Techno-economic and Sustainability Assessment of Integrated Annatto Seed Biorefinery for Natural Pigments, Starch, and Nutraceuticals

Abstract

Annatto (Bixa orellana L.) seeds, traditionally exploited as a natural pigment source, remain underused despite their richness in bioactive oil and functional carbohydrates. We propose an integrated biorefinery that couples supercritical CO₂ oil extraction, ultrasound- and low-pressure solvent-assisted bixin recovery, aqueous starch isolation, and oil encapsulation into nutraceutical powders. Experimental data were scaled with SuperPro Designer to quantify techno-economic performance, and sustainability was assessed using a 12-principle green-extraction metric (Path2Green) to benchmark process choices across environmental, economic, and scalability dimensions. The integrated process achieved a gross margin of 21.8%, ROI 27.9%, NPV USD 5.8 million (7% rate), and a 3–4 year payback time; sensitivity analysis identified feedstock cost and product price as the dominant profitability drivers, while labor and utilities had comparatively minor effects. Sustainability results highlighted the superiority of supercritical CO₂ over Soxhlet for oil (solvent safety/recyclability), energy trade-offs between ultrasound and low-pressure solvent extraction for bixin, and the valorization potential of aqueous starch recovery. Collectively, the findings position annatto as a model biomass for zero-waste, circular biorefineries delivering natural pigments, functional carbohydrates, and nutraceutical ingredients through processes that are both economically viable and metrics-driven in sustainability.