Equilibrium data for the separation of oleoresin capsicum using supercritical CO2: A theoretical design of a countercurrent gas extraction column

Oleoresin capsicum (ORCap) is the commercial liquid product obtained after the solvent extraction of peppers (Capsicum annuum L.). With high content of lipid matter and a noticeable amount of pigments, such as capsaicinoids and carotenoids, oleoresin capsicum is usually used in food industry. Besides, if an enrichment of carotenoids and capsaicinoids is reached, many applications in pharmaceutical and cosmetic industry can be covered by the products obtained. In this work, the fractionation of oleoresin capsicum using supercritical CO2 countercurrent extraction was studied to obtain an extract enriched in capsaicinoids and a raffinate enriched in carotenoids. Moreover, the separation column was designed. Phase equilibrium of the system CO2–oleoresin capsicum was determined along the interval of temperature (314–338 K) and pressures (90–310 bar), and samples of both phases were analytically characterized. Due to the inadequacy of the binary approach to study the separation problem, a pseudoternary approach was selected and oleoresin capsicum was described by two pseudocompounds according to its distribution coefficients. At 337.8 K and 206 bar a maximum selectivity of 5.6 between the pseudocompound enriched in capsaicinoids and the pseudocompound enriched in carotenoids was obtained. This fact showed that countercurrent gas separation could be employed and could be economically interesting. The column design was performed according to two different short-cut methods and different separation parameters, such as the number of theoretical stages (nth), the reflux ratio (ν) and the solvent-to-feed ratio (S/F), were calculated. Jänecke method presented the best result according to the change in composition along the separation column. Finally, the minimum diameter of the column to be designed, which is necessary to avoid flooding conditions, was also calculated for different packings.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights► Oleoresin capsicum was defined as two pseudo-compounds according to Ki. ► To achieve the countercurrent gas extraction 206 bar and 337.8 K were selected. ► Jänecke was the most suitable short-cut method to perform the column design. ► Good design conditions were selected as nth = 6.6, ν = 27.4, S/F = 250. ► Minimum diameters to avoid flooding were bigger for random packings.