Chlorophyll degradation and lipid oxidation in frozen unblanched peas

Storage of hand‐podded unblanched frozen peas for 20 months at –9·4° resulted in considerable conversion of chlorophylls to pheophytins, the formation of phytol‐free derivatives, a decrease in total pigment and the formation of peroxides and TBA‐reactive materials. Greater storage stability was found in samples blanched prior to storage, and to a lesser extent in unblanched peas stored in nitrogen or at –23·3°. Lipoxygenase and chlorophyll bleaching activities of extracts from frozen unblanched peas decreased during storage, lipoxygenase being the more stable. Model system studies with pea and soya extracts indicated that chlorophyll loss and lipid oxidation during storage were most likely caused by lipoxygenase and a lipohydroperoxide breakdown factor shown to be present in crude extracts.