Pickering emulsions stabilized by protein/polysaccharide polyelectrolyte complexes for lipase catalysis

The Pickering emulsion stabilized by ovalbumin/pectin polyelectrolyte complex with porcine pancreatic lipase (PPL) dissolved in the aqueous phase was investigated for its feasibility in biphasic catalysis. CLSM and QCM-D analysis revealed that PPL discretely adsorbed to emulsion interface, though they were both negatively charged. The hydrolysis of p-NPP was favored in low stabilizer concentrations and could be saturated by PPL, and the optimum conditions were pH 6.5, ovalbumin to pectin mass ratio 1:3, complex concentration 0.25 %, and PPL dosage 0.6 %. Under these conditions, the Pickering emulsion conferred a conversion rate of 0.87 μmol/h and product yield of 46.8 % after reaction for 5 h, which were significantly lower than 1.37 μmol/h and 73.6 % of the conventional oil/water system. Hence, Pickering emulsions stabilized by protein/polysaccharide polyelectrolyte complexes might not be ideal media for biphasic catalysis, possibly due to the viscoelastic property of the complexes that could better cover emulsion interfaces.