Influence of preparation methods on the physico-chemical properties and oxidative stability of three kinds of nut oils

The physico-chemical properties of oils from walnut, almond and sweet apricot kernels were determined following extraction either using solvent or aqueous enzymatic methods. In addition, the fatty acid profiles of different nut oils were investigated by GC and oxidative stability were evaluated by Rancimat method. Results showed that the preparation methods had important effects on the physico-chemical properties and oxidative stability. On the whole, compared with the solvent method, the obtained aqueous enzymatic nut oils had the following quality attributes : the higher transparency, better taste, and lower free fatty acid value. But their oxidative stabilities were lower than that extraction by solvent method. Also, it found that the extraction methods had no different influence on the properties such as refractive index, iodine value, saponification value, unsaponifiable matter and fatty acid composition and so on. Finally, according to the changes of their peroxide value and OSI, the sweet apricot kernel oil was the most stable while walnut oil was easily oxidative during the accelerated oxidation test.