Studies On Saccharification Proces And Establish The Dynamics Model For Lisbon Yam

Given the deteriorating of fossil energy crisis and environment pollution, it is imperative to search for renewable energy. Fuel ethanol is generally regarded as a kind of highly ideal renewable energy. When biomass is used to produce fuel ethanol, the degree of hydrolyzation of the former decides the output of ethanol, and hence the production cost. Using Lisbon yam, which is abundant in Hainan province, as raw material, this study explores the influence of various hydrolysis methods to the starch of Lisbon yam and the hydrolysis of amylose, and, using percentage distribution of reducing sugars as the evaluation indicator, explores the best technological conditions of saccharification of the dry powder of Lisbon yam and establishes the dynamics model or parameters of the hydrolytic process.Lisbon yam contains abundant starch and heteropoly carbohydrates, after preliminary analysis:the total reducing sugar content is as high as71.96%, and the hydrolyzate of the Lisbon yam is the best raw material to produce fuel ethanol. This project takes glucose as the standard, DNS as the color-developing agent, selects470nm as the maximum absorption wavelength, to inspect the total reducing sugar content of the Lisbon yam. This method has good inspection reproducibility, high standard recovery rate, with comparative smaller error, the relative standard deviation of the reproducible test is2.98%(n=12), and the standard average recovery rate is100.78%. It’s simple and effective to take this method to follow up the whole process of the Lisbon yam hydrolysis and the hydrolysates fermentation to produce the fuel ethanol.This paper reports the studies on various saccharification method, such as Lisbon yam dry powder enzyme hydrolysis, acid hydrolysis and microwave aided acid hydrolysis etc. The acid used in acid hydrolysis is hydrochloric acid, and the enzyme used in the enzyme hydrolysis is a-amylase and glucoamylase. This paper explores the influence of different factors in each saccharification method on Lisbon yam. Specifically, first, to study the main factor of the Lisbon yam hydrolysis through single factor experiment, and then determine the best technological condition of each saccharification method through orthogonal or response surface analysis experiments, that can determine relative hydrolysis parameters and establish relative dynamics models of the hydrolysis reaction. The results are as follows: High temperature liquid a-amylase acting on Lisbon yam follow Michaelis-Menten equator, the Michaelis constant is Km=80.84mg/mL, the maximum reaction velocity is Vm=1.26mg/(mL·min)-1. The best liquefaction conditions is:temperature90℃> pH value is5.6%substrate concentration is40mg/mL, the enzyme dosage is0.07mL/g, liquefaction time is50mins, the reducing sugar rate after liquefaction is52.95%. After the liquefaction of the Lisbon yam slurry, to use glucoamylase for further saccharification, the dosage of the glucoamylase is0.003g/g, pH4.4, saccharification temperature is60℃, saccharification reaction time is8h, the reducing sugar rates in the hydrolyzate is as high as76.57%, compared with emulsion, it improved23.62%. The polysaccharide hydrolysis rate in the Lisbon yam slurry is95.77%. Using high temperature liquid a-amylase to hydrolyze Lisbon yam slurry, after saccharification, it can inoculate and ferment successfully to produce fuel ethanol.The experiment results of the hydrochloric acid acting on the Lisbon yam slurry suggested that when one factor fixed, to reach the optimal reaction condition, the relationship between the other factors and wavelength. Under the condition the solid-liquid ratio is fixed, the higher the temperature of the hydrolysis is, the lower the needed acid concentration in the hydrolysis, and the time for hydrolysis will be shorter. The material particle size is100mesh, solid-liquid ratio is1:10, reaction temperature is115℃, hydrochloric acid concentration is0.6mol/L, the hydrolysis time is1h, the reducing sugar rate in the hydrolyzates can be82.13%. Provided the polysaccharide acid hydrolysis process in the Lisbon yam slurry follow a continuous irreversible homogeneous reaction, use Saeman models to have dynamic fitting of the hydrolysis process, to establish the simplified hydrolysis reaction kinetics equation, which can reflect the hydrolysis process, and forecast the experiment results. In the process of polysaccharide acid hydrolysis process of the Lisbon yam, glucose generation rate is far outweigh the glucose decomposition rate, to increase the hydrolysis temperature appropriately can improve the K1/K2ratio, it’s conducive to formation reaction of the glucose generation, the reaction activation energy is41.841KJ/mol.Furthermore, this paper tries to explore the acid saccharification of the Lisbon yam under the microwave-aided condition. By the single factor experiment, to determine the ideal range of each factor’s level value preliminarily. Using Box-Benhnken center combination experimental principle, and the analysis software of Design-Expert, through the multiple regression fitting, the best hydrolysis conditions are:hydrochloric acid concentration is0.49mol/L、liquid-solid ratio is27.65mL/g、wavelength time is37.17min、wavelength power is160W, the theoretical value of the reducing sugar rate in the hydrolysis is73.99%,the experimental value is73.26%. The response surface methodology is feasible for the optimization of the polysaccharide acid hydrolysis of the Lisbon yam, with its actual practical value.