Brief exposure of mature-green tomato fruit to hot water enhances tissue antioxidant capacity of ripe fruit

In response to stress, plants upregulate their antioxidant system to protect against oxidative damage by reactive oxygen species (ROS). Antioxidants have other purposes in plants such as generation of color and as precursors of volatiles, and also have beneficial effects on human health as nutrients. Therefore, we hypothesized that this response can potentially be used to increase the quality of tomatoes. A mild, sub-lethal controlled stress in the form of a hot-water bath was used to stimulate the antioxidant system in mature-green tomatoes during subsequent ripening. The objective of this research was to determine the effect of hot-water treatment applied to several commercial tomatoes varieties harvested at the mature-green stage on the physicochemical quality and antioxidant content of those fruit during ripening and when fully ripe. Mature-green ?Florida 47?, ?Soraya? and ?Tasti Lee? tomatoes were exposed to water at 52?C for 5 min or 25?C for 5 min (control), then exposed to 100 uL/L ethylene for 48 h at 20?C and 95% RH, discarding fruit that did not show any sign of red color after 48 h ethylene exposure. The fruit were stored at a 20?C and 95% RH until fully ripe. The postharvest quality of the tomatoes was evaluated by measuring firmness, basic physicochemical parameteris, content of antioxidants and antioxidant capacity. Hot-water treatment promoted higher accumulation of carotenoids preferentially in the peripheral pericarp tissue. Higher accumulation of carotenoids in hot-water treated fruit was most visible at the pink or light-red ripeness stage. Also the hot-water treatment induced higher content of lipophilic phenolics, but this was limited to the outer fruit section. Heat treatment was also able to induce higher concentrations of ascorbic acid and hydrophilic phenolic compounds depending on the genetic potential of the tomato cultivar. ? SourcesBrief exposure of mature-green tomato fruit to hot water enhances tissue antioxidant capacity of ripe fruitFrancisco E. Loayza1, Jeffrey K. Brecht1, Amarat H. Simonne2, Anne Plotto3, Elizabeth A. Baldwin3, Jinhe Bai3, Elena E.Lon Kan41Horticultural Sciences Dept., University of Florida, Gainesville FL 32611, United States of America2Food Science Human Nutrition Dept., University of Florida, Gainesville FL 32611, United States of America3U.S. Horticultural Research Lab., USDA-ARS, Fort Pierce FL 34945, United States of America4Nutrition and Food Technology Dept., Universidad Le Cordon Bleu, Lima, PeruVIII International Postharvest Symposium, Cartagena, Spain, 21-24 June 2016 Picture:?Sakata