作为全球公认的三大无酒精饮料之一，茶及其制品具有丰富的营养价值和独特的保健功效。本实验以自制的绿茶和红茶为原料，采用1, 1-二苯基-2-三硝基法（DPPH）、氧自由基吸收能力法（ORAC）和细胞抗氧化法（CAA）对两种茶浸提液的抗氧化能力进行测定和比较，并研究了两种茶浸提液中各类功能性成分含量的差异。实验结果表明：两种自制茶浸提液均具有较高的抗氧化活性，但是其抗氧化能力随茶浸提液发酵程度的加深而降低（DPPH法IC50值：绿茶14.58 μg DM/mL<红茶24.14 μg DM/mL；ORAC值：绿茶5313.92±318.75 μmol TE/g DM>红茶3684.14±233.59 μmol TE/g DM；CAA值：绿茶26.23±0.43 μmol QE/100 mg DM>红茶16.41±0.17 μmol QE/100 mg DM）；随着发酵程度的加深，茶浸提液干物质总量降低，尤以茶多酚含量降低最为显著；茶多酚是影响茶浸提液抗氧化能力的主要功能性成分。

As one of the globally recognized nonalcoholic beverages, tea and their products have high nutritional values and unique health benefits. In this study, the antioxidant activities of two types of tea, homemade green and black teas, were measured and compared using the 2,2-diphenyl-1-(2,4,6-trinitrophenyl)hydrazyl (DPPH), oxygen radical absorbance capacity (ORAC), and cellular antioxidant activity (CAA) methods. The difference between the contents of the functional components of green and black tea extracts was also measured. The results showed that both the homemade tea extracts had high antioxidant activity; however, their antioxidant activity decreased with increasing fermentation time. IC50 of DPPH ingreen tea (14.58 μg DM/mL) was lower that in black tea (24.14 μg DM/mL); while ORAC and CAA values of green tea (5313.92 ± 318.75 μmol TE/g DM and 26.23 ± 0.43 μmol QE/100 mg DM, respectively) were higher than those of black tea (3684.14 ± 233.59 μmol TE/g DM and 16.41 ± 0.17 μmol QE/100 mg DM, respectively). The results indicated that with increasing fermentation time, the total dry matter of tea extracts decreased; in particular, the amount of tea polyphenols (TP) showed the highest decrease among the functional components. Thus, tea polyphenols are the major functional components that affect the antioxidant activity of tea extracts.

广东省科技计划项目(2010B020312005)；广州市科技计划项目（2010Z1-E221）