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

Abstract

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 (K232), 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 O2/kg) after 12 days of storage, while PV values of AKO reached the maximum value (54.5 meq O2/kg) after 10 days of storage. K232 values exhibited similar behavior under accelerated oxidation conditions, wherein the highest K232 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 O2/kg for PKO and AKO, respectively. Similarly, the maximum K232 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 × 106 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 × 106 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.