Effect of Thermal Processes on S-Allyl Cysteine Content in Black Garlic

Abstract

As a key component of black garlic (BG) products, S-allyl cysteine (SAC) is useful in reducing oxidative stress and inflammation. Several BG products with a high SAC content have been developed by thermal processing; however, the optimum conditions for thermal treatment for producing Thai garlic (multicloves) with a high SAC content compared to Chinese garlic (single clove) are still unknown. Moreover, the mechanism underlying the increase in SAC content in BG is unclear. Thus, this study aimed to investigate the optimum thermal condition for developing Thai BG with high SAC content base on methods A (70 °C and 80% RH) and B (60–75 °C and 80–85% RH). The total phenolic contents and antioxidant activities of Thai fresh garlic, Thai BG, and their powder forms were also compared. Method A worked the best for both types of garlic. The results indicated that the SAC content increased significantly after 7 days of fermentation and decreased drastically afterward with prolonged heat treatment. The optimum thermal condition for producing Thai fresh garlic and Chinese fresh garlic with high SAC content was 70 °C and a relative humidity of 80% for 12 days in an industrial fermentation chamber. The SAC content of Thai BG and Chinese BG increased approximately 139- and 122-fold, respectively. Furthermore, significant antioxidant capabilities determined by ferric ion-reducing antioxidant power, 2,2-diphenyl-1-picrylhydrazyl radical scavenging, and oxygen radical absorbance capacity assays were 34-, 6-, and 3-fold higher, respectively, than those of fresh garlic.

Anti-Cancer and Anti-Inflammatory Properties of Black Garlic

“…Furthermore, black garlic's antioxidant capacity is also affected by its type, moisture, and fermentation time-as shown in Table 2. To maximize antioxidant abilities, garlic fermentation should last for 8-12 days at 70-75 • C with a moisture content of 80-85% [24,38]. Using a temperature that is lower than those mentioned will prevent the garlic from turning black and keep its pungent aroma, whereas using a temperature that is higher than those mentioned will cause the garlic to become bitter [13].…”