Biological activities of cheonggukjang prepared with several soybean cultivars

To select proper soybean cultivars for producing functional cheonggukjang, a comparison was made of the physiological activities of different cheonggukjang prepared with 30 different soybean cultivars. The isoflavone content was highest in the cheonggukjang made from ‘Daepung’ soybeans at 208.75 mg%. In general, the contents of glycone types (and derivatives) of isoflavone, specifically daidzin, glycitin, genistin, and malonylgenistin, were higher than that of aglycone types. The polyphenol contents ranged from 30.62 to 80.32 mg%. The DPPH radical scavenging activity and superoxide dismutase (SOD)-like activity of the cheonggukjang made from yellow soybeans had a higher activity than those of black soybeans. Although there are no consistent tendencies in the functional activity of cheonggukjang according to soybean color and size, the antioxidative activity is highest in the cheonggukjang made of yellow soybeans. Additionally, the fibrinolytic and inhibitory activities against angiotensin I-converting enzyme are highest in the cheonggukjang made of black soybeans. From these results, it can be concluded that the DPPH free radical scavenging activity and SOD-like activity in cheonggukjang depends on the phenolic compound content in soybean.     

Organic whey as a source of Lactobacillus strains with selected technological and antimicrobial properties

Twenty‐five strains, isolated from raw, non‐pasteurised, organic whey samples, were identified phenotypically and genotypically. Biochemical tests were performed, and enzyme profiles, antibiotic resistance and antimicrobial properties were investigated. Sixteen strains were identified as genus Lactobacillus. Based on 16S rDNA gene sequence, the strains were identified as Lb. plantarum and Lb. fermentum. All of the strains had β‐galactosidase activity, and some of them reduced nitrate content. All strains utilised carbohydrates. The tested strains were characterised by low or average lipolytic and esterolytic activity. Moreover, the strains showed low proteolytic activity which is advantageous for their use as starter cultures for foods with low protein content. Strains Lb. fermentum S20, SM1, SM3, S2R and Lb. plantarum SM5 produced harmful N‐acetyl‐β‐glucosaminidase; moreover, the strain S20 produced also β‐glucuronidase. None of the strains produced α‐chymotrypsin. In phenotypic studies, most of the test strains were susceptible to gentamicin, ampicillin, tetracycline, chloramphenicol, penicillin and erythromycin. Strains Lb. plantarum S1 and Lb. fermentum S4, S7, S8, S10, SM1 and SM3 did not possess any transfer resistance genes. Antagonistic activity of the culture LAB strains was assessed as high or moderate in relation to the indicator strains, with the greatest zones of inhibition for E.coli and the smallest for L. monocytogenes ATCC 15313. This study reveals that the LAB strains isolated from organic whey have high potential for food application. Some strains of species Lb. fermentum (S4, S7, S8, S10) have been identified as the best candidates.     

Enhancement of total phenolic and isoflavone-aglycone contents and antioxidant activities during Cheonggukjang fermentation of brown soybeans by the potential probiotic Bacillus subtilis CSY191

Changes in β-glycosidase activity, total phenolic and isoflavone contents, and antioxidant activities during the fermentation of brown soybeans (Galmi) fermented food cheonggukjang by the potential probiotic Bacillus subtilis CSY191 were investigated. The total phenolic and isoflavone-glycoside and -aglycone contents as well as ABTS radical scavenging activity and FRAP assays of extracts increased, but malonylglycoside content decreased after a steaming process. It was found that fermentation enhanced the total phenolic and isoflavone-aglycone and -malonylglycoside contents, corresponding to antioxidant activities increased, but isoflavone-glycoside content decreased. The highest levels of daidzein, glycitein, and gensitein were present at concentrations of 156.5 μg/g, 10.2 μg/g, and 2.5 μg/g after 48 h of fermentation. In addition, ABTS radical scavenging activity and FRAP assay increased significantly during fermentation. We suggest that the high antioxidant activity of cheonggukjang of brown soybeans might be related to the markedly higher levels of total phenolic content and isoflavone-aglycones achieved during fermentation.     

Antioxidant properties of 1,2,3,4,6-penta-O-galloyl-β-d-glucose from Elaeocarpus sylvestris var. ellipticus

The antioxidant potential of 1,2,3,4,6-penta-O-galloyl-β-d-glucose (PGG), isolated from Elaeocarpus sylvestris var. ellipticus, was investigated by various established systems based on cell-free and cell system experiments, such as radical detection, antioxidant enzyme assay, lipid peroxidation detection, and cell viability assay. PGG was found to quench the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and intracellular reactive oxygen species. PGG recovered the cellular antioxidant enzyme activities of superoxide dismutase, catalase, and glutathione peroxidase, which were reduced by H₂O₂ treatment, thereby resulting in the inhibition of lipid peroxidation. Cytoprotective effects of PGG were based on the results of DNA fragmentation, mitochondrial membrane potential (Δψ), apoptotic body formation, and caspase-3 activity. The results suggest that PGG protects cells against H₂O₂-induced cell damage via antioxidant properties.