Microwave-Assisted Extraction Optimisation of Lycopene from Nigerian Tomato Varieties

Lycopene is a carotenoid with documented chemopreventive properties against prostate cancer and cardiovascular disease, and tomato (Solanum lycopersicum) is its primary dietary source. Conventional solvent extraction of lycopene from tomatoes is time-consuming and solvent-intensive, while microwave-assisted extraction offers faster extraction with lower solvent consumption. This study optimises microwave-assisted extraction of lycopene from two tomato varieties produced in Kano State, North West Nigeria, namely Roma VF and a local Dambatta variety. Optimisation was conducted using response surface methodology with a central composite design, investigating microwave power (200 to 600 W), extraction time (1 to 5 minutes), and solvent-to-solid ratio (5 to 15 ml per gram) as independent variables. Lycopene yield, extraction efficiency, and colour values were measured as responses. Lycopene was quantified spectrophotometrically at 503 nm after hexane extraction and confirmed by high-performance liquid chromatography. Optimal conditions identified were 450 W, 3 minutes, and 12 ml per gram, yielding lycopene at 142 mg per 100g dry weight for Roma VF and 98 mg per 100g for the local variety. The optimised extraction was 4.2-fold faster and used 60 percent less solvent than conventional Soxhlet extraction. Lycopene purity and stability under the optimised conditions were confirmed by liquid chromatography-mass spectrometry. The study contributes to green extraction methodology and lycopene characterisation for Nigerian tomato varieties. Findings are relevant to nutraceutical and food ingredient manufacturers. Keywords: lycopene, microwave-assisted extraction, tomato, response surface, optimisation