One-step recovery of latex papain from Carica papaya using three phase partitioning and its use as milk-clotting and meat-tenderizing agent.

Three Phase Partitioning (TPP) system as an elegant non-chromatographic and bulk separation method was successfully applied for the extraction and recovery of papain from the latex of Carica papaya. The optimized parameters of TPP allowed achieving a purification fold of 11.45 and activity recovery of 134% with 40% (NH4)2SO4, 1.0:0.75 ratio of crude extract: t-BuOH at pH and temperature of 6.0 and 25 °C, respectively. The recovered papain had a molecular weight of 23.2 kDa and revealed maximum activity at pH 6.0 and temperature of 50 °C. The maximum values of Km and Vmax parameters were 10.83 mg mL-1 and 33.33 U mL-1, respectively. The protease with 4 isoforms was stable at 40-80 °C and a pH range of 6.0-7.5 against numerous metal ions and none of them inactivated the recovered protease. Moreover, 10 mM Ca2+ improved 2-folds the activity and half-life of the protease at temperatures from 30 to 50 °C. The milk-clotting activity tests revealed high stability of latex papain at storage, namely at -20 °C compared to 4 °C and 25 °C for up than 5 weeks. As a meat tenderizing agent, it showed promising role under different treatments by improving the texture of tough meat. The findings indicated that one-step TPP system is a simple, quick, economical and very attractive process for fast recovery of latex papain compared to other proposed protocols.