Impact of proteins-κ-carrageenan interactions on foam properties

Foaming properties of kappa-carrageenan (kappa-C) + beta-lactoglobulin (beta-lg), native and denatured soy protein and the thermal stability of foams were investigated. Apparent viscosity measurements were used to obtain the gelation rate and maximum viscosity of foams. Gelling and melting temperatures of the solutions determined by dynamic rheology were related to the thermal stability of foams. Foam expansion of the mixed kappa-C + protein solutions followed the same order as the pure protein solutions (beta-lg > DSP > NSP). However, the presence Of kappa-C reduced foam expansion due to the higher viscosity of the systems. No liquid drainage or collapse was observed while apparent viscosity was measured. DSP induced a greater synergistic effect with K-C, reflected in a faster gelling rate and increased foam stability. The thermal stability of foams stored at temperatures between 5degreesC and 45degreesC showed significant differences when they were pre-gelled at 5degreesC. A large increase in foam stability was observed at 25degreesC, which is above the average T-gel and below the melting temperatures of the systems. The kinetic analysis of the process revealed that different mechanisms were involved in the drainage of pre-gelled or non-gelled foams. (C) 2004 Swiss Society of Food Science and Technology. Published by Elsevier Ltd. All rights reserved.