الفهرس 
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Abstract
The study was carried out by using four samples of sweet potato roots (Mabrouka, Minufiya 6, Assiut 201 and Assiut 202). The chemical composition of raw sweet potato roots indicate that raw roots had high content of moisture as well as total carbohydrate ranged from (58.54 – 73.46 %) and (87.34 – 91.79 %), respectively. The content total sugars ranged from (11.66 – 20.81%), protein (4.10 – 4.77%), ash (3.04 – 3.93%), ascorbic acid (20.65 – 44.79 mg/100g.) and trypsin inhibitor activity (3.67- 4.44 unit/g).The effect of different cooking method (boiling, steaming, baking and microwave) on the chemical composition of raw roots were differed on its effect, the moisture contents were decreased by baking for all roots and it were increased by others cooking methods, starch contents were decreased after cooking due to the action of amylase enzymes, ascorbic acid contents were decreased ranged from 14.72 – 78.37 %, the activity of trypsin inhibitors were decreased. In general, minerals contents were decreased after cooking process the degree of decreasing were differed as the differences between samples and cooking methods. Sweet potato roots were could be used to produce nutritional products to maximize its highest nutritional value such as, starch and flour The physical properties of sweet potato starch were determined, sweet potato starch granules had many shape (polygonal, spherical and oval) with central hilum, the size of granules were differed by different of samples, the diameter of granules ranged from 3 – 40 µm. sweet potato starch granules had highest degree of (L) and lowest degree of (a and b) compare with raw roots and flour, pH values ranged from 4.95 and 6.59, gelatinization temperature ranged from 62 – 83 ˚C. and had highest degree of consistency, synersis, viscosity, swelling power and solubility. The chemical composition of sweet potato flour was related to it for raw roots, it had high content of carbohydrates and low content of protein and lipid, however, the content of carotenoids, ascorbic acid and trypsin inhibitor activity were lower than raw roots. Rheological properties of wheat flour were affected by adding sweet potato flour at level (5, 10 and 15%). Sweet potato flour could be benefit in balady bread making and biscuit manufacture. Sensory evaluation of balady bread made from wheat flour and level of sweet potato flour at level (5, 10 and 15%) indicted that no significant differences between control samples and all others samples, except clone Assiut 202 at level 10, 15%. Sensory evaluation of biscuit made from wheat flour and level of sweet potato flour at level (10, 20 and 30%) were satisfied.