Celiac disease is a kind of digestive disease which damages intestinal villi and leads to failure of nutritionals absorption such as iron, calcium, fat soluble vitamins, and in some cases causes low weight, diarrhea, anemia, fatigue, stomach bloat. On the other hand, it leads to thyroid disease, cancer, bone disorders, infertility, as well as nerve and psychiatric problems (Mezaize
et al., 2009). Patients suffering from celiac disease cannot bear the gluten protein that exists in wheat, barley, and rye, consequently they have problem in consumption of foods such as cake, bread, spaghetti, etc. (Mezaize
et al., 2009). Rice, with very low amounts of gluten, a little sodium, protein, fat, fiber, and high amounts of digestible carbohydrates, is one of the foods which can replace wheat in non-gluten products (Turabi
et al., 2008).
Gluten proteins, available in flour have an important role in biking quality. Gluten protein is composed of gliadin and glutinin, which has significant effect on physical properties of batter such as elasticity, consistency, the ability of gas maintaining, and etc. The elimination of this protein results a product with brittle texture, weak color, low volume, and porosity (Gallagher
et al., 2004). Hence, using gluten appropriate substitutes such as hydrocolloids (Lopez
et al., 2004) is essential in non-gluten products' baking industries. Hydrocolloids are hydrophilic biopolymers resulting from plants, animals, microbes, and/ or synthetic materials that generally include a large number of hydroxyl groups (Guarda
et al., 2004). Generally, hydrochlorides are applicable for improvement of quality and viscoelastic characteristics, increasing of moisture maintaining capacity, slowing down starch alteration process, and as fat substitutes in producing nutritional products (Elke and Dal Bello, 2008).
Gums (hydrocolloids) are compounds added to nutritional products because of their role in providing jelly and consolidation properties to products (Turabi
et al., 2008). Persian gum is a clear gum harvested from Arjan tree (peanuts) of Rosacease family that is also called Shirazi gum and Zedu. This polysaccharide gum is water soluble with high water absorption capacity besides industrial usages. Today, Persian gum is used as a emulsion with Tragacanth and Arabic gum in pharmaceutical industry (Khalesi. H
et al., 2012).
Tragacanth gum is a secretory gum that has an important role in nutritional, medicinal, textile, paper, and other industrial materials. Tragacanth is a complex polysaccharide with numerous heterogeneous branches which is naturally available in slightly acidic salt of calcium, magnesium, and potassium. Tragacanth gum includes two parts: Tragacanthic acid or basourin that is insoluble in water but can distend in water and form jelly, and the other part is Tragacanth which is water soluble. Both units contain small amounts of proteins and metoxyl groups that the latter are more frequent in water soluble unit (Haj Mohammadi
et al., 2013).
Up to now, some studies have been conducted about use of gums, such as xanthan gum, guar gum, luckast seed gum, etc. and also use of hydrochlorides, such as sodium alginate, carginane, pectin, hydroxyl propyl methyl cellulose, etc. to prepare cakes from rice flour (Rodriguez-Garcia
et al., 2012, Sumnu
et al., 2010, Turabi
et al., 2008) and quinoa flour (Khalesi. H
et al., 2012). The results indicated improvement of cake quality. During conducted evaluations, the combination of Persian gum and Tragacanth was not used in any formulations of non-gluten cakes.
With regard to the fact that celiac patients are sensitive to gluten protein, this study tried to prepare non-gluten cakes based on rice and quinoa flour with using the combination of Persian gum and Tragacanth in its formulation. The effect of addition of different levels of these gums and their combinations on quantitative, qualitative, and sensory characteristics of products were also evaluated.
Materials and Methods
Rice flour (protein 9.3%, ash 0.9%, moisture 11.02%), quinoa flour, sugar, shortening, water, egg, salt, baking powder, Persian gum (protein 0.5%, ash 1.62%, moisture 9.4%, and carbohydrate 88.4%), as well as Tragacanth were purchased from food stores. After grinding Tragacanth laminas, Tragacanth and other powders were passed from the mesh-40 to separate big particles and impurities.
Batter preparation and cake production: The cake batter was prepared from rice flour, quinoa flour, sugar, oil, water, egg, baking powder, vanilla, and salt, all components were calculated according to the weight of rice and quinoa flour. The materials were mixed and prepared in 3 stages. At the first stage, sugar, egg, and vanilla were mixed and at the second stage the rest of liquid materials, such as water and oil were added. At the final stage, solid materials of formula including flour, gums (each gum and their combination in 3 levels of 0.5, 1 and 1.5%) were added and mixed. Mixing was performed for 3 minutes in each stage. After preparation and mixing of the materials, the batter was filled in molds, placed in microwave and baked for 20 minutes. After baking and chilling in environment temperature, the cakes were packed for evaluation of their qualitative and quantitative properties. Treatments used in this study are shown in T
able 1.