Thermal oxidative stability and kinetics of lipophilic bioactive compounds degradation during accelerated storage of unroasted and roasted peanut oil

Abstract

Due to the susceptibility of peanut lipids to autooxidation, which compromises food quality and safety, shelf-life studies are conducted. This research aimed to examine and compare the thermal oxidative stability of cold-pressed peanut oils (POs) from unroasted and roasted varieties (Virginia and Valencia) under accelerated storage conditions (60°C, in the dark) for 28 days. Degradation kinetics of phytonutrients and changes in the fatty acid profile, chemical oxidation indicators, and antioxidant activity were continuously monitored to assess the extent of oxidation. Results showed that acid, peroxide, and p-anisidine values, UV-spectrophotometric indexes, and total oxidation value increased in POs during storage with significant differences. Total tocopherols and phytosterols decreased with storage time, following a second-order kinetic model. After 28 days of storage, 25.5442.08% of phytosterols and 25.9248.17% of tocopherols were lost. The degradation rates of tocopherol were higher in roasted POs, while unroasted POs exhibited the highest rate of phytosterols degradation. Besides, there were slight differences in the fatty acid composition of all stored oils. In addition, all POs' DPPH radical inhibition decreased with storage time, reaching values between 35.72% and 44.73%. This study has provided important insights into the evolution of key chemical parameters of unroasted and roasted POs of two commercial varieties during storage.