Anthracene as a chemical probe is usually used to trap the singlet oxygen and then detection and quantification can be based on absorbance. In this study, oxidation of anthracene declared that rate of singlet oxygen quenching in the presence of pasipay (passiflora incarnate L.) as a natural antioxidant, 1,4 Diazabicyclo [2.2.2] octane (DABCO) as a well‐known singlet oxygen scavenger and highly effective synthetic antioxidants in food industry such as Butylated hydroxytoluene (BHT), Butylated hydroxyanisole (BHA), tert‐Butylhydroquinone (TBHQ) decreased in the order of DABCO >pasipay > TBHQ > BHT > BHA. On the other hand, lipid photooxidation is the undesirable chemical process in which singlet oxygen result in the peroxidation of fatty acids. The results of this study also showed that oleic acid oxidation with singlet oxygen in the presence of pasipay (contains 0.4576 mg flavonoid compounds) diminished about 11% which shows pasipay has an effective role to inhibit lipid peroxidation.

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Lipid photooxidation is the undesirable chemical process in which singlet oxygen result in the peroxidation of fatty acids. In this study leaves methanolic extracts of peppermint (Mentha piperita L.), marjoram (Origanum majorana L.), rosemary (Rosmarinus officinalis L.) and sage (Salvia officinalis L.) were applied as the natural singlet oxygen scavenger. Amount of flavonoid compounds as the singlet oxygen scavenger agent in these plant species were decreased in the order of peppermint > marjoram> sage > rosemary. Also, The rate of quenching of singlet oxygen in the presence of 1,4-Diazabicyclo[2.2.2]octane (DABCO) as a well-known singlet oxygen scavenger and highly effective synthetic antioxidants in food industry such as Butylated hydroxyanisole (BHA), tert-Butylhydroquinone (TBHQ) and peppermint decreased in the order of peppermint > BHA > TBHQ > DABCO >. Furthermore, photooxidation of oleic acid as an unsaturated fatty acid in the presence of DABCO, peppermint, BHA and TBHQ indicated a preservation of 82.77%, 73.39%, 71.57% and 53.10% on peroxidation of oleic acid, respectively which reveals peppermint has an efficient role on protection of fatty acids from photooxidation. Practical application: In this study, it was confirmed that peppermint (Mentha piperita L.) performs an effective role in restricting or limitation of singlet oxygen generation and fatty acid photooxidation. In vitro study of scavenging effect of peppermint can correlate laboratory results to commercial scale up. However, this would also necessitate the progress of improved methods for the measurement of lipid peroxidation in vivo in the presence of peppermint.