Impact of cooking techniques on the formation of 7-ketocholesterol in food: a comprehensive review

Thermal processing of foods promotes cholesterol oxidation, leading to the formation of 7-ketocholesterol (7-K), a major secondary oxysterol generated through radical- and photo-oxidative mechanisms. Cooking technologies differently affect its accumulation, depending on temperature/time combinations, oxygen exposure, moisture loss, and matrix characteristics (lipid composition, endogenous antioxidants, pre-treatments). Dry-heat methods (such as grilling, roasting, pan-frying and deep-frying) generally intensify oxidation, while microwaving may further accelerate hydroperoxide degradation and interface-driven radical reactions. Conversely, vacuum-based low-temperature systems (such as sous-vide) may lead to lower 7-K formation. However, post-cooking conditions (including storage, reheating, and warm holding) can significantly enhance 7-K production, especially in PUFA-rich matrices and products previously subjected to oxidative stress. Considering that 7-K is absorbed to a limited extent but can reach systemic circulation, the evaluation of dietary exposure to 7-K present in commonly consumed cooked foods is relevant for assessing its potential contribution to diet-related oxidative burden. This review compiles current knowledge on formation mechanisms, technological drivers, and dietary occurrence of 7-K in thermally processed foods, highlighting key factors influencing its development across cooking methods.