Studies On Cultivation Conditions And Properties And Application Of Rhizopus Sp.Eterifying Enzyme

Esters of short chain fatty acids and alcohols are known as flavour and fragrance compounds, and they are widely used in the food, beverage, cosmetic and pharmaceutical industries. The flavour and fragrance esters prepared by enzymatic synthesis may be labeled as"natural food". A new method to produce natural esters is opened by enzyme catalysis. Esterifying enzyme of Rhizopus sp. not only has the ability to synthesize ethyl hexanoate but also synthesize other esters.The medium components, cultivation conditions and enzyme properties of Rhizopus sp. were studied in this research. Esterifying enzyme was used in sour apple beverage. Primarily study results as follows:1,This thesis has used Rhizopus sp. as the experiment bacterial and carried research on the effects of the ratio of carbon and nitrogen source,nitrogen source,carbon source,density of component of fermented culture,and the results indicated that: The best nitrogen source was the mixture of soybean powder and albumen peptone, the best ratio of carbon and nitrogen source was 5.The enzyme activity would be higher if 4% olive oil was added. Optimal liquid medium components were as follows: soybean powder 0.5%, bran 6%,K₂HPO₄ 0.2%, the enzyme activity could be reached the highest after 36h.2,Esterifying enzyme activity of Rhizopus sp. was affected by the inoculating volume,culture density,flask of fermentation volume,initial pH value, temperature and agitation frequency. The optimal fermentation conditions were pH 7.0, inoculating amount12%, fermentation temperature 30℃,the agitation frequency 150r/m and 35mL/250ml flask of fermentation volume.3,The optimum temperature of esterifying enzyme was 40℃.It also had activity at a range from 30℃to 50℃.The optimum pH was 7.0.The activity was maintained by heating at 40℃and pH 6⁸. The enzyme activity was promoted by Ca²⁺ ,but was inhibited by Zn²⁺,Cu²⁺. In reaction time within 1³...