Flavor and mouth-feel of soy-protein drinks should not present a barrier to consumer preferences, claim researchers, assessing the acceptability of soy drinks compared to those made with whey protein.
With growing recognition of the health benefits of soy protein, seen in new heart health claims in the UK and the US, manufacturers will be keen to incorporate the ingredient into foods. But soy has traditionally been associated with a strong, unpleasant taste.
Resarchers from Penn State University recruited 30 male student athletes to test two chocolate-flavoured nutrition drinks - nutritionally identical, except that one was made with isolated whey protein and the other with isolated soy protein. The soy drink met requirements for the FDA heart healthy claim, containing 6.25g of soy protein and less than 3g of fat.
The students randomly received either the soy or whey-based drink twice daily for three weeks, and after a 10-day washout period, changed to the other drink. The researchers used tasting acceptance questionnaires to assess flavor, mouthfeel, sweetness, thickness and overall liking.
For each of the five acceptance measures, there was no significant difference between the two drinks, suggesting that soy drinks are just as popular as whey-based beverages. A further test on preferences found that most of the students preferred the soy drink (18 out of 28 responses), although the researchers found no significant link between the degree of preference and taste or acceptability.
"Flavor is the most important factor in developing the use of soy protein in foods. We believe that this study validates this point and you can develop a food that tastes good using soy protein isolate," writes Dr Peter Bordi, assistant professor of hospitality management at Pennsylvania State University.