When it comes to these texture attributes, whole wheat is just plain different. Additives such as dough conditioners and emulsifiers will adjust texture, but some formulators want improvers that add to the nutritional content of the tortilla as well.
A novel approach puts inulin to work providing soluble dietary fiber along with textural and taste benefits to whole wheat tortillas. Several manufacturers are now testing this application, and commercial products may be on the market soon, according to Connie Lin, PhD, applications manager, Sensus America, Inc., Lawrenceville, NJ. She and Sensus’ Fred Kaper collaborated with Paul Takhistov, PhD, associate professor, food engineering, in the Department of Food Science at Rutgers, the State University of New Jersey, New Brunswick, NJ. They evaluated inulin in whole wheat tortillas and presented their study at the AACC International’s 2012 annual meeting.
Extracted from chicory roots, inulin is a natural ingredient. It consists of a mixture of fructose-based polymers with different degrees of polymerization (DP). It can substitute for sugar and fat, thus lowering the glycemic index and calories. In addition, bread bakers have long used inulin for its humectant properties and its ability to mask the bitter flavor of bran in whole wheat products.
A soluble fiber, inulin acts as a prebiotic. Its fiber benefits are considerable. “Most whole grain tortilla products already contain 1 to 2 g of dietary fiber per 50-g serving size from whole grain flour,” Dr. Lin said. “Therefore, the actual use level of inulin to make ‘good source’ or ‘excellent source’ fiber claims in the whole grain tortilla can be less than the 6% or 10% [normally required to make such statements].”
To test their idea about inulin’s ability to improve whole wheat tortillas, the researchers used Sensus America’s Frutafit HD inulin powder and Frutalose L90 inulin syrup, the former with an average medium DP of 10 and the latter a low DP of 5. They made heat-pressed tortillas with varying proportions of ConAgra Mill’s Ultragrain whole white wheat flour and regular white flour. Ratios for whole wheat mixed with regular flours were 100:0, 80:20, 60:40, 40:60, 20:80 and 0:100. They added inulin at rates of 0 to 6% (formula weight basis).
Tests showed improvements in rheological behavior using both forms of inulin. Its addition helped reduce firmness and boosted extensibility of finished tortillas across all the flour blends. The DP 5 form was more effective in keeping tortillas softer over time, while the DP 10 form significantly improved extensibility.
“Inulin modifies viscoelastic characteristics of tortilla dough, resulting in more pliable dough and softer finished tortillas for better shelf stability,” Dr. Lin explained. “Neither Frutafit HD or Frutalose L90 brought any noticeable flavor or taste changes.” Although the tortillas in the study were handmade, she said industrial-scale preparation should not exhibit diameter changes.
How does inulin work in this application? Because it more strongly absorbs water than do starch granules, inulin forms gels between the granules, enhancing the water retention capability of the dough. The inulin gels also serve as lubricants between granules, which significantly improves the dough’s viscoelasticity, making finished products more pliable and softer.
Bound water in an inulin-containing dough is well distributed, and less free water exists on the surface. The result is greater hydrophobicity with a lower surface energy. In these experiments, surface energy decreased as more inulin was added to a high of 6%. “Inulin helps reduce surface energy of the dough, meaning inulin-containing dough sticks less to the surface of tortilla manufacturing machinery,” Dr. Lin observed.
There’s also the matter of replacing the calories of sweeteners at 4 Cal per g with inulin’s much lower level. Both the powder and syrup contribute just 1.5 Cal per g. European processors must follow the EC directive that sets the caloric value of inulin at 2 Cal per g.
In the US, the Food and Drug Administration accepted Sensus’ filing of inulin as Generally Recognized as Safe. The Sensus inulin ingredients are kosher, halal and ISO 22000 certified. On packaging ingredient statements, they are labeled as “inulin” or “chicory root fiber.” In January, Canada recognized Frutalose chicory root fiber (inulin) as a dietary fiber, complementing the approval of Frutafit inulin in 2006.