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In recent years, water-in-oil Pickering emulsions have been introduced as promising reaction systems for multiphase enzyme catalysis, in particular lipase-catalyzed esterification and transesterification. Here, we for the first time gained insight into the effects that the presence of the proteins exert on the fineness and stability of the emulsion system and thus, the catalytic performance. We demonstrated a distinct, concentration-and enzyme-dependent decrease of droplet sizes in the dispersed phase, accompanied by decreasing stability against coalescence. This was due to a probably quantitative adsorption of lipases at the interphase intercalating the solid particles. Destabilization was reduced slightly at increased particle content and increased volume portion of the dispersed phase, respectively. However, the low tolerable lipase concentrations in the reaction system considerably limited its productivity. Thus, our study points at the enzyme content, or rather enzyme location, in Pickering emulsions being the crucial parameter for optimizing catalytic performance. |
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