Polyols choice critical for nutritional bar acceptability
Other polyols, particularly propylene glycol, should not be used, as these lead to a hardening of intermediate-moisture foods like nutrition bars. These are food products with moderate moisture content that are shelf-stable without requiring refrigeration, according to findings published in the Journal of Agricultural and Food Chemistry.
The study, a collaboration between scientists from Jiangnan University in China and the University of Minnesota in the US, provides important insights for formulators of these foods.
“Among the polyols that were studied in the present research, glycerol is the most effective one in lowering water activity and providing the softest texture in model systems, followed by sorbitol and maltitol,” wrote the researchers, led by Ted Labuza.
“A good combination of these polyols will help to stabilize whey proteins and maintain a desired soft texture of IMF through decreased protein aggregation.”
Study details
Labuza and his co-workers formulated a range of intermediate-moisture foods, containing between 10 and 40 per cent moisture, containing whey proteins, and using four polyols, glycerol, propylene glycol, maltitol, and sorbitol.
The most effective additive for lowering water-activity, a measure of the hardening of the bar, was glycerol. This polyol maintained the soft texture of the formulation, said the researchers, followed by sorbitol and maltitol.
These three polyols were found to stabilize the native structure of the whey proteins, and slow the hardening of the food.
On the other hand, addition of propylene glycol had detrimental effects on product acceptability, with the polyol producing changes in the protein structure and stability. This resulted in aggregation of the proteins and a hardening of the bar texture.
Source: Journal of Agricultural and Food Chemistry Published online ahead of print, ASAP Article, doi: 10.1021/jf802789y “Effects of Polyols on the Stability of Whey Proteins in Intermediate-Moisture Food Model Systems” Authors: X. Liu, P. Zhou, A. Tran, T.P. Labuza
