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- Screening of antioxidant activity of fermented papayaPublication . Leitão, Mariana; Barreiros, Luísa; Moreira, Fernando; García, Pablo; Correia, PatríciaPapaya is the fruit of Carica papayaL., consumed for its beneficial proprieties, directlyor as a fermented fruitsupplement. Compare the total phenolic content (TPC) and the antioxidant activity (Ferric Reducing Antioxidant Power, FRAP) evolution in a variety of papaya fermentation experiments using fruit natural microorganisms (spontaneous fermentation) versus fermentation with Gluconobacter oxydansbioinoculation. Different papaya fermentations were performed: spontaneous (P1 and P2, during 7 days; P3, P4 and P5, during 9 days) and with bioinoculation (P6 and P7, during 9days). Then, TPC was determined according to the Folin-Ciocalteu (FC) procedure, mixing 250 μL of sample with 2.5 mL of FCreagent, followed by an addition of 2 mL of sodium carbonate solution (7.5 % w/v). This mixture wa sincubated at 45 °C for 15 minutes, and then kept in the dark at room temperature for 30 minutes. Absorbance was measured at 765 nm. The FRAP method was performed mixing 1.2 μL of freshly FRAP reagent with 40 μL of sample,and then incubating for 15 minutes at 37 °C. Absorbance was read at 593 nm. The lowest TPC was observed on day7of P4 (121.20±0.12 μg GAE·mL-1), and the highest content was observed on day 8 of P7 (260.18 ± 0.02 μg GAE·mL-1). TPC decreased from the first to the last day of fermentation in all tests, except for the tests where bioinoculation strategy was used. Those tests also showed a higher FRAP content, although from day 1 today 7, FRAP also slightly increased in P1, P2, and P3 (spontaneous fermentations). Antioxidant capacity increased as a result of fermentation with G. oxydans, probably due to the increased amount of phenolic compounds observed. The final product may be used as a functional food or cosmetic applications.
- Screening of antioxidant effect of spontaneous and bioinoculated with gluconobacter oxydans fermented papaya: a comparative studyPublication . Leitão, Mariana; Ferreira, Beatriz; Guedes, Beatriz; Moreira, Daniela; García, Pablo A.; Barreiros, Luísa; Correia, Patrícia Carla dos SantosFermented papaya is recognized as a nutraceutical with a diverse and rich composition. Fermentation of fruit with desirable microorganisms could be a strategy to improve the nutritional quality and profile of the fruit. Despite the popularity of fermented papaya, there is still a lack of knowledge on the effects of various fermentation parameters. The goal of this study was to screen the antioxidant and other properties of the products obtained through a variety of fermentation experiments, as well as the impact of adding Gluconobacter oxydans on their physicochemical properties. The strategies used to produce the fermented papaya extracts were spontaneous fermentation and bioinoculation with G. oxydans. Different fermentation tests were performed to measure pH, total soluble solids, reducing sugars, sodium pyruvate content, total phenolic content (TPC), and ferric reducing antioxidant power (FRAP). There was a decrease in TPC during spontaneous fer mentations (five assays). However, it can be observed that in the fermentation assays with G. ox ydans, there was an increase in TPC and antioxidant properties. The highest content of TPC was observed on the eighth day of P7 (260.18 ± 0.02 µg gallic acid equivalents· mL−1) which was fer mented with the bacteria and supplemented with glucose. Therefore, phenolic compounds in fer mented papaya were found to increase antioxidant capacity as a result of bioinoculation with G. oxydans.