Objective To explore the mixing ratio of different oil seeds in microwave-assisted blended cold pressing process, and develop polyunsaturated fatty acid balanced oil that meets the recommended dietary intake ratio. Methods The safflower seed and flaxseed were used as raw materials. The process parameters were optimized by single factor experiment (microwave treatment time, pressing temperature and moisture content of oil seed) and Box-Behnken response surface experiment. The oxidation characteristics of blended cold pressed oil were compared and analyzed. Results The mass ratio method determined that the blended mass ratio range was 1.8-2.4 (safflower seed:flaxseed, Ws:Wf). This method was simple and the results did not need to be verified, but it had the disadvantages of large demand for raw materials and low accuracy of boundary value. The mixing ratio range determined and verified by the fatty acid ratio method was 1.66-2.59 (Ws:Wf). This method had less raw material demand and high accuracy near the boundary value. However, due to the interaction of oil seeds, verification experiments needed to be carried out. Response surface methodology was used to optimize the process parameters of microwave-assisted blended cold pressing. The optimal extraction conditions were as follows: Microwave (800 W) treatment time 1.5 min, cold pressing temperature 64 °C, oil seed moisture content 6.7%, oil extraction rate 19.83%±0.21 %, which was 17.2% higher than that before optimization. The basic physical and chemical indexes of blended cold-pressed oil and traditional cold-pressed blend oil were compared and analyzed. The oil oxidation degree was lower under the condition of microwave-assisted blended cold-pressed process. Conclusion Microwave-assisted blended cold pressing oil has lower primary and secondary oxidation product indexes than traditional cold-pressed blended oil. The results can provide a theoretical basis for the preparation of polyunsaturated fatty acid equilibrium oil and the application of microwave-assisted blended cold pressing process in the field of grain and oil processing.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |