Integrated enzymatic and sonication strategy for sustainable soybean processing: from cell wall deconstruction to product separation

TL;DR

This paper introduces a sustainable method for processing soybeans using enzymes and sonication to efficiently extract oil, protein, and carbohydrates without using harmful chemicals or high heat.

Contribution

The study introduces an integrated enzymatic-sonication strategy for sustainable soybean processing, enabling hexane-free, low-temperature extraction of high-value components.

Findings

ESP with sonication reduced processing time to 24 hours and increased carbohydrate solubilization to up to 90%.

Centrifugation efficiently separated intact oil bodies, native proteins, and monomerized carbohydrates.

Using water as a reaction medium and limiting processing time reduced protein dissolution to below 20%.

Abstract

Conventional soybean processing relies on hexane extraction and high-temperature treatments, which cause protein denaturation and hinder the separate recovery of oil, protein, and carbohydrate. To address this limitation, this study aimed to establish a sustainable enzymatic soybean processing (ESP) strategy for separate collection of all three major components: intact oil bodies, undenatured protein, and monomerized carbohydrate. This is the first demonstration that ESP efficiency can be significantly enhanced by integrating pulsed sonication. Multi-enzyme systems were produced via solid-state fermentation (SSF) of soyhull by Aspergillus niger and applied to cracked soybean particles. Screening of 15 SSF enzyme extracts revealed that pectinase, polygalacturonase, and invertase were the limiting carbohydrase activities for cell wall degradation. Effects of processing variables including protease activity, reaction media, and reaction time were evaluated to minimize protein loss. Using water instead of citrate buffer as reaction medium and limiting processing time to ≤ 48 h reduced protein dissolution to below 20%. ESP was further enhanced through pulsed probe-sonication (12 W/mL, 1 s on/23 s off), which reduced processing time to 24 h while increasing carbohydrate solubilization to up to approximately 90% depending on enzyme loading. Simple centrifugation enabled efficient fractionation into intact oil bodies (100%), native proteins (≈70%), and hydrolysates containing soluble proteins (≈30%) and monomerized carbohydrate (≈90%). These findings demonstrate an integrated enzymatic-sonication approach that enables hexane-free, low-temperature soybean processing with minimally denatured, high-value products and offers a pathway for sustainable soybean biorefinery.

The online version contains supplementary material available at 10.1186/s40643-025-00991-5.

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