A gluten-soy protein isolate combination has significant potential as a carbohydrate replacer in cookies aimed at the low-carbohydrate diet sector, say researchers.
Researchers at the USDA's Cereal Products and Food Science Research Unit said the approach showed the "definite potential for increasing the nutritional quality of cookies while reducing the carbohydrates."
The researchers state that, while the concept of using composite flours is not new, previous attempts have produced a mixed bag of results, with some resulting cookies being harder, while others were reported to be crumbly.
"The objective of this study was to determine the effect of wheat gluten and soy protein blends with added water on sugar snap cookie quality. The earlier studies on the subject did not compensate for the need of additional water by the proteins," they stated.
Writing in the journal LWT Food Science and Technology, the researchers report the results of their studies using protein blends of vital gluten (MGP Ingredients of Illinois) and soy protein isolates (soy nuggets, NRG Foods), formulated at different ratios (70:30, 50:50, and 30:70, respectively). Replacement of flour varied from 10 to 30 per cent.
"The increase in protein content indicated a corresponding decrease in the carbohydrate content of the cookies with increasing replacement of flour," they said.
For the 70:30 and 50:50 blends used, the researchers report that 20 per cent flour replacement resulted in cookie texture approximately the same as cookies made with no flour replacement. For the 30:70 blend, a flour replacement of 25 per cent appeared the most promising.
Changes to the colour of the cookies was also observed, with the higher SPI blends found to be darker than the lower SPI blends, all of which were darker than the control cookies.
"Low-carbohydrate cookies can be made by partially replacing the flour with gluten and SPI protein blends without adversely affecting the texture and the keeping quality," said the researchers.
Despite a drop-off in consumer attention towards low-carbohydrate-type diets, the researchers said that this was still a significant market and that market potential was apparent.
"Weight loss by means of restricting carbohydrates in the diet is one of the strategies adopted by many individuals. Grain-based products are traditionally higher in carbohydrates, so they are not consumed or are consumed in smaller quantities by those on such types of diets," said the researchers. "There is a need to produce low-carbohydrate cookies for this sector of consumers."
The presence of soy could also bring additional health benefits, in additional to the low-carbohydrate load, with the health benefits of soy well established. Studies have linked the nutrient to cancer prevention and the lowering of bad' LDL cholesterol.
And according to research from the US National Cancer Institute, high consumption of soy-based foods during childhood could reduce the risk of developing breast cancer later in life by 58 per cent.
Source: LWT Food Science and Technology Volume 40, Issue 2, Pages 353-360 "Influence of glutensoy protein blends on the quality of reduced carbohydrates cookies"
Authors: M. Singh and A. Mohamed