Study On Hot Water Pretreatment Process Of Cassava Residue

This paper studied the hydrolysis of cassava residue by hot water pretreatment.The effect of different pretreatment conditions on hemicellulose degradation was studied.The change of hemicellulose structure was investigated by FTIR and NMR.The effects of pretreatment conditions on the crystallinity,lignin content and enzymolysis efficiency of hydrolysis residue were studied,and the thermal stability of hemicellulose was studied,too.Finally,the comparison of sugar dissolution and inhibition of hot water and ultra-low acid pretreatment was carried out.This paper will provide theoretical and technical support for the classification and high value utilization of cassava residue.The conclusions are as follows:(1)The dissolution rate of carbohydrate in hydrolyzate increases with temperature and time under hot water pretreatment.Under mild conditions,carbohydrates mainly exist in oligosaccharides,and under more severe conditions,carbohydrates begin to degrade.Arabinose and galactose are easy to dissolve and degrade and holding time plays an important role in the degradation of mannose.The highest dissolution rates of glucose,xylose,Arabia sugar,galactose and mannose in cassava residue were 14.97%,23.80%,51.50%,47.25%,37.87%,respectively.And the main chain of hemicellulose in the hydrolysate was glucan.(2)The crystallinity,lignin content and enzymolysis efficiency of hydrolysis residue were improved.In conditions of 190? and 30 min,the yield of hexose and pentose were up to 89.85%and 42.90%,respectively.The hemicellulose in the pretreated residue was mainly xylan.(3)The thermal stability analysis of hemicellulose revealed that it had significant four weight loss intervals.Hemicellulose with complex and branched structure is unstable,and requires less activation energy.(4)Extreme low acid pretreatment significantly shortened the reaction time and improve the dissolution rate of sugar.The yield of hexose and pentose was 30.63%and 49.60%under extreme low acid pretreatment conditions,which was higher than that of hot water pretreatment(22.30%and 30.87%).Aggravating conditions promote carbohydrate degradation as an inhibitor,and pentose degradation is more serious than hexose.