Walnut oil is in great demand due to its high nutritional value. However, it is easily oxidized and often loses its typical flavor. This study focused on the role of microwave pretreatment in improving the flavor and oxidative stability of walnut oil, and also investigated the effects of microwave pretreatment on unsaturated fatty acids (oleic, palmitoleic, linoleic, and linolenic acids) and antioxidant components (tocopherols and phytosterols). The results indicate that microwave pretreatment is effective in generating pyrazine compounds. The typical ‘roasted’ flavor was present when pretreatment for 2 min or more was applied. Meanwhile, compared with the control sample, only the highly treated sample (microwave‐pretreated for 4 min) showed higher oxidative stability. Only small changes were found in the composition of the unsaturated fatty acids, while the levels of tocopherols and phytosterols significantly decreased with increasing duration of microwave treatment (P < 0.05). The results suggest that the Maillard reaction caused the improvement of oxidative stability, since this reaction can also generate antioxidant products (melanoidins) in addition to pyrazines. Moreover, microwave pretreatment was found to be effective for enhancing the oil yield during pressing. Therefore, despite its adverse effects on tocopherols and phytosterols, microwave pretreatment could be used to improve the flavor and oxidative stability of walnut oil.

In this study, a 10‐day accelerated storage at 60 °C was carried out to investigate the evolution of volatile profiles of walnut oils from three cultivars (cvs. Santai, Xiangling, Qingxiang). Eighteen volatile oxidation compounds, including three alcohols, 11 aldehydes, one furan, one ketone, and two acids, were identified in all oil samples. Data from the three cultivars were combined and the analysis showed that 2‐heptenal and 1‐octen‐3‐ol exhibited the strongest linear correlations with peroxide value (PV), p‐anisidine value (p‐AnV), and the residual content of total tocopherols (Rtocos). The contents of both compounds were also proved to be significant variables for PV, p‐AnV, and Rtocos, according to the jack‐knife uncertainty test applied in partial least squares analysis. Hence, 2‐heptenal and 1‐octen‐3‐ol could be used as potential markers of walnut oil quality. Besides, the oleic‐derived compounds such as octanal and nonanal were suggested to be used to indicate notable decrease of PUFAs during walnut oil oxidation, since they showed the strongest negative correlations with the residual content of PUFAs (RPUFAs). Practical Application Nowadays a large‐scale planting of walnut has taken place in China. Since walnut contains more than 60% of oil, the development of walnut oil is of great significance. Volatiles such as aldehydes are secondary oxidation products. Study on the dynamic changes of their types and contents could be helpful to understand the process of walnut oil oxidation. The measurement of walnut oil quality could also be more convenient and predictable with the use of volatile markers. Hence, this research provides insights for the future development of online quality control system for walnut oil.

In the recently published article cited above, the first affiliation was incorrectly printed. The correct name of the institution published above.