Germination and Exposure to UV Light and Chemical Elicitors Enhance the Phenolic Content and Antioxidant Activity of 13 Different

Germination and exposure to UV light and chemical elicitors enhance the phenolic content and antioxidant activity of 13 different seeds

2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana

Session 36E, Fruit & Vegetable Products: General
B. A. CEVALLOS-CASALS and L. A. Cisneros-Zevallos. Dept. of Horticultural Sciences, Texas A&M Univ., 2133 TAMU, College Station, TX 77843-2133

Crops high in phenolic compounds are being increasingly desired due to their health-giving properties. Sprouts could offer such attributes; however, a thorough evaluation of phenolic synthesis in seeds from different genera throughout the germination process has not been conducted, as well as their response to environmental conditions, known to enhance phenylpropanoid metabolism. Our objective was to determine how phenolic content and antioxidant activity (AOX) of 13 different seeds changed throughout the germination process and after exposure to UV light and chemical elicitors. Seeds were imbibed overnight in water or in water with a chemical elicitor (chitosan, gellan gum, proline, sucrose) and dark-grown in petri plates for up to 8 d. UVB or UVC were used for UV treatments. Total phenolics were assayed with Folin-Ciocalteu reagent and AOX with DPPH radicals, with results expressed in mg chlorogenic-acid/100g and ug Trolox/g, respectively. Results showed that phenolic content and AOX in Dry Basis (DB) and Per Seed Basis (PSB) were higher for 7 day-old sprouts than for dry and imbibed seeds, indicating a continued phenolic synthesis throughout the germination process. Phenolic contents for these sprouts on wet basis (WB), DB, and PSB ranged from 122 (alfalfa) to 555 (sunflower), from 490 (lentil) to 5676 (mustard), and from 0.02 (alfalfa) to 6.4 (Fava bean), respectively. Seven day-old radish sprouts exposed to UVB had 33% higher AOX than controls. With UVC, mungbean had 67% higher AOX than controls. With sucrose elicitation, Fava bean hypocotyl had 41%, 47%, and 76% higher phenolic content PSB than controls, after 2, 5 and 8 d, respectively. Wheat showed similar responses to sucrose. Monitoring phenolics and AOX throughout germination and understanding the effect of physical and chemical elicitors might help us obtain sprouts with enhanced nutraceutical levels. Sprouts could also serve as models for applying similar strategies to other crops.