Compressed fluid-based technology for downstream isolation of bluish anthocyanin-derived pigments obtained from blueberry surplus

A dynamic compressed fluid-based separation process combining carbon dioxide and ethanol was explored to isolate portisins previously hemi-synthesized from blueberry surplus anthocyanins. The influence of process parameters such as pressure (100-500 bar), temperature (40-60 °C), and ethanol content in the compressed fluid mixture (20-50 wt%) on extraction yield, portisins yield, and portisins content in the extract was investigated. The two-step isolation process includes (1) a first step at 100 bar, 60 °C, and 20 wt% ethanol content in the compressed fluid mixture to remove the low polarity compounds; and (2) a second step at 500 bar, 40 °C, and 100 wt% ethanol to recover portisins, resulting in a 1.5-fold increase in portisins content. The performance of the two-step separation process was compared to centrifugal partitional chromatography and conventional reverse phase liquid chromatography already reported in terms of portisins content in the extract, process throughput, process efficiency, and total solvent used. The two-step separation process decreased the total solvent used, although with a decrease in the throughput and efficiency. Nevertheless, the choice of the best separation technology depends on the application, as these techniques result in different portisins purities. Overall, this study contributed to a scalable and more sustainable process for natural colorant production, specifically focusing on blue pigments, with several industrial applications.