Effect of thermal and photo oxidation on the stability of cold-pressed plum and apricot kernel oils

Oxidative stability of cold-pressed plum (Prunus domestica) kernel oil (PKO), and apricot (Prunus armeniaca) kernel oil (AKO) were evaluated under thermal-oxidation and photo-oxidation conditions. Changes in peroxide value (PV), conjugated dienes (K-232), and levels of volatile compounds in the cold-pressed oils were monitored during storage for 12 days under oxidation conditions. Under thermal oxidation conditions, PV values of PKO reached the maximum value (63.8 meq O-2/kg) after 12 days of storage, while PV values of AKO reached the maximum value (54.5 meq O-2/kg) after 10 days of storage. K-232 values exhibited similar behavior under accelerated oxidation conditions, wherein the highest K-232 values were 12.38 and 10.91 for PKO and AKO at the 12th and the 10th day of storage, respectively. Under photo-oxidation conditions, both values recorded similar behavior. At the end of storage (12th day), PV values reached 117.5 and 67.62 meq O-2/kg for PKO and AKO, respectively. Similarly, the maximum K-232 values were 5.72 and 4.56 for PKO and AKO, respectively. Hexanal, and E-2-heptenal recorded the values of 149.2 and 41.83 x 10(6) AU for the PKO after 12 days of storage under thermal oxidation conditions, while hexanal, and E-2-heptenal reach up to 199.2 and 58.88 x 10(6) AU for the AKO after only 10 days of storage. At the end of 12 days of storage under photo-oxidation of PKO and AKO, the aldehydes were detected as the most identified chemical group (especially hexanal, and E-2-heptenal) in the photo-oxidized PKO and AKO.