关键词: 乳脂；发酵乳；风味

Abstract: Fermented milks were prepared using raw milk with different fat contents, and their flavor was evaluated. The pH trend during fermentation indicated that the change in milk fat content had no effect on the acid production of lactic acid bacteria. Rheological and texture measurements showed that with the increase in milk fat content, the elastic modulus and the viscous modulus decreased, hardness and cohesiveness did not obviously change, but gumminess significantly increased (P < 0.05). By gas chromatography-mass spectrometry (GC-MS), a total of 34 flavor substances were detected from 5 groups of fermented milk samples, including 7 hydrophilic ones and 27 lipophilic ones. Change in milk fat content greatly affected the content of flavor substanc es. Principal component analysis and correlation analysis showed that change in milk fat content caused significant differences in flavor between fermented milk samples, and the trend of flavor contents was related to their hydrophobicity. With the increase in milk fat content, the content of milk fat degradation products such as 2-nonanone and hexanal but not γ-butyrolactone increased first and then decreased. Among other substances, the content of hydrophilic flavor compounds increased first and then decreased, and the content of lipophilic compounds decreased continuously.

Key words: milk fat; fermented milk; flavor