الفهرس 
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Abstract
The celiac disease (CD) is consider an enteropathy caused by ingestion of gluten in genetically susceptible individuals. The CD is one of the most common genetic disorders in the human population, its prevalence is 1–2% of world population, global average of patient people is estimated to increase 10-fold factor and appears to be increasing in recent years. The CD is due to a permanent intolerance to prolamines present in certain cereals such as wheat, rye, barley and possibly oat. Ingestion of these substances causes intestinal mucosal damage injury characterized by complete loss of absorptive villi and hyperplasia of the crypts, hence, maldigestion and malabsorption of nutrients, which impacts many of the body’s systems. Their deficiencies could be accompanied by slower physical and mental development, rachitis, osteoporosis, anaemia and limited immunological response to various infections. The only effective treatment for CD is to maintain a strict gluten-free diet (GFD), which leads to recovery of the intestinal mucosa. If, however, gluten is reintroduced to the diet, a CD relapse will occur.
Currently, many gluten-free (GF) products available on the market are of low quality and low in nutritional value, in comparison to traditional products, as they contain less dietary fiber, protein and microelements. Also, not widely available and are both poor in quality and more expensive than gluten-containing products. The elimination of gluten further translates into a poor supply of minerals, amino acids, vitamins, and calories in the diet and poor sensory properties.
Among GF products, bread and biscuit are the most important, where they form constitute the basis of most people’s diets both because of its relative high their nutritional values and its unique sensory their characteristics (texture, taste, and flavor).
The aim of this study, an attempt are made to products both gluten-free bread and biscuit and to improvement the physico-chemical, nutritional and sensory properties of these products by using ingredients and additives with a high nutritional value, which would elevate nutritional value of the products and improve their sensory properties in a way similar to gluten, in order to determine their contribution to the daily intake of nutrients. Among the ingredients used pseudocereals (quinoa and buckwheat), millet, rice, chickpea flours and corn starch in addition to xanthan gum showed that these ingredients can improve technological and nutritional qualities as well as shelf-life of final products compared with commercially mixtures available in the market. It can also be compared with wheat flour products.
The obtained results could be summarized as follows:
I- Physico-chemical characters of raw materials:
a- Gross chemical composition and caloric value of raw materials:
1- Wheat flour (extraction 72%) contained 11.30% moisture, 12.26% crude protein, 2.46% fat, 0.59% ash, 0.61% crude fiber, 82.57% starch, 84.08% carbohydrates and 407.50 Kcal /100 g on dry weight basis.
2- The corn starch content was 9.33, 0.61, 0.39, 98.97, 99.00% and 401.95 Kcal /100 g on dry weight basis of moisture, crude protein, fat, starch, carbohydrates and caloric value, respectively.
3- The moisture content of GF flour types was 10.34, 10.72, 11.16, 11.71 and 11.43% for quinoa, buckwheat, millet, rice and chickpea flours, respectively.
4- The calculated crude protein varied from 7.28 to 22.52% on dry weight basis for rice and chickpea flours, respectively.
5- The crude fat content of quinoa, buckwheat, millet, rice and chickpea flours was 6.09, 3.37, 3.40, 2.03 and 5.34% on dry weight basis, respectively. While, the ash content of the quinoa, buckwheat, millet, rice and chickpea flours was 2.40, 2.37, 1.27, 0.45 and 2.90% on dry weight basis, respectively.
6- Crude fiber ranged from 0.34% of rice flour to 5.56% of buckwheat flour on dry weight basis. While, the starch content ranged between 61.89 – 88.91% on dry weight basis for chickpea and rice flours, respectively.
7- The carbohydrates of quinoa, buckwheat, millet, rice and chickpea flours was 74.81, 72.47, 80.20, 89.90 and 66.82% on dry weight basis, respectively.
8- The rice flour recorded the highest calorific value (406.99 Kcal /100 g) followed by quinoa flour (406.33 Kcal /100 g), chickpea flour (405.42 Kcal /100 g), millet flour (399.60 Kcal /100 g) and buckwheat flour (385.13 Kcal /100 g) on dry weight basis.
