15C-13 |
Particle size effects on the physical and rheological properties of derivitize whey protein concentrate powders |
J. J. RESCH, Department of Food Science, North Carolina State University, Raleigh, NC 27695-7624 and C. R. Daubert. A process has been established to modify whey protein concentrate into an ingredient offering thickening functionality similar to starches and hydrocolloids over a wide variety of conditions. This derivitization process yields a powder with a range of particle sizes that affect the performance of the powder upon reconstitution. Therefore, the role of particle size on the functionality of the powder must be evaluated in order to optimize the derivitization procedure. The objective of this study was to investigate the effect of particle size on the ability of derivitized whey protein concentrate to thicken and stabilize food systems. WPC powders were modified by hydration in deionized water, acid hydrolysis with HCl, thermal treatment at 80 °C, drying, and grinding. The derivitized powder was separated into four fractions of different particle sizes using a series of fine mesh sieves. Each fraction was independently evaluated and compared with the non-sieved powder. The powder dispersibility, intrinsic viscosity, and water holding capacity as well as small strain and steady shear behavior were evaluated as a function of particle size. The derivitization process yielded a distribution of particle sizes, with an average size of 25 µm. Particle size was found to be inversely proportional to powder dispersibility and water holding capacity. Reduction in particle size also increased the steady shear and complex viscosity of the reconstituted powder. The powder exhibited greater intrinsic viscosity as the particle size increased. A derivitized WPC powder of optimal particle size can be produced that will maximize thickening and stabilizing functionality over a wide range of applications.
Session 15C, Dairy Foods
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