FOOD. Science. Technology. Quality

Food. SCIENCE. Technology. Quality

Food. Science. TECHNOLOGY. Quality

Food. Science. Technology. QUALITY




Effect of chlorophyll pigments on the course of photosensitized oxidation of rapeseed oil


The presence of chlorophyll pigments in oils has a negative effect on their taste, smell, colour, clearness, thermal stability and shelf life. Those compounds are strong photosensitisers in oxidation processes of unsaturated bonds of lipids, what negatively impacts the oxidative stability of oil during storage.The objective of the research study  was to evaluate the photooxidation activity of chlorophyll pigments in rapeseed oil by the UV-A radiation. A  refined rapeseed oil and its triacylglycerols (TAG) constituted a research material. As photosensitisers were used  chlorophyll a and pheophytin a. The photooxidation process was monitored using the determination of the  content of singlet oxygen, volatile compounds and chlorophyll pigments. It was shown that chlorophyll pigments  were photosensitisers in photooxidation of rapeseed oil and TAG during their exposure to the UV-A radiation.  Chlorophyll a and pheophytin a participate in the generation of singlet oxygen. The photosensitising efficiency of  chlorophyll a is higher than that of pheophytin a. Chlorophyll pigments have a diversified effect on the content and  profile of volatile substances formed during the photooxidation of oil and TAG. The type of photosensitiser  has a significant impact on the total volatile compounds and hexanal content in the TAG. The maximum level of volatile compounds is found at a photosensitiser dose of 0.5 mg/kg. Chlorophyll pigments are degraded as a  result of the oxidation with singlet oxygen during photooxidation of the rapeseed oil and TAG. Pheophytin a is  more difficult to degrade than chlorophyll a. The accompanying substances play an important protective role  against the photooxidation of rapeseed oil. Their removal contributes to a higher singlet oxygen uptake, an  increase in the total volatile compounds content, changes in their profile and an increased degradation of  chlorophyll pigments. Chlorophyll pigments adversely affect the oxidative stability of rapeseed oil when exposed to  the UV-A radiation and they should be removed therefrom.


rapeseed oil, photosensitized oxidation, chlorophyll pigments, singlet oxygen, volatile compounds