Effect of postharvest storage and processing on the antioxidant constituents (flavonoids and vitamin C) of fresh-cut spinach.
The effect of modified atmosphere packaging (MAP) and cooking on the flavonoids and vitamin C content (ascorbic + dehydroascorbic acid; AA + DHAA) of fresh-cut spinach was evaluated. The total flavonoid content (approximately 1000 mg kg(-)(1) f.w.) remained quite constant during storage in both air and MAP atmospheres, while vitamin C (750 mg kg(-)(1)f.w.) was better preserved in MAP-stored spinach. AA was transformed to DHAA during storage, and its concentration was higher in MAP-stored tissues. The free-radical scavenging activity of the isolated flavonoids was tested, and only those flavonoids with either a dihydroxyl grouping or acylated with ferulic acid showed significant activity. A decrease in the total antioxidant activity was observed during storage, particularly important in MAP-stored spinach. The higher content of DHAA and lower content of both AA and antioxidant flavonoids in the MAP-stored samples could explain this antioxidant activity decrease. Boiling extracted 50% of total flavonoids and 60% vitamin C in the cooking water. However, flavonoid glucuronides were extracted more in the cooking water than the other glycosides. The vitamin C content of the cooked tissue was higher in those samples stored in MAP.
Gil
M I
MI
Departamento de Ciencia y Tecnología de Alimentos, CEBAS (CSIC), Murcia, Spain.
Ferreres
F
F
Tomás-Barberán
F A
FA
D000975:Antioxidants / Q000032:analysis*; D001205:Ascorbic Acid / Q000032:analysis*; D003296:Cooking; D005419:Flavonoids / Q000032:analysis*; D005511:Food Handling; D016166:Free Radical Scavengers / Q000032:analysis; D018724:Spinacia oleracea / Q000737:chemistry*
D000975:Antioxidants; D005419:Flavonoids; D016166:Free Radical Scavengers; D001205:Ascorbic Acid