Whipping test for the determination of foaming capacity of protein: a collaborative study

Summary A standard whipping test, which involved preparing a 0.5% protein dispersion, whipping the dispersion in a Kenwood Chef food mixer and measuring the foaming properties (foam expansion, FE; foam volume stability, FVS; foam liquid stability, FLS) was collaboratively evaluated. A total of sixty determinations was made involving six laboratories, each of which analysed five samples in duplicate. The repeatability coefficient of variation (CV0) in the estimation of FE and FVS properties of proteins was 6.25%. The reproducibility coefficient of variation (CVX) for FE and FVS was 9.8%, excluding the FE value (i.e. 20%) for spray-dried albumen. The CV0 and CVX values for FLS properties of proteins ranged from 7.4 to 13.4% and 17.2 to 24.6%, respectively. Thus, FE, FVS and FLS properties can be used for intralaboratory comparisons (e.g. to determine batch-to-batch variation in commercial protein products), whereas FE and FVS values are more reliable for inter-laboratory comparisons of the foaming properties of proteins.