Study On Ginger Protease

Ginger protease is a new plant protease. The measurement of enzyme activity, the extraction method of crude ginger protease,the stability and the application of ginger protease were studied in this paper.The measurement of enzyme activity of protease from Ginger rhizome were investigated. Enzyme activity was assayed using casein(1% in 0.05mol/L citric acid―disodium hydrogen phosphate buffer,pH6.0) at 50℃for 4min.The enzyme catalytic reaction was stopped by addition of 2mL Trichloroacetic acid (TCA)(0.4mol/L), The product tyrosine was assayed using the UV. The RSD is 1.397%, so the method has a better repeatability, it can be used in the measurement of ginger protease activity.The extraction method of crude ginger protease was studied, and the extraction technology was determined. Fresh diced ginger was homogenized with 4 part (w/v) cold buffer. The mixture was placed at 4℃for 1h before filtrated, adding 1.7times(v/v) industrial alcohol(95%) to the filtrate slowly.The crude enzyme was obtained after filtrated and dried.The activity of the crude enzyme can reach to 481.62U/g dry ginger.Through research on stability of ginger protease, it was found that the protease in ginger had no inactivation when the ginger was preserved at -20℃for 63d, and also found that pulpous stage was a better storage method than massive stage. Temperature had significant effect on ginger protease, crude ginger protease had no activity loss at -20℃for 14d, and made rapid inactivation at 4℃and room temperature. Cu2+,Zn2+,Mg2+had an inhibitory effect on ginger protease, inhibiting ability was in sequence of Cu2+>Mg2+>Zn2+. Na+,Mn2+,Ca2+had no effect on ginger protease. Fe2+ had the activation effect on ginger protease, the protease activity had an increase of 9.82times than the blank. Sulfhydryl reagents had the activation effect on ginger protease, activition ability was in sequence of cysteine> mercaptoethanol>DTT. EDTA can increase 12.62%of the activity than the blank. Sodium erythorbate had the inhibitory effect on ginger protease.The application of ginger protease in beer and yellow rice wine production was studied. Through research on the application of ginger protease in beer saccharification, it was found that the ginger protease could be added when the saccharification temperature was 63℃,and when the addition is 105.98U/kg material,the content ofα-amino nitrogen can reach to 181.46mg/L,which could meet the need of yeast's growth and metabolism. Through research on the application of ginger protease in beer clarification, it was proved that the clarification of beer can increase21.43%, and the beer color can decrease 17.83% when the addition of ginger protease was 1.32U/L.Through research on the application of ginger protease in yellow rice wine clarification, it was proved that the clarification of yellow rice wine can increase 5.62% when the addition of ginger protease was 1.32U/L and the reaction time was 1h.