Characteristics And Application Of Higher Alcohol Degrading Enzymes Form Apples

Higher alcohols are the alcohols having more than three carbons.They are widely found in foods.Too much higher alcohols are harmful to food flavor and human health.However,higher alcohols are unavoidable byproducts of food processing,especially alcohol fermentation.It is difficult to inhibit the production of higher alcohols during food processing.Up to now,there has not an efficient and high specific way to degrade higher alcohols,This thesis systemly researched the characteristics of higher alcohol degrading enzymes isolated from different apple varieties.The main results obtained in the study were as follows.(1)Among the tested five apple varieties,enzymes isolated from Fuji,Rattan,and Gala apple fruits exhibited higher activity on degrading five higher alcohols with the highest in Fuji.Enzyme isolated from Matsumoto had lower activity on degrading higher alcohols,however,it had higher activity on decreasing 1-propanol than apple varieties.Enzymes isolated from the five apple varieties were separated into three peaks in Sephadex G-100.Peak 1(Fuji,Starking,and Gala),Peak 2(Rattan)and Peak 3(Matsumoto)showed the highest activity on degrading 1-hexnaol.Nearly all crude enzymes showed two bands in active SDS-PAGE gel,corresponding to molecular weight of 29.0 KDa and 40 KDa.The bigger one showed lower in hexnaol degrading activity or enzyme content(2)EDTA had significant influence on hexnaol-degrading activity of enzyme from Fuji apples,with increasing effect at low EDTA concentration and inhibition effect at high EDTA concentration,illustrating the enzyme was a kind of metal containing enzyme.For substrate specificity,Fuji enzyme had the highest activity on hexnaol followed by isoamylol,and the low activity on methanol and ethanol.It had not activity on 1-propanol at all.In addition,the enzyme showed a NAD-depending characteristic.(3)Different apples higher alcohol degrading enzyme degradation of higher alcohols in wine samples 2 are different,for the same enzyme in apples,higher alcohol degradation rate of SA-IEP is the highest,followed by the EP,ES,CTS-IES,and SA-IES,Fuji SA-IEP for the most efficient degradation of higher alcohols,Conditions for immolizing apple enzymes were optimized as follows,0.3 g enzyme powder in 10 mL of 40 g/L sodium alginate solution(SA).After mixed thoroughly,the mixture of SA and enzyme was dropped into 10 mL of 20 g/L CaCl2 water solution followed by keeping at 4? for 2 h to immolize the enzymes.Immobilized enzyme balls were obtained after water clearing.When the obtained immolized enzymes were used to treat different liquors,efficient decrease of higher alcohols was observed.Such immobilized enzyme prepares could be used to treat 100 mL wine samples 2.