Antioxidant and antimicrobial properties of wine byproducts and their potential uses in the food industry.

Wine pomace (WP) is one of the agricultural byproducts that has received most attention from food scientists due to the wide range of interesting compounds that remain after the winemaking process. Different powdered products rich in phenolic compounds, with interesting antioxidant and antimicrobial activities, were obtained from WP by applying processes that are both environmentally friendly and economically affordable for the food industry. The products obtained showed high global antioxidant activities (ABTS assay), successfully delayed the onset of lipid oxidation in the Rancimat test, and showed different antimicrobial properties. Products derived from seed-free WP showed bactericidal effects against total aerobic mesophilic bacteria (TAMB) and lactic acid bacteria (LAB) and inhibited Enterobacteriaceae growth completely. The product derived from whole WP presented bacteriostatic activity against the three microorganism groups tested, whereas the product obtained from grape seed promoted TAMB and LAB growth but delayed Enterobacteriaceae proliferation.

Inhibition of induced DNA oxidative damage by beers: correlation with the content of polyphenols and melanoidins.

Beers are a source of dietary flavonoids; however, there exist differences in composition, alcohol concentration, and beneficial activities. To characterize these differences, three kinds of lager beer of habitual consumption in Spain, dark, blond, and alcohol-free, were assayed for total phenolic content, antioxidant activity, superoxide and hydroxyl radical scavenging activities, and in vitro inhibitory effect on DNA oxidative damage. Furthermore, their melanoidin content and correlation with antioxidant activity were evaluated. Dark beer contained the highest total phenolic (489 +/- 52 mg/L) and melanoidin (1.49 +/- 0.02 g/L) contents with a 2-fold difference observed when compared to the alcohol-free beer. For the three kinds of beer, the antioxidant activity measured as N,N-dimethyl-p-phenylenediamine dihydrochloride concentration was strongly correlated with the total polyphenol content (R(2) = 0.91102, p < 0.005) and with the melanoidin content (R(2) = 0.7999, p < 0.05). The results support a positive effect of beers on the protection of DNA oxidative damage, by decreasing the deoxyribose degradation, DNA scission (measured by electrophoresis), and inhibition of 8-hydroxydeoxyguanosine (8-OH-dG) formation. Furthermore, a correlation between the total melanoidin content (R(2) = 0.7309, p < 0.01) and inhibition of 8-OH-dG was observed.