Optimization of the Fermentation Conditions of Poly-γ-Glutamic Acid from Natto by PB Experiment Combined with BBD ResponseSurface Method

Abstract

In order to explore the optimal fermentation conditions for the poly-γ-glutamic acid (γ-PGA) production and sensory quality of fermented natto, the comprehensive score of γ-PGA production and sensory evaluation after natto fermentation was used as an index to optimize the natto fermentation process by single factor test, Plackett-Burman test design, steepest climbing test and Box-Behnken response surface method. The optimum fermentation conditions of natto were determined as follows: Soybean soaking pH7.2, fermentation temperature 37.10 ℃, fermentation time 24.20 h, inoculation amount 4.00%, bottling amount 19.90%. Under the optimized conditions, the production of γ-PGA was 3.65 mg/g, the sensory score was 31.67, and the comprehensive score was 10.04. There was no significant difference between the experimental results and the model prediction values, which was stable and reliable.

Keywords

• natto
• γ-pga
• sensory evaluation
• plackett-burman experiment design
• box-behnken response surface methodology