Improving edible oil quality by low- and high-temperature selective adsorption on the example of walnut oil (Juglans regia L.)

Abstract This study evaluated the effects of adsorbent type, dosage, and temperature on walnut oil quality and selected bioactive compounds. Adsorption efficiency depended on the combination of processing conditions, with statistically significant effects observed for individual factors and their interactions. Differences among adsorbents may be related to their composition and surface properties, which were not directly characterised in this study. The relative effects of temperature and adsorbent dosage varied depending on the adsorbent and parameter analysed. Treatment at a relatively low temperature (approximately 30 °C), combined with an appropriate adsorbent dosage, may help improve selected quality characteristics while retaining valuable bioactive compounds. However, carotenoid and tocopherol retention varied among adsorbents, and no single treatment condition was optimal for all parameters. Overall, walnut oil adsorption requires joint consideration of adsorbent type, dosage, and temperature. Further research should characterise adsorbent surface properties and evaluate the oxidative stability of treated oil to clarify the mechanisms underlying the observed changes and their implications for oil quality.