S19 - Session O5 - Blueberry color and brightness is affected by cuticular wax composition

Authors: Yifan Yan *, Michael Dossette, Simone Diego Castellarin

Blueberries production and consumption have strongly increased in the past decades. Fruit color greatly affects consumers' choices; darker colors are often preferred and are normally linked with a higher level of anthocyanins. Despite that most consumers prefer fruits with a darker color, a recent survey indicates that fruits with a light blue color covered by a thick waxy bloom n that determines low glossiness n are also very attractive to consumers (Gilbert et al. 2014). However, knowledge about the influence of cuticular waxes on fruit color is limited in blueberries. The current study aims to characterize the cuticular wax amount and profile in different blueberry genotypes and reveal the relationship between cuticular waxes and fruit color. A total of 12 blueberry genotypes with visual differences in fruit color and glossiness were selected and sampled at commercial harvest and one week after commercial harvest. Five berries with intact cuticular waxes were collected for each genotype at each sampling. Single berries were subjected to surface color and glossiness measurements by a colorimeter and a glossmeter, respectively, before and after removal of cuticular waxes. Total wax content varied from 25.50-95.83 m g/cm 2 among genotypes, with the content being generally lower at the second than at the first sampling. Triterpenoids and beta -diketones were the most abundant wax groups in all cultivars, except for Chippewa where alkanes were proportionally higher than beta -diketones. Wax removal increased the redness, blueness, and glossiness, but reduced the lightness of the fruits in all genotypes. Total beta -diketone content was found to be highly correlated with the difference in lightness before and after wax removal, indicating a potential role of beta -diketones in influencing blueberry surface color. Future researches should investigate the role of cuticular wax structure as well as the relationships between cuticular waxes and anthocyanins in affecting the fruit color.