Dairy Powder Rehydration: Influence of Protein State, Incorporation Mode, and Agglomeration

Diagrams of the 2 incorporation modes for codrying (1) and dry mixing (2) powders. For each method, 2 types of powders were prepared: agglomerate (A) and nonagglomerate (NA) powder. The chemical properties of the concentrates were also reported. CD = codrying, DM = dry-mixing, NPC = native phosphocaseinate, TN = total nitrogen, TS = total solids, WPI = whey protein isolate.

Scanning electron micrographs of the powders (× 500, scale bar = 60μm). A = agglomerate native phosphocaseinate (NPC); B = agglomerate whey protein isolate (WPI); C = agglomerate codried NPC+WPI; D = nonagglomerate NPC; E = nonagglomerate WPI, F = nonagglomerate codried NPC+WPI.

Typical turbidity profile (solid curve) and particle size (dotted curve) are shown as a function of log time obtained during rehydration of 5% native phosphocaseinate (NPC) powder at 24° C for 80,000s. A = nonagglomerate NPC powder; B = agglomerate NPC powder; a = wetting time, b = swelling time, c = time to rehydrate the powder. NTU = nephelometry turbidity units.

Turbidity profile as a function of log time during rehydration of 5% whey protein isolate (WPI) powder at 24° C for 80,000s. A = nonagglomerate WPI powder; B = agglomerate WPI; a–c = phase that includes wetting time and time to rehydrate. NTU = nephelometry turbidity units.

Turbidity profiles as a function of log time during rehydration of 5% native phosphocaseinate + whey protein isolate (NPC+WPI) at 24° C for 80,000s. A = nonagglomerate codried powder; B = agglomerate codried powder; C = nonagglomerate dry mixed powder; D = agglomerate dry mixed powder; a = wetting time; b = swelling time; c = time to rehydrate the powder; NTU = nephelometry turbidity units.

Relation between the dispersibility (American Dairy Products Institute standard) and the time to rehydrate the powder obtained with our experimental setup. A = agglomerate; CD = codrying; DM = dry-mixing; NA = nonagglomerate; NPC = native phosphocaseinate; WPI = whey protein isolate.