Development of a process for the enhanced enzymatic digestibility of solid waste from tofu to yield fermentable biosugars

Abstract

Tofu solid waste (TSW), an abundant agricultural waste product from the soy industry, can be used as an excellent source of renewable biomass by the action of microbes, indicating a better utilization prospect as opposed to its disposal in landfills or being incinerated. In this study, the composition of TSW was investigated. The waste material was used to produce lactic acid by enzymatic saccharification and fermentation using Bacillus sp. NL01. TSW was determined to be rich in carbohydrates and protein, and could, therefore, be used as a nutrient to facilitate microbial growth. Without pre-treatment, a maximum glucan saccharification rate of 91.6% was achieved by using a mixture of cellulase CTec2 and hemicellulose H2125. Using 1000 g dry weight of TSW as the starting material, 160 g of glucose was recovered and subsequently used to yield 150 g of lactic acid by the action of Bacillus sp. NL01. Thus, the method developed in this study was effective in the production of lactic acid from TSW and can likely provide a deeper insight into the utilization of TSW in biorefineries.

Keywords:

• Tofu solid waste
• enzymatic hydrolysis
• fermentation
• lactic acid

Disclosure statement

The authors in this article have no conflicts of interest.

Additional information

Funding

This study was supported by the National Key Research and Development Program of China [2018YFA0902200] and the National Natural Science Foundation of China [51776099].