Optimization of Vacuum Frying Process and Quality Analysis of Macadamia Kernels by Response Surface Methodology

Vacuum-fried products were prepared with macadamia kernels as raw material. Single factor experiment and response surface Box-Behnken test were used to optimize the vacuum frying process of macadamia kernels. Oil content, acid value, peroxidation value, color difference and sensory quality of vacuum-fried kernel were determined by comparing with raw kernel. The results showed that the effects of freezing temperature, vacuum frying temperature, vacuum frying time and vacuum degree on taste and flavor quality of macadamia kernels were significantly different (P<0.01). The optimum conditions for vacuum frying of macadamia kernels were as follows: Freezing temperature −24 ℃, vacuum frying temperature 113 ℃, vacuum frying time 58 min, vacuum degree −0.095 MPa. Macadamia kernels were rich in flavor, crisp and delicious, and the sensory score reached 95.90 points. Acid value and peroxide value were 0.23 mg/g and 0.14 g/100 g respectively, which were in the low level and met the standard of LY/T 1963-2018. Therefore, the vacuum frying process significantly improved the quality of macadamia kernels.