Gas Chromatography Analysis of Diallyl Disulphide and Diallyl Trisulphide and Antioxidant Activity in Black Garlic

Background: Diallyl disulphide (DADS) and diallyl trisulphide (DATS) found in garlic provide biological activity which protects against oxidative damage. This study aimed to confirm the presence of DADS and DATS compounds in black garlic, formed from heads of fresh garlic through a process of heating and fermentation. Methods: Analysis was performed using Shimadzu GC-17A gas chromatography with DB-5 column and flame ionisation detector at column temperatures of 140°C with programmed temperature rises of 1°C/min to 180°C, injector and detector temperatures of 200°C and 0.8 mL/min flow rate. Antioxidant activity were tested against the stable DPPH (2,2‐diphenyl‐1‐picryl‐hydrazyl‐hydrate) free‐radical. The ability to scavenge DPPH radical was measured in these experiments by the discoloration of the solution. Results: The validation results showed that the coefficients of correlation (r) for DADS and DATS are 0.9999 in the range of 0.1–10 μg/mL. The values limit of detection and limit of quantitation were 0.0096 and 0.0210 μg/mL for DADS compounds and 0.0198 and 0.0662 μg/mL for DATS compounds. Extraction using ethyl acetate produced average content of DADS and DATS of 0.0012 and 0.0009%, respectively. Conclusion: Among heating at 80°C and humidity of 75% for three months, it was shown that there were decreasing levels of these compounds during the ageing process from fresh garlic to black garlic and the shorter time are those that generally have a higher antioxidant activity.