Effect of Postharvest Storage Temperature on the Conversion of ¹⁴C-Mevalonic Acid to Carotenes in Tomato Fruit

Abstract

The carotenoid metabolism in tomato fruit in relation to high temperature inhibition of pigmentation was investigated with pericarp sections of tomato fruits stored at 20°C, 30°C, and 35°C. The pericarp sections were incubated with 2-¹⁴C-mevalonic acid for 10 hours at the same temperatures as the storage temperatures. When tomatoes were stored longer and at higher temperatures, the radioactivity of lycopene extracted from pericarp sections was low, whereas, that of β-carotene was high. The specific radioactivity of the carotenes decreased in order of the steps of carotenoid biosynthetic pathway, phytoene→lycopene→β-carotene, in all the sections of the fruit stored at each of the temperatures. We postulate from these results that high temperature inhibits the accumulation of lycopene in tomato fruit because the conversion of lycopene to β-carotene is stimulated instead.