Sigmoidal kinetics of anthocyanin accumulation during fruit ripening : a comparison between açai fruits (Euterpe oleracea) and other anthocyanin-rich fruits

Anthocyanins are natural colorants with increasing interest. Euterpe oleracea fruits (EOF) (açai) are an interesting phenolic compounds source. They are extremely rich in two anthocyanins: cyanidin-3-glucoside and cyanidin-3-rutinoside. In this study, the anthocyanin content was evaluated in EOF during their ripening, allowing to characterize very important parameters for the post-harvest industry: their maximum accumulation rate, per day, (Δy), their maximum concentration in fruits (CMAX) and the corresponding maturity class (S). Samples of 12 racemes from three plantations were collected twice a month during their ripening process. The maturity class of EOF was recorded at each harvesting and their anthocyanin content was determined by an HPLC method after solvent extraction. Anthocyanin accumulation was described (p < 0.05) by sigmoidal equations and Δy, CMAX and S values were determined. The Δy of EOF reached 35.63 mg kg*−1 fruits day*−1, whereas CMAX reached 1443 mg kg*−1 fruits. On average, in the beginning of maturation, both anthocyanins were present in similar proportions. However, in the last maturity stages, cyanidin-3-glucoside became less abundant than cyanidin-3-rutinoside. On the basis of the data available on strawberries, grapes, pomegranates and lychees, it was possible to verify that the sigmoidal mathematical model of anthocyanin accumulation is transposable.