The Taste Characteristics Of Typical Phenolic Acids And Their Effects On The Bitterness And Astringeney Of Green Tea Infusion

Phenolic acids is a class of aromatic compounds with carboxyl and hydroxyl groups in molecules.Phenolic acids are important substances in tea polyphenols.Polyphenols are mainly bitter and astringent,among which catechins is the main source of bitterness and astringency in tea infusion,flavonoids contribute significantly to the astringency of black tea.Although phenolie acids have been reported to be astringent,there are few studies on the taste characteristics of phenolic acids and the effects of phenolic acids on the bittermess and astringency in green tea infusion.Therefore,the taste characteristics of typical phenolic acids and their effects on the bitterness and astringency in green tea infusion were studied in this paper.By analyzing the relationship between the bitterness and astringency of spring and autumn green tea infusion and the components in tea infusion,the contribution degree of major polyphenols compounds to the bitterness and astringency in tea infusion was determined.The concentration-taste intensity curve of typical phenolic acids was established,and the effects of typical phenolic acids and other polyphenols on the taste of EGCG and tea infusion were investigated.The main results were as follows:(l)By analyzing the relationship between the results of sensory evaluation of bitterness and astringency in green tea infusion and the components in tea infusion,the results showed that catechins were significantly positively correlated with the bitterness and astringency in green tea infusion and were the main contributing substances to the bitterness and astringency.The flavonoids were positively correlated with the bitterness and astringency in green tea infusion,but it contributed a lot to the astringency.There was a significant positive correlation between phenolic acids and the bittermess and astringency in green tea infusion,but it contributed less to the bitterness and astringency because of its lower content.(2)Through sensory evaluation,it was found that caffeic acid,chlorogenic acid and gallic acid were sour and astringent,and the curves of concentration-astringency intensity of three typical phenolic acids were established.The results showed that the curves of concentration-astringency intensity of three typical phenolic acids could be fitted by cubic function.The astringency score of caffeic acid was y=2.2222x3-10.857x2+9.7373x-0.0038,R2=0.9995;The astringency score of chlorogenic acid was y=66.667x3-40.19x2+ 9.3762x+0.0062,R2=0.9988;The astringency score of gallic acid was y=1.1574x3-2.9861x2+3.5271x+ 0.0008,R2=0.9999.(x is the concentration of corresponding phenolic acid compounds,in mmol/L).(3)Through sensory evaluation,the effects of cafleic acid,chlorogenic acid and gallic acid on the taste of EGCG were determined.The results showed that when the concentration of caffeic acid and chlorogenic acid was O?0.2 mmol/L,there was bitterness synergy and astringency inhibition between caffeic acid,chlorogenic acid and EGCG.When the concentration of caffeic acid and chlorogenic acid increased to above 0.2 mmol/L,there was bittermess and astringency synergy between the caffeic acid,chlorogenic acid and EGCG.There was bitterness and astringency synergy between gallic acid and EGCG.The higher the concentration of gallic acid,the stronger its enhancement effect on the bittermess and astringency of EGCG.(4)Through sensory evaluation,the effects of caffeic acid,chlorogenic acid and gallic acid on the taste of green tea infusion were deteramined.The results showed that there was a certain bittermess and astringency synergy between caffeic acid,chlorogenic acid,gallic acid and green tea infusion.With the increase of the concentration of three phenolic acids,the enhancement effect of three phenolic acids on the bittermess and astringency of tea infusion was more obvious.(5)Through the sensory evaluation,the effect of rutin on the taste of EGCG was determined.The results showed that when the concentration of rutin was 0?0.05 mmol/L,there was bitterness synergy and astringency inhibition between rutin and EGCG.When the eoncentration of rutin increased to above 0.05 mmol/L there was bittermess and astringency synergy between rutin and EGCG.(6)Through the sensory evaluation,the effects of EGCG and rutin on the taste of green tea infusion were determined.The results showed that there was bitterness and astringency synergy between EGCG and tea infusion.When the concentration of rutin was 0?0.05 mmol/L,there was bitterness synergy and simple astringency superposition between rutin and tea infusion.When the concentration of rutin increased to above 0.05 mmol/L,there was bitterness and astringency synergy between rutin and tea infusion.