The Searches On The Relationships Of Flavor And Enzymes In Yoghourt

The laboratory preservative three L.bulgaricus(L.bulgaricus 01,L.bulgaricus 02,L.bulgaricus 06)and three S.thermophilus(S.thermophilus 02,S.thermophilus 06,S.thermophilus 07)were studied. The content of flavor substance comprising lactic acid,diacetyle,aldehydes and the activities ofβ-galactosidase,protease,hexokinases,pyruvate kinase,lactate dehydrogenase during fermation and storage test were measured, and the enzymology foundation of flavor substance were discussed.the purpose is to provide new path for lactobacillus choosing and yoghourt production controling.1. the changes and correlation of flavor substances in testing lactobacillus during fermation and storage testDuring the fermation process, the content of lactic acid kept rising ,and the diversity of the capability of acidity producing were exist.Correlation and regression analysis showed that there were quite strong correlation between acidity and the content of diacetyle (correlative modulus=0.5718～0.9630).During the storage process, the increasing trend of acidity became tardily in testing lactobacillus,the acidity of L.b06 was higher than other lactobacillus, the acidity of S.t02,S.t06 were on middling level. The content of diacetyle kept rising in prophase and metaphase while became dropping in anaphase. The content of aldehydes kept declining slowly at the first time and then dropped rapidly. Correlation and regression analysis showed that there were strong correlation(correlative modulus=-0.8419～-0.9893) and obvious linear regression between acidity and the content of aldehydes.2. The changes of enzymes activities in testing lactobacillus during fermation and storage testDuring the fermation process, the activities ofβ-galactosidase kept rising, and the increasing trend were rapid in metaphase and anaphase. the activities of protease showed increasing trend tardily compared with the activities ofβ-galactosidase.the activities of hexokinases showed fluctuant change trend erratically. the activities of pruvate kinase showed fluctuant change trend erratically. the activities of lactate dehydrogenase kept rising during the fermation process.During the storage process, the activities ofβ-galactosidase kept dropping tardily along with the storage process.the activities of protease showed fluctuant change trend erratically and tardily.the activities of hexokinases and pruvate kinase showed fluctuant change trend erratically. the activities of lactate dehydrogenase kept rising in the first time and then dropping, and the change trend were tardily.3. The correlation of flavor substances and enzymes in testing lactobacillusDuring the fermation process, the activities ofβ-galactosidas,protease and lactate dehydrogenase were positive correlated with acidity significantly(correlative modulus=-0.8703～-0.9800,0.7599～0.9589,0.8611～0.9954),and the acidity of S.t02,S.t06,S.t07,L.b06,L.b01,L.b02 had significant regression with the activities ofβ-galactosidase,protease and lactate dehydrogenase.During the storage process, there were negative correlation between the activities ofβ-galactosidase and acidity(correlative modulus=-0.6905～-0.9617), and positive correlation between the activitives ofβ-galactosidase and the content of aldehydes were exist (correlative modulus=0.8526～0.9667).significant regression exist between the activitives ofβ-galactosidase and acidity in S.t07,L.b06 and L.b02, and significant regression exist between the activitives ofβ-galactosidase and the content of aldehydes in S.t06,S.t07 and L.b06.