Influence of the Addition of Ovalbumin and Emulsifier on the Physical Properties and Stability of Yacon (Smallanthus sonchifolius) Juice Foams Prepared for Foam Mat Drying Process

Yacon juice and concentrated yacon juice were added with an ovalbumin or emulsifier in order to form foams which were subjected to different whipping times according to a 2(2) factorial design. After formation of the foams, their density, overrun, physical stability, yield stress, and structural microscopy were assessed. The data analysis obtained by response surface methodology was able to identify that the concentration of the foaming agent together with the time of air incorporation led to reduced density, increased expansion and air volume fraction, and physical stability of the product. Foams formed with the addition of an ovalbumin showed higher yield stress values than those added with an emulsifier. During the resting period, the yield stress was reduced for both foaming agents. By analyzing the images of the foams, it was found that the greater the number of air bubbles present, the smaller their diameter, a behavior affected by the resting time. Foams formed with higher concentrations of foaming agent and longer whipping times showed the most desirable characteristics for the purpose of foam mat drying.