Effect of Different Tea Process on Antioxidant Capacity and Consumer Acceptance of Doi Saket Purple Rice Leaf Tea

Abstract

The aim of this research is to study the effect of different tea process of Doi saket purple rice leaf tea on antioxidant capacity and the consumer acceptance. Doi saket purple rice leaf tea were processed in 4 different tea processes which were green tea process, English tea process, Chinese tea process and Oolong tea process. After that, the physical (moisture content and colour (L*, a* and b*) in CIE system, chemical properties (antioxidant capacity) and sensory test of the products were analyzed. The results showed that the moisture content of Doi saket purple rice leaf tea samples from 4 different processes were not over than the standard value (the standard value of moisture content of tea was indicated as 8% by Thai industrial standards institute (TISI)), their moisture content were between 6.46 and 7.59%. It also was found that the different tea processes had a significant effect on the color of both of purple rice leaf tea and tea in term of L*, a* and b* colour at the confidence level of 95% (p<0.05). However, the different tea processes had no significant effect on antioxidant capacity. Purple rice Oolong tea leaf had the highest antioxidant capacity (82.27±1.90%) following by purple rice Green tea leaf, purple rice English tea leaf and purple rice Chinese tea leaf (81.99±0.00%, 81.78±0.76% and 80.79±0.61%, respectively). The customer acceptance was evaluated by sensory test in 4 attributes which were colour, flavour, taste and overall. The sensory analysis result showed that the score of all sample from difference 4 tea processes were slightly to moderately like in all attributes. However, the highest score was found in Oolong tea process which had the score of 7.08±1.21, 6.76±1.53, 6.56±1.76 and 6.78±1.54 in color, odor, taste and overall, respectively.