9- The total phenolic compound content and antioxidant activity were (279.89, 517.92, 163.99, 50.67 and 232.19 mg/100g on dry weight basis) and (16.92, 43.83, 4.27, 2.75 and 8.20%) for quinoa, buckwheat, millet, rice and chickpea flours, respectively. The total phenolic compound content and antioxidant activity for wheat flour (WF) and corn starch were (147.56 and 33.55 mg/100g) and (4.26 and 0.84%) on dry weight basis, respectively.
b- Functional properties of raw materials:
1- The results of water and oil holding capacity indicated that quinoa and buckwheat flours gave higher values than that observed for WF.
2- It was found that quinoa, buckwheat, millet, rice and chickpea flours were higher soluble protein than the WF.
3- Buckwheat, millet, rice and chickpea flours showed markedly higher foaming stability than of WF.
II- Physico-chemical and rheological characters of wheat flour and gluten-free formulas flour
a- Gross chemical composition and caloric value of wheat flour and gluten-free formulas flour:
1- The moisture content of WF and gluten-free flour (GFF) commercial formula sold in the local market was 11.30 and 12.60%, respectively. On the other hand, the prepared formulas moisture content ranged from 12.23% (F2) to 12.90% (F3).
2- The highest protein content was recorded with F2 and F4 formulas with no significant difference (P˃0.05) when compared to WF. The GFF formula had the lowest protein content, about half the amount (5.07% on dry weight basis).
3- The F1 formula had the highest crude fat content (2.96% on dry weight basis). Furthermore, no significant differences in fat content (P˃0.05) were found between other GF flours formulas and controls.
4- In comparison to controls (WF and GFF), the amount of ash and crude fiber recorded in F2 doubled. The ash and crude fiber contents of the various formulas differed significantly. The GFF had the lowest ash and crude fiber content (0.51 and 0.31%, respectively on dry weight basis).
5- There was no significant difference in starch content (P˃0.05) between WF and the formulas F1 and F3, while the GFF formula had the highest level of starch (90.02% on dry weight basis).
6- The GFF formula had the highest carbohydrate content and caloric value (91.88% and 407.80 Kcal /100 g, respectively), while the F2 formula had the lowest values (83.25 and 401.70.43 Kcal /100 g, respectively) on dry weight basis.
7- The highest values of total phenolic compounds and antioxidant activity were observed in F2 formula (313.15 mg/100g and 7.95%, respectively), followed by F4 formula (226.56 mg/100g and 7.22%, respectively), then F1 formula (223.57 mg/100g and 6.62%, respectively) on dry weight basis. While, the lowest value was in the commercial formula GFF (75.10 mg/100g and 3.23%, respectively).
b- Functional properties of wheat flour and gluten-free formulas flour:
1- The GF formulas flour exhibited high values of the water holding capacity in samples F2 (164.98%) and F1 (134.17%), which may be due to the high protein content (12.25%) in the sample F2. While, GFF formula flour showed lower water value compared with the GF formulas flour.
2- Significant differences in the oil holding capacity of GF formulas flour were also observed. The mean values showed higher oil holding capacity for F2 (145.92%), followed by F4 (138.51%), F1 (130.11%) and F3 (126.64%), whereas, the lowest 75.43% was for GFF.
3- The GF composite flour samples have close values and non-significant variations at P˃0.05 in the protein solubility.
4- The increase in the values of emulsion stability and foam stability determined for GF composite flours were significant at P≤0.05 as compared with those determined for wheat and GFF flour samples.
c- Dough rheological characteristics of wheat flour and gluten-free formulas flour:
1- Water absorption ranged from 53.60% (F2) to 60.60% (F3), with a significant difference between tested flour formulas. There was no significant difference (P˃0.05) between the F1, F4 formulas and control samples.
2- The dough of F1 and F3 formulas flour had a high dough development time (7.28 and 5.83 min, respectively). This indicates that these flours require more time to hydrate all compounds than the other flour samples.
3- The F1 formula dough had the longest stability (9.60 min), followed by formula F4 (8.80 min) and formula F2 (8.74 min). There was a significant difference (P≤0.05) between these three formulas and the control formula.
4- The C1 values were slightly differing between WF and GF formulas flour with the addition of xanthan gum.
5- The C2 values of WF were lower than GF composite flours. The protein of the F1 formula (0.61 Nm) was expressed as weakening lower due to mechanical and thermal constraints, implying higher flour protein quality than the GFF formula (0.51 Nm), followed by the F4 formula (0.53 Nm). There is no statistically significant (P˃0.05) difference between F2, F3, and F4 and control samples. As a result, the WF protein was classified as having a higher reduction profile.
