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BACKGROUND Gentiana lutea root is a medicinal herb that contains many active compounds which contribute to physiological effects, and it has recently attracted much attention as a natural source of antioxidants. The aim of this study was to evaluate the effects on the colour, pH, microbial activities, sensory quality and resistance to lipid oxidation (through the thiobarbituric acid method) during storage of beef patties containing different concentrations of G. lutea. Fresh beef patties were formulated with 0-5 g kg−1 of G. lutea and 0 or 0.5 g kg−1 of ascorbic acid and packed in two different atmospheres, Modified Atmosphere 1 (MAP1) and Modified Atmosphere 2 (MAP2), and stored at 4 ± 1 °C for 10 days. MAP1 contained 20:80 (v/v) O2:CO2 and MAP2 contained 80:20 (v/v) O2:CO2. RESULTS G. lutea extracts possessed antioxidant activity measured by the ferric reducing antioxidant power and the oxygen radical absorbance capacity assays. Beef patties containing 2 g kg−1 of lyophilised G. lutea were stable towards lipid oxidation in both atmospheres ( P < 0.05). Beef patties containing a combination of 2 g kg−1 G. lutea and 0.5 g kg−1 ascorbic acid showed significantly reduced changes in colour and in lipid oxidation ( P < 0.05). CONCLUSION The results from this study demonstrate the potential of G. lutea as a food ingredient in the design of healthier meat commodities. © 2014 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

BACKGROUND The successful replacement of some synthetic food antioxidants by safe natural antioxidants has fostered intensive search for new vegetable sources of antioxidants. In our study the phenol and flavonoid content of extracts of tara pods was determined. The antioxidant activity was also studied by three different analytical assays: the measurement of scavenging capacity against a radical ABTS+, the oxygen radical absorbance capacity ( ORAC) and the ferric reducing antioxidant power ( FRAP). RESULTS All analyzed samples showed a good antioxidant capacity, but the use of a solution of ethanol 75% in a 1 h ultrasonic process allowed achieving the greatest quantity of phenolics (0.464 mg gallic acid equivalent ( GAE) g−1 dry weight ( DW) ) and the highest antioxidant activity measured by the ABTS+ and ORAC methods (10.17 and 4.29 mmol L−1 Trolox equivalents ( TE) g−1 DW, respectively). The best method for efficient extraction of flavonoids (3.08 mg catechin equivalent ( CE) g−1 DW) was a 24 h maceration in cold water. Two extracts obtained with ethanol 75% and water were added to a model food system (oil-in-water emulsion) and the oxidative stability was studied during storage at 38 °C. Oxidation was monitored by determination of the peroxide value. The addition of 48 µg mL−1 ethanol extract to the emulsion delayed oxidation to the same extent as 17.8 µg mL−1 of Trolox, while water extract was only effective in the early stages of the oxidation process. CONCLUSION The results of this study indicate that ethanolic tara extracts may be suitable for use in food, cosmetic and nutraceutical applications. © 2013 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Antioxidant and antimicrobial activity of the ethyl acetate and water subfractions of methanolic extracts of three Spanish onion varieties were assayed. Flavonoids were mainly present in ethyl acetate subfraction being 34.92 ± 0.75, 7.95 ± 0.16, 0.38 ± 0.01 μmol of rutin eq. g−1 D.W. and its antioxidant capacity was 74.86 ± 1.77, 24.59 ± 0.67, 4.55 ± 0.44 μmol Trolox g−1 D.W. of Grano de Oro, Fuentes de Ebro and Calçot de Valls varieties, respectively. The antimicrobial activity of flavonol standards and onion extracts was evaluated against some food spoiler microorganisms. Quercetin and kaempferol were inhibitory against gram positive bacteria such as Bacillus cereus, Staphylococcus aureus, Microcroccus luteus and Listeria monocytogenes. Gram negative bacteria Escherichia coli and Pseudomonas aeruginosa were less sensible to the antimicrobial effect of both flavonol standards and Candida albicans was totally resistant. Among the onion extracts tested only ethyl acetate subfraction showed antimicrobial inhibition. [ABSTRACT FROM AUTHOR]