Despite significant innovation in sports drink formulation, beverages that contain whey protein often have poor clarity or the presence of a white precipitate that consumers perceive as undesirable, according to a new study in the Journal of Food Science.
New findings indicate that adding sugar alcohols such as erythritol, sorbitol, and xylitol may reduce this undesirable turbidity. In addition, maintaining the pH of the solution below pH 3.6 also improved the clarity of the beverages.
“[Our work] presents the effect of common ingredients on beverage clarity and provides approaches to increase clarity of thermally processed beverages that contain whey protein,” wrote Caitlin LaClair and Mark Etzel from the Department of Food Science at the University of Wisconsin.
“These beverages may serve as the next generation of sports beverages that improve athletic performance and aid in healthy weight management,” they added.
The sports drinks segment has reported annual retails sales of $7bn (€5.4bn), and is clearly no longer a niche consumer area. As such this has opened up the market to a much wider scope for product innovation. Consumer analyst Zenith International said last year that the shift towards mainstream acceptance may have diluted some brands’ image among athletes as a specialised nutrition source.
The analyst claimed that in no longer being the sole domain of athletes, the sport drink shows signs of becoming polarised between products catering for the everyday consumer and those for light and heavy exercisers.
“Most sport beverages contain no protein and are clear or slightly cloudy,” explained the researchers. “For consumers to accept sports beverages that contain whey protein, these beverages should not have high turbidity.”
In an attempt to improve the clarity, and therefore consumer acceptance of heat-treated whey-based sports beverages, LaClair and Etzel tested three approaches: Centrifugation to remove protein aggregates; the effect of different ingredients; and the effects of pH.
Results showed that all samples were clear both before and after heating for all the ingredients used when the acidity of the beverage was maintained at pH 3.6 and below. Above this, however, and ingredient selection became crucial with sorbitol, erythritol and the amino acids, asparagine, proline, and glutamine, all boosting drink clarity. Above pH 4.0 and the ingredients were associated with increases in the turbidity of the beverages.
In terms of sugar alcohols at pH 4.0, when erythritol, sorbitol, and xylitol were used at a higher concentration of 50 millimoles, the clarity of the beverages was improved.
“Understanding these results at the molecular level will assist food scientists in selecting processing treatments, ingredients, and pH in the development of shelf-stable clear beverages that contain whey protein,” concluded the researchers.
Source: Journal of Food Science
January/February 2010, Volume 75, Issue 1, Pages C21-C27, doi: 10.1111/j.1750-3841.2009.01400.x
“Ingredients and pH are Key to Clear Beverages that Contain Whey Protein”
Authors: C.E. LaClair, M.R. Etzel