End of Project ReportThe main objective of this project was to produce dried, denatured, whey
protein-based powders, which on reconstitution in food formulations show an increased
ability to bind water in the presence of added salts, especially in the ambient temperature
range. To achieve this, a number of secondary objectives were set to observe the behaviour
of the whey protein system. These included the effects of salt on increases in viscosity
during the heating process, the requirement for pH adjustment during processing and the
ability of the pre-treated whey protein to interact with fat.
The main conclusions were as follows:
* It was shown that, compared to a commercial 75% whey protein concentrate, a preheated
whey protein ingredient (cold-setting whey protein) improved the consistency of
surimi and a cold-set dessert system.
* For cold-setting applications, the whey proteins need to withstand heating without gel
formation. For example, as the protein concentration was increased, the salt
concentration had to be decreased and pH increased to prevent the initiation of gelling
during processing. When the salt concentration was increased, a lower heat treatment
was needed to prevent viscosity increase. However, lower heat treatment resulted in a
lower degree of protein unfolding and weaker cold-set gels. This example implies that
only certain whey sources are suitable starting materials for cold-set applications.
* Model oil-in-water emulsions were studied using whey proteins pre-treated at different
homogenisation and heating conditions to evaluate the potential of cold-setting whey
proteins in yoghurt, mayonnaise and sauces. It was found that with these pretreatments,
emulsion viscosity increases were observed at very low whey protein
concentration (< 1%), when salt was added after emulsion formation, indicating that
cold-set whey proteins are much more effective gelling agents than normal whey protein
ingredients. For this reason, they have potential in acidified dairy products such as
yoghurt.
* Pre-heated whey protein dispersions are also capable of binding and stabilising calcium
phosphate. This property can be exploited in the stabilisation of calcium-fortified milkbased
beverages. * The commercial production of cold-setting whey protein ingredients will depend on the
ability to retain whey protein solubility during processing. A number of mechanisms
exist to achieve this but, in all cases, very exact control of the process is required.
* Because low salt levels prevent the aggregation and gelling of denatured whey proteins,
whey protein isolate is an ideal starting material for the production of these ingredients,
but due to the high cost, de-mineralised whey was chosen instead as the starting
material. Careful consideration has also to be given to the processing equipment and
the economics involved.
* The development of whey protein ingredients especially for cold-set end uses is a
product specific exercise. General guidelines were developed in the current work, but
further work with industry partners will be necessary before commercial success is
achieved.Department of Agriculture, Food and the Marin
