# Box–Behnken Optimization of Soybean Meal Enzymatic Digestion for Small-Peptide Production

## TL;DR

This study optimizes the enzymatic breakdown of soybean meal to produce more small peptides, which could be useful for making high-value protein products.

## Contribution

The study introduces an optimized enzymatic hydrolysis method for soybean meal using Box–Behnken design to maximize small-peptide yield and functionality.

## Key findings

- Optimal enzymatic hydrolysis conditions increased small-peptide content 16.33-fold.
- Enzymatic treatment altered protein structure, increasing free amino acids by 114.2%.
- DPPH radical-scavenging activity improved from 18.37% to 57.99%.

## Abstract

This study used soybean meal as the substrate and systematically optimized its enzymatic hydrolysis through single-factor experiments and response surface methodology. A predictive model based on a Box–Behnken design was developed to improve protein hydrolysis efficiency and increase the yield of functional products. The optimal conditions were 1.45% enzyme addition, a reaction time of 62 h, a temperature of 36.5 °C, and a moisture content of 35%. Under these conditions, the small-peptide content increased 16.33-fold. Structural analyses showed that enzymatic treatment markedly disrupted the compact surface of soybean meal, converting it into a loose, porous matrix. In addition, enzymolysis altered the protein secondary structure from ordered α-helices and folded conformations to more disordered, flexible forms, thereby improving the molecular-weight distribution. Composition analyses showed an 114.2% increase in total free amino acids, including essential amino acids. Moreover, DPPH radical-scavenging activity increased from 18.37% to 57.99%. Overall, this study optimized the enzymatic hydrolysis conditions for soybean meal and provides valuable insights for the development of high-value protein-peptide products.