Garlic augments the functional and nutritional behavior of Doenjang, a traditional Korean fermented soybean paste

Abstract

Three different forms of garlic, namely, fresh garlic (2%, 6%, 10%), heat-dried (1%, 2%, 3%) and freeze-dried (1%, 2%, 3%), were supplemented in soybean paste to prepare Doenjang and further evaluated for functional, nutritional and safety aspects. Results showed a considerable antioxidant and anti-proliferative activity of garlic-supplemented Doenjang. As a measure of nutritive value, a high amount of total free amino acids, 4,290.73 mg/100 g–5,492.94 mg/100 g, was observed in prepared Doenjang. Among all preparations, 3% freeze-dried garlic-supplemented Doenjang proved the most effective against gastric adenocarcinoma and lung adenocarcinoma with 50% inhibition concentration of 7.66 ± 0.53 mg/mL and 7.82 ± 0.34 mg/mL, respectively. However 10% fresh-garlicsupplemented Doenjang (GGD-10) showed better activity against colorectal adenocarcinoma (HT29) cell line. Furthermore, GGD-10 effectively reduced colony formation and altered mitochondrial membrane potential of HT29 cells. Absence of pathogenic bacteria (Staphylococcus aureus, Salmonella species and Bacillus cereus) and aflatoxin was observed in Doenjang samples. In addition, nontoxic amount of anti-nutritional biogenic amines was observed in all the samples. The results collectively suggest that the addition of garlic in Doenjang can improve its nutritional and functional value, resulting in the protection of consumers from protein deficiencies and various stress conditions.