The effects of maturity on colour and concentration of pigments in the blush and shaded sides of ‘Gala’ apple fruit during cool storage

Abstract

SummaryTo examine the influence of maturity on changes in skin colour and the pigment concentration during cool storage of apple fruit, the skin pigment concentration and colour were measured in immature and in mature ‘Gala’ apples for two consecutive seasons. The blush side skin of the fruit had higher pigment concentrations than the shaded side at harvest and the differences were maintained during storage at 1°C. Anthocyanin and quercetin glycoside concentrations did not change significantly, whereas the chlorophyll concentrations in fruit skin decreased and carotenoid concentrations increased during storage. The increase of carotenoid appeared constant with time of storage whereas the decrease of chlorophyll was curvilinear with time and greater in the shaded side skin. The CIE colour value, a*, increased only in the shaded side of immature fruit whereas the b* value increased in a linear and parallel manner for immature and mature fruit. Chlorophyll, carotenoid and quercetin concentrations significantly affected the b* (yellow) value for the blush side. For the two years investigated, the differences in pigment concentrations were small and non significant. From the linear and constant increase in the b* colour value on both the blush and shaded sides of mature and immature fruit, it may be possible to predict the yellow hue of the fruit, particularly the shaded side, after cool storage.