INFLUENCE OF THE GENOTYPE ON THE ANTHOCYANIN COMPOSITION, ANTIOXIDANT CAPACITY AND COLOR OF CHILEAN POMEGRANATE (Punica granatum L.) JUICES

Abstract

The bioactive compounds content in pomegranate (Punica granatum L.) juice is variable and depends on agronomic factors, genetic and fruit maturity. In Chile, the areas with this crop have increased more than 65% in the last 5 years. This paper aims to determine the phenolic composition, antioxidant capacity and chromatic parameters of juices from eight Chilean pomegranate genotypes (PG2 to PG9), containing red (PG2 to PG6) or pink arils (PG7 to PG9). Color, total polyphenol content (using Folin-Ciocalteu reagent), total anthocyanins (by differences in absorbance at different pHs of the juice) and antioxidant capacity (oxygen-radical absorbance capacity, ORAC) were determined. Anthocyanins were identified and quantify using HPLC-DAD and HPLC/ESI-MS, the results were expressed as cyanidin-3-glucoside. ANOVA was used for establish differences between total polyphenols (TP), antioxidant capacity, total anthocyanins (TA), total polyphenols/total anthocyanins relations (TP/TA) and colour parameters. Statgraphics plus 7.0 was used. Genotypes PG2-PG6 (red arils) showing higher values for total polyphenols (1055-1280 mg L-1) and anthocyanins (588-1328 mg L-1) and higher ORAC values (21.2-24.4 μmol Trolox mL-1) than the pink arils PG7-PG9 (12.7-16.8 μmol Trolox mL-1) values. The latter genotypes showed the highest values of pH (3.5-3.7). The anthocyanin compounds identified in the juices were the 3-glucoside and 3,5-diglucoside derivatives of delphinidin, cyanidin and pelargonidin. Differences in their relative amounts were found among the Chilean pomegranate genotypes studied. The relationships between TP/TA and Pg/Cy (pelargonidin 3-glucoside and pelargonidine 3,5-diglucoside/cyanidin 3-glucoside and cyanidin 3,5-diglucoside) could be useful in the analytical characterization of Chilean pomegranate genotypes, as well as in the differentiation with other juices containing anthocyanins.