Showing papers by "Jorge Regueiro published in 2011"

Influence of alcoholic fermentation process on antioxidant activity and phenolic levels from mulberries (Morus nigra L.)

Abstract: The aim of the present study was to evaluate the profile of the phenolic constituents of Morus nigra fruits and their antioxidant activity (DPPH) and to compare their contents before and after fermentation. Antioxidant phenolics of black mulberry ( M. nigra L.) samples grown in Galicia (NW Spain) were extracted with methanol/formic acid/water (MFW) and determined by high performance liquid chromatography (HPLC). Two major anthocyanins (cyanidin 3-glucoside and cyanidin 3-rutinoside) and two flavonols (quercetin 3-glucoside and rutin) were isolated, together with caffeic acid and other hydroxycinnamic and ellagic acid derivatives. Their chemical structures were identified by spectral analyses with diode array detection (DAD), but also with alkaline saponification and acid hydrolysis of the mulberry phenolics. Good correlations ( r 2 = 0.6229) were observed among total flavonols contents and the IC 50 radical scavenging capacities of mulberry fruits. Anthocyanins are the major flavonoids present in mulberry. It would be expected that anthocyanins contribute significantly to their antioxidant activity; nevertheless, alcohol generated during fermentation may also contribute to antioxidant activity. Our results provide useful antioxidant nutritional information of fresh and fermented mulberry fruits.

Influence of new fungicides – metiram and pyraclostrobin – on Saccharomyces cerevisiae yeast growth and alcoholic fermentation course for wine production Influencia de los nuevos fungicidas – metiram y piraclostrobín – en el crecimiento de la levadura Saccharomyces cerevisiae y en el curso de la fermentación alcohólica para la elaboración de vino

Abstract: The influence of different concentrations of two new fungicides (metiram and pyraclostrobin) on the fermentative activity of Saccharomyces cerevisiae yeast during winemaking process has been evaluated through in vitro assays. These fungicides were assayed as pure active compounds (single and in combination) and as a commercial formulation which contains both fungicides (55% metiram + 5% pyraclostrobin). The presence of pyraclostrobin pure standard in the culture medium, at the highest concentration evaluated (10 mg/L), increased the biomass and ethanol production rate. No effect on the alcoholic fermentation was observed for metiram pure standard due to its low solubility in the synthetic medium. However, a total inhibition of yeast growth was observed in presence of ≥40 mg/L of the commercial formulation. Se analizo, mediante ensayos in vitro, la influencia de diferentes concentraciones de dos nuevos fungicidas - metiram y piraclostrobin - sobre la actividad fermentativa de la levadura Saccharomyces cere...