Examination of the quality and oxidative stability of cold-pressed nut oils produced in Bosnia and Herzegovina

Cold-pressed nut oils, including almond, walnut, and hazelnut oils, are obtained mechanically without heat or refining, retaining high levels of bioactive compounds and antioxidants. These oils are nutritionally valuable but prone to oxidation. This study evaluated the quality and oxidative stability of base samples and the effect of natural (mint, bergamot, tea tree) and synthetic (BHA, BHT, PG) antioxidants. Quality parameters included fatty acid composition, nutritional indices, free fatty acids, peroxide value, moisture, insoluble impurities, saponification value, total phenols, carotenoids, and chlorophyll content. The results showed a dominance of unsaturated fatty acids, with MUFA being the highest in hazelnut and PUFA in walnut oil. Walnut oil showed the highest peroxide values, while synthetic PG effectively stabilized all the oils. Among natural antioxidants, mint was the most effective for almond and walnut oils, and bergamot for hazelnut oil. These findings demonstrate that antioxidant selection must be tailored to the oil matrix, as natural essential oils exhibited matrix-dependent protective or pro-oxidative activities.