Associate professor Wuhan Polytechnic University, Hubei, China (People's Republic)
A comparison study has been performed on processing methods (cold pressing, roasting pressing, n-hexane extraction, subcritical butane extraction and supercritical carbon dioxide extraction) of walnut oils. The results showed that n-hexane extraction was a good approach in terms of walnut lipid extraction, the C18:1 contents of roasting pressing (18.74%) and n-hexane extraction (18.52%) walnut oils were significantly higher than other samples, while the C18:2 and LLL contents of roasting pressing (63.06% and 32.82%, respectively) and n-hexane extraction (62.95% and 32.06%, respectively) walnut oils were lower than that of others. Moreover, the tocopherol (371.08 mg/kg) and the phytosterol (1206.30 mg/kg) contents of subcritical butane extraction walnut oil, the polyphenol content of n-hexane extraction walnut oil (45.43 mg/kg), and the squalene content of roasting pressing walnut oil (14.19 mg/kg) were higher than other samples. In addition, the MLR was employed in order to evaluate the contributions of chemical components to antioxidant capacity (oxidative stability and free radical scavenging capacity) of walnut oils, and the antioxidant capacity evaluation model of walnut oil can be established: Y = 0.32 (C16:0) + 0.13 (Polyphenol) + 0.12 (Δ5-Avenasterol) + 0.12 (SOS) + 0.11 (γ-Tocopherol) - 0.08 (PLL) + 0.07 (C18:3) + 0.03 (LLL) -0.02 (C18:0).
