They study, published in LWT - Food Science and Technology, investigates the effect of whey protein addition on textural properties of yoghurt at different protein and fat contents, finding that “the use of whey proteins impart the possibility to replace parts of fat.”
The team of researchers, led by Alina Krzeminski from the institute of food science and biotechnology at the University of Hohenheim, Germany, reported that the firmness and viscosity of yoghurt samples increased with the addition of whey protein.
“It is evident that the addition of whey proteins reinforces firmness properties of low-fat yoghurts comparable to characteristics of full-fat yoghurt,” wrote Krzeminski and colleagues.
As consumer demand for healthy products grows, many food producers are being forced to develop new low-fat products without altering sensory and functional properties of products.
Hydrocolloids and stabilizers have been used to imitate the fat perception and enhance the stability of yoghurt, however the reduced fat levels still led to a loss in viscosity and structure, “resulting in an altered appearance, texture, and mouthfeel,” said the authors.
One alternative to fat replacement with hydrocolloids is the use of milk ingredients such as whey proteins. Krzeminski and colleagues noted that previous research has highlighted the potential application for the use whey proteins in cheese production.
Although several studies have been carried out on the textural effects of whey protein-enriched yoghurts, there is little knowledge about the characteristics of those yoghurt systems depending on protein and fat content, particularly for low-fat yoghurt products, said Krzeminski and co-workers.
The authors reported that the addition of whey protein increased the firmness (elastic modulus) and apparent viscosity of yoghurt samples. They noted that the increases were a result of increased inter particle interactions, “mainly caused by self-aggregation of whey proteins or aggregated whey protein-coated fat globules, respectively.”
Krzeminski and colleagues noted that as whey protein content raised, the particle size, viscosity, and network firmness also increased.
The research team concluded that that the use of whey proteins imparts the possibility to replace parts of fat in yoghurt.
Source: LWT - Food Science and Technology
Published online ahead of print, doi: 10.1016/j.lwt.2011.05.018
“Structural properties of stirred yoghurt as influenced by whey proteins”
Authors: A. Krzeminski, K. Großhable, J. Hinrichs