Short communication: Determination of the whey protein index in milk protein concentrates

摘要

Milk protein concentrates are common ingredientsin the dairy industry, with varying processing historiesand composition. The objective of this research was todetermine the feasibility of using the whey protein nitrogen(WPN) index, a well-established index for skimmilk powder and nonfat dry milk, as a quality parameterfor milk protein concentrates. The WPN index isa value based on the moisture-adjusted weight of skimmilk powder. We hypothesized that WPN, even whenstandardized based on protein, may change dependingon solubilization conditions of milk protein concentratesbecause of differences in solubilization conditionsor processing history. The WPN was measured formodel concentrates with different thermal history orreconstitution conditions. The WPN was not affectedby an increased concentration of soluble casein in thedispersions nor after solubilization of the powder at 22or 60°C. All reconstituted samples were standardizedfor protein. The WPN was also in full accordance withresidual native protein measured by chromatography.