Studies On Enzymatic Properties And Application Of Rennet In Glutinous Rice Wine

This paper studied on enzymological characterization of milk-clotting enzyme extracted from Glutinous rice wine.The results showed that highest milk-clotting activity was between35～40℃.The enzyme was completely inactivated by heating for20min at60℃, its approprite range is pH1～7, highest milk-clotting activity was at pH5.2. Mg2+,Ca2+,Ba2+,Mn2+,Al3+,Fe2+had a very clear functions to accelerate milk coagulation where as Na+, K+resulted in decreased in activity slightly. Different surface active agent have different effect on milk-clotting activity. As dressing agent,Polyol,beta-mercaptoethanol and EDTA have effect on milk-clotting activity. Km is0.703mg/mL, Vmax is1.63ml/s.The cheese manufacture including the dosage of chymosin, starter and CaCl2were optimized firstly. The best manufacture process:Fresh milkis pasterurized at63℃for30min,then cool it down to31℃. Add the sterter as pH is6.4, then add the rennet (6U/mL, dissovle in2%NaCl)、CaCl2saturated solution (0.01%).When milk form the curd, then cut it to small cube (1.5cm3). Heat up them to40℃and sirt them, then removing whey.At last, make it into mold and cool it overnight (overtuning2times in24h).then press it and add salt.In the end, ripe the cheese at4℃for two months.cover it (plastic bag, vacuum-pumping)Using Glutinous rice wine chymosin to make cheddar cheese, studing the movement of physicochemical property and flavory, amd compare with the commercial rennet.The results showed that, during ripening, the change of two cheeses in water content, pH, acidity, soluble N content is coincident.Using GS-MS to analyse the fatty acid and flavory in two cheeses, found that the kind of fatty acid in Glutinous rice wine chymosin increased from8to17during ripening.while the kind of fatty acid in Glutinous rice wine chymosin increased from5to24during ripening.Using scanning electron microscope to observe two cheeses, found the texture of glutinous rice wine chymosin cheese was more compact.Evaluating two cheeses after two month ripening, glutinous rice wine chymosin cheese had more milk odour than commercial rennet cheese, physical and chemical indices is close to Codex Stan C-1—1966. matching the standard of hard cheese.Using solid fermentation, ultrafiltration, concentration and spray drying to prepare chymosin preparation.its clotting activity is248776±20U/g.