Study on the formation, structural characterization, and antioxidant activity of Amadori compound Fru-SAC during...

Amadori compounds (ACs) are key intermediates in the Maillard reaction, with significant bioactivity. However, ACs derived from Allium species, such as S-allyl cysteine (SAC), have not been extensively studied, despite their recognized contribution to flavor and bioactivity. The present study investigated the effect of alliinase on the stability of alliin. In addition, the Amadori rearrangement product Fru-SAC, formed from SAC and glucose, was synthesized, characterized, and its synthesis conditions optimized. Optimal parameters were determined to be a glucose-to-SAC ratio of 1:3, a pH of 9 and a temperature of 120 °C, yielding 34.74 %. To assess the relevance of these findings in black garlic, the levels of 15 ACs, including Fru-SAC, were analyzed in single-bulb and multi-clove black garlic. The total AC content was 8.02 ± 0.71 mg/g DW and 6.29 ± 0.47 mg/g DW, respectively, while the Fru-SAC levels were comparable at 0.13 ± 0.02 and 0.12 ± 0.02 mg/g DW. Before and after processing, the alliin concentration in garlic decreased from 15.00 ± 0.25 mg/g DW to 2.35 ± 0.37 mg/g DW, while the SAC concentration in black garlic decreased from 8.34 ± 0.27 mg/g DW to 5.16 ± 0.27 mg/g DW. Black garlic, rich in ACs, exhibited superior antioxidant activity compared to raw garlic. The findings of this study will help elucidate the biological functions of Allium species and their ACs, and contribute to the standardization of Allium-based product production.