Unveiling the transformations in phytochemicals and grape features: a thorough examination of 'Italia' and 'Bronx Seedless' cultivars throughout multiple berry development stages

Abstract

Understanding the physical and phytochemical characteristics of grape cultivars across different berry development stages is crucial for optimizing grape production and quality in the agricultural and viticultural industries. The study, therefore, investigated the physical characteristics and phytochemical composition of 'Italia' and 'Bronx Seedless' grape cultivars harvested across six distinct periods. In grape cultivars displayed an intriguing journey in terms of resveratrol, ranging from 5.96 mg/kg in Period I to 11.59 mg/kg in Period VI. These vital compounds known for contributing to grape color and potential health benefits showed substantial variation across the grape cultivars and harvest periods. In addition, significant variations in phytochemical compositions were observed between 'Italia' and 'Bronx Seedless' grape cultivars, with 'Italia' generally exhibiting higher concentrations of key compounds such as resveratrol, pterostilbene, anthocyanidins, and flavonoids. The longitudinal analysis across six berry developmental periods highlighted a progressive increase in the concentrations of these phytochemicals in cultivar, indicating a dynamic evolution of grape biochemistry over time. Particularly, delphinidin-3-O-glycoside, cyanidin-3-O-glycoside, and petunidin-3-O-glycoside showed marked increases, indicating significant growth in anthocyanin content from Period I to Period VI. Utilizing PCA biplots and a hierarchical clustering heatmap, the study visually represented the relationships and variances among various phytochemical components. The insights revealed how certain compounds clustered together, suggesting similarities and dissimilarities. The positioning of compounds on these plots indicated their significance in characterizing grape cultivars and their maturation over time. In summary, the data underlined the strong influence of berry development time on phytochemical composition, emphasizing the importance of strategic grape harvesting to attain desired phytochemical profiles for wine or other grape products. The findings provide valuable insights for grape growers, winemakers, and researchers aiming to exploit the full potential of these compounds in grape-based products and for those interested in understanding the dynamics of grape phytochemistry.