Enhanced NaHDESs Extraction of Carotenoids from Pepper By-products: A Sustainable Approach

The by-products from processing fresh yellow and red peppers are a valuable source of carotenoids, which can be efficiently extracted using Natural Hydrophobic Deep Eutectic Solvents (NaHDESs). In this study, the extraction capability of nine NaHDESs was physicochemically evaluated. The screening process identified thymol/DL-menthol (1:1) as the optimal NaHDES for yellow pepper peels and thymol/decanoic acid (3:2) for red pepper peels. Using Box-Behnken Design (BBD) and Response Surface Methodology (RSM), the extraction process was optimized, yielding 0.363 ± 0.042 mg/mL of lutein from yellow pepper peels, while 0.625 ± 0.052 mg/mL and 0.836 ± 0.033 mg/mL of β-carotene and lutein, respectively were found in red pepper peels. These results were comparable to or exceeded those obtained using acetone as a solvent. From a green chemistry perspective, NaHDESs offer significant advantages, including higher extraction efficiency, reduced energy consumption, and a lower environmental impact. These findings suggest that NaHDESs are a promising alternative to conventional solvents, providing a sustainable method for extracting natural compounds from raw materials, food wastes, or by-products, with potential applications in the food industry.