不同茶饮料贮藏过程中品质的变化

本文从色泽、浊度及活性成分含量三个方面分析不同茶饮料的品质变化特征，分别对高酸绿茶饮料、低酸绿茶饮料、高酸红茶饮料及低酸红茶饮料在不同贮藏条件下的可溶性固形物含量、透光率、浊度、色差、茶多酚含量、表没食子儿茶素没食子酸酯（Epigallocatechin gallate，EGCG）含量等指标进行测定，探究不同茶饮料在不同贮藏条件（温度、时间）下品质变化的情况。结果表明:不同茶饮料在贮藏过程中，透光率无显著变化；高酸绿茶饮料在4 ℃及25 ℃条件下贮藏，随贮藏时间的延长，浊度显著增加，贮藏至第180 d，分别增加了52.04%、34.12%，红茶饮料浊度无显著变化；不同茶饮料在贮藏过程中，随贮藏时间的延长，L*值降低，a*值及b*值增加，25 ℃条件下贮藏至180 d，高酸绿茶饮料、低酸绿茶饮料、高酸红茶饮料及低酸红茶饮料的L*值分别降低了31.86%、39.98%、30.22%及37.73%；茶饮料中的茶多酚及EGCG含量随着贮藏时间的延长而降低，EGCG降解程度较茶多酚高，在55 ℃条件下贮藏15 d，高酸绿茶饮料、低酸绿茶饮料、高酸红茶饮料及低酸红茶饮料的茶多酚含量分别降低9.08%、10.28%、13.39%及18.63%，EGCG含量分别下降了35.32%、42.18%、47.22%及49.03%。

Quality Changes of Different Tea Beverages during Storage

The quality changes of tea beverages including color stability, turbidity and nutritional component stability were analyzed in this article. Four kinds of tea beverages, namely high-acid green tea, low-acid green tea, high-acid black tea and low-acid black tea drinks, were stored under different storage conditions. The impact of different storage temperature and storage periods on the quality of tea beverages was investigated by the measurements of soluble solid contents, transmittance, turbidity, color difference, catechin and epigallocatechin gallate (EGCG) contents. The results showed that, there was no significant difference in the transmittance of tea beverages during different storage conditions; Under the storage condition of 4 ℃ and 25 ℃, turbidities of high-acid green tea product were increased significantly. To 180 days, the turbidity increased by 52.04% and 34.12% under 4 ℃ and 25 ℃, respectively; There was no significant difference in the turbidities of black tea product. During storage, the brightness values(L*) of different tea beverages decreased significantly, and the red value (a*) and blue value (b*) increased significantly. When stored at 25 ℃ for 180 d, the brightness values (L*) of four tea products (high-acid green tea, low-acid green tea, high-acid black tea and low-acid black tea drinks) were decreased by 31.86%, 39.98%, 30.22% and 37.73%. The content of tea polyphenol and EGCG decreased significantly with the extension of storage time. When stored at 55 ℃ for 15 days, the contents of catechins in high-acid green tea, low-acid green tea, high-acid black tea and low-acid black tea products were dropped by 9.08%, 10.28%, 13.39%, 18.63%, the contents of EGCG were dropped by 35.32%, 42.18%, 49.03%, 47.22%, respectively.