Physical properties of egg albumen and cassava starch composite network formed by a salt-induced gelation method

Effect of cassava starch (CS) filler on the physical properties of egg albumen (EA) and cassava starch composite (EA-CS) gels and films was investigated using EA as the continuous matrix embedded with CS granules. The composite network was formed at 55 °C; below the thermal gelation temperature of both EA and CS, using the salt-induced gelation method. Increasing the pH from 8 to 11 and NaCl from 50 to 200 mM resulted in a softer but more cohesive EA gel (p ⩽ 0.05). Raising CS content increased Young's modulus, stress and opacity but reduced the cohesiveness of the mixed gel network (p ⩽ 0.05). The release of paprika oleoresin (O/R) from the dried EA-CS composite film into the oil phase was determined as the effective diffusion coefficient (Deff) based on Fick's second law of diffusion. Deff of O/R decreased with increases in the strength and elasticity of the composite film and relative humidity (RH) during film aging. Overall, the study showed that the salt-induced gelation method could be used to form an EA-CS composite film at room temperature. In addition to the strength and elasticity of the protein network, RH during aging could also provide a mean to regulate the controlled-release properties of such a composite film.