Changes in anthocyanidin and anthocyanin pigments in highbush blueberry (Vaccinium corymbosum cv. Bluecrop) fruits during ripening

Abstract

We monitored accumulation in terms of different types of anthocyanidin, in association with fruit skin coloration, in ‘Bluecrop’ highbush blueberry (Vaccinium corymbosum L.) at three stages of ripening: pale green, ca. 30 days after full bloom (DAFB); reddish purple, ca. 40 DAFB; and dark purple, ca. 50 DAFB. Total anthocyanin contents increased during ripening, while fruit skin color steadily became darker and bluer, as reflected in decreasing L* (a color space coordinate describing lightness) and b* (describing blue-yellow coloration). Of the six anthocyanidins commonly found in fruits, pelargonidin was absent throughout the ripening process. Cyanidin was first detected at the pale green stage. Peonidin, delphinidin, petunidin, and malvidin were first detected after fruits had passed through the reddish purple stage. The contents of delphinidin and malvidin increased more rapidly than those of other anthocyanidins, and were closely correlated with changes in fruit skin color, demonstrating that the types and quantities of anthocyanidins, which in turn form anthocyanins, were major determinants of fruit skin coloration. Four anthocyanins were detected at the reddish purple stage, and 22 were identified at the dark purple stage. All anthocyanins detected were glycosylated with glucose, galactose, or arabinose.