Postharvest Quality of Early Season Grapefruit after Forced-air Vapor Heat Treatment

Abstract

`Marsh' and `Ruby Red' grapefruit (Citrus paradisi Macf.) were harvested in Florida during Oct. and Nov. 1990, degreened in an ethylene chamber, exposed to vapor heat (VH) treatment (43.5 ± 0.1C for ≈240 min), and evaluated for deterioration in quality and development of injury after various storage regimes. Symptoms of aging averaged 6% and 8% of the surface on `Ruby Red' and `Marsh' fruit, respectively, and the VH treatment had reduced the incidence of aging by 45% after 5 weeks of storage (4 weeks at 16C plus 1 week at 21C). Total decay, mostly stem-end rots (Diplodia spp. and Phomopsis spp.), remained relatively low (≈5%) in both treated and nontreated fruit after 5 weeks of storage. The VH treatment had little effect on change in peel color during treatment or subsequent storage. After the final inspection, `Marsh' fruit was higher in total soluble solids and titratable acidity than `Ruby Red' fruit, but these quality indicators and pH were not affected by the VH treatment. VH treatment did not adversely affect the quality of `Marsh' or `Ruby Red' grapefruit harvested early in the season; hence, VH should be considered as a viable quarantine treatment for Florida grapefruit.