6- The flour formulas F2, F1, and F4 contributed to higher starch gelatinization, peak torques (C3), and gelatinization rates than the other samples, implying high dough viscosity during heating. However, there were no significant differences (P˃0.05) between the F3 and control sample (GFF).
7- The C4 torque showed higher values for all GF formulated samples than the control, indicating a high starch resistance to amylase enzymatic hydrolysis. In terms of C4, the F2 formula dough had the highest value of 2.23 Nm, indicating that it was the most stable gel in the hot phase.
8- During the cooling period, the WF and F3 formula had low starch retrogradation and recrystallization (1.48 and 2.61 Nm, respectively).
9- The flour formula F1 had the highest value of the α, β and γ slopes (-0.018, 0.498 and 0.022 Nm/min, respectively). On the other hand, the GFF formula recorded the lowest value of the α, and β slopes (-0.088 and 0.220 Nm/min, respectively). Moreover, WF sample recorded the lowest value of the γ slope (-0.072 Nm/min), which indicated the speed of the protein network weakness due to heating (α), gelatinization rate (β) and cooking stability rate (γ).
III- Physico-chemical, nutritional and sensorial evaluation of the prepared pan bread
a- Gross chemical composition and caloric values of pan bread
1- The control sample (wheat bread) contained 34.55% moisture, 12.63% Protein, 4.19% fat, 1.91% ash, 0.87% crude fiber, 80.40% carbohydrate and 409.83 Kcal/100g on dry weight basis.
2- The moisture content of GFB was ranged from 39.56 to 46.01%. It can be observed that all pan bread baked from GF flours had high moisture content compared to wheat bread as a control.
3- The pan bread baked from 100% WF and buckwheat flour (F2) had the highest protein content, followed by F1, F4 and F3 bread samples. The lowest protein content for bread baked from GF commercial flour formula was recorded for GFF bread sample.
4- The highest crude fat content was found in F1 (6.12%), followed by GFF (4.66%), F4 (4.55%) and F2 (4.49%) bread samples on dry weight basis. The lowest of fat content (4.18 and 4.19% on dry weight basis) was recorded in F3 and wheat bread, respectively.
5- Ash and crude fiber contents of all pan bread baked from the composite GF flours were higher than that of wheat (WF) and GFB from the commercial formula (GFF). Among the bread baked from composite GF flours, F4 formula bread showed high ash content (2.83%) followed by F2 bread sample (2.78%) on dry weight basis. The highest crude fiber content recorded in F2 (1.28%), while the lowest content was found in GFF bread (0.43%) on dry weight basis.
6- The carbohydrate content of pan bread decrease as proportion of pseudocereals and legumes flours adding in the GF flour blends. This may be due to the higher carbohydrate content of WF compared to pseudocereals and legume flours.
7- The pan bread of F1 sample recorded the highest calorific value (416.12 Kcal /100 g), while the F2 sample had the lowest value (406.21 Kcal/100 g) on dry weight basis.
8- The bread baked from F2 formula flour showed highest TPC and antioxidant activity (301.60 mg/100g and 14.93% on dry weight basis, respectively), followed by the F1 bread (191.69 mg/100g and 11.98%, respectively), while the bread baked from GFF flour exhibited the lowest value (85.31 mg/100g and 1.06%, respectively) comparing to breads baked from WF.
b- The minerals content of pan bread
1- The GFF pan bread had the lowest content of calcium 78.05, Sodium 138.20, potassium 167.83 and phosphorus 65.53 mg/100g; on dry weight basis. While, WF pan bread had the lowest magnesium and iron content (32.27 and 8.29 mg/100g, respectively) and the highest copper and zinc content (6.49 and 5.00 mg/100g, respectively).
2- On the other hand, F2 pan bread had the highest content of Macro-elements (calcium 108.64, magnesium 66.03, Sodium 157.68, potassium 352.65 and phosphorus 136.36 mg/100g; on dry weight basis) and the lowest content of copper and zinc (3.51 and 2.70 mg/100g, respectively). Whereas, F3 pan bread had the highest iron content (11.29 mg/100g) compared to other types of pan bread.
c- Amino acids content of pan bread
1- All pan bread baked of GF composite flours was superior in its content of the essential amino acids; valine, methionine, isoleucine, leucine, phenylalanine and tryptophan compared to WF bread, and was higher than the values recommended by FAO/WHO. While, WF pan bread was higher in its content of the lysine and close equal in its content of the threonine with other types of pan bread.
