EFFECTS OF GAMMA-IRRADIATION AND STORAGE-TEMPERATURE ON LIPOXYGENASE ACTIVITY AND CAROTENOID DISAPPEARANCE IN POTATO-TUBERS (SOLANUM-TUBEROSUM L)

With the aim of exploring the causes for the enhanced destruction of carotenoids in irradiated potato tubers during storage at 15°C, changes in carotenoids and lipoxygenase activity of irradiated and nonirradiated tubers (cv. Kufri chandramukhi) were compared during 6 months of storage at 4,15, 20, and 25–30 °C (ambient temperature). Carotenoid content tended to decrease in potatoes stored at 15 and 20 °C, while at 4 and 25–30 °C it increased with advancing storage. Irradiation enhanced the carotenoid disappearance in potatoes stored at 15 and 20 °C and reduced its formation at 4 and 25–30 °C. Irradiation at a sprout-inhibiting dose of 100 Gy caused an immediate decline in lipoxygenase activity and also its capacity for cooxidation of β-carotene. The reduced lipoxygenase activity of irradiated potatoes was seen throughout storage regardless of the storage temperature. Irradiated tubers showed decreased protein content and increased levels of peptides and amino acids. No interrelationship seems to exist between lipoxygenase activity and destruction of carotenoids in irradiated potato tubers. © 1990, American Chemical Society. All rights reserved.