| Total proteose-peptone (TPP) fractions were extracted from skimmed milk (UHT) and whey protein concentrate (WPC) on a laboratory scale. Protein solutions (0.1, 0.5 and 1 % w/w) were characterized as function of pH: 4.0, 4.6-4.7 (native pH) and 7.0. Their foaming capacities and stabilities were studied. Beforehand, the surface properties that govern them were investigated, notably the kinetics of adsorption and mechanical properties of monolayer films at the air-water interface involved in the formation and the stability of foams respectively. The TPP extracted from skimmed milk showed the lowest values as well as a significant reduction in surface tension and presented a good mechanically resistant film. The TPP extracted from WPC presented a better foaming capacity and stability which was unexpected. However, foaming properties and surface properties of TPP fractions depended on the pH. The considerable influence of extraction source and method on proteose-peptone's properties were highlighted. |
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