Formation Control Of Methanol In Pear Fruit Liquor From Solid-State Fermentation

The utilization rate of raw materials are improved in the production of pear distilled liquor by solid fermentation technology, the raw materials can be fully utilized, it can reduce the waste of resources, simplify the operation and cost savings.Because the pear contains more pectin, the methanols will be produced in the fermentation of fruit wine production. It is an effective way to improve the product quality of the wine by reducing the methanol content in the raw material processing and control technology. In this experiment, Laixi pear are used as raw materials, the influences of fermentation time, temperature, raw material processing and pectinase treatment are studied on the wine production rate and methanol content of raw materials in solid state fermentation of pear liquor. The main results and conclutions are as follows:1. The influence factors of methanol content in Pear distilled liquor by solid state fermentation: The factors that influencing solid state fermentation are studied, it is obtained that with the extension of fermentation time and the increase of temperature, the methanol content of fermentation broth increased. Yeast has little effect on the fermentation; The methanol content in distilled liquor decreased significantly after cooking or microwave treatment, and the longer the processing time is, the lower the methanol content is. Through the study it is deter mined the atmospheric cooking treatment for 15 min or microwave for 4min is the best way of raw material processing; pectinase can improve the alcohol yield of raw material, but the content of methanols also increased in distilled liquor.2. The effect of different pectinase on methanol content: Through the enzyme activity of poly galacturonic acid enzyme(PG) and pectate lyase(PL), pectin esterase(PE) are deter mined on five different pectinase, the enzyme activity of PG and PL have a significant positive correlation and wine production rate, the higher the enzyme activity of PG and PL was, the higher the wine production rate was; the enzyme activity of PE is close with the methanol content in distilled liquor, the higher the enzyme activity of PE was, the higher the methanol content was. Through comparison and analysis, PG, PL enzyme activity of pectinase C is the highest, PE enzyme activity is the lowest. In the production of pear liquor by solid fermentation, the higher wine production rate and low methanol content distillation wine can be obtained by adding pectinase C.3. The processing optimization of pear wine by solid state fermentation: The experiment results show that, after the raw materials are crushed, add pectinase C in them, the mixture was maintained for 3 h under the condition of 40 ℃ then boiling water bath treatment for 15 minutes or microwave(700 w) for 4 min, after cooled, it was inoculated with yeast, the fermentation lasts 5 d at 22 ℃, the alcohol of fermentation liquid is 7.1 %, methanol content is 7.83 mg/100 m L, the wine production rate of raw materials reached 95.94 %.