COLOUR IN ACTINIDIA FRUIT

Most Actinidia species have green-fleshed fruit but fruit of A. chinensis genotypes have yellow flesh and the ripe fruit of A. macrosperma and A. polygama are yellow or orange. Red pigments are found in fruit of some genotypes of A. arguta and A. melanandra and in the inner pericarps of some genotypes of A. chinensis and A. deliciosa. The relative amounts of chlorophylls and carotenoids determine the shades of yellow and green. Lutein and β-carotene are the most abundant carotenoids; these, together with a number of xanthophylls, are considered to be accessory pigments to chlorophylls a and b and are present with them in the plastids. The shape and internal structure of plastids are often affected by their content of stored starch: the two main forms are the chloroplasts, which are rich in thylakoid membranes organised into grana, and chromoplasts containing few thylakoid membranes. The red colour in the inner fruit pericarp of some genotypes of A. chinensis and A. deliciosa is due to anthocyanins. These have a common aglycone, cyanidin, bound to different sugars, thereby producing different cyanidin glycosides. The most usual glycoside, found in highest amounts in the inner pericarps of some A. chinensis fruit, appears to be 3-O-xylo(1-2)-galactoside.