Characterization and optimization of carotenoid extracted from the peels of tomato Lycopersicon esculentum grown in Nigeria

The application of synthetic colourants to foods, snacks, and beverages has increased within the past 50 years, and up to a 500% increase has been reported in Nigeria. Consumers of coloured foods and beverages have been showing worries about the possible health hazards of such products over time. Hence, researchers have shifted attention to alternative and natural colourants that are harmless. Extraction of carotenoid from tomato peel by-product will not only solve the problem associated with consuming synthetic colourant but solve the pollution problem connected with tomato processing. This research was conducted to study the kinetics and determine the thermodynamics of carotenoid extraction from tomato peel (Lycopersicon esculentum) using ethanol. Tomato peel by-product was collected, cleaned, oven-dried, and ground. It was characterized to determine the proximate and phytochemicals composition. The carotenoid extraction process parameters were optimized using response surface methodology, and the carotenoid extracted was analysed using a gas chromatograph-mass spectrophotometer. The kinetics and thermodynamics of extraction were studied using a first-order mass transfer model and thermodynamics to determine energy changes involved in the extraction. The result of the proximate analysis showed the following values; crude protein (0.69%), Fibre (20.63%), Ash (17.40%), Fat (8.53%), Moisture (8.13%), and Carbohydrate (44.62%). The phytochemical analysis showed that the tomato peel contains terpenoid, alkaloid, saponin, and flavonoid. The optimal conditions for carotenoid extraction were 0.306 mL/g solvent/solid ratio, 20 minutes extraction time, and temperature of 36 °C with the optimal yield of 82.35%. The result indicates that tomatoes contain 82.35 g of carotenoid. It is observed that the carotenoid contains lutein 1.89%, lycopene 88.11%, β- carotene 2.25%, cis-ζ-carotene 2.41%, γ-carotene 1.23%, cis-lycopene 0.89%, phytofluene 0.62%,ζ-carotene 1.2% and phytoene 1.52%. Therefore, among the components, lycopene is the most dominant with the composition of 88.11% yield, and the extraction was endothermic, spontaneous, and feasible. Ethanol is a good solvent for the extraction of carotenoid from tomatoes peel.