Transient Changes in Oil Quality Under Frying: Effect of ß-Carotene and BHT

ß-carotene is a carotenoid, known as one of the main sources of provitamin A and its low diet assumption is one of the major deficiencies among children in Africa and Asia. Even when incorporated into oils, it degrades at high temperatures, which leads to the loss of its antioxidant properties, affecting the nutritional quality and shelf life of the oil. The objectives of this research were (1) to study the degradation kinetics of ß-carotene in selected commercial cooking oils at frying temperatures (180°C) over time (up to 30 min); and (2) to investigate the effect of the addition of the synthetic antioxidant BHT (butylated hydroxytoluene) on preventing the degradation of ß-carotene during frying. Five different oils (olive oil, extra virgin olive oil, sunflower oil, rapeseed oil and coconut oil) were analysed, and degradation of ß-carotene was monitored based on a spectrophotometric method. The oxidative state of the oils was assessed by measuring the acidity and peroxide values. Finally, the fatty acid profile of sunflower and coconut oil was evaluated through GC-FID. The findings revealed that BHT does not significantly protect ß-carotene from thermal degradation in all oils. Notably, ß-carotene degraded faster in coconut oil, which is rich in saturated fatty acids, compared to sunflower oil, which contains a higher proportion of polyunsaturated fatty acids. So, the fatty acid composition of the oil plays a crucial role in the degradation process.