2- On other hand, the content of non-essential amino acids; glutamine was the highest followed by proline in wheat bread than the corresponding amino acids that observed in bread from GF composite flours.
d- Chemical score and limiting amino acids of pan bread
1- The first limiting amino acid in wheat bread, F1, F3 and F4 breads was the lysine, while, it was tryptophan in GFF bread and isoleucine in F2 bread. On other hand, the second limiting amino acid was tryptophan in wheat and F3 breads, lysine in GFF and F2 breads and isoleucine in F1 and F4 breads.
e- Protein efficiency ratio, biological value and in vitro protein digestibility of pan bread
1- The all bread from GF composite flours had higher protein efficiency ratio values than the bread of WF as control. The highest protein efficiency ratio was recorded in F3 bread sample (3.23), while the lowest ratio (2.13 and 2.47) was recorded in wheat bread as control and F1 bread; respectively. In addition, the bread from GF composite flours showed increasing in biological values than that observed in bread of WF. The value of in vitro protein digestibility by pepsin for wheat bread was lower than the other determined values for bread baked from GF composite flours. Furthermore, the protein digestibility by pepsin followed by trypsin gave higher values than that recorded for the treatment by pepsin alone in all bread samples.
f- Physical characteristics of pan bread
1- The using GF flours caused increasing in the pan bread weight of composite compared with wheat bread loaf as the control. While, the volume and specific volume of bread was decreased by using GF composite flours in bread making. The reason of this decrease in volume and specific volume was due to the loaf cell structure being unable to retain gas during proofing and baking. Among the studied GF composite flours, F4 flour appear to has lesser effect on reduction of the specific volume of bread as compared with that of bread of WF and other GF composite flours any.
g- Sensory evaluation of pan bread
1- The use of F3 composite flour in pan bread making resulted the better crumb color, aroma, texture, taste and overall acceptability and it was better than other GF composite flours and close to WF pan bread as a control with no significant difference between them (P˃0.05).
2- The F3 and F4 bread had crumb with good grain cell structure and similar to that of wheat bread. Grain cell structure was homogenous and has regular pores. The crumb texture of such bread was stretchy and has fine feel. Generally, all samples of GFB was organoleptically acceptable and gave lesser score than that of WF bread as the control. As accepted, wheat bread has the highest total score followed by breads from F3, F1 and F4. The lowest total score was found in bread of GFF.
h- Staling of pan bread
1- Wheat pan bread as control had at zero time recorded 265.85% as freshness and this value gradually decreased during the bread storage for 3 days at room temperature reached to 237.58%. The freshness loss for wheat pan bread accounted as 2.41, 6.00 and 10.63 after 1, 2 and 3 days, respectively.
2- The AWRC as indicator for bread freshness showed increasing with GF composite flours. In addition, the bread from F4 GF flour exhibited the highest AWRC as freshness (338.63%) at zero time than all bread of other flours, followed by F2 sample (329.87%) and F3 sample (320.62%).
3- After the first day of storage, the bread from F1 composite flour showed less freshness loss than the bread of other GF samples, while in second and third days of storage, the F4 bread least freshness loss. On the other hand, the highest freshness loss during the first, second and third days was found in the GFF bread followed by WF bread.
IIII- Physico-chemical, nutritional and sensorial evaluation of the prepared biscuit
a- Gross chemical composition and caloric values of biscuit
1- Results revealed that moisture content of biscuit made from 100% WF was 5.35%, while biscuit of GF composite flours ranged from 4.24 - 5.90%.
2- The crude protein of wheat biscuit sample was 8.44%, while, it was 3.63, 7.03, 7.40, 7.55 and 7.58% on dry weight basis for GFF, F3, F1, F4 and F2 samples, respectively. The crude fat content ranged from 13.18 to 14.28% on dry weight basis for all GF biscuit. The crude fat content indicated that biscuit control made from 100% WF had the lowest value (12.44%); while GF biscuit with quinoa flour (F1) had the highest value (14.28%) on dry weight basis.
