Bioavailability of Isoflavone Metabolites After Korean Fermented Soybean Paste (Doenjang) Ingestion in Estrogen‐Deficient Rats

Doenjang (DJ), a fermented soybean product used in soups, stews, and sauces, contains high quality proteins, fats, vitamins, minerals, and other functional ingredients, including isoflavones and saponins. This study investigated whether DJ improves the bioavailability of isoflavones compared to boiled soybean (BS) in sham‐operated or ovariectomized (OVX) rats. We also examined the effects of ovariectomy on the differences in bioavailability of isoflavones. BS and DJ were administered in sham‐operated and OVX rats, and blood samples were collected. Twenty‐six isoflavone‐derived metabolites were identified. Pharmacokinetic analysis revealed that T_1/2 values of the individual isoflavone metabolites were most different in sham and OVX rats, even after the same sample treatment; however, T_max values were significant different in a few metabolites such as daidzein 4′‐glucuronide, daidzein 4′‐sulfate, 2‐(4‐hydroxyphenyl)propionic acid, and benzoic acid. For most of the individual metabolites, C_max was higher in both sham and OVX rats administered BS than those administered DJ. The AUC was generally lower in OVX rats than in sham rats. The AUC of daidzein and genistein in BS‐fed sham rats was approximately 1.7‐fold higher than those administered DJ, whereas glycitein was detected only in the DJ group. No significant differences in AUC of daidzein and genistein were observed between BS and DJ administration in OVX rats, although the total isoflavone content of DJ was lower; thus, DJ‐mediated isoflavone bioavailability was more effective in OVX rats. Similar tendencies were observed for phase II and gut‐mediated metabolites. These results suggested that DJ enhanced isoflavone bioavailability under estrogen deficiency, even when the total isoflavone content was decreased by fermentation.     

Evaluation of red bean protein [Vigna angularis] isolate on rheological properties of pork myofibrillar protein gels induced by microbial transglutaminase

The effects of 1% red bean protein isolate (RBPI) on the gel properties of myofibrillar protein (MP) in various levels of microbial transglutaminase (MTG: 0%, 0.1%, 0.5%, & 1%) were evaluated. The cooking yield (CY) of the MP gels decreased with increasing MTG level, while the addition of RBPI improved the CY of the MP gels. Gel strength (GS) was also improved when RBPI was incorporated into the MP gels containing higher than 0.5% of MTG. The addition of MTG and RBPI was slightly changed the endothermic peak temperatures. Scanning electron microscopy (SEM) showed that the three‐dimensional structure of MP with RBPI alone or in combined with MTG was compacted as compared to the control. Based on the results, RBPI could be functioned as a substrate for MTG (0.5–1.0%) and a water binder of meat protein gel mediated by MTG.     

Effects of Different Salt Treatments on the Fermentation Metabolites and Bacterial Profiles of Kimchi

The effects of purified salt (PS) and mineral‐rich sea salt (MRS), both with different mineral profiles, on kimchi fermentation were studied using a culture‐dependent 16S rRNA sequencing technique and mass‐based metabolomic analysis. The different mineral profiles in the fermentation medium caused changes in the bacterial profiles of the 2 kimchi products. An increase of Leuconostoc species in MRS‐kimchi decreased the Lactobacillus/Leuconostoc ratio, which led to changes in metabolites (including sugars, amino acids, organic acids, lipids, sulfur compounds, and terpenoids) associated with kimchi quality. Although further studies on the relationship between these salt types and kimchi fermentation are needed, these results suggested that the MRS treatment had positively affected the changes of the kimchi mineral contents, bacterial growth, and metabolite profiles, which are linked to kimchi quality.     

Whitening effects of 4-hydroxyphenethyl alcohol isolated from water boiled with Hizikia fusiformis

Isolation of phenolic compounds from water boiled with Hizikia fusiformis and purificartrion of the extracts from solvent fractions was achieved using column chromatography. The simple phenolic compound, 4-hydroxyphenethyl alcohol (4-HPEA) with an elemental composition C₈H₁₀O₂ was identified on the basis of spectroscopic data. The whitening effects of 4-HPEA, inhibitory activity against mushroom tyrosinase, and inhibitory activity against melanin production in B16 melanoma cells were evaluated using an in vitro assay system. The whitening effect of 4-HPEA was also measured using a colorimeter and visual assessment of UVB induced hyperpigmentation of brown guinea pig skin. Topical application of 4-HPEA promoted depigmentation of UVB-induced hyperpigmented spots. 4-HPEA has a potential for use as a safe and effective ingredient for whitening in cosmetic and medical applications.     

