**6. Effects on food processing and texture**

In addition to health, nutrition, and palatability effects, dietary fiber inclusion brings challenges to food processing and texture. As the health food segments expanded in retail stores, so has the number of fiber-added foods and supplements. Common examples of foods that are enriched with fiber include breakfast cereals, bakery goods, pet foods and treats. The two main processes used to manufacture these products are extrusion and baking. In the case of extrusion, fibrous ingredients impact product expansion negatively. Expansion occurs at the end of the die as material is exiting the extruder barrel. At this point there is a pressure difference (inside extruder barrel vs. ambient) which causes the superheated water droplets contained within the starchy matrix to vaporize. This pushes out on the starch matrix which quickly expands to form a foam-like structure. This attribute has been extensively

#### *Miscanthus Grass as a Nutritional Fiber Source for Monogastric Animals DOI: http://dx.doi.org/10.5772/intechopen.99951*

discussed in other publications [31, 86, 87]. During this expansion process there are three key effects fibers have on expansion in these products. First, more dietary fiber means less starch in the formula – starch is the component responsible for the formation of the continuous matrix that expands and creates the product structure. Second, fibrous ingredients may compete with starch for water and limit its [starch] hydration. Third, fibers can disrupt the continuous melt formation (in the case of insoluble fibers) or create weaker melts (when soluble fibers are present). Regardless of the type of fiber, expansion will be impaired as the bubbles formed will prematurely burst [88–90]. As confirmation of this phenomenon, the addition of Miscanthus grass (an insoluble fiber source) decreased radial expansion and increased longitudinal expansion compared to beet pulp (a more soluble fiber source). These differences in how the kibble expanded also impacted sectional expansion ratio index, which was higher for beet pulp diet compared with Miscanthus grass containing food. As the structure is altered due to differences in expansion, Miscanthus grass kibbles required more energy to compress compared to beet pulp kibbles; however, hardness was similar [4]. For the cat foods addition of Miscanthus grass had no effects on tested extrusion parameters or kibble traits [6] compared to cellulose and beet pulp. Conversely, dog foods with Miscanthus grass required less mechanical energy to process compared to beet pulp supplementation [4].

Various fiber sources have been used in human foods at different inclusion levels and for different purposes [91–93]; however, to our knowledge, Miscanthus grass has not been tested for human foods or supplements as of this date.
