الفهرس 
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Abstract
This study was conducted to evaluate the nutritional and functional properties of stabilized rice bran and rice bran protein concentrate. Cupcake and pan bread were prepared by replacing wheat flour with 5, 10, 15, 20, and 25% of stabilized rice bran flours. Tortilla was also prepared by replacing yellow corn flour with 2.5, 5, 7.5 and 10% of rice bran protein concentrate. The chemical, physical and sensory properties of the cupcake, pan bread and tortilla were evaluated.
The obtained results can be summarized as follows:
6.1. Proximate composition of raw materials and rice bran protein concentrate:
The RBPC had the higher (p ≤ 0.05) crude protein (72.38%) than SRB (17.58%), WF (11.53%) and YCF (9.17). The SRB had the higher (p < 0.05) crude fat (15.98%), total ash (7.54%) and crude fiber (7.15%) contents than RBPC, YCF and WF.
6.2. Amino acid profiles of stabilized rice bran and rice bran protein concentrate:
Amino acid profiles of RBPC had higher levels of essential amino acids than SRB except for threonine and sulfur amino acids which were similar to SRB. The major essential amino acids in SRB and RBPC were aromatic amino acids, leucine, valine, lysine, and sulfur amino acids.
6.3. Functional properties of stabilized rice bran and rice bran protein concentrate:
The maximum protein solubility of RBP was 61.79% at pH 10. However, the minimum protein solubility was 22.71% at pH 4. The RBPC had higher (p ≤ 0.05) water absorption, oil absorption, foaming capacity, foaming stability and emulsifying stability than SRB. However, SRB had a higher (p ≤ 0.05) bulk density than RBPC. A non-significant difference was observed in emulsifying activity between SRB and RBPC.
6.4. Phenolic compounds of stabilized rice bran and rice bran protein concentrate:
The most plentiful phenolic compounds in SRB and RBPC were E-vanillic, Benzoic, Chlorogenic, Catechin, Pyrogallol and Ellagic which represented 68.20% of the total phenolic compounds.
6.5. Flavonoid compounds of stabilized rice bran and rice bran protein concentrate:
The major flavonoid compounds in SRB and RBPC were Hespertin, Hesperdin, Naringin, Quercetin, Rosemarinic and Luteolin which represented 82.42% of the total flavonoid compounds.
6.6. Cupcake with stabilized rice bran:
6.6.1. Proximate composition of cupcake:
The moisture, crude protein, total ash, crude fat, crude fiber contents and caloric values of cupcake were increased (p ≤ 0.05) by increasing the level of SRB. However, total carbohydrates content had an opposite trend.
6.6.2. Physical properties of cupcake:
The specific volume and specific gravity of cupcake prepared with 5 and 10% SRB were similar to (P > 0.05) control cupcake. However at higher replacement levels, they were decreased (P ≤ 0.05).
6.6.3. In-vitro protein digestibility of cupcake:
In-vitro protein digestibility of cupcake prepared with SRB was gradually (P ≤ 0.05) decreased by increasing the level of SRB.
6.6.4. Crust color of cupcake:
Cupcake prepared with SRB had darker (P ≤ 0.05) crust color than control. The dark crust color was increased (P ≤ 0.05) by increasing the level of SRB.
6.6.5. Crumb color of cupcake:
Crumb color of cupcake prepared with SRB was darker (P ≤ 0.05) than control. The dark crumb color of the cupcake was increased (P ≤ 0.05) by increasing the level of SRB.
6.6.6. Textural profile of cupcake:
Firmness, gumminess, and chewiness were increased by increasing the level of SRB, while cohesiveness was decreased. Springiness was not affected by SRB up to 10% level however, at higher SRB levels springiness decreased.
6.6.7. Sensory properties of cupcake:
Sensory properties of cupcake prepared with 5% SRB were similar to (P > 0.05) the control, however, the gradual decrease was observed at higher SRB levels. Control cupcake had rating scores ranged from 6.95 to 6.99 (like very much) for all sensory properties. However, cupcake prepared with SRB had rating scores ranged from 4.09 (neither like nor dislike) to 6.93 (like very much) for all sensory properties.
