Effects of Fixation Methods on the Quality of Huangjinya Green Tea Produced in Autumn
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Abstract:
In this study, the fresh leaves of Huangjinya green tea obtained in Autumn were used as the raw materials to process green tea, and the effects of three different fixation methods, drum rolling, steaming and microwaving, on the quality of Huangjinya green tea products were studied. The sensory evaluation combined with quality analysis revealed that the Huangjinya green tea products produced with the three different fixation methods were all of excellent quality, but there were great differences in tea color, aroma and taste. The dry tea fixed by drum rolling had the greenest color and best aroma with an obvious chestnut aroma. Compared with thosed fixed by steaming and microwaving, the tea fixed by drum rolling had a higher amino acid content (increased by 11.01% and 5.20%, respectively) and lower content of tea polyphenols is (decreased by 3.54% and 3.94%, respectively), making the green tea taste mellow and fresh. The tea fixed by steaming had the highest taste score with the highest theanine content (7.69 mg/g) and the lowest caffeine content (27.91 mg/g), and exhibited the highest umami taste and abundance but lowest bitterness in the electronic tongue analysis. The correlation analysis of taste attributes detected by the electronic tongue and chemical composition showed that the umami value of the Autumn Huangjinya green tea was significantly and positively correlated with the theanine content (p<0.05), with the correlation coefficient as 0.99. There was a significant positive correlation between the bitterness value and the bitter-tasting catechin content (p<0.05), with the correlation coefficient as 0.99; In addition, the Huangjinya green tea fixed with different methods had different abilities to scavenge different free radicals, with the total antioxidant capacity decreased in the order of microwaving (0.83) > steaming (0.80) > drum rolling (0.66). In summary, the tea fixed by drum rolling tastes mellow with a strong and long aroma; the tea fxied by steaming had a mellow and thick taste and yellow-green color. Although there are some distinct favorable attributes, the Huangjinya green teas all show variety advantages.
