Microbial Formation of Pheophorbide a and Pyropheophorbide a in “Takana” during Brining and Fermentation

Abstract

Pheophorbide a (PHEO-a) and pyropheophorbide a (PYRO-a), decomposition products of chlorophyll a, were found to be responsible for photosensitivity disease. The photosensitizing activity of PYRO-a was markedly higher than that of PHEO-a.Since PYRO-a was reported to exist in salted green vegetables, a green vegetable “TAKANA” was salted and fermented under various conditions to clarify the formation mechanism of both substances during fermentation, and the formation of PYRO-a (and PHEO-a) and the changes of microbial flora in salted Takana were pursued. For the first 7 days, production of PHEO-a and PYRO-a increased in quantity with the increase of the number of total microbial flora and genus Lactobacillus.Boiling of Takana and addition of sorbate reduced the quantities of PHEO-a, and PYRO-a.The supernatant of a homogenate of Takana salted for 7 days was filtered through a Millipore filter, and the residue (bacterial fraction) and the filtrate (bacteria-free fraction) were prepared. Production of PHEO-a and PYRO-a by addition of the residue to chlorophyll a was larger in quantity than that by the addition of the filtrate. In the case of addition of each fraction to PHEO-a, PYRO-a production was similarly seen.From those results it is assumed that PHEO-a was produced by bacterial enzyme(s) in addition to chlorophyllase, and the main cause of the formation of PYRO-a during storage and fermentation of salted Takana is the action of bacterial enzymes in the salted vegetable.