Effects of roasting treatment on non-volatile compounds and taste of green tea

The effects of roasting treatment on sensory quality and related compounds in green tea were investigated. The combined application of roasting temperature and time 100 degrees C for 90 min, 120 degrees C for 60 min and 140 degrees C for 30 min achieved the most satisfying sensory quality. The HPLC analysis showed that the contents of cis-catechins, bitter and umami amino acids reduced with increase in temperature, while the contents of trans-catechins and soluble sugar increased with the temperature rise. The content of caffeine and sweet amino acids did not change significantly compared with untreated tea sample. The decrease in cis-catechins, total polyphenols and bitter amino acids reduced the bitterness and astringency of the green tea, while the increase in total soluble sugars improved the sweetness and mellow taste. The sensory evaluation results showed that the sensory quality of the tea was significantly enhanced through roasting treatment.