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. Practical applications Organizations responsible for public health throughout the world are increasingly concerned with the feeding of populations, and great efforts are made to promote the adoption of nutritious and balanced diet in order to decrease the occurrence of the chronic diseases constantly related to inadequate diets. Cereal bars were introduced over a decade ago as a “healthy” alternative confectionery, and became a convenience food, as they can be easily consumed, do not require any preparation and are a source of essential nutrients, such as vitamins, minerals, fibers, proteins, and complex carbohydrates. The effect of the combination of different levels (0%, 0.05%, and 0.1% wt/wt) of locust bean gum, pectin, and carboxymethyl cellulose, and three drying temperatures (20°C, 60°C and 70°C), on microstructure, sensory, and texture properties of the cereal bars was analyzed. Results obtained with this work showed that it is possible to produce a gluten- and lactose-free cereal bar with no-added sugar, suitable for lactose intolerants and for celiac people. This can be achieved by taking advantage of the synergy between two hydrocolloids in different concentrations to improve the hardness of the cereal bar. Also, with the help of an experimental design based on Taguchi method it was possible to find out the optimum formulation and processing temperature of the cereal bars. In this work, the results show that the temperature also has a great influence, with 70°C being the most suitable to promote greater hardness.