低温螺旋压榨核桃油工艺优化及其营养成分分析Process optimization of low temperature screw pressed walnut oil and its nutritional components analysis

为了促进核桃油的开发和利用，以核桃仁出油率为指标，采用单因素试验和响应面试验优化低温螺旋压榨核桃油的工艺条件（核桃仁含水量、榨头温度、出渣孔径），并在最优条件下对不同品种核桃油的脂肪酸组成和活性成分进行分析。结果表明：在出渣孔径12 mm、核桃仁含水量6%、榨头温度100 ℃条件下，核桃仁出油率最高，达57.63%；最优条件下压榨所得的新疆纸皮核桃油、美国山核桃油和临安山核桃油的不饱和脂肪酸含量均超过90%，其中油酸含量为18.08%~63.44%，亚油酸含量为26.63%~60.96%，α-亚麻酸含量为1.90%~11.45%，3种核桃油的角鲨烯含量为214.9~282.1 mg/kg，总多酚含量为20.2~23.1 mg/kg，维生素E含量为2.68~13.31 mg/100 g，美国山核桃油的角鲨烯含量和维生素E含量最高。综上，通过低温螺旋压榨法可以获得出油率高且富含多种活性成分的核桃油。To promote the development and utilization of walnut oil, the low temperature screw pressing process conditions (moisture content of walnut kernels, pressing temperature, and outlet size) based on the walnut oil yield using single-factor experiments and response surface methodology were optimized. The fatty acid composition and active components of walnut oils from different varieties prepared under the optimal conditions were analyzed. The results indicated that the highest oil yield of 57.63% was achieved with an outlet size of 12 mm, a walnut kernel moisture content of 6%, and a pressing temperature of 100 ℃. The unsaturated fatty acid content in walnut oils from Xinjiang paper-shelled walnuts, American pecans, and Lin′an hickory nuts all exceeded 90%. Specifically, oleic acid content ranged from 18.08% to 63.44%, linoleic acid from 26.63% to 60.96%, and alpha-linolenic acid from 1.90% to 1145%. Squalene content in the three walnut oils was between 214.9 mg/kg and 282.1 mg/kg, total polyphenols content ranged from 20.2 mg/kg to 23.1 mg/kg, and vitamin E content varied from 2.68 mg/100 g to 13.31 mg/100 g, with the highest squalene and vitamin E contents found in American pecan oil. In conclusion, walnut oil with high yield and rich in various active ingredients can be obtained by low temperature screw pressing method.