Evaluating different static in vitro digestion models and lipolysis profiles of single and double water/oil emulsions
In vitro lipolysis of single and double water/oil emulsions was studied to evaluate static in vitro digestion models. Two common static methods were evaluated; the pH-stat titrimetry technique and another batch digestion model that enzymatically quantifies liberated free fatty acids (FFA). Parameters affecting the in vitro intestinal lipolysis of long (LCT) and medium chain triglycerides (MCT) in O/W emulsions were investigated. Increasing the pH of titration to 9 alleviate the underestimation of lipolysis of LCT. Calcium interfered with the estimation of FFA using the enzymatic method. Another static digestion model developed with international consensus was used to evaluate the lipolysis profile and bioactive miceller transfer of a model hydrophilic bioactive, β-carotene (β-C), in W/O/W and O/W emulsion samples. Slower rates and extents of lipolysis and β-C transfer were measured in double emulsions. The differences in lipolysis were attributed to microstructure and instability of the double emulsions in simulated intestinal fluids.