Changes of anthocyanins and hydroxycinnamic acids affecting the skin colour during maturation of sweet cherries (Prunus avium L.)

The content and relative amounts of anthocyanins and hydroxycinnamic acids (HCA) were determined in local sweet cherries (cultivar Petrovka) at 7 stages of maturity, by means of high performance liquid chromatography (HPLC), and compared to instrumentally assessed skin colour of the same sweet cherries. Skin colour of harvested samples was measured using the CIE L*, a*, b* system. The contents of neochlorogenic and 3-p-coumarylquinnic acids decreased with no significant change in ratio during ripening, except for the first 4 days of maturation, when the ratio changed due to increased content of neochlorogenic acid. The linear increase of total anthocyanins during maturation was observed without the trend of stabilization in the final stages of maturity. The colour change of Petrovka during maturation was influenced by the increase of total anthocyanins, consisting mostly of cyanidin-3-rutinoside and cyanidin-3-glucoside (97-98% of the total). The chroma and L* values appeared to be optimal indicators of anthocyanin accumulation during maturation, and better than the a* value and hue angle. The accumulation of anthocyanins from 507.1 to 1150.9 mg of cyanidin-3-rutinoside/kg of fresh weight (FW) during the second half of maturation caused the formation of a new colour cast of Petrovka, which influenced the decrease of redness and colour intensity, as recognized by CIE L*, a*, b* colour space. (C) 2003 Swiss Society of Food Science and Technology. Published by Elsevier Ltd. All rights reserved.