Joan M. King, Christopher Ringuette and Gabriella Paz
Food products with higher fiber — equal or greater than 20% of the daily value — and high protein are in demand by consumers in the United States, with 63% of consumers trying to add fiber and 60% of consumers trying to add protein to their diets. The U.S. Department of Agriculture recommends a daily fiber intake of 25 to 34 grams. The recommended diet for consumers ages 65 and older consists of foods with high fiber, high protein and low glycemic loads to increase health and minimize digestion problems and diabetes, as well as to achieve the recommended daily intake.
LSU AgCenter researchers undertook a study to determine which grocery store foods had high levels of dietary fiber and a low glycemic index, which is the number that estimates how much a food will raise the blood glucose level, and then to make pasta with a lower glycemic index and higher fiber content.
A market survey of approximately 400 items in grocery stores in the greater Baton Rouge area showed that prepared meals with high levels of dietary fiber and low glycemic loads were rare. Most pasta items in grocery stores were found to have low or medium fiber contents and high glycemic levels. Therefore, a part of this research focused on developing a healthier ravioli by substituting bean flour — a good source of dietary fiber and protein — for a portion of the wheat flour. Raviolis with 50% and 75% navy bean flour added had a 14% to 21% daily value increase in dietary fiber and a 7 to 10 gram decrease in glycemic load. The color, texture, aroma, appearance and liking preferences by consumers were not significantly changed by substituting navy bean flour by 50%. Therefore, an acceptable higher fiber, lower glycemic index bean-wheat flour ravioli was produced.
Many people, and not just those with celiac disease, are now seeking gluten-free products because they are perceived as being healthier. This has resulted in increased use of rice and other alternatives to wheat in food products. Gluten-free products, however, are typically low in protein. Although rice is not a good source of protein, there are varieties being produced that have higher protein content than traditional rice. A high-protein rice line developed at the LSU AgCenter H. Rouse Caffey Rice Research Station has around 10.6% protein. Using a high-protein rice is one way to increase protein without extra fortification or processing. The focus of another AgCenter study was to identify which grocery products used rice flour as an ingredient and to develop a gluten-free, higher-protein rice flour muffin.
A market survey of products made with rice flour indicated that snacks were the main category at 36%, while breads were at 13%. Baked snacks had the lowest protein content at 1.3 grams per serving. Muffins were chosen as the focus for developing a higher-protein, rice-flour-based product. Muffins made with high-protein brown rice flour and high-protein white rice flour were compared to muffins made with commercial brown rice flour. The high-protein brown rice flour muffins contained about 5 grams of protein, and the high-protein white rice flour muffins had 4 grams of protein.
In sensory acceptability studies, the color of the high-protein white rice flour muffins was favored over the other samples. Other attributes were not statistically different among the three treatments; the high-protein rice flour muffins were judged to be just as good as muffins made with commercial flours. Although not statistically different, acceptability ratings of the high-protein rice muffins tended to be greater than those for the commercial brown rice muffins. Muffin crumbliness, moistness and softness for each sample were found to be just about right for most panelists, with the high-protein rice flour muffins having greater frequencies of appropriate levels than the commercial control. Commercial brown rice muffins were least acceptable across the board.
Purchase intent was greater for both high-protein rice flour muffins than for commercial brown rice muffins. After a message was displayed stating the products were gluten-free and that the high-protein rice flour muffins were made with a rice flour naturally higher in protein, purchase intent increased by 9% and 12% for the high-protein rice muffins and by only 5% for the commercial brown rice muffins. Therefore, the addition of higher-protein rice flour resulted in an even larger increase in purchase intent beyond the gluten-free message alone.
Any food or ingredient company could use this information to market their products if claims made are related to increased protein and nongluten-containing ingredients. These results show that replacing commercial rice flour with higher-protein rice flour has a positive effect on consumer acceptance of gluten-free muffins.
Joan M. King is a professor, and Christopher Ringuette and Gabriella Paz are master’s degree graduates in the School of Nutrition and Food Sciences.
(This article appears in the fall 2019 issue of Louisiana Agriculture.)
Christopher Ringuette, former master’s student in the School of Nutrition and Food Sciences, prepares a fettucine with wheat flour as a control. Photo by Westin Cobb