6.7. Pan bread with stabilized rice bran:
6.7.1. Mixolab properties of pan bread:
Water absorption was decreased by increasing the replacement levels of SRB. However, the stability, C1 and C3 of dough were not affected by replacing wheat flour with SRB. However, C2 values were slightly affected by replacing wheat flour with different levels of SRB. The C4 and C5 values were decreased by increasing the replacement levels of SRB.
6.7.2. Mixolab indices of pan bread:
Water absorption, amylolysis and retrogradation indices were decreased by increasing the replacement levels of SRB in wheat flour dough. Mixing and viscosity indices of wheat flour dough were not affected up to 15% and 10% replacement levels of SRB, respectively.
However, at higher replacement levels, mixing and viscosity indices were decreased. Gluten index was not affected by SRB.
6.7.3. Proximate composition and caloric values of pan bread:
Increasing the level of SRB in pan bread formula increased (p≤0.05) moisture, crude protein, total ash, crude fat and crude fiber contents, while total carbohydrates had an opposite trend. Caloric values were not affected (p > 0.05) by replacing wheat flour with SRB.
6.7.4. Physical properties of pan bread:
The specific volume of pan bread were decreased (P ≤ 0.05) with increasing of SRB. However, specific gravity had an opposite trend.
6.7.5. Alkaline water retention capacity of pan bread:
Alkaline water retention capacity of pan bread was increased (p≤0.05) by increasing SRB levels. However, it was decreased (p ≤ 0.05) by increasing the storage period from 24 to 72 h.
6.7.6. In-vitro protein digestibility of pan bread:
Increasing the level of SRB in pan bread formula resulted in a gradual (P ≤ 0.05) decreased in in-vitro protein digestibility.
6.7.7. Crust color of pan bread:
The dark crust color was increased (P ≤ 0.05) by increasing the level of SRB in pan bread formula than control.
6.7.8. Crumb color of pan bread:
The dark crumb color of the pan bread was gradually increased (P ≤ 0.05) by increasing the level of SRB in pan bread formula than control.
6.7.9. Textural profile of pan bread:
Firmness, gumminess, and chewiness were increased by increasing SRB, while cohesiveness was decreased. Springiness was not affected by SRB up to 10%, however, at higher SRB levels springiness decreased.
6.7.10. Sensory properties of pan bread:
Sensory properties of pan bread were decreased (P ≤ 0.05) by increasing the replacement level of SRB except for flavor, taste, texture and overall acceptability of 5% replacement level which were similar to (P > 0.05) control pan bread. Control pan bread had rating scores ranged from 6.95 to 6.98 (like very much) for all sensory properties. However, pan bread prepared with SRB had rating scores ranged from 4.21 (neither like nor dislike) to 6.78 (like very much) for all sensory properties.
6.8. Tortilla with rice bran protein concentrate:
6.8.1. Proximate composition of tortilla:
The crude protein and total ash contents of tortilla were increased (p ≤ 0.05) by increasing the level of RBPC in a tortilla. However, total carbohydrates, crude fat and crude fiber had an opposite trend
6.8.2. In-vitro protein digestibility of tortilla:
In-vitro protein digestibility of tortilla was significantly (p ≤ 0.05) increased by increasing the RBPC up to 7.5%.
6.8.3. Alkaline water retention capacity of tortilla:
Alkaline water retention capacity of the tortilla was (p ≤ 0.05) increased by increasing RBPC levels in the tortilla. However, it was (p≤0.05) decreased by increasing the storage period from 24 to 72 hours.
6.8.4. Color of tortilla:
Color of tortilla prepared with RBPC had lower (P ≤ 0.05) L* and b* and higher (P ≤ 0.05) a* as compared with the control tortilla.
6.8.5. Sensory properties of tortilla:
Control tortilla had rating scores ranged from 4.35 (neither like nor dislike) to 6.75 (like very much) for all sensory properties. However, tortilla prepared with 7.5% RBPC had rating scores ranged from 5.35 (like moderately) and 6.95 (like very much) for all sensory properties.
6.8.6. Amino acid profile of tortilla:
Leucine and aromatic amino acids were the major essential amino acids in control tortilla and tortilla prepared by replacing corn flour with 7.5% of RBPC. Tortilla prepared with 7.5% RBPC had higher lysine (27.31%) and tryptophan (33.33%) than control tortilla.