Caracterização das mudanças na qualidade e no potencial antioxidante como indicadores do ponto de colheita das uvas 'Sweet Sunshine ®' e 'Sweet Sapphire ®' para o submédiodo Vale do São Francisco

Abstract

Viticulture in the region of the Middle-Lower São Francisco Valley is an outstanding activity, mainly due to the cultivation of seedless table grapes. However, new cultivars of fine table grapes, especially seedless grapes, are constantly being evaluated in tropical regions, as there is an interest in establishing benchmarks and characterizing new genotypes intended for in natura consumption. Thus, the aim of this study was to characterize changes in quality and antioxidant activity during maturation of 'Sweet Sunshine®' and 'Sweet Sapphire®' grapes as indicators for harvest time for Middle-Lower São Francisco Valley. We evaluated four consecutive production cycles for each cultivar, during the period from 2013 to 2015. The 'Sweet Sunshine®' grapes were harvested in 2013 and 2015 vintages, since the 'Sweet Sapphire®' grapes were harvested in 2014 the harvests 2015. The bunches were collected periodically from the development stage of the fruit to overripening phase in the four production cycles of the 'Sweet Sunshine®' grapes. In order to cultivate 'Sweet Sapphire ®', the clusters were periodically collected from maturation to the overdilation phase in the four production cycles. The treatments corresponded to the number of days after pruning (DAP), in which the samples were collected. The experiment was carried out in a randomized block design, with four replications, consisting of five bunches, periodically collected from five plants that constituted each plot in the field. The data were submitted to statistical analysis separately, due to the differences between the beginning of the development of the fruit and the maturation duration each cycle, for both cultivars. The ideal harvest time for ‘Sweet Sunshine®' table grapes occurred 107 days after pruning for fruits harvested in the first half of the year and 109 days after pruning for fruits harvested in the second half of the year. For ‘Sweet Sapphire®’ grapes, the ideal harvest time was recorded at 125 days after pruning, for fruits harvested in the first half of the year, and 115 days after pruning, for those harvested in the second half. Both cultivars gathered high contents of flavonoids, total extractable polyphenols as well as high antioxidant activity at the time of harvest. In addition, the cultivars studied showed differences in the duration of the production cycle. The 'Sweet Sunshine®' grapes presented the shortest cycle in the four production seasons, while 'Sweet Sapphire®' grapes was characterized by the later cycle.