| Popis: |
Whey protein isolate (WPI) powders are used in many formulations to boost nutrients. To predict the pasting behavior of proteins, WPI was tested under varying temperatures, using the Rapid Visco Analyzer (RVA), under pasting temperatures from 65 to 75C, RVA speeds from 100 to 500 rpm and protein concentrations from 2.5 to 40%. The optimal pasting profiles for WPI were obtained at 75C, 300 rpm and 30% protein concentration. The concentrations of the other food proteins evaluated were calcium caseinate (CC) 20%, egg albumin (EA) 20%, soy protein isolate (SPI) 10% and extrusion-texturized whey protein isolates (tWPI) 30%. Multiple (12) RVA pasting runs of WPI resulted in a superimposed profile with peak paste value of 1.50 ± 0.3 Pa·s and a standard error of ± 0.43 Pa·s. The RVA pasting peaks (Pa·s) were: CC (6.2), EA (4.6), SPI (0.6) and tWPI (1.7). Protein concentration needed for RVA pasting profile ranged from 5 to 30%. Practical Applications The rate of change in protein viscosity with respect to temperature can be measured using the RVA. Understanding how the pasting viscoelastic behavior of food proteins change with heating can help predict the type of networks formed during food manufacturing. Rapid assays of protein pastes will help avoid flow problems that may result from protein coagulation during food processing. |
