Molecular Evolution of Sunflower and Cottonseed Oils During Preparation of Uzbek Palov.

Understanding how vegetable-oil composition evolves during food preparation is essential for evaluating food quality and nutritional value. Palov is Uzbekistan's most widely consumed and culturally significant dish, serving as an everyday meal and a central element of hospitality and communal traditions. We hypothesised that food-oil interactions during Palov preparation direct molecular changes that cannot be reproduced by controlled heating alone. Two independent batches of Palov were prepared with sunflower or cottonseed oil under household cooking conditions. Oils were sampled at six stages and compared with heating controls conducted under closely matched temperature-time profiles without food ingredients. Samples were analysed using Fourier-transform infrared spectroscopy, benchtop and high-field 1H nuclear magnetic resonance spectroscopy. Cooking caused substantially greater fatty-acid changes than heating alone. In cottonseed oil, polyunsaturated fatty acids decreased from approximately 44 to 32 mol%, monounsaturated fatty acids increased from approximately 19 to 26 mol%, saturated fatty acids increased from approximately 36.5 to 41.5 mol%, and trans-fatty acids increased from approximately 0 to 2%. Heating alone produced greater accumulation of conjugated dienes and hydroperoxides, whereas cooking produced more dynamic changes in sterol-, aldehyde- and glyceride-related signals. These findings demonstrate that food-oil interactions redirect fatty-acid composition, hydrolysis and oxidation-product evolution rather than merely altering the extent of thermal damage. Realistic culinary models therefore provide a more representative description of edible-oil transformation than heating-only experiments.