EFFECTS OF FREEZING ON THE PIGMENT CONTENT IN GREEN BEANS AND PADRON PEPPERS

The amounts of chlorophylls a and b, beta-carotene and lutein in green beans, blanched green beans and Padron peppers, all frozen at -22 deg rees C, were monitored over 12 months by reverse-phase, gradient HPLC (C18 column, visible detection). In unblanched beans, these amounts of the pigments decreased considerably during month 1, but were generall y stable during the next 11 months (beta-carotene content decreased fu rther in month 2 before stabilizing). Similar results were obtained fo r blanched beans, but decreases were offset by increases due to blanch ing (carotenoids) and lipoxygenase deactivation (beta-carotene), or en hanced by blanching-induced decreases (chlorophylls). In contrast, the amounts of pigments in frozen Padron peppers fluctuated around more o r less constant values over the 12 months. Freezing in bags sealed und er vacuum lead to moderate decreases in chlorophyll a in Padron pepper s and in beta-carotene in blanched green beans.