Chlorophyll bleaching by legume seeds

Legume seeds and extracts made from them bleached chlorophyll in the presence of long‐chain fatty acids. The most effective acids were substrates for lipoxidase, but oleic acid and even palmitic and stearic acid were also active. The bleaching was inhibited by commercial antioxidants.

Chlorophyll was bleached by extracts which had lipoxidase activity but not by purified lipoxidase preparations. Addition of lipoxidase to seed extracts stimulated bleaching 2‐ to 3‐fold with linoleic acid but only slightly with oleic acid.

The optimum pH for bleaching was about 6, and for linoleate hydroperoxide formation was near 8. Evidence is given that at pH 6 hydroperoxide was being destroyed.

Chlorophyll appears to be bleached by co‐oxidation during a chain reaction involving peroxidation of fatty acid and the breakdown of hydroperoxide by a heat‐labile factor.
RESP-5208