Organosulphide profile and hydrogen sulphide-releasing activity of garlic fermented by Lactobacillus plantarum

•A method of fermenting garlic using Lactobacillus plantarum Lp-115 as starter culture.•Fermentation decreases allicin and vinyl dithiins, but increased the concentration of diallyl polysulphides.•Blanching significantly decreases organosulphide content and H2S-releasing activity of blanched-fermented garlic.•Fermentation without blanching retains the H2S-releasing activity of garlic. Blanched and unblanched garlic were fermented using L. plantarum for investigation of organosulphide profiles, hydrogen sulphide-releasing activity, pH, titratable activity and microbial growth. Both raw and blanched garlic preparations allowed growth of L. plantarum with corresponding lowering of pH below 4.0 and an increase in titratable acidity from an initial value of less 0.05% to 0.3 and 0.5%, respectively. Fermentation, alone, decreased allicin and vinyl dithiins, but increased the concentration of DATS. The H2S-releasing activity, expressed as DATS-E (mmol DATS/g oil), of raw-fermented (2.91) garlic was not significantly different to that of raw (4.74) garlic, but values in blanched (0.41) and blanched-fermented (0.71) samples significantly decreased. Reductions in DATS-E values in blanched and blanched-fermented garlic corresponded well with the negative effect of blanching on the organosulphide concentrations of the products. Fermentation with L. plantarum retains H2S-releasing activity by increasing DATS, despite notable losses in allicin and allicin transformation products.