Sodium caseinate or soy protein isolate and Gellan gum composite emulgels induced by acidification: Textural characterization

Abstract

The textural characterization via compression, penetration, and extrusion of acid-induced emulgels was determined. Emulsions of sodium caseinate or soy protein isolate mixed with gellan gum in different proportions were acid-gelled with glucono-lactone. In the formulated emulgels, when the proportion of protein was higher, the samples were less cohesive or easy to compress (0.53 N and 9.26 for 100 and 0 sodium caseinate protein proportion, respectively), softer or easy to penetrate (5.13 N and 14.96 for 100 and 0 sodium caseinate protein proportion, respectively), and more extrudable (5.26 N and 36.20 for 100 and 0 sodium caseinate protein proportion, respectively). This was because the final pH of the emulgel was below both proteins’ isoelectric point. As the gellan gum proportion increased, the emulgel became stiffer, since the negatively charged carboxyl groups of gellan gum were dissociated, retaining more water in the continuous phase of the emulgel. Since the oil phase was constant, the texture of acid-induced emulgel can be manipulated according to the protein/gellan gum ratio, depending on the application to replace saturated fat, focused on fermented dairy products as yogurt.