الفهرس 
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Abstract
”The purpose of this study was to evaluate the effect of partial replacement of yellow corn flour with 10, 20 and 30% of sweet lupine, sweet potato, carob and tiger nut powders on dough rheological properties and chemical, sensory and physical properties of sudied gluten-free bakery products (cupcakes, biscuits) compared to control samples (made from yellow corn flour). The obtained results could be summerized as follows: 1. Chemical composition of raw materials : •Yellow corn flour, sweet lupine, sweet potato, carob, and tiger nut powders were used in preparation of gluten free cupcakes and biscuits. The moisture, crude protein, lipids, ash, crude fibers and available carbohydrates contents were determined on dry weight basis being 11.92, 8.47, 1.96, 1.43, 1.87 and 86.27% respectively, in yellow corn flour, 8.71, 34.01, 9.35, 3.69, 6.42 and 46.53% respectively, in sweet lupine powder, 5.86, 2.27, 0.90, 2.94, 3.26 and 90.63% respectively, in sweet potato powder, 11.17, 6.16, 2.87, 3.20, 7.38 and 80.39% respectively, in carob powder and 6.06, 5.78, 26.43, 2.36, 6.24 and 59.19% respectively, in tiger nut powder. 2. Minerals content of raw materials : • Carob powder proved to be of the highest in potassium (850.46 mg/100g), calcium (210.86 mg/100g), Magnesium (240.03 mg/100g), iron (8.90 mg/100g) and zinc (2.52 mg/100g) as compared to other studied flours. Low concentration of sodium was found in carob powder (58.21 mg/100g) while sweet potato powder scored the highest in sodium content (142.96 mg/100g) as compared to other studied flours. • Also, other elements such as phosphorus (412.37 mg/100g) and manganese (5.00 mg/100g) recorded high content in sweet lupine powder compared with their content in other studied flours. 3. Total, soluble and insoluble dietary fibers of raw materials: • Carob powder recorded the highest dietary fibers content (52.17 and 45.62 g/100g dry weigh basis) for total and insoluble dietary fibers followed by, tiger nut powder (43.28 and 34.53 g/100g), sweet lupine powder (35.46 and 30.55 g/100g) and sweet potato powder (24.63 and 17.29 g/100g), respectively.• The highest soluble dietary fibers content was found in tiger nut powder (8.75 g/100g dry weigh basis) followed by sweet potato powder (7.34 g/100g), carob powder (6.55 g/100g) and sweet lupine powder (4.91 g/100g), respectively while, yellow corn flour recorded the lowest dietary fibers content (14.78, 12.36 and 2.42 g/100g) for total, insoluble and soluble dietary fibers, respectively. 4. Beta-carotene content of raw materials : • Sweet potato powder recorded highest beta-carotene content being (428.34 μg/100g dry weigh basis) followed by, sweet lupine powder (280.25 μg/100g), yellow corn flour (227.96 μg/100g), carob powder (140.61 μg/100g) and tiger nut powder (105.29 μg/100g), respectively. 5. Rheological Properties of studied blends dough: • Data for protein characteristics indicate that the water absorption, dough development time and dough stability of yellow corn flour was gradually increased as the level of substitution with sweet lupine, sweet potato, carob and tiger powders increased in compare to control sample (yellow corn flour). This increase in water absorption is due to the high content of fibers, protein or and starch. On the other hand, dough weakening value decreased as the substitution level increased in all blends which associated to quality of the protein-starch network.• According to starch properties, it could be seen that blends of sweet potato powder and yellow corn flour had the highest values of starch gelatinization, amylase activity and gelling ability compared to the blends which contained sweet lupine, carob and tiger nut powders. This increase in starch gelatinization owing to the high content of starch and the low protein and fat content. Also, it could be seen the blends of sweet potato powder and yellow corn flour had the highest values of starch retrogradation in compare to other studied blends which is related to starch composition and the presence of non-starch components. 6. Chemical composition of gluten-free cupcakes and biscuits: • Obtained results indicated that, the partial replacement of yellow corn flour with 10, 20 and 30% sweet lupine powder showed gradually increase in moisture, crude protein, lipids, ash and crude fibers contents and gradually decrease in available carbohydrates contents of gluten free cupcakes and biscuits samples as the level of replacement increased in compare to control sample (100% yellow corn flour).• Also, the partial replacement of yellow corn flour with 10, 20 and 30% sweet potato powder showed gradually increase in moisture, ash, crude fibers and available carbohydrates contents and gradually decrease in crude protein and lipids contents of gluten free cupcakes and biscuits samples as the level of replacement increased in compare to control sample (100% yellow corn flour).• It could be noticed that, the partial replacement of yellow corn flour with 10, 20 and 30% carob and tiger nut powder caused gradually increase in moisture, lipids, ash and crude fibers contents and gradually decrease in crude protein and available carbohydrates contents of gluten free cupcakes and biscuits samples as the level of replacement increased in compare to control sample (100% yellow corn flour). 