Three-liquid-phase salting-out extraction of effective components from waste liquor of processing sea cucumber

• A TLP system was applying to separate oils, saponins, proteins and polysaccharides.
• The scale was up from lab scale to 25 kg and the effects of recycling determined.
• Over 82% of saponins, oils, proteins and polysaccharides were achieved simultaneously.
• 81.4% of n-hexane, 80.8% of ethanol and 72% of sodium carbonate were recovered.

A three-liquid-phase (TLP) salting-out extraction system composed of n-hexane/ethanol/sodium carbonate/water was investigated to extract oils, saponins, proteins and polysaccharides simultaneously from waste liquor of processing sea cucumber. The effects of the ratio of ethanol to sodium carbonate, n-hexane concentration and extraction time were investigated. The results showed that 86.7% of oils were distributed in the top n-hexane phase, 82.9% of saponins in the middle ethanol phase, 93.2% of proteins and 92.9% of polysaccharides in the interface between the middle and the bottom salt phase when the system composed of 28% (w/w) n-hexane/11.52% (w/w) ethanol/8.64% (w/w) sodium carbonate was used at 37 °C for 0.5 h. When the system was progressively enlarged from 30 g to 25 kg, the yield of polysaccharides, proteins, oils and saponins was decreased only by 1.0%, 2.8%, 1.0% and 2.6%, respectively. The recycle of salt and solvents in three-liquid-phase system was also studied, and the results showed that the recovery of n-hexane, ethanol and salt were 81.4%, 80.8% and 72.0%, respectively. Recycling materials for the extraction, the yield for proteins and oils decreased by 2.0% and 5.4%, respectively, comparing with the pure system.