Comparative assessment of quality parameters and bioactive compounds of white and black garlic

Quality parameters and bioactive compounds of two white garlic samples from two regions of Turkey (Gaziantep and Kastamonu) and five commercial black garlic samples were investigated. It was found that the black garlic samples had greater total sugar content. Black garlic samples had also higher total amino acids (112.9–684.8 mg/100 g) as compared to the white garlics (250.8–411.9 mg/100 g). Arginine and glutamic acid were the dominant amino acids in both product types. Cysteine, the key amino acid responsible for the principal health-promoting properties of garlics, was found to be much higher in black garlic samples (112.0 µg/100 g in BG4) when compared to white garlic samples (21.4 µg/100 g in KWG). Black garlic samples had 4–7 times more antioxidant potential as compared to the white garlics. It was also found that the predominant sugar compound was sucrose (702.3–884.7 mg/100 g) in white garlic and fructose (3277.0–27,232.2 mg/100 g) in black garlic samples and the total amount of sugar was 4- to 17-fold higher in black garlic compared to the white garlic. 13 and 14 phenolic compounds were quantified by LC-DAD-ESI-MS/MS in the white and black garlic samples, respectively. Black garlic was found to have a higher phenolic content (26.3–37.9 mg/100 g) than white garlic (18.0–23.3 mg/100 g) while caffeic acid was the dominant phenolic in both product types. In general, black garlic could be recommended to consumers due to its higher potential of bioactive compounds.