Green Tea Infusion Analysis,Reconstruction And Evaluation

This study analyzed and reconstructed the key taste components of Longjing tea infusion.Response patterns and characteristics of taste sensitive areas in cerebral cortex under tea aroma olfactory)stimulation and taste(gustatory)stimulation were investigated with functional near infrared spectroscopy(fNIRS).The results are as follows:(1)7 kinds of catechins,2 kinds of alkaloids,2 kinds of phenolic acids and 20 kinds of amino acids were quantitatively detected from the tea infusions by liquid chromatography-mass spectrometry and automatic amino acid analyzer.Caffeine,EGCg,EGC and theogallin are found to be key flavor compounds in tea infusion.Then,caffeine,EGCg and sodium glutamate were used to reconstruct the green tea taste reconstruction solution.The reconstruction solution can give similar tastes of bitterness,astringency,and umami intensity of green tea infusion with a concentration of 1/2 caffeine,EGCg and sodium glutamate.(2)A method was established using functional near infrared spectroscopy(fNIRS)for localizing taste stimulus response region and for calculating response intensity value based on the change of oxygenated hemoglobin concentration.This method was used to compare the characteristics of prefrontal cortex taste response caused by the difference of taste type and intensity.The results of taste response analysis under different taste stimuli showed that the regions with higher response values of sucrose(sweet)and caffeine(bitter)were located in orbitofrontal cortex(OFC)and dorsomedial prefrontal cortex(dmPFC)associated with food aversion or preference;while the regions with higher response values of EGCg(bitter and astringency)were located in the dmPFC and right dorsolateral prefrontal cortex(dlPFC)associated with negative emotion,and the regions with higher response values of monosodium glutamate(umami)were located in the dmPFC,OFC and the left dlPFC associated with positive emotion.The results of taste response analysis under different taste intensity solutions showed that the response intensity of channel 4 located in OFC was positively correlated with the concentration changes of theine solution and sucrose solution.The response intensity in dmPFC channel 9 was positively correlated with sucrose and EGCg concentrations.The response intensity of channel 15 located at dlPFC is positively correlated with the concentration of sodium glutamate solution.(3)Responses of the prefrontal cortex and the taste perception under the stimulation of the reconstruction solution(A),the reconstruction solution with added aroma(B)and green tea infusion(C)were compared.The results showed that the superposition of aroma significantly reduced the response intensity of prefrontal cortex activation channel,and weakened the bitter taste perception intensity caused by EGCg and caffeine.In addition,the B solution superimposed with aroma is closer to C in terms of the response intensity of activation channels,as well as in terms of smell and taste perception.