Optimization of process and mechanism of extracting astaxanthin from shrimp shells with deep eutectic solvent

Development of efficient and safe extraction technology of astaxanthin from shrimp shells is crucial for transforming waste into valuable resources. In this study, astaxanthin in shrimp shells was extracted with deep eutectic solvent composed of lactic acid-choline chloride. A single-factor test was carried out to explore the influence of extraction conditions on the extraction rate, and a response surface test was adopted to optimize the extraction process. The mechanism of astaxanthin extraction with deep eutectic solvent was explored by physical and chemical analysis. The optimized process conditions were: molar ratio of 2.5∶1, water content of 9.5%, ultrasonic time of 30.5 min, and actual yield of 24.41 μg·g⁻¹. The Fourier transform infrared spectroscopy shows that there was no change in functional groups during deep eutectic solvent synthesis, but hydrogen bond might be the reason for effective extraction of astaxanthin, and viscosity would affect the extraction process of product.