The effect of sterilization processing methods on the quality of canned green tea

Effect of oxygen content in green tea infusion and head space of can packed green tea infusion on L-ascorbic acid content, color and flavor changes of canned green tea drinks was investigated by comparing retort sterilization method with aseptic canning method, The decrease of oxygen content was correlated with the decrease of L-ascorbic acid content in green tea infusion during sterilization processing. The lower the content of oxygen was, the smaller the loss of L-ascorbic acid was. These effects were almost the same between the both processing methods. The color tone of green tea infusion changed noticeably on retort sterilization products compared aseptic canning products. The color changes of aseptic canned samples were mild and not concerned to the oxygen contents in green tea infusions. The flavor of canned green tea drinks were kept under the aseptic sterilization process. However, that of retort sterilized samples had an off-flavor, (retort-flavor). These results showed that the aseptic sterilization processing method was the best for the sterilization of canned green tea in terms of the low oxygen content owing to deoxygenation of extraction Rater and exclusion of head space volume of canned drink.