown rice (4.18 mg/g).