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Lactic acid bacteria produce a-amylase which is used in food and nutraceutical products. This study aims to detect a-amylase stabilities of Lactobacillus satsumensis EN 38-32 and Fructobacillus fructosus EN 17-20 at storage temperatures and times. The stabilities of a-amylase were determined at 4°C and -20°C, and storage times of 0, 7, 14, 21 and 28 days. The DNS method was used to test a-amylase activity. The relative activity of a-amylase >= 50% was expressed as a-amylase activity in stable conditions. Data were analyzed by standard deviation with three replications. The results showed that the a-amylase stabilities of L. satsumensis EN 38-32 and Fr. fructosus EN 17-20 at storage temperatures decreased with increasing storage times. The longer the storage times, the lower the a-amylase stabilities. The relative activities of L. satsumensis EN 38-32 a-amylase at storage temperatures for 7- 28 days were in the range of 72.79-93.70% and 72-89.18%, while Fr. fructosus EN 17-20 at 56.69-93.11% and 56.70-93.11%.
Based on the a-amylase stabilities, it was concluded that Fr. fructosus EN 17-20 produced better a-amylase than L. satsumensis EN 38-32. So, it is recommended to use Fr. fructosus EN 17-20 to produce a-amylase as a biocatalyst rather than L. satsumensis EN 38-32.