Ripening-Related Changes in the Nutritional Profile of a Little-Known Red ‘Isabel’ Grape (Vitis vinifera L. × Vitis labrusca L.)

Regular consumption of table grape berries bestows various health benefits due to their rich vitamin, mineral, and polyphenol contents. This study examined the physicochemical properties and nutritional composition of berries (skin, flesh, and seed) of red ‘Isabel’ (Vitis vinifera L. × V. labrusca L.) grape during ripening (232–293 days after full bloom) grown in Türkiye. The results showed that fruit size and dry matter content in the berry increased gradually throughout ripening, while moisture content and firmness decreased. Fructose was the major soluble sugar in all parts of the grape, followed by glucose and sucrose. In general terms, the sugar contents of the grape increased in a stage-dependent manner. Malic acid was the most abundant organic acid in the skin and flesh, and tartaric acid in the seed, their contents decreasing in the same manner during ripening. The skin and flesh exhibited higher palmitic acid content than the seed, as well a high linoleic acid content in the berry parts. Potassium was the major element in all parts of the grape, followed by Na, Fe and Mg. These results indicate that these nutrients are present at high levels in this grape berry and that the full red stages are the most suitable for obtaining benefit from the grape nutrients.