Colour changes during chilling of tomato (Lycopersicon esculentum Mill.) fruit, surface topology of injury and some physiological changes.
Dodds, Georges Thomas.
Thesis of Ph.D., Cornell University, 1991, 357 pages
1991
บทคัดย่อ
The effect of chilling stress on surface colour of mature green (MG) tomato fruit (Lycopersicon esculentum Mill. and related species) during low temperature storage was investigated. Colour was measured with a tristimulus colorimeter (L, a, b values) and data analyzed by multivariate analysis of variance and canonical variates analysis. Changes in surface colour of MG fruit during chilling were not correlated overall with relative chilling sensitivity of cultivars/lines; however, within standard and cherry types, chilling-tolerant fruit changed surface colour more during chilling than chilling-sensitive fruit, when fruit were picked early in the season. Fruit of early harvests were less chilling-sensitive, showing more surface colour change during chilling than fruit of late harvests. Hours below 15.6C in the 200 h before harvest were positively correlated with postharvest chilling sensitivity. Chilling-induced percent change in colour was greater at 5circ than at 2circ, but no difference
was found between high and ambient relative humidity storage. Tobacco mosaic virus resistance led to less, and Verticillium albo-atrum Reinke & Berthier resistance to more chilling-induced colour change. Chilling injury symptoms on the surface of tomato fruit were mapped with respect to subtending locules. Tomato fruit ripening begins over the septa and on the blossom scar end of the fruit, reaching the regions over the locules and on the shoulder last. Mature green fruit chilled at 5circ for 10-25 days and then ripened to red ripe at 20circ, showed a majority of injury over subtending locules and on the stem end, corresponding to the least mature regions. In contrast, injury to immature-green fruit occurred equally over subtending locules and septa and predominantly on the blossom end. An attempt was made to devise a simple colorimetric test for chilled tomato fruit. Assays measuring fructosamines, lipid peroxidation, reducing sugars, alpha unsubstituted pyrroles, amino-ketones, or indoles showed no
consistent variation with chilling. Reactivity with benzidine, measured at 412 nm, showed increases with both ripening and chilling duration. Benzidine reactivity appeared to be linked with a water soluble compound, yellow in colour, phenolic in nature, possibly a flavonoid, but not an aldehyde, peroxide, sugar, or amino acid.