Food engineering and bioengineering
LIU Lu, PU Gen, WU Cuifang, DONG Shujia, FANG Songping, WU Wenrui, KONG Qing, SHANG Zhiying
In this study,jasmine black tea leaves,whole milk powder and white sugar were used as the main raw materials,and commercially available lactic acid bacteria starter culture was used to optimize the fermentation process of jasmine black tea yogurt with sensory score as the index,and the optimal fermentation process conditions of jasmine black tea yogurt were obtained by designing response surface optimization test based on single-factor,Plackett-Burman test and steepest climb test.The physical and chemical indexes such as acidity and sugar content,microbial indexes such as lactic acid bacteria and volatile flavor substances were tested.The results showed that the optimal fermentation process for jasmine black tea yogurt was 4.1% jasmine black tea addition,14.3% milk powder addition,0.4% fermenting agent inoculation,6.2% sugar addition,9 h fermentation time and 42 ℃ fermentation temperature.Under these optimized conditions,the sensory score of the yogurt was 90 points;the acidity of jasmine black tea yogurt was 83 °T,the sugar content was 10.2%,and the lactic acid bacteria count was 2.2×109 CFU/mL.28 volatile flavor substances were detected in jasmine black tea yogurt by gas chromatography tandem mass spectrometry,including three characteristic aroma substances of jasmine black tea,such as benzyl alcohol,linalool,and benzyl acetate.