Locust bean has seen massive price rises on the back of a bad crop and supply chain problems, with some figures putting the increase at about 70 per cent.
In order to offer industry with an alternative to this gelling agent, the researchers looked at the potential of using non-gelling tara gum (TG) galactomannan on the thermal gelation of beta-lactoglobulin, considered to be the primary gelling agent of whey.
"Adding a polysaccharide to a protein solution may bring important modifications of the gelation process," explained lead author Wancheng Sittikijyothin. "When these mixtures are heated, competition between phase separation and gelling can lead to many different gel microstructures depending on the interplay of the kinetics of the two processes, resulting in a wide range of properties.
"Such systems are therefore interesting in food formulation, offering the opportunity for the development of novel products."
The researchers prepared gels and used confocal scanning laser microscopy (CSLM) to study the microstructure. This revealed two-phase gels and that the state of aggregation of beta-lactoglobulin depended on both the pH of the mix and the tara gum concentration.
Tara gum, known in Europe as E417, is already used to boost the gelling activity of agar and carrageenan. The gum is the endosperm of the seeds of the tara tree (Cesalpinia spinosa lin).
The tara gum was found to affect the rate of gelation, the gel strength, with gels formed at lower pH (pH4.6) being stronger than the gels formed at neutral pH (pH 7.0).
"From our results, we can conclude that the addition of TG affected the heat-set gelation behaviour of beta-lactoglobulin solutions. However, no marked effects were seen, at both pHs, in the rheological properties of the pure and mixed protein final gels, though they had very different microstructures," concluded the researchers.
Locust bean gum, known as E410 in the EU, is a galactomannan extracted from the seed of the Carob tree. It has a chemical structure similar to guar gum.
Source: Food Hydrocolloids (Elsevier)
Volume 21, Issue 7, Pages 1046-1055
"Heat-induced gelation of beta-lactoglobulin at varying pH: Effect of tara gum on the rheological and structural properties of the gels"
Authors: W. Sittikijyothin, P. Sampaio and M.P. Goncalves