The Effect of Extrusion Technology on the Quality Characteristics of Gluten-free Cookies Based on Whole Chickpea Flour-xanthan Gum-broken Rice

IntroductionGastrointestinal diseases are very important among human societies, especially in developing countries. Celiac disease is one of these diseases, caused by the interference of gluten in food, the body's immune system, genetics and environmental factors. Therefore, it is necessary to provide a solution for the production of gluten-free products and also to improve their quality. The tremendous growth in the nutritional knowledge of the public has caused the development and production of healthy food products for certain groups. Baked products such as cookies are very popular among the society because of their textural characteristics as well as flavoring and attractive colors. Therefore, their enrichment is of interest. Most commercial gluten-free bakery products are based on pure starch or the combination of corn starch with gluten-free flour, which is associated with dryness and sandiness in the product. Materials and MethodsThe aim of this research was to investigate the functional characteristics of non-extruded and extruded chickpea flour samples and then the effect of adding different levels of it (0, 20 and 40%) on physicochemical, Lightness, porosity and sensory characteristics using completely randomized factorial design. The blend of chick pea flour- xanthan gum was extruded by a parallel twin-screw extruder (Jinan Saxin, China). Process was performed with die of 3 mm, and extrusion temperature of 140 ℃. The chemical composition of raw materials was measured by standard AOAC (2000) methods. The hardness of cookies was measured using Texture Analyzer (TA plus Ametek, UK). The cylinder steel probe (2 mm diameter) was set to move at a speed of 1 mm/s. Samples were punctured by the probe to a distance of 10 mm. The color values of L* (lightness), a*(redness), b*(yellowness) of the samples were determined by the Hunterlab instrument (Reston VA, US) (Rhee et al., 2004). Water absorption index in terms of grams of bonded water was calculated per gram of dry material in percent. Sensory evaluation was performed using a 5-point hedonic test. Results and DiscussionIn general, gluten-free products are unable to maintain carbon dioxide gas due to the lack of a coherent and uniform gluten network, which causes an increase in volume. As a result, the product is small in volume and the structure of the crumb is compressed. The extrusion baking process had a high potential to improve cookie quality. In such a way that the addition of extruded chickpea flour increased the porosity of the cookie samples. The results of the texture analysis show that the addition of extruded chickpeas up to a 40% improved the texture of the cookie and also increased its shelf life. Also, the sensory test results showed that the favorable effect of adding extruded chickpea flour up to 20%. Consequently, by summarizing the results of physical and sensory tests, it was determined that cookies with appropriate sensory and quality characteristics can be produced using 40% of extruded chickpea flour. Peas, and especially extruded peas, rich in protein and dietary fiber content and high water absorption ability, led to increase the moisture and reduced the hardness of the cookie texture. Considering the increase in demand for gluten-free products, it seems that enriching these products with nutrients such as chickpea flour can be an alternative method to improve the nutritional value of these products. Adding legumes is a good way to increase the consumption of legumes, which are rich in the amino acid lysine. Legumes, especially peas, have high nutritional value and functional characteristics, and including them in the diet by adding them to bakery products is a good way to increase their consumption. The use of chickpea flour as a nutrient source in cookie formulation increases the nutritional value, reduces the glycemic index and improves the variety of such products.