Study on Macroscopic Properties, Microstructure and Aggregation Process of Monoglyceride and Vegetable Wax Based Oleofoams

Liyang Du, Yuanfa Liu

Jiangnan University; School of Food Science and Technology, State Key Laboratory of Food Science and Technology, Jiangnan University

Different concentrations of monoglyceride (MAG) and beeswax were employed to structure the whipped oleogel, respectively. The concentration influenced the growing and the distribution of crystals network. Oleofoam samples were characterized with microstructure, whipping time, foamability, air bubble size distribution, rheological behavior, thermodynamics, visible appearance, and the link between the macroscopic properties to the microstructure of samples. The shape of the air bubbles, crystals distribution in the continuous phase and adsorption layer at air-oil interface were closely related to the MAG and beeswax concentration. All the whipped oleogels had the similar high overrun, nevertheless, increasing concentration meant less whipping time under the same conditions. In contrast, oil foams prepared at high concentration improved foaming ability as well as foam stability. Oleofoams at all concentrations showed solid-like viscoelastic behavior as measured by the frequency sweep experiment, and them exhibited favorable thixotropic recovery at alternating high and low shear rates. Temperature sweep tests indicated that oil foams underwent a sol-gel transition when heating and cooling, and transition temperatures were increasing in turn. Furthermore, the evolution of microstructure of oleofoams provided a more intuitive understanding of the foaming process. It was clarified that partial coalescence was happened with further whipping when passed the endpoint. In addition, partial coalescence would cause a merger between air bubbles and led to the decrease of the foam overrun. This study gave more information on the application of the edible oleofoams.