Improvement of Enzymatic Glucose Conversion from Chestnut Shells through Optimization of KOH Pretreatment.

Kang Hyun Lee,Hah Young Yoo,Chulhwan Park,Soo Kweon Lee,Jeongho Lee,Seung Wook Kim,Seunghee Kim

doi:10.3390/ijerph18073772

Abstract

Worldwide, about one-third of food produced for human consumption is wasted, which includes byproducts from food processing, with a significant portion of the waste still being landfilled. The aim of this study is to convert chestnut shells (CNSs) from food processing into a valuable resource through bioprocesses. Currently, one of the highest barriers to bioprocess commercialization is low conversion of sugar from biomass, and KOH pretreatment was suggested to improve enzymatic digestibility (ED) of CNS. KOH concentration of 3% (w/w) was determined as a suitable pretreatment solution by a fundamental experiment. The reaction factors including temperature, time and solid/liquid (S/L) ratio were optimized (77.1 g/L CNS loading at 75 °C for 2.8 h) by response surface methodology (RSM). In the statistical model, temperature and time showed a relatively significant effect on the glucan content (GC) and ED, but S/L ratio was not. GC and ED of the untreated CNS were 45.1% and 12.7%, respectively. On the other hand, GC and ED of pretreated CNS were 83.2% and 48.4%, respectively, and which were significantly improved by about 1.8-fold and 3.8-fold compared to the control group. The improved ED through the optimization is expected to contribute to increasing the value of byproducts generated in food processing.

Highlights

According to the Food and Agriculture Organization of the United Nations (FAO), a huge amount of food is produced every year for human consumption, about one-third is lost or wasted
The HPLC analysis conditions to investigate the chemical compositions of chestnut shells (CNSs) and the concentration of glucose released by enzymatic hydrolysis were as follows: Shodex SUGAR SH1011 H+ ion exclusion column
CNS is composed of 63.7% carbohydrate and 9.4% protein, which can be utilized as carbon and nitrogen sources in fermentation

Summary

Introduction

According to the Food and Agriculture Organization of the United Nations (FAO), a huge amount of food is produced every year for human consumption, about one-third is lost or wasted. Wastes generated from food processing have a significant proportion, but most of them are landfilled. The concept of biorefining has emerged to produce value-added substances including fuels, chemicals and substances from biomass, economical biorefinery design requires the supply of inexpensive raw materials such as agri-food waste [2,3]. Outer shells (8.9–13.5%) and inner shells (6.3–10.1%) are generated as the residues [6]. These residues are commonly used for animal

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