Investigations on thermostability of carotenoids from tomato peels in oils using a kinetic approach

Abstract

Our study focused on the characterization of the extract obtained from tomato peels. The chromatographic profile revealed the presence of lycopene and β-carotene. The in silico tests suggested that the thermal treatment of lycopene molecules pairs at temperatures over 100°C cause the alteration of all-trans conformation into 9,9′cis lycopene, which might decrease its biological activity. Also, the thermal degradation of the total carotenoids, β-carotene, and lycopene was studied in the temperature range 100–145°C and followed a first-order kinetic model, with activation energy of 81.76 ± 6.82 kJ/M, 89.81 ± 8.48 kJ/M, and 79.66 ± 4.03 kJ/M, respectively. The Rancimat analysis indicated that the enriched peanut and cotton oils with extract displayed higher induction time values, thus showing a protection factor of the tomato-derived carotenoids. The present results highlighted the thermostability of carotenoids in vegetable oils and the potential of using tomato peel as a valuable source of biologically active compounds, with antioxidative properties. Practical applications Our study explores the possibilities of reuse the underutilized tomato-derived by-products, rich in biologically active compounds such as lycopene and β-carotene. The results are valuable because the thermal degradation mechanisms of the main biologically active compounds extracted from tomato peels are described by two methods: classical kinetic models and in silico approach. Both methods have highlighted the degradation of lycopene and β-carotene, with an impact on antioxidant activity. The present study provides cumulative information for the selection of industrial processing parameters from the perspective of preservation of bioactives and obtaining the desired quality end products. The extracts have gained also applicative value in our study, being tested for its protective effect on commercial vegetable oils, but also for improving their antioxidant activity and color.