Skim milk powder (SMP) is normally used as ingredient for product formulation. For this purpose, SMP has to be dissolved in water for protein hydration, but ¿How to ensure that the hydration was done? The aim was to test several methods for SMP hydration. SMP was dispersed in water (40ºC) under agitation (250 rpm) during 30 min and resting for 30 min at room temperature. Then, four treatment conditions at 4ºC were tested i) store during 30 minutes; ii) store during 17 h; iii) agitation during 17 h at 150 rpm and iv) agitation during 24 h at 150 rpm.
Results by laser diffraction showed that only the treatment iv) was able to disperse all the micelle caseins (MC) which has a profile of size particle distribution (SPD) like natural milk, due to the 100% of MC were in the proper range (0.1-0.4 µm). On the other hand, treatments i), ii) and iii) leaded to an untypical profile of SPD with two picks. The first pick (FP) was in the range for MC. The second one showed a higher size (2-230 µm). Clearly, the second pick (SP) could be explained as an undesirable aggregation phenomenon. The results were: Treatment i) 23.50%v/v (FP) and 76.51%v/v (SP); Treatment ii) 37.98%v/v (FP) and 62.05%v/v (SP) and Treatment iii) 76.75%v/v (FP) and 23.29%v/v (SP).
Therefore, the treatment iv) ensure complete MC hydration and lead to a SPD equivalent to natural milk, which is the best ingredient for product formulation.
Acknowledgement: Initiation FONDECYT 11110402 Project.