Optimization the conversion of glucosinolate to isothiocyanate in yellow mustard seeds (Sinapis alba) by response surface methodology

Yellow mustards are widely cultivated for their spicy flavor and are rich source of glucosinolates and myrosinase. The predominant glucosinolate in yellow mustard seeds is sinalbin and corresponding isothiocyanate is 4-hydroxybenzyl isothiocyanate upon hydrolysis by endogenous myrosinase. The isothiocyanates from sinalbin hydrolysis draws unique interest because of their broad-spectrum antimicrobial activities and has been applied in various food products for extending the shelf life. In this study, the hydrolysis of sinalbin for the production of 4-hydroxybenzyl isothiocyanate from yellow mustard seeds was optimized based on myrosinase activity by applying the response surface methodology with three-factor-three-level Box-Behnken Design (BBD). It was found that the sinalbin content in yellow mustard seeds could reach up to 87.9 mg/g seeds. The highest hydrolysis of sinalbin to 4-hydroxybenzyl isothiocyanate 20.1 (mg/g seeds) was achieved under optimum hydrolysis conditions of homogenization for 5 min at pH 5.8 with 4.5 mM ascorbic acid and incubation at 51°C for 15.8 min. This study showed that the production of 4-hydroxybenzyl isothiocyanate from sinalbin was correlated with the myrosinase activity and high amounts of active isothiocyanate could be obtained under optimized hydroxylation conditions. This study also provides new insights into the future design of products rich in isothiocyanates from mustard seeds.