Impact of deacidification processes on the quality and oxidative stability of walnut oil

Abstract

In order to select an appropriate deacidification process and improve the quality of walnut oil, low-temperature cold-pressed crude walnut oil was used as raw material. Deacidified walnut oil was prepared using three deacidification processes: chemical deacidification (CD), adsorption deacidification (AD), and molecular distillation deacidification (MDD). The physicochemical properties, nutritional components, and in vitro antioxidant activities of the resulting deacidified walnut oils were comparatively analyzed. The results indicate that the fatty acid content in walnut oil exhibits fluctuating changes during the three different deacidification processes. The MDD shows a higher deacidification rate, reaching 94.06%, which is superior to the other two methods. Additionally, the AD retains more total phenols and tocopherols, with retention rates of 95.79% and 74.62%, respectively; whereas MDD is more effective at retaining phytosterols, achieving a retention rate of 98.09%. All these methods displayed positive impacts on the in vitro antioxidant capacity and oil stability of walnut oil, with ferric-reducing antioxidant power (FRAP) content and oxidative stability time were significantly reduced.whencompared to the untreated crude oil Among them, AD had the greatest impact on oxidative stability index (OSI), with its decreasing from 2.06 ​h to 0.82 ​h. Overall, compared to CD or MDD, the AD has best application prospects in preserving nutritional components.

Keywords

• Walnut oil
• Refining
• Deacidification
• Adsorption
• Oxidative stability