This study was aimed at determining the antioxidant activity of commercial grape juices in inhibiting the copper-catalyzed oxidation of human low-density lipoproteins (LDL) in vitro and at relating this activity to the phenolic composition of the juices. This work also evaluated the effect of vitamin C on this antioxidant activity. When standardized to a total phenolic concentration of 10 μM gallic acid equivalents (GAE), samples of grape juices inhibited LDL oxidation from 62 to 75%. White grape juices inhibited LDL oxidation on the average by 72%, Concord purple grape juice by 67%, and grape juice blends (mixture of white and Concord grape juice) by 63%. Vitamin C had no significant effect on the antioxidant activity of the grape juices tested. The antioxidant activity of Concord juice samples was related to their anthocyanin levels, while that of the white grape juices was related to their levels of flavan-3-ols and hydroxycinnamates, as determined by HPLC. On the basis of the same total phenolic concentration, the antioxidant activity of grape juices toward LDL oxidation was comparable to that of several California red wine. However, based on their undiluted total phenolic concentration, the Concord and blends of grape juices had comparable activity to that of the red wines, while the white grape juices were less active. Keywords: LDL oxidation; phenolic compounds; antioxidants; grape juice; flavonoids; hexanal; HPLC
We have isolated two soil bacteria (identified as Arthrobacter aurescens TW17 and Nocardia sp. strain TW2) capable of degrading p-nitrophenol (PNP) and numerous other phenolic compounds. A. aurescens TW17 contains a large plasmid which correlated with the PNP degradation phenotype. Degradation of PNP by A. aurescens TW17 was induced by preexposure to PNP, 4-nitrocatechol, 3-methyl-4-nitrophenol, or m-nitrophenol, whereas PNP degradation by Nocardia sp. strain TW2 was induced by PNP, 4-nitrocatechol, phenol, p-cresol, or m-nitrophenol. A. aurescens TW17 initially degraded PNP to hydroquinone and nitrite. Nocardia sp. strain TW2 initially converted PNP to hydroquinone or 4-nitrocatechol, depending upon the inducing compound.
Vegetable soybean (VS), known as edamame, is appreciated for its robust flavor and exceptional nutrient content. Although the United States is one of the world's leading producers of soy, only a fraction is harvested as edamame. Research involving varietal differences is very limited, particularly among U.S. consumers. Sensory attributes of three VS varieties grown in Northern California (with organic methods) were assessed: Giant Midori (GM), ButterBean (BB), and Kuroshinja (KU). Participants (n = 74) rated four characteristics: flavor, texture, appearance, and overall liking on unlabeled, 11‐point hedonic scales and were asked if they would purchase the variety. A small portion of these participants would again evaluate the varieties, using free choice profiling (FCP) methodology. After these evaluations, texture analyzer, colorimeter, and high‐performance liquid chromatography (free amino acids, sugars, and isoflavones) testing were performed. Among tested varieties, distinct differences in quality were found, with GM preferred first, followed by KU, and BB. GM was significantly harder, a more intense green, had more free sugars and isoflavones and fewer free amino acids, whereas KU and BB trended to be the opposite. Analyzing FCP data with a General Procrustes Analysis, varieties were separated in different factors for flavor and texture, but not appearance. Although repeated, and larger trials are needed, our study signifies that consumers are able to detect differences among VS varieties. Further research may influence producers to grow the variety likely to be most profitable and marketable.
Aims:The aim was to develop a cheap cereal-based alternative medium for the large-scale production of biopreservative Lactobacillus plantarum VTT E-79098. We examined the effect of growth medium and pH control on the cell yield of Lact. plantarum E-79098 and the antimicrobial activity of the cell-free extracts. Methods: Fermentations using a novel Malt Sprout Extract Medium (MSE) were performed with different pH regimes. The antimicrobial activity of the cell-free extracts against Pantoea agglomerans VTT E-90396 and Fusarium avenaceum VTT D-80147 was assessed with automated turbidometry. Significance and Impact of the Study: When compared with MRS, the MSE medium cultures produced equal growth yields of Lact. plantarum VTT E-79098 and enhanced antimicrobial potential against the Gram-negative bacterium P. agglomerans and a Fusarium fungus. The MSE medium can be used as a low-cost alternative to MRS for producing high cell yields and good antimicrobial activity of Lact. plantarum.
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