Ultrasound-assisted hydrolysis of food waste using glucoamylase: Statistical optimization and mechanistic analysis with molecular simulations

Abstract

This paper reports investigations in food waste hydrolysis using ternary approach that combines statistical optimization, ultrasound-assisted enhancement of hydrolysis kinetics, and molecular simulations that provide physical insight into the process. Initial optimization of hydrolysis parameters (Box–Behnken design) resulted in total reducing sugar yield of 263.4 mg/g biomass in 42 h. Sonication of hydrolysis mixture at 35 kHz at 20 % duty cycle yielded 4× reduction in hydrolysis time with 22 % enhancement in TRS yield (320 mg/g biomass). Analysis of GLCM's secondary structure through FTIR spectra deconvolution revealed significant changes induced by sonication. Sonication led to reduction in α-helix, and increase in random coil content. Molecular dynamics simulations unveiled majority of amino acid residues associated with GLCM binding pocket in α-helix and random coil regions. Consequently, sonication widened the binding pockets, facilitating easier transport of substrate and product. This effect translated into faster kinetics of enzymatic food waste hydrolysis.