Pre-harvest UV-C could be used for enhancing the polyphenol content of strawberries. - GreenMedInfo Summary
Preharvest Ultraviolet C Irradiation Increased the Level of Polyphenol Accumulation and Flavonoid Pathway Gene Expression in Strawberry Fruit.
J Agric Food Chem. 2017 Nov 22 ;65(46):9970-9979. Epub 2017 Nov 8. PMID: 29091440
Preharvest ultraviolet C (UV-C) irradiation is an innovative approach for increasing the bioactive phytochemical content of strawberries to increase the disease resistance and nutritional value. This study investigated the changes in individual flavonoids in strawberry developed with three different cumulative doses of preharvest UV-C treatment (low, 9.6 kJ m; middle, 15 kJ m; and high , 29.4 kJ m). Significant accumulation (p<0.05) of phenolics (25-75% increase), namely, cyanidin 3-glucoside, pelargonidin 3-glucoside/rutinoside, glucoside and glucuronide of quercetin and kaempferol, and ellagic acid, was found in the fruit subjected to low and middle supplemental doses of UV-C radiation. The expression of the flavonoid pathway structural genes, i.e., FaCHS1, FaCHI, FaFHT, FaDFR, FaFLS, and FaFGT, was upregulated in the low- and middle-dose groups, while the early stage genes were not affected by the high dose. FaMYB1 was also relatively enhanced in the low- and middle-dose groups, while FaASR was upregulated in only the low-dose group. Hormetic preharvest UV-C dose ranges for enhancing the polyphenol content of strawberries were established for the first time.