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  • Acetification: an approach to valorize non marketed fruits
    Publication . Mehrpour, Gisou Raouf; Quintas, Célia; Nunes, Patrícia A.
    Four different vinegars (Fig enxario, Fig, Sweet potato and Grape) were collected from a vinegar production factory, Fateixa, located in Algarve, Portugal and were examined for different physico-chemical and antimicrobial characteristics. Results of the physico-chemical experiments revealed that in the tested vinegar samples, the pH ranged from 2.83 to 3.49 and the titratable acidity was between 4.84% and 6.75%. Moreover, the lowest Brix value was found in Grape vinegar (4.80) while the highest value was in Fig vinegar (11.20). Total phenolic and total flavonoid contents ranged from 0.35 to 2.03 mg GAE/ml and 93.68-357.31 mg catechin/ml, respectively. Antioxidant activity revealed no significant difference between samples. Color properties showed that L* values of the tested vinegars varied from 25.47 to 28.36, and values of a* and b* were found in the range of -0.49-0.48 and 2.01-3.23, respectively. The antibacterial properties of the vinegars were evaluated against eight bacterial isolates, Gram-positive (Staphylococcus aureus ATCC 25923, Listeria innocua ATCC 33090, Staphylococcus epidermidis ATCC 12228 and Bacillus cereus ATCC 10876) and Gram-negative (Cronobacter sakazakii ATCC 29544, Salmonella enterica Typhimurium ATCC 14028, Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853) bacteria. The highest antibacterial activity was found in Grape vinegar, however in the case of C. sakazakii and S. Typhimurium, Sweet potato vinegar had the greatest growth-inhibitory effects. It was also observed that P. aeruginosa was the most sensitive strain, particularly against Grape vinegar. Furthermore, antifungal activity of the vinegars against seven yeast strains (namely, Candida albicans ATCC 10231, Candida albicans ATCC 90028, Cryptococcus neoformans YPO 186, Saccharomyces cerevisiae PYCC 3507, Pichia membranifaciens PYCC 2489, Zygosaccharomyces bailii PYCC 4806 and Debaryomyces hansenii PYCC 2968) was examined. None of the vinegars showed fungicidal activity against C. albicans, S. cerevisiae and Z. bailii. On the contrary, growth of D. hansenii was considerably affected by all samples, while the highest level of growth-inhibitory effect was observed for Sweet potato vinegar. In conclusion, the bacteria tested were more sensitive to the vinegars than the yeasts.
    2022-03-30Master thesis Open access Show more