Pentenols and pentene dimers are biosynthetized in plants by homolytic fatty acid hydroperoxide lyase (HPL) or HPL-like enzymes. It has been found that these compounds can modify the flavor of olive oil. Reactions between hematin and 13-hydroperoxy-octadecatrienoic acid resulted in the formation of the same compounds via a free radical reaction in which an alkoxyl radical derived from linolenic acid hydroperoxide undergoes a beta -scission. (Z)-3-Hexenal has also been detected as a minor product of the reaction. It is bioconversed from the same substrate in plants by heterolytic HPL. Thanks to the redox cycle of its central iron, hematin has both homolytic and heterolytic HPL-like activities.