Dynamic changes of phenol and antioxidant capacity during fruit development of three Actinidia species (kiwifruit)

Abstract

Three Actinidia species fruit have been used to study the dynamic changes of the phenolic composition and concentration during their fruit development with high performance liquid chromatography (HPLC). The results showed that there was a clear downward trend of the total phenol contents in fruit of the three Actinidia species, but it was significantly different among them. Total phenol content in fruit of A. eriantha ‘Ganmi No. 6’ was the highest, more than ten times higher compared to the other two species. All nine phenolic monomer of gallic acid, catechin, p-hydroxybenzoic acid, epicatechin, caffeic acid, vanillic acid, rutin, ferulic acid and quercetin were detected in the three species during their fruit development. However, the dynamic change pattern and the proportion of each phenolic monomer as part of the total phenols varied greatly among the three species. During fruit development, the content of each phenolic monomer in fruit of ‘Ganmi No. 6’ was significantly higher than that in fruit of A. chinensis ‘Hongyang’ and A. deliciosa ‘Jinkui’ (P < 0.01), especially the content of gallic acid (up to 620.55 mg/100 g FW). Gallic acid, epicatechin and catechin were the major phenolic components in fruit of ‘Jinkui’, which also contained lower amounts of caffeic acid. However, the fruit of ‘Hongyang’ mainly contained epicatechin, rutin, caffeic acid followed by p-hydroxybenzoic acid. ‘Ganmi No. 6’ also exhibited stronger antioxidant capacity with higher ferric reducing ability of plasma (FRAP) value and O2− clearance rate than that in fruit of the other two species. Correlation analysis showed that although the antioxidant activity of each of the three species was significantly correlated with the total phenol content, there were significant differences in the types of the antioxidant activities measured, which was correlated with different phenolic levels and compositions in the different species of Actinidia. This study provides a better understanding of the phenolic characteristics of the three Actinidia species and how they affect antioxidant properties. Some of these compounds are especially useful as a nutritional resource for human consumption, e.g., ferulic acid and highlights the potential of new A. eriantha germplasm resource for utilization toward breeding of novel kiwifruit to benefit human health.