Effect of roasting pre-treatment of two grafted pine nuts (Pinus koraiensis) on yield, color, chemical compositions, antioxidant activity, and oxidative stability of the oil

In this study, pine nut kernels from two grafted species: Pinus koraiensis (PK) and Pinus sylvestris var . (PKS) were roasted (130, 150, 180℃ for 10, 20, 30 min) to investigate the effect of roasting pre-treatment on chemical components, antioxidant activity, and oxidative stability of oils prepared from kernels. Increased temperature or time was found to cause a significant increase in oil yield, color, total phenolic content (TPC), carotenoid, and browning index (BI) of oils compared to unroasted samples. Roasting could also elevate the antioxidant activity and oxidative stability of pine nut oil. The levels of tocopherol decreased significantly at high temperatures (150℃, 180℃), while the fatty acid compositions were almost independent of roasting conditions. The FTIR spectra of oils from different roasted pine nuts showed minor variation in peak intensities. Therefore, roasting is a great option and critical step to improve the quality of pine nut oil. Novelty impact statement The oil yield, color, total phenolic content (TPC), carotenoid, and browning index (BI) of pine nut oil from two grafted species were influenced by different roasting conditions. Roasting could improve the antioxidant activity and oxidative stability of pine nut oil. Roasting (180℃ for 10 min) is a great option to improve the quality of pine nut oil.