Process Optimization and Quality Evaluation of Enhanced Fermented Tibetan Tea
The objective of this study is to optimize the technological parameters of Bacillus licheniformis enhanced fermentation of Tibetan tea,and to investigate its antioxidant activity in vitro and aroma components.On the basis of single factor experiment,with fermentation temperature,fermentation time and inoculation amount as the influencing factors and total antioxidant value as the evaluation index,orthogonal experiment has been used to optimize the fermentation process,and the differences of total antioxidant capacity,ABTS free radical scavenging ability,total phenolic content,flavonoids content and aroma composition between intensive fermented Tibetan tea and natural fermented Tibetan tea are compared.The results show that the total antioxidant capacity and ABTS free radical scavenging capacity of enhanced fermented Tibetan tea are 8.09 and 2.48 times as much as those of natural fermented Tibetan tea,respectively,when the fermentation temperature is 37℃,fermentation time is 3 d and inoculation amount is 1.0%.Meanwhile,the polyphenol content of intensive fermented Tibetan tea is increased,which is 1.35 times as much as that of natural fermented Tibetan tea,while the flavonoid content of intensive fermented Tibetan tea is decreased,which is only 54%of that of natural fermented Tibetan tea.Solid phase microextraction technology and gas chromatography-mass spectrometry(GC-MS)hyphenated technology detect that the number of aroma substances in enhanced fermentation Tibetan tea is more than that in natural fermentation,and the aroma substances increase by 15 kinds,and the contents of ketone,alcohol,aldehyde and acid are higher than those in natural fermentation Tibetan tea.The results show that the enhanced fermentation of bacillus licheniformis could improve the antioxidant capacity and aroma components of Tibetan tea,even effectively improve the quality of Tibetan tea.