Preparation And Flavor Analysis Of Dendrobium Officinale Fermented Milk

Since the pilot project of Dendrobium officinale for medicine and food in Zhejiang Province in 2020,its development and application have become a current hot spot.In this paper,the flavor variation of Dendrobium officinale fermented milk was explored from three aspects: the addition amount of Dendrobium officinale,fermentation conditions and Dendrobium officinale mesh,which laid the foundation for its application in fermented milk.The main research work and results of this paper are as follows:1.The free amino acid content and volatile flavor substances of Dendrobium officinale fermented milk with different additions were investigated by SPME-GC-MS and amino acid analyzer,and the free amino acids were analyzed by correlation analysis,principal component analysis and TAV taste presentation characteristics,and the main flavor substances were determined by odor activity value(ROAV).The results showed that the types of free amino acids were unchanged,the contents were different,and there were strong correlations among most of the free amino acid indicators,and Glu contributed more to the flavor presentation of Dendrobium officinale fermented milk,and two principal components were extracted by principal component analysis,principal component 1 accounted for 99.90% and principal component 2 accounted for0.04%,which could reflect most of the information of free amino acids in each group.The types and contents of volatile flavor substances varied widely among different groups,and diacetyl and ethyl coupling were the key flavor substances in the control fermented milk and Dendrobium officinale fermented milk.The addition of Dendrobium officinale to the fermented milk was beneficial to improve its nutritional quality and flavor.2.The changes in quality and volatile compounds of Dendrobium officinale fermented milk during fermentation were investigated.The results showed that the addition of Dendrobium officinale increased the acidity and apparent viscosity while decreasing the p H and water holding capacity of the fermented milk.the results of OAV analysis indicated that 2-heptanone was the main contributor to the flavor during the fermentation of the fermented milk.The results of cluster analysis showed that the volatile compounds were similar for fermentation times of 1.5 h,2 h,2.5 h and 4 h,and for fermentation times of 3 h,3.5 h and 1 h.These results can provide a reference for future development and process quality control of Dendrobium officinale fermented milk.3.To study the changes of volatile compounds in the fermented milk of Dendrobium officinale at different fermentation temperatures.The results showed that a total of 48 volatile compounds were identified in six groups of samples at different temperatures,with ketones having the highest content of all volatile compounds.In the samples fermented at 40°C,2,3-butanedione was identified as the main contributor to the flavor.Volatile compounds were similar in samples fermented at 41,42 and 44°C,similar in samples fermented at 43 and 45°C,and a separate category at 40°C.2-Butanone,2,3-dimethyl-2-butanol,3-pentanol,2,3-pentanedione,2-heptanone,2,3-butanedione,5-nonanone,and ethanediol were identified as characteristic differential metabolites.4.The effects of different Dendrobium officinale powder mesh on the quality and volatile compounds of fermented milk were investigated,and it was found that the larger the Dendrobium officinale mesh,the smaller the p H of fermented milk and the increase in acidity,water holding capacity and viscosity.A total of 36 volatile compounds,including 14 ketones,6 acids,11 alcohols,3 esters and 2 furans,were identified in the fermented milk of Dendrobium officinale under different meshes treatments.The results of principal component analysis and clustering heat map showed that the differences of volatile compounds were smaller in the samples with powder mesh of 160 and 120;the differences of volatile compounds were smaller in the samples with powder mesh of 80 and 100.