76C-4 |
Antioxidant capacity and phenolic content of spinach as affected by genetics and growing season |
N. PANDJAITAN1, L. R. Howard, and T. Morelock. (1) Food Science Department, University of Arkansas, 2650 N. Young Avenue, Fayetteville, AR 72704 Spinach contains high levels of unique flavonoids that exhibit numerous biological and pharmacological properties. Unfortunately, no information is available concerning the effects of genetics and growing season on phenolic content and antioxidant capacity of spinach. This study was undertaken to determine how spinach cultivars and advanced breeding lines vary in flavonoid content, and to determine how different growing seasons known to vary in biotic and abiotic stresses influence phenolic content and antioxidant capacity. Leaves from 11 commercial cultivars and 14 advanced breeding lines were sampled from field-grown over winter and fall spinach, and analyzed for total phenolics using the Folin-Ciocalteu assay and oxygen radical absorbing capacity (ORAC) using a microplate reader. Individual and total flavonoid content of spinach cultivars grown in the fall was determined by HPLC. Over winter spinach, which is harvested in the spring had 27% and 88% higher levels of ORAC and total phenolics, respectively than spinach grown in the fall, indicating that environmental growing conditions as well as biotic and abiotic stresses influenced phenolic metabolism. Genetics also appeared to play an important role in affecting phenolic metabolism and antioxidant capacity in spinach, with ORAC and total phenolic values ranging from 11.6-20.4 mM TE/g, and 2033-3539 mg/kg, respectively for cultivars grown over both seasons. Total flavonoid content ranged from 654-1848 mg/kg in spinach cultivars grown in the fall, and several patuletin derivatives correlated highly with ORAC (rxy=0.74 and 0.71). Advanced breeding lines of spinach had higher levels of total phenolics, individual flavonoids and antioxidant capacity than commercial cultivars. Our results indicate that plant breeders can select for increased phenolic content in spinach cultivars to increase antioxidant capacity, and possibly confer greater disease protection.
Session 76C, Fruit & Vegetable Product: Fresh Fruits and Vegetables
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