الفهرس 
Chemical composition of wheat flour (Extraction rate 72%)Only 14 pages are availabe for public view
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Abstract
The objective of this study was to evaluate the effect of adding enzymes on the quality characteristics of pan bread. The optimization of enzymes dosage was investigated by using predictive modeling on the rheological characteristics of wheat flour. The response of different concentrations of enzymes, and ascorbic acid on rheological characteristics of weak wheat flour was studied by the three dimension polynomial quaternary model. Flour physicochemical characteristics, dough extensogram, bread texture profile analysis and sensory properties of pan bread were determined.
Predicting individual extensograph parameters (Y) was assumed by quadratic or quadratic and cubic polynomial regression model for the independent variables (fungal α-amylase, glucose oxidase, phospholipase and ascorbic acid concentrations (X)) to optimize the extensograph parameters (Y) used regression analysis. Three-dimension contour plot was used as a method to study the response surface of different extensograph parameters (Y) as dependent variables with enzyme concentration and Ascorbic acid concentration (X and Z) as independent variables. The obtained optimum predicting concentrations ware verified, by using applied extensograph trials and then manufacturing pan bread.
The obtained results could be summarized as follows:
5.1. Chemical composition and physical properties of wheat flour
• The obtained results refer to the percentage of moisture, ash, protein, total lipid and nitrogen free extract. It was 13.5, 0.53, 10.6, 1.11 and 87.7 % respectively; for all-purpose flour, but it was 13.5, 0.56, 13.5, 1.02 and 84.92% respectively; for strong flour.
• Physicochemical characteristics of wheat flour; wet gluten, dry gluten, gluten index, falling number and starch damage which was 25.8%, 12.7%, 96%, 389 sec., and 5.4% respectively; for all-purpose flour, and it was 32.4%, 13.3%, 91%, 363 sec., and 5.6% respectively; for strong flour.
5.2. Rheological study
5.2.1. Farinograph parameters
5.2.1.1. Farinogram of dough in the presence of ascorbic acid and fungal α.amylase
• Results revealed that the water absorption was decreased significantly (P≤0.05) with increasing fungal α. amylase concentration.
• Water absorption also was decreased significantly (P≤0.05) with the increasing of ascorbic acid concentration.
• Peak time (dough development time “the time that accordance with maximum consistency”) data showed that there were no significant (P≤0.05) differences at all treatments.
• The results indicated that no significant (P≤0.05) differences with ascorbic acid concentrations but indicate significant (P≤0.05) decrease with increasing fungal α. amylase.
• Regarding mixing tolerance index (MTI) the data revealed that there was no significant (P≤0.05) effect with the increasing of ascorbic acid concentration, but it showed significant (P≤0.05) increase with the increasing of fungal α. amylase.
• Degree of softening results showed that there was no significant (P≤0.05) effect with the increasing of ascorbic acid concentration or fungal α.amylase, but it showed significant (P≤0.05) increase with the addition of fungal α. amylase.
5.2.1.2. Farinogram of dough in the presence of ascorbic acid and fungal glucose oxidase
• Results revealed that the water absorption was decreased significantly (P≤0.05) with adding fungal glucose oxidase, but no significant (P≤0.05) effects with increasing the fungal glucose oxidase concentration.
• Peak time data showed no significant (P≤0.05) differences at all treatments.
• Data showed also that increasing of fungal glucose oxidase alone may increase the stability time.