Low-malt beer (happoshu) in Japan use high amount of adjuncts such as corn and rice. The adjuncts were treated with malt (10% weight of adjuncts) at 100 ℃ for effective gelatinization during mashing. Most of the happoshu was successful in gelatinization at 100℃. However, deterioration of leutering speed was observed at some with high starch content. Therefore, the objective of the study was to improve the leutering speed of high starch content happoshu. Gelatinization begins at 80℃ and it occurs effectively at higher temperature. Our hypothesis was that with starch degradation enzymes, gelatinization might take place effectively even at lower temperature. Therefore we have tried mashing at 83℃, which both starch degradation and enzyme activity take place. 2 kl pilot scale trials were undertaken with mashing temperature at 120, 100, and 83℃. Number of loosening of spent grains and total time of the leutering, and sensory analysis of final beer were observed. Compared to 100℃, 83℃ improved both leutering condition and flavor quality. Number of loosening of spent grains for 120, 100, and 83℃ were 10, 15, and 12 times respectively and total time of the leutering for 83℃ was 5% shorter than that of 100℃. 50kl scale plant trials also showed similar results.Soluble sugar content and AAL increased at 83℃ compared to 100℃. Therefore it is obvious that starch liquefaction took place during gelatinization at 83℃. Starch gelatinization and liquefaction at the same time might be effected leutering speed for high starch content happoshu.