REDUCTION OF GLUCOSINOLATES CONTENT DURING SAYUR ASIN FERMENTATION

Abstract

Glucosinolates (GLSs), health promoting compounds commonly found in Brassica vegetables, were studied during sayur asin fermentation made from Indian mustard ( B. juncea ). The current preliminary study aims to investigate the changes of glucosinolates content during 3 and 7 days of fermentation in two different media, i.e. coconut water and tajin liquor, and salt concentrations of 2.5 and 10%. The glucosinolates were analysed by HPLC after sample extraction in hot methanol followed by purification and de-sulphation. Results show that sinigrin was the most dominant glucosinolate among others, i.e. gluconapin, glucobrassicin, 4-hydroxy-glucobrassicin, 4-methoxy-glucobrassicin, and neo glucobrassicin, accounting for about 1000 and 4000 µmol/10 g dw in raw Indian mustard. Unfortunately, fermentation has substantially reduced the glucosinolates content in sayur asin . After 3 days of fermentation the sinigrin content was reduced by 95% as compared to that in the raw vegetable. The indole GLSs 4-methoxy-glucobrassicin and neo-glucobrassicin concentration decreased to 80-90% of the fresh materials. However, the decreasing mechanisms as well as factors contributing to the decrease of the glucosinolates could not be explained yet.