7. Minerals content of gluten-free cupcakes and biscuits samples: •Obtained results indicated that, the partial replacement of yellow corn flour with 10, 20 and 30% sweet lupine powder showed gradually increase in all investigated minerals contents of gluten free cupcakes and biscuits samples as the level of replacement increased in compare to control sample (100% yellow corn flour).• Also, the partial replacement of yellow corn flour with 10, 20 and 30% carob powder showed gradually increase in all investigated minerals contents of gluten free cupcakes and biscuits samples as the level of replacement increased except sodium in compare to control sample (100% yellow corn flour).• It could be noticed that, the partial replacement of yellow corn flour with 10, 20 and 30% sweet potato or tiger nut powder caused gradually increase in K, Ca, Mg and Na and gradually decrease in P and Mn contents of gluten free cupcakes and biscuits samples as the level of replacement increased in compare to control sample (100% yellow corn flour). 8. Total, soluble and insoluble dietary fibers of gluten free cupcakes and biscuits samples: • Replacement of yellow corn flour with 10, 20 and 30% of sweet lupine, sweet potato, carob and tiger nut powders caused gradually increase in both of total, soluble and insoluble dietary fibers contents of gluten free cupcakes and biscuits samples as the level of replacement increased in compare to control sample (100% yellow corn flour). 9. Beta-carotene content of gluten free cupcakes and biscuits : •Obtained results indicated that, the partial replacement of yellow corn flour with 10, 20 and 30% sweet lupine powder showed gradually increase in beta-carotene content of gluten free cupcakes and biscuits samples as the level of replacement increased in compare to control sample (100% yellow corn flour).•On the other hand, it could be noticed that, the partial replacement of yellow corn flour with 10, 20 and 30% carob or tiger nut powder caused gradually increase in beta-carotene content of gluten free cupcake and biscuits samples as the level of replacement increased in compare to control sample (100% yellow corn flour).10. Physical properties of gluten-free cupcakes and biscuits:•For gluten-free cupcakes samples, it was observed that there was a gradual increase in cupcakes weight and a gradual decrease in volume and specific volume by increasing substitution levels with sweet lupine, sweet potato, carob, and tiger nut powders compared to the control sample (100% yellow corn flour).•Regarding the alkaline water retention capacity, water retention capacity gradually decreased in gluten free cupcakes samples parallel to the increase in storage periods for all samples from zero time to 3 days. It was also observed that there was a gradual increase in gluten-free cupcakes freshness by increasing substitution levels with sweet potato, carob and tiger nut powders. • Concerning gluten-free biscuit samples, it was observed that there was a gradual increase in biscuits weight and a gradual decrease in volume and specific volume by increasing substitution levels with sweet lupine, sweet potato, carob, and tiger nut powders compared to the control sample (100% yellow corn flour).11. Sensory evaluation of Gluten-free cupcakes and biscuits :•For gluten-free cupcake samples no significant differences were recorded between the control sample (100% yellow corn flour) and all gluten-free cupcake samples in all parameters. The most acceptable formulations by the panelists were the ones with 20% sweet lupine, 30% sweet potato, 10% carob and 10% tiger nut powders in the mixtures showing better sensory characteristics (texture, moistness, adhesiveness, height, crumb color, sweetness and total acceptability).• Concerning gluten-free biscuits samples, no significant differences were recorded between the control sample (100% yellow corn flour) and all gluten-free biscuit samples in all parameters except in appearance and odor. The most acceptable formulations by the panelists were the ones with 20% sweet lupine, 10% sweet potato, 30% carob and 30% tiger nut powders in the mixtures, showing better sensory characteristics (appearance, color, thickness, crispiness, shrinkage, taste, odor and total acceptability).CONCLUSION from the present study, it can be concluded that• Prepared gluten free products showed a good fibers content which can reduce the nutritional imbalances in gluten free diet. • Sweet lupine, sweet potato, carob and tiger nut powders proved to have relatively higher contents of minerals (potassium, calcium, Magnesium and zinc) that can be used to combat the micronutrient insufficiency in gluten-free diet and other food programs. • Combining sweet lupine with cereals can be promote the protein quality of gluten-free products. •The possibility of utilizing sweet potato and sweet lupine as rich sources of beta carotene. Based on this study, sweet lupine, sweet potato, carob and tiger nut powders can be recommended as gluten-free sources to improve the nutritional and sensory properties of gluten-free products for people suffering from celiac disease.