The Action Rules And Application Technique Of Mold Esterifying Enzymes

Esterifying enzyme is a kind of enzyme which can make precursor substance form flavor components.Esterifying enzyme of Rhizopus sp, esterifying enzyme of Monascus sp and functional daqu are mainly used in liquor-making industry to increase the main fragrance of luzhou-flavour liquor, but there are many practical problems, such as low enzyme activity, unstable effect and unwide usage and so on. In order to definite the action rules and improve application of mold esterifying enzymes, this text studied the substrate specifity of mold esterifying enzymes, the technique of synthesis of ethyl hexanoate in aqueous medium and the preparation technique of esterifying liquid . Primarily study results as follows:1. Study on the Substrate Specifity of Mold Esterifying Enzymes: The esterification rate of acetic acid, butyric acid, valeric acid, hexanoic acid, heptanoic acid and octanoic acid increased with the increase of acid carbon number by the three different esterifying enzymes. The three esterifying enzymes inhibited the formation of ethyl lactate.The reason might be related to the chemical structure of lactic acid.There were different synthesis effects of different enzymes. The esterification rates of acetic acid, lactic acid and heptanoic acid were higher by esterifying enzyme of Rhizopus sp.The esterification rate of octanoic acid was higher by esterifying enzyme of Monascus sp.The esterification rates of butyric acid, valeric acid and hexanoic acid were higher by functional daqu. But ethyl hexanoate was highly synthesized by all different enzymes in the reaction system of four-mixed acid and ethanol2. Research on the Technique of Synthesis of Ethyl Hexanoate in Aqueous Medium:The conditions of synthesis of ethyl hexanoate in aqueous medium were different by different kinds of esterifying enzymes.The appropiate conditions for three esterifying enzymes were : the temperature 35~40℃; the concentration of hexanoic acid 1mL/100mL; the concentration of ethanol 10~12mL/100mL;the dosage of esterifying enzyme7~9g/100mL.The optimum conditions for the synthesis of ethyl hexanoate by mixed esterifying enzyme were:the concentration of ethanol 10mL/100mL,the concentration of hexanoic acid 1.5mL/100mL,the dosage of functional daqu 9g/100mL and temperature 40℃。3. Research on the Preparation Technique of Esterifying Liquid:The preparation technique of esterifying liquid was studied by using yellow water, ending liquor and functional daqu as main materals.With the aid of single factor experiments and orthogonal experiment, the optimal preparation technique of esterifying liquid was the concentration of ethanol 10mL/100mL, the addition of hexanoic acid 1.5mL/100mL,the dosage of functional daqu 7g/100mL and temperature 30℃.