Pigment Changes in the Flavedo of Dancy Tangerine (Citrus reticulata) during Ripening

Abstract

Summary Pigment changes in the flavedo of the Dancy tangerine were followed for an entire maturation period at two weeks intervals. The chlorophylls a and b gradually decreased at first but abruptly near the colour break and disappeared completely only in the mature fruit. The total carotenoid content decreased by half immediately at the beginning of the season and remained constant during a period of 14 weeks. Afterwards the level increased at an accelerated rate and reached a maximum value of about 300 µg/g. In the first period prior to the colour break the main carotenoid pattern was that found in photosynthetic tissue, containing: carotenes 20%, lutein 30%, violaxanthin 11% and neoxanthin 17%. A high level of α-carotene before the colour break was noteworthy. During maturation the chloroplast pigments decreased to minimal level of 1–2% except violaxanthin which rose to a level of 50%. Exactly at the colour break the biosynthesis of new pigments began, especially of the red β;-citraurin and the orange cryptoxanthin. Although their levels were not very high 8% and 14%, they are the pigments responsible for the orange-reddish colour of the tangerine. Phytofluene, ζ-carotene and the epoxides of cryptoxanthin were detectable at low levels in the last maturity stages. Some possible pathways of the C 30 -apocarotenals biosynthesis are discussed.