Characterization of Penicillium crustosum L-asparaginase and its acrylamide alleviation efficiency in roasted coffee beans at non-cytotoxic levels.

This work aims at isolating a fungal source for L-asparaginase production to be applied in reducing acrylamide levels in coffee beans at non-cytotoxic levels. An L-asparaginase-producing fungus was isolated from an agricultural soil sample and identified as Penicillium crustosum NMKA 511. A maximum L-asparaginase activity of 19.10 U/mL was obtained by the above-mentioned fungus when grown under optimum conditions (i.e. 16.96 g/L sucrose as carbon source, 1.92 g/L peptone as nitrogen source, pH 7.7 and 33.5 °C). Further, the produced L-asparaginase was purified and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that P. crustosum L-asparaginase was a heterodimer enzyme with molecular weights of approximately 41.3 and 44.4 kDa. Also, the purified P. crustosum L-asparaginase was specific towards L-asparagine and showed negligible and no effects towards L-glutamine and D-asparagine, respectively. Additionally, the purified L-asparaginase reduced the acrylamide levels by 80.7% and 75.8% in light and dark roasted coffee beans, respectively. The amount of L-asparaginase used to reduce acrylamide was considered safe when cell viability reached 94.6%.