Cloud point extraction based on non-ionic surfactants: An ecofriendly tool for recovering papain from papaya latex

The potential use of cloud point extraction with aqueous micellar two-phase systems (AMTPS), formed by the non-ionic biodegradable surfactants Triton X-114 (TX-114) and Genapol X-080 (GX-080), to recover papain (PAP) from fresh papaya latex was evaluated. Binodal curves obtained for both surfactants, in absence and presence of PAP, showed cloud points below 40°C, the PAP presence slightly favoring the phase separation phenomenon. Partitioning experiments showed that PAP migrated toward the micelle-poor phase independently of the surfactant and the working temperature assayed, this behavior being consistent with this enzyme hydrophilic character. PAP recoveries of over 60% in the poor-micelle phase were obtained when partitioned fresh papaya latex in both surfactant-based AMTPS. TX-114 systems (4.00% w/w, 33°C) allowed recovering 66% of PAP with a purification factor of 4.6. On GX-080 systems (4.00% w/w, 42°C) a yield of 78% PAP and a purification factor of 3.7 were achieved. This AMTPS also allowed the separation of PAP from reducing sugars present in papaya latex. These results show that TX-114 and GX-080-based AMTPS could be potentially used as simple and economical tools at recovering PAP from papaya latex. • Cloud point extraction was used to recover papain from Carica papaya latex. • Triton-114 and Genapol X-080 micellar systems were suitable to recover papain. • Genapol X-080 systems achieved a papain yield of 78% and purification factor of 3.7. • Papain exhibited thermal stability in surfactant solutions (0-1%) up 48 °C.