Techno-economic insights into one-pot bacterial astaxanthin extraction and sustainable therapeutic product development using natural solvent mixtures

The increasing demand for sustainable and safe products is driving the replacement of synthetic pigments with natural alternatives in the cosmetics industry. Additionally, the use of green solvents, such as natural solvent mixtures (NaSoMix), is essential to minimize the environmental impact of extraction processes. This study explores the innovative application of NaSoMix for extracting astaxanthin-rich extracts (ARE) from the bacterium Paracoccus carotinifaciens, a promising source of natural colorants and antioxidants. By employing menthol-based natural deep eutectic solvents (NaDES) combined with bio-based solvents, viz., ethyl acetate and ethanol, the research achieved remarkable ARE extraction yields of up to 1.3 mg/mL using conventional procedures. Notably, process intensification through microwave-assisted extraction resulted in a 400 % increase in ARE recovery yields compared to traditional methods. The therapeutic soaps formulated with these ARE extracts exhibited significant antioxidant activity, achieving a 75 % reduction in DPPH• free radical signals, and maintained excellent color stability over a month, with minimal perceptual changes. Safety assessments confirmed the non-irritating properties of the therapeutic soaps, with an irritation score of 0 at low ARE concentrations. Furthermore, an economic analysis revealed a highly favorable Internal Rate of Return (IRR) of 183 % and a Return on Investment (ROI) of 2890 %, underscoring the commercial viability of this sustainable approach. Overall, this study highlights the effectiveness and safety of utilizing NaSoMix for extracting high-value compounds and formulating innovative therapeutic cosmetic products, aligning with consumer preferences for natural ingredients while promoting environmental sustainability and economic feasibility.