Effects of drying methods on the quality and volatile flavor compounds of oil tea powder
Objective:This study aimed to explore suitable drying methods for oil tea powder,making it easier for oil tea consumption and storage.Methods:Spray drying,vacuum freeze drying and vacuum drying were used to dry oil tea soup,and the quality(moisture content,sensory evaluation and color)and volatile substances of dried oil tea powder were evaluated.Results:The sensory score of vacuum freeze-drying oil tea powder was the highest(93),the water content was the lowest(3.78%),and the color was better(△E value 49.74).104 volatile substances were identified from three drying methods of oil tea powder using SPME-GC-MS technology,of which 14 affected the flavor of oil tea powder.The characteristic flavor substances(nonanal,decanal,(Z)-2-decanal,(Z)-2-nonenal,(E)-3,7-dimethyl-2,6-octadienal)of freeze-drying present green fragrance and fat fragrance.The special aromas of spray drying and vacuum drying are(Z)-3,7-dimethyl-2,6-octadienal,(E)-3,7-dimethyl-2,6-octadienal and decanal,presenting green fragrance,fruit fragrance,and wax fragrance.PCA and comprehensive evaluation indicate that vacuum freeze-drying has the best flavor quality,which is consistent with sensory evaluation results.Conclusion:The flavor quality of vacuum freeze-drying was the best.