Organosulfide profile and hydrogen sulfide-releasing capacity of stinky bean (Parkia speciosa) oil: Effects of pH and extraction methods.

Stinky beans (Parkia speciosa) were hydrodistilled and solvent-extracted and the oil obtained was analyzed by GC-MS/FID. Nine cyclic and one acyclic organosulfides were identified comprising 36% of total volatiles. Solvent extracts contained significantly (p < 0.05) higher total organosulfides (680 ppm) as compared to distilled oil (444 ppm). The concentrations of organosulfides are highly dependent on the pH values of the matrix, with control sample (pH 5.40) giving the highest total organosulfides (424 ppm) followed by that of pH 7.0 (234 ppm), pH 9.0 (195 ppm), and pH 3.0 (152 ppm). The H2S-releasing capacity, expressed as diallyl trisulfide equivalents (DATS-E in mmol DATS/g), corresponded well with the differences in organosulfide concentrations as affected by pH with control having the highest value (24.35) followed pH 7.0 (7.27), pH 9.0 (3.27), and pH 3.0 (1.80). We conclude that stinky bean oil is a potent H2S-releasing agent that could have health-beneficial properties.