Analysis of microstructure and texture of gluten- and lactose-free cereal bars, produced with different hydrocolloids and drying temperatures and no-added sugar

Abstract

A gluten- and lactose-free cereal bar with no-added sugar, suitable for lactose intolerants and for celiac people was developed. The cereal bar was formulated with extruded rice, oat flakes, flaxseeds, sesame, sunflower lecithin, hydrocolloids, maltodextrin, mannitol, maltitol syrup, and sodium chloride. The effect of three different hydrocolloids (locust bean gum, pectin, and carboxymethyl cellulose), and processing temperature on microstructure, moisture content, Aw, texture, and sensory properties of cereal bars was assessed by an L9 orthogonal experimental design based on Taguchi methods. Results indicated that Aw and moisture content were not affected by the type or levels of the hydrocolloids studied, but decreased with the increase in drying temperature. Hardness and fracturability values increased with temperature increase. From the Scanning Electron Microscopy analysis, it was concluded that increasing processing temperature provides a more uniform microstructure of cereal bars. The application of the Taguchi method, allowed identifying the temperature as being the factor of greater influence on the characteristics of the cereal bars. In addition, according to this method, the optimum formulation is 0.05% locust bean gum and 0.1% pectin with 70°C as the optimum processing temperature.