"This could be of substantial practical value in industry, either by giving much stronger gels at the same concentration of protein, or by giving gels of the same strength at lower protein concentration, with consequent reduction in cost," wrote lead author Sinead Fitzsimons from University College Cork.
Whey proteins form gels naturally on heating and this allows them to be employed as the main structuring agent in food products such as gelled desserts.
The new study, published on-line in the Elsevier journal Food Hydrocolloids , suggests that even stronger gels could be formed by adding small amounts of guar gum, or that cost reduction can be achieved by using the guar gum and smaller amounts of whey protein.
Galactomannans, like guar gum, are commercially important for the food industry and are extensively used as stabilizers, thickeners, emulsifiers and gelling agents.
The researchers looked at the effect of adding guar gum (Sigma) in concentrations ranging from 0 to 0.5 per cent to a whey protein isolate (WPI, Bipro, Davisco Foods).
The guar gum was dissolved in a salt solution at 85 degrees Celsius, cooled to 45 degrees and then added to a WPI salt solution.
Fitzsimons and her co-workers report that whey protein gel prepared with no guar gum was to too weak to form a self-supporting gel, while addition of even the smallest amount of guar gum (0.01 per cent) increased gel strength.
Measures of the elastic strengths of the gels (defined as the storage modulus) showed that the strength of the gels increased on increasing values of guar gum addition from 0.01 to 0.1 per cent.
However, the strengths of the gels decreased when the guar gum addition exceeded 0.2 per cent, said the researchers.
"The results of this investigation demonstrate clearly that incorporation of very low concentrations of guar gum (about 0.1 per cent) can increase the strength of whey protein gels by more than an order of magnitude," said the researchers.
"However, since higher concentrations of guar gum cause a reduction in gel strength, and the optimum concentration appears to depend on the temperature to which the gels cooled and/or the time for which they are stored, careful selection of formulation and processing conditions would be required to obtain maximum benefit," they concluded.
The global whey protein concentrates and isolates market is estimated at 395,000 MT in 2004 representing a value of just over $1bn.
The US remains the biggest producer at 187,000 MT followed by Europe with 159,000.
Source: Food Hydrocolloids Published on-line ahead of print, doi: 10.1016/j.foodhyd.2007.01.013 "Large enhancements in thermogelation of whey protein isolate by incorporation of very low concentrations of guar gum"
Authors: S.M. Fitzsimons, D.M. Mulvihill, E.R. Morris