Abstract Citrus fruits are significant sources of bioactive compounds, such as ascorbic acid, polyphenols and carotenoids, due to their antioxidant properties important for human nutrition. In addition, since oranges possess high sugar content (8-15%), making vinegars from alcoholic orange substrates, with functional characteristics is a possible development of novel products. The aim of this research work was to analyze changes in ascorbic acid, total phenolics, total carotenoids and antioxidant activity during orange vinegar processing. In order to analyze the influence of acetification and aging in these characteristics, samples were taken in three stages: orange alcoholic substrate for acetification (SNA), young orange vinegar or recently obtained (Vn0) and orange vinegar after six month-aging in bottles (Vn6). Statistically significant differences (p < 0.05) were found among bioactive compounds concentrations; antioxidant activity decreased along the process, but total phenolics and carotenoids remained constant during aging period (Vn0-Vn6). The highest reduction was recorded during the acetification stage, possibly due to components oxidation caused by continuous air flow to the system. A higher contribution (p < 0.05) to antioxidant activity was associated to ascorbic acid and phenolic compounds concentration.

AbstractAscorbic acid, carotenoids and polyphenols stand out among the orange juice natural antioxidants. The winemaking process affects their bioavailability and bioactivity. Antioxidant activities (AA) were estimated in different process conditions to asses those properties. The AA and their correlation with ascorbic acid, total phenolics and carotenoids content were calculated. The variables and levels analyzed were: pasteurized and natural must (PJ and NJ), pH 3.5 and 4.0 and fermentation temperatures at 10°C and 20°C. Statistically significant differences (α=0.05) were found among bioactive compounds concentrations. Antioxidant compounds concentration was higher in raw material than in orange wine. Juice pasteurization caused the major losses while subsequent vinification affects them to a lesser extent. Highest antioxidants retention was measured in wines from JN fermented at pH 3.5 and 10 °C (JN-3.5-10) followed by wines from JP and fermented at the same conditions (JP-3.5-10). AA determined by DPPH showed a positive and close correlation with FRAP, while ABTS showed a low correlation with former assays. Juice pasteurization process and fermentation temperature influenced bioactive compound reduction which correlates with the AA variation.

El estudio de levaduras autóctonas para ser usadas en la elaboración de vino de naranja, incluye aislamiento, identificación y obtención de biomasa. Para optimizar su crecimiento se deben establecer los requerimientos nutricionales. El objetivo de este estudio fue definir las necesidades de vitaminas y factores orgánicos de crecimiento de S. cerevisiae aislada de jugo de naranja fermentado. Se formuló un medio de cultivo con sacarosa (4 g/L) como fuente de carbono y energia (FCE) y urea como fuente de nitrógeno (FN), con 6 vitaminas (pantotenato de calcio, piridoxina, tiamina, biotina, niacina, ác. fólico) e inositol y ácido p-aminobenzoico (PABA) como factores de crecimiento. El medio completo se usó como testigo, preparándose además otros tres medios: con ausencia de todas las vitaminas y factores orgánicos de crecimiento, con pantotenato de Ca, piridoxina, tiamina, biotina e inositol y con esas 4 vitaminas, pero sin inositol. Finalmente, se procedió a eliminar una vitamina. Los cultivos se realizaron en aerobiosis a 30 ºC y pH 5,0. La cepa autóctona de S. cerevisiae requiere las vitaminas pantotenato de calcio, piridoxina, tiamina y biotina para crecer adecuadamente en condiciones aeróbicas en sistema batch; en cambio, no es auxótrofa para niacina, ácido fólico, PABA e inositol.

The study of the yeasts present in the orange juice microbiota and used in the winemaking involves the isolation, identification and production of biomass. In order to optimize the yeast growth, the nutritional requirements should be determined. The aim of this work was to determine the vitamin and other growth organic factors demand for the S. cerevisiae isolated from fermented orange juice. The culture medium was formulated with sucrose (4 g/L) as carbon and energy source (CES), urea as nitrogen source (NS), six vitamins (calcium pantothenate, pyridoxine, thiamine, biotin, niacin, folic acid), and inositol and p-aminobenzoic acid (PABA) as growth factors. The complete culture medium was used as blank, and three other media were prepared: without the vitamins and growth organic factors, with calcium pantothenate, pyridoxine, thiamine, biotin and inositol and with the latter four vitamins, but for inositol. Finally, four new media were obtained by elimination of one vitamin at a time. The temperature was set at 30 ºC and the pH, at 5.0. The S. cerevisiae present in the orange juice needs calcium pantothenate, pyridoxine, thiamine and biotin to grow adequately under aerobic conditions in a batch system, not being auxotroph for niacin, folic acid, PABA and inositol.