The fate of carotenoid contents in apple varieties with different scald susceptibility

A statical approach based on Principal Component Analysis (PCA) was performed to study the contents of carotenoids present in the cuticle of four apple varieties (Golden Reinders; Fuji Zhen Aztec; Fuji Fubrax and Superchief) with different scald susceptibility after harvest and low temperature storage. The scald phenomenon results from the damage and death within the surface layers of cells in localized regions of apple and pears. Our study demonstrates that the four apples varieties showed different carotenoid profiles in the cuticle and also that the fate of these carotenoids was different during the conservation of the four varieties at low temperature for 7 month. The two PCs explained 81.4% of the variability at harvest. A clear separation in PC1 between the two Fuji cultivars and Golden Reinders and Superchief was observed. In addition, the loadings plot indicated that Fuji cultivars had a more heterogeneous content of carotenoids, while Superchief and Golden Reinders were highly correlated with β-carotene, (all-E)-lutein and (all-E)-violaxanthin. In contrast, more biosynthetic evolved oxidized carotenoids, such as luteoxanthin isomers, neochrome and neoxhanthin isomers, would explain the behaviour of the Fuji varieties. After seven months of cold storage PC1 and PC2 explained 86.4% of the variability of carotenoid. A clear separation of the four cultivars was observed. In this regard, as in samples at harvest, the scores plot revealed separation between Fuji cultivars and Golden Reinders, and Superchief in the PC1. However, in this case, a separation between Golden Reinders and Superchief is shown in PC2. The loadings plot indicates that Fuji cultivars presented a higher correlation with diverse carotenoids, mainly those same oxocarotenoids as at the time of harvesting. Superchief was still positively correlated with the content of (all-E)-lutein. (9'Z)-Neoxanthin also appeared to be responsible for the PC1 differentiation between Golden Reinders and Superchief, and the two Fuji varieties. In addition, neochrome and auroxanthin B, and β-carotene would participate in the PC2 differentiation between Golden Reinders and Superchief. We hypothesize that the different scald susceptibility of the four apples varieties could partially be a consequence of these differences in profile and fate. Indeed, carotenoids are considered natural antioxidants, however their antioxidant capability depends on their chemical structure.