الفهرس 
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Abstract
The present study was conducted in order to shed some light on the properties of OM, as a new hydrocolloid agent, extracted from okra industrial waste. The use of OM instead of CMC in the preparation of gluten-free rice bread (GFRB) was studied. Further technological and nutritional improvements to this bread were also studied, by partially replacing RF with SPF. The current study sought to cover the following topics: a) Determining the chemical, physical, and functional properties of OM. b) Making GFRB by partially substituting of RF with SPF and replacing gluten with hydrocolloids such OM and CMC. c) Determination the chemical composition as well as functional characteristics of WF, RF, OSPF, and WSPF. d) Estimation of the chemical composition of the bread prepared from rice and sweet potato composite flour. e) Utilizing Mixolab apparatus to evaluate the rheological properties of the GF dough. f) Determining the bread physical characteristics. g) Conducting the TPA and determining the SR of the prepared bread. h) Evaluating the sensory properties of the prepared bread in order to test their acceptability for human consumption. The obtained results revealing that: 1. The chemical composition of OM , WF, RF, OSPF, and WSPF were 1.71, 12.10, 9.43, 3.05, and 1.68 % for moisture content, 3.37, 0.75, 0.57, 3.69, and 3.12% for ash content, 0.13, 1.28, 0.44, 2.02, and1.01% for EE content, 2.9, 10.49, 7.22, 4.65, and 3.05% for CP content, 4.47, 1.02, 0.78, 9.56, and 7.27% for CF content, 93.50, 87.48, 91.77, 89.63, and 92.86% for TC content, respectively. 2. The HPLC analysis indicated that the main monosaccharides of OM were galactose (9.63%), rhamnose (8.51%), glucose (7.47%), arabinose (5.32%), fructose (4.31%), and xylose (0.86%). Uronic acid (40.66 %), and other saccharides (23.24%) were also found.The yield of OM extracted from okra heads by cold water was 1.60 g/100. In addition, the solution (1.0 % w/v) pH of this gum was 6.69. Thus, the viscosity of this solution was 205.33 cp. This confirms that okra gum increases the viscosity of the solutions. 3. The WHC and OHC values of the studied materials were 301.46 and 235.75% for OM, 138.84 and 153.07% for WF, 165.12 and 149.14% for RF, 171.00 and 124.25% for OSPF, 163.58 and 109.05% for WSPF, respectively. 4. The S and SI of the extracted OM were 18.38%. Where, OM was soluble in warm water, slightly soluble in cold water, but insoluble in benzene, ethanol, and acetone. The SI of OM was 4.77 % which indicated that OM had excellent swelling properties. 5. Concerning EA and ES of OM, they were 61.92 % and 45.87 %, respectively. This result confirmed that OM can be used as ideal hydrocolloidal emulsifier agent. 6. The WA was raised by increasing the SPF ratio in blends, and was aligned between 52.2 % WF (T1) and 58.7% for RF partially substituted by OSPF at 30% (T7). Parallel to that, the torque C1 increased gradually by inserting SPF in the formula. 7. The WF sample exhibited the greatest value of DDT (5.38min) and had the most stable dough. Also, it recorded the highest value of amplitude (0.13 Nm). 8. The DDT parameter was gradually increased, while, the ST (min) and amplitude (Nm) of OSPF and/or WSPF-containing flours have decreased. 9. The sample of RF replaced by WSPF at 50% (T12), had the highest C3 value, followed by RF samples replaced by OSPF at 20% (T4), T5, and T1 (2.54, 1.95, 1.88, and 1.86 Nm, respectively). 10. With respect to C3-C2 and slope β, they raised in T12 and T4 more than WF, demonstrating that the SPF formula was capable of dough formation. 11. The RF sample replaced by OSPF at 30% (T5) had the greatest value of the torque C4 (2.89 Nm), indicating the most stable hot gel. The parameters C4-C3 and slope ɣ (1.01 Nm and -0.002 Nm/min, respectively) showed the same pattern. 12. Incorporating SPF (OSPF or WSPF) into cereal flour could increase the ash, EE, and CF contents of GFRB. Consequently raises its nutritional value. As ash is a good indicator of a high amount of minerals in any food sample. 13. The augment of the CF in foods is an indication of the nutritional value at the same time the CP, TC, NFE, and total calories decreased. However, replacing RF with SPFs leads to a decrease in the rheological properties, and thus gives an undesirable loaf to the consumer. 14. The physical characteristics of WB made from WF (T1) had the significantly (p<0.05) highest BW, BV, and SV with the lowest BL and BD among the other treatments and vice versa for RB prepared from RF (T2). 15. There is no significant difference (p>0.05) between WB (T1) and RB containing 3.0g CMC/100g flour (T8) in BW (52.70 g), and BL % (12.62 g/100g). 16. RB with 3% OM formula recorded the best results (139 cm3, 2.71 cm3/g, and 0.36 g/cm3 followed by bread with 2 % CMC formula (130 cm3, 2.53 cm3/g, and 0.39 g/cm3) in the regard of BV, SV, and BD, respectively with no significant differences among them (p> 0.05). 17. The aw of fresh WB and RB is 0.898 and 0.885, respectively.which increases due to the increasing proportion of CMC and/or OM in the formula of the bread. 18. Theaw rises when SPFs are inserted in the formulas. On the opposite, the aw values of all bread samples were decreased after 24 and 48 hrs of storage at room temperature. 19. The WB (T1) was superior in all texture characteristics to those of RB (T2). 20. The CH of WB (T1) was lower than that of RB (T2) after 24 and 48 hrs of storage. 21. The values of RB (T2) SR gradually decreased with the addition of the hydro-colloidal agent (CMC or OM).The lowest value was recorded by the RB having 3.0g OM/100 g flour and SPFs at 30 %. On the other hand, CH increases in all types of the loaves after 24 and 48 hrs of storage. 22. The WB made from WF (T1) was significantly (p<0.05) superior in most sensory properties to RB made from RF (T2). 23. The significant differences disappeared (p>0.05) between WB and RB loaf when RB contained ≥ 2.0g CMC or OM /100g RF and SPFs at 30%. 24. The loaves of WB and RB which contained 2.0 g CMC /100g RF or 2.5 and/or 3.0 g OM/100g RF have no significant differences(p>0.05) in overall acceptability. In addition, in this regard, there were no significant differences (p>0.05) among WB prepared by WF (T1) and RB made from RF replaced by OSPF up to 30 - 40 %.