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This study aimed to evaluate the effect of nitrogen fertilization on the physical and physico-chemical characteristics and antioxidant potential of sapodilla at different stages of development. The experiment was installed at the Norfruit farm, located in the rural community of Pau Branco, Mossoró/RN, Brazil. A randomized block with two factorial schemes experimental design, was adopted. The first 5 x 6 with lost parcels, consisting of five doses of nitrogen (N) (0, 300, 600, 900 and 1200 g of N.plant-1) and six stages of fruit development; and the second 2 x 3 consisting of two levels of nitrogen (N) (0; 600 g of N plant-1) and three stages of development, both with five replications. The fruits were labeled with a 10 to 15 mm long mark in the plant. In fact, were harvested and analyzed after 90, 120, 150, 180 and 200 days of its marking and 208 days (fully mature, after 8 days of storage at 25 ± 2 °C and RH 58 ± 5%), respectively. The results showed a nitrogen fertilization at the dose of 600 g of N.plant-1, produced fruit with higher sugar content and fresh weight, reaching greater mass and sugar content, at 200 and 180 days of fruit development, respectively. An increase in nitrogen fertilization, promoted a reduction in the levels of yellow flavonoids and anthocyanins. Bioactive compounds (total polyphenols, vitamin C, flavonoids and anthocyanins) and sapodilla antioxidant activity decreased with the further development of fruit. The antioxidant activity of the sapodilla is more related to the high content of total polyphenols. The knowledge obtained in this study is extremely important for the sapodilla production chain due to information of the nutritional and antioxidant composition of the fruits. This also proves beneficial for the fruit marketing, because nowadays the public seeks foods rich in antioxidants, and the sapodilla is marketed both in natura and processed, in addition to its use in the cosmetics manufacture.

RESUMO A composição química e o estádio de maturação podem interferir no ponto de colheita do sapoti, a depender da destinação do fruto. Consequentemente, objetivou-se, com este trabalho, avaliar a influência da adubação potássica na qualidade e no potencial antioxidante do sapoti, em diferentes estádios de desenvolvimento. O experimento foi instalado na fazenda Norfruit, em Pau Branco, Mossoró, RN. O delineamento adotado foi em blocos casualizados, em esquema fatorial 5 x 6, composto por cinco doses de potássio (0, 200, 400, 600 e 800 g de K por planta) e seis estádios de desenvolvimento, com cinco repetições. Os frutos foram marcados ao atingirem 10 a 15 mm de comprimento; sendo colhidos e avaliados 90, 120, 150, 180 e 200 dias após sua marcação e completamente maduros (após oito dias de armazenamento a 25 ± 2 ºC e 58 ± 5% UR). O sapoti pode ser colhido 200 dias após a floração plena, quando atinge seu tamanho máximo e apresenta qualidade adequada para o consumo. O sapoti maduro tem maior teor de açúcares e menor concentração de compostos bioativos e atividade antioxidante. A dose de 400 g por planta de K proporciona frutos de maior massa, com maiores concentrações de polifenóis extraíveis totais e atividade antioxidante. A atividade antioxidante do sapoti está mais correlacionada com a concentração de polifenóis extraíveis totais. ABSTRACT The chemical composition and stage of maturation may interfere with harvest point of sapodilla depending on the destination of the fruit. This study aimed at evaluating the influence of potassium fertilization on quality and antioxidant potential of sapodilla at different development stages. The experiment was carried out on farm Norfruit, in Pau Branco, Mossoró, RN. The experimental design was completely randomized blocks in a 5 × 6 factorial scheme, consisting of five doses of potassium (0, 200, 400, 600, and 800 g K for plant) and six development stages, with five repetitions. The fruits were marked when reaching 10 to 15 mm in length, being collected and evaluated after 90, 120, 150, 180, and 200 days after being marked and when they were fully mature (after eight days of storage at 25 ± 2 °C and RH 58 ± 5%). Sapodilla can be harvested 200 days after full bloom, when it reaches its maximum size and presents adequate quality for consumption. The ripe sapodilla has higher concentration of sugar and lower concentration of bioactive compounds and antioxidant activity. The dose of 400 g of K per plant generated fruits of greater mass, with higher concentration of polyphenols and antioxidant activity. The antioxidant activity of sapodilla is more correlated with total extractable polyphenol concentration.