Synergy between hot water treatment and high temperature ethylene treatment in promoting antioxidants in mature-green tomatoes

Authors: LOAYZA, FRANCISCO - University Of Florida; BRECHT, JEFFREY - University Of Florida; SIMONNE, AMARAT - University Of Florida; Plotto, Anne; Baldwin, Elizabeth - Liz; Bai, Jinhe; LON-KAN, ELENA - University Of Florida

Submitted to: Postharvest Biology and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/31/2020
Publication Date: 8/23/2020
Citation: Loayza, F., Brecht, J., Simonne, A., Plotto, A., Baldwin, E.A., Bai, J., Lon-Kan, E. 2020. Synergy between hot water treatment and high temperature ethylene treatment in up-regulating the antioxidant system in mature-green tomatoes. Postharvest Biology and Technology. 170:111314. https://doi.org/10.1016/j.postharvbio.2020.111314.
DOI: https://doi.org/10.1016/j.postharvbio.2020.111314

Interpretive Summary: In Florida, tomatoes are harvested at the mature green stage; after harvest, they are washed, packed, and ripening is induced by placing fruit in ethylene chambers for about 24-48 hours. Previous studies showed that mild stress applied as heat after harvest could increase tomato fruit content of health benefit compounds such as carotenoids and phenolic antioxidants. The present study shows that when tomatoes were subjected to a combination of heat stresses in the form of hot water (125F for 5 minutes) and hot ethylene (95F for 24 to 72 hours), there was a synergy between the two types of heat applications, resulting in tomatoes with higher content of phenolic compounds and greater oxygen radical absorbance capacity (ORAC), thus tomatoes with enhanced nutritional value and increased resistance to decay and chilling injury.

Technical Abstract: Controlled postharvest stresses were used to induce the synthesis of antioxidants in tomato fruit. In this study, a HW treatment of 52 °C for 5 min promoted higher total oxygen radical absorbance capacity (ORAC) compared to fruit immersed in 25 °C water for 5 min (p=0.0003). Whereas, ethylene treatment at high temperature , particularly at 35 °C for 24, 48 or 72 h, induced higher content of total phenolics (p=0.0001) and ferric reducing ability of plasma (FRAP) (p=0.0015) than fruit treated with ethylene at 20 or 30 °C. In combination, there was synergy between the treatments, and this was most notable in HW-treated tomatoes exposed to ethylene at 35 °C, which showed higher content of phenolic compounds and ORAC antioxidant capacity than control fruit. In conclusion, HW immersion in combination with fruit ripening temperature management can improve tomato nutritional quality and possibly increase resistance to chilling conditions and decay microorganisms.