Effect of High Temperature on the Postharvest Biosynthesis of Carotenes and ^|^alpha;-Tocopherol in Tomato Fruit

Mature green tomato fruits were initially stored at 20°, 30° and 35 °C and then transferred to other temperatures at various times within a 25-day storage period.1. Fruits transferred from 20 °C to 30 °C (20°→30 °C) or from 20 °C to 35 °C (25°→35 °C) developed less color depth and contents of phytoene and lycopene than did those retained at 20 °C, but carotene contents increased temporarily in the 20°→30 °C treatment. Conversely, fruit transferred from 30 °C to 20 °C (30°→20 °C) or from 35 °C to 20 °C (35°→20 °C) progressively became redder.2. Ratio of lycopene precursors, phytoene, phytofluene and ζ-carotene to total carotenes was highest in tomatoes kept at 20 °C. In the 30°→20 °C or 35°→20 °C treatments, total carotene contents became almost the same as those kept at 20 °C, but the ratio of the precursors to total carotenes became smaller while that of lycopene to total carotenes increased.3. Tomatoes at 30 °C, β-carotene content and level of cis-isomer increased, but those in the 20 °→30 °C treatment, the β-carotene remained constant.4. α-Tocopherol content increased in tomatoes kept at 30 °C and 35 °C, whereas it did not increase significantly at 20 °C; it increased after the tomatoes were transferred from 30° to 20 °C or from 35° to 20 °C.The data indicated that the rates of synthesis of lycopene, β-carotene and α-tocopherol differ according to temperature. The effect of high temperature or treatment with changing temperature on each pathway may be explained by changes in metabolism of precursors of both carotenoid and tocopherol.