Developing an integrated green biorefinery for harnessing a high-stability and high-bioaccessibility lycopene product from tomato waste

Tomato processing industry generates large amounts of waste that contain lycopene, but lycopene extraction requires use of hazardous and toxic solvents. Moreover, lycopene degrades in the presence of light and oxygen. Hence, there is a need for clean methods to isolate lycopene from tomato waste and then convert it into a stable form. Therefore, the objective of this study was to develop an integrated green process to separate and enrich lycopene from tomato wastes and then to convert it to a high-value lycopene formulation.

An integrated inline extraction-reaction-particle formation process based on supercritical carbon dioxide (SC-CO2) was developed. Tomato waste was extracted by SC-CO2 and the lycopene was separated from the oil in a packed bed enzyme reactor using. Then, the separated lycopene was converted into free-flowing lipid powder in the particle formation system using SC-CO2. The maximum lycopene yield was obtained at 80 °C/50 MPa and 70/30 peel/seeds ratio based on mathematical modeling using mass conservation law. The lycopene yield had a direct relationship with external mass transfer coefficient. In the bioreactor, lower ethanol flow rate and increased enzyme bed length significantly increased separation of lycopene (800 mg/100 g) (p < 0.05). Approximately 90% of the triacylglycerols in the extract were converted into ethyl ester form. Free-flowing powder lycopene was generated via loading the separated lycopene into hollow solid lipid microparticles in the particle formation unit. Stability of the lycopene particles increased 4 folds during one-month storage at room temperature (24 °C).

A novel integrated extraction-reaction-particle formation process to separate a bioactive from a waste, then purify and convert it into a high-value food product was developed. The process does not use toxic chemicals and solvents, minimizes waste generation, and maximizes utilization of bioactives from agricultural products. This is a first step to developing integrated green supercritical fluid biorefineries.