Comparison of the antimicrobial and antioxidant activities of selected wheat varieties

Antibacterial and antioxidant activities of wheat seed ethyl acetate extracts for Jokyoung (JK), Dark northern spring (DNS), Keumkang (KK), Woori (WR), and Winter wheat (WW) were investigated. Antibacterial activities were evaluated in vitro against the common food and cosmetic industry contaminants Escherichia coli, Salmonella typhimurium, and Staphylococcus aureus using well diffusion assays. WW had the highest inhibitory activity against all tested strains, with S. aureus being the most sensitive strain. The minimum inhibitory concentration (MIC) values of WW and WR against S. aureus were 0.50 and 1.25 mg/mL, respectively. The 2,6-dimethoxy-1,4- benzoquinone (DMBQ) content was measured using HPLC. The antibacterial activities of wheat seed extracts were correlated with the total phenolic contents (Pearson’s correlation coefficient=0.994), with the ABTS radical scavenging activity (0.978), and with the DMBQ content (0.968). WW and WR have potential for use as natural antimicrobials for prevention of food and cosmetics spoilage.     

Inhibitory effect of cinnamon essential oils on selected cheese-contaminating fungi (Penicillium spp.) during the cheese-ripening process

The antifungal effects of essential oils (EOs) on cultures of the known cheese fungal contaminants Penicillium spp. were evaluated. Cinnamon leaf and bark EOs were the most effective among 8 EOs tested. The main components of both cinnamon EOs were eugenol, cinnamaldehyde, and linalool. Both inhibited growth of Penicillium spp. at a concentration of 10% v/v (2,000 ppm/mm²) on a lawn cell plate. When tested using 3 commercially available cheese starters, cinnamon EOs showed no effect against the FD-DVS ABT-5 cheese starter. However, growth of lactobacilli was inhibited in the presence of ≥10% (v/v) of leaf and bark EOs for the KAZU 1 starter, and ≥5% (v/v) for the FD-DVS FLORA-DANICA starter. A concentration of 4,000 ppm/mm² of cinnamon EOs completely inhibited growth of the Penicillium spp. that naturally contaminates the surface of Appenzeller cheese.     

Antioxidant potentials of buntan pumelo (Citrus grandis Osbeck) and its ethanolic and acetified fermentation products

The antioxidant potentials of buntan pumelo (Citrus grandis Osbeck) and its fermented products were determined. The essential oil from peel had higher total phenolic (214 mM) and flavonoid (134 mg QE/g of dried material) contents than those of different solvent extracts from fruit pulp. In addition, DPPH free radical-scavenging activity and ferric-reducing antioxidant power values determined for the essential oil were 26.1 ± 1.2% and 2.3 ± 0.3 mM, respectively, which were significantly higher than those of various fruit pulp extracts. The ethanol-fermented products of pumelo juice had higher total phenolic and flavonoid contents than those of fresh juice. For maintenance of the substantial antioxidant properties of pumelo products, ethanol-fermented juice rather than fresh or acetate-fermented juice is recommended. Through correlation analysis, the phenolic compounds in the fermented pumelo products were found to be the major contributors to the free radical-scavenging activity and ferric-reducing power.     

Preparation of a polymethoxyflavone-rich fraction (PRF) of Citrus sunki Hort. ex Tanaka and its antiproliferative effects

The peel of Citrus sunki is a rich source of polymethoxyflavones (PMFs). In this study, a PMF-rich fraction (PRF) was obtained from the peels of C. sunki by hot-water extraction and subsequent fractionation with n-hexane. Six PMFs and two demethylated PMFs were isolated by semi-preparative HPLC, and their structures were identified by ¹H NMR and ¹³C NMR. To define the synergistic effects of PRF, the PRF and its eight individual components were assessed for antiproliferative activity using HL-60 cells. The PRF showed greater growth inhibitory activity (IC₅₀ value = 25.14 μg/ml), compared with its individual components. Flow cytometric analysis confirmed that the PRF significantly increased the percentage of sub-G₁ cells (30.1% at 25 μg/ml). Our study provides an efficient method for preparing a PRF for use as a functional food ingredient.