3- The ash content of GF biscuit samples ranged from 1.68 to 2.05%, which was higher than control samples (WF and GFF) it was 1.55 and 1.26% on dry weight basis, respectively. Crude fiber content of GF biscuit was also found to be higher than control samples.
4- Incorporation of GF flours in biscuit resulted in a decrease in the carbohydrate content in samples F1, F2 and F4 as compared to the control sample. Besides, WF sample had the lowest caloric value (453.48 kcal/100g), while biscuit contained 30% quinoa flour had the highest value (460.56 kcal/100g) on dry weight basis.
5- The F2 biscuit showed highest content of TPC (131.61 mg/100g), followed by F1 sample (110.05 mg/100g), while the GFF biscuit had the lowest value (67.28 mg/100g) on dry weight basis. On other hand, the F1 biscuit showed the highest antioxidant activity, followed by the F2 biscuit, while the GFF biscuit was the lowest.
b- The minerals content of biscuit
1- The F3 biscuit sample was relatively higher in calcium (78.67 mg /100g), phosphorus (129.07 mg /100g), copper (7.24 mg /100g) and zinc (6.29 mg /100g), while F2 biscuit sample was relatively higher in magnesium and iron (49.75 and 13.99 mg /100g; on dry weight basis, respectively).
2- Whereas, F2 biscuit sample was relatively higher in sodium and potassium (105.34 and 256.62 mg /100g, respectively). On other hand, it had lower content of calcium, magnesium, potassium, phosphorus, iron, copper and zinc (59.44, 20.78, 102.90, 42.06, 7.99, 2.07 and 1.80 mg /100g; on dry weight basis, respectively).
c- Amino acids content of biscuit
1- The content of total essential amino acids was 26.11, 31.94, 34.39, 34.16, 33.99 and 33.49 g/100g protein for WF, GFF, F1, F2, F3 and F4 biscuit samples, respectively.
2- Among the essential amino acids, leucine recorded the highest amino acids value, followed by phenylalanine, while tryptophan and methionine recorded the lowest values.
d- Chemical score and limiting amino acids of biscuit
1- Lysine was the first limiting amino acid in WF, F3 and F4 biscuit samples, while tryptophan was the first limiting amino acid in GFF biscuit sample and isoleucine in F1 and F2 biscuit samples compared with human milk proteins. Meanwhile, the second limiting amino acid was tryptophan of WF and F3 biscuit samples, while lysine was the second limiting amino acid for GFF, F1 and F2 biscuit samples and isoleucine in F4 biscuit sample.
e- Protein efficiency ratio, biological value and in vitro protein digestibility of biscuit
1- The highest protein efficiency ratio was recorded for F3 biscuit sample (3.40), followed by F4 biscuit (2.78%), while the lowest value was recorded for wheat biscuit as control (2.28). The biscuit from GF composite flours also showed increasing in biological values than that observed for biscuit from WF. On other hand, the value of in vitro protein digestibility by pepsin for wheat biscuit was lower than the other values determined for biscuit made from GF composite flours. Furthermore, the protein digestibility by pepsin followed by trypsin gave higher values than that recorded by pepsin treatment alone in all biscuit samples.
f- Physical characteristics of biscuit
1- Data recorded increment of width and thickness (4.80 and 0.77 cm, respectively) for WF biscuit compared with GF biscuit. While, maximum width and thickness was observed in GF biscuit (F3) sample (4.74 and 0.67 cm, respectively), whereas minimum width and thickness were observed in GFF biscuit sample (4.56 and 0.37 cm, respectively).
2- On the other hand, the spread ratio and spread factor increased slightly in F3 and F2 biscuit samples comparison with WF biscuit, with no significant difference between them (P˃0.05).
g- Sensory evaluation of biscuit
1- The sensory scores for appearance, color, aroma and taste of F1, F2, F3 and F4 biscuit decreased slightly in comparison with WF biscuit, with no significant difference (P˃0.05). While, the texture scores of biscuit was increased, F3 biscuit sample had the best texture score (9.17), while lowest score was observed in GFF biscuit sample (7.42).
2- Both WF biscuit and F3 biscuit sample had the best taste score (9.00 and 8.83, respectively). Whereas, lowest score was observed in GFF biscuit sample (8.00). As for the overall acceptability, all samples of GF biscuit was acceptable from the sensory point view, with no big significant difference between them and WF biscuit.