الفهرس 
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Abstract
This investigation was carried out to produce high fiber, high protein and high fiber/high protein extrudates. It is intended to evaluate the effect of some raw materials rich in protein such as peanut, sesame, chickpeas, soybean, mung bean and cowpeas as well as soy protein isolate and milk powder which were added to blends in different ratios and extruded in a single screw extruder, on the quality characteristics of extrudates produced from cereals and legumes, as well as the effect of increasing fiber and protein ratios in the blends used for producing high fiber - high protein extrudates.
Chemical analysis, physical characteristics and sensory evaluation were evaluated after processing. Quality stability of extrudates and some changes which occurred during six months of storage, at room temperature of the blends were studied. In addition, an amino acids profile of all blends before and after processing was also studied. Six preparations of blends using cereals and legume were studied in order to produce good, nutritional extrudates.
The results obtained could be summarized as follows :
1- Chemical analysis of raw materials indicated that :
1.1 The highest protein content was found in defatted soybeans (52.44%) followed by skim milk powder (38.85%), then.
full fat soybeans (30.3 5%), mung beans (27.16%), faba beans (26.52%), cowpeas (25.47%), full fat peanuts (24.97%), then’ chickpeas (24.39%),, full fat sesame (20.38%), wheat bran (15.68%), malt (13.00%), sorghum (12.13%), whole wheat (11.78%) and white corn (10.03%). By contrast rice had the lowest amount of protein (7.98%).
1.2- The highest content of total hydrolysable carbohydrates was found in rice (76.41%) followed by white corn (68.82%), while the lowest value was observed in full fat peanut and sesame 18.34% and 15.78%, respectively.
1.3- Both wheat bran and faba bean showed the highest content of fiber ( 11.20% and 9.83%, respectively), followed by full fat soybeans, mung beans and defatted soybeans. Skim milk powder and defatted soybeans had the highest level of ash content ( 8.56% - 7.09%, respectively), followed by full fat sesame, wheat bran, full fat soybean and mung bean.
1.4- Ether extract was found in higher amounts in full fat sesame then peanut (49.11% and 45.92%, respectively). Skim milk powder showed the lowest content (1.13%) followed by defatted soybean (2.04%) .
2- The chemical analysis of the extrudates showed that:
2.1- Protein and fat content varied from (16.88% - 33.81%) and from (1.25% - 13.54%) respectively, depending on type and level of fortifying raw materials and their fat content.
2.2- Moisture content varied from 8.29% to 11.36%, also ash and fiber content varied from 39% - 2.98 and from 6% - 10.50%, respectively.
2.3- Nitrogen free extract (NFE) was found in higher amounts in blend No. 3 (58.87%) followed by blend No. l (53.18, while blend No. 5 showed the lowest content, 35.33%.
2.4- Calorific value of blends before processing by extrusion varied from 398.42 k.cal for blend No. 5 followed by blend No. 6 (366.78 k.cal), blend No. 2, (358.6 k.cal), while blend No. 1 had the lowest content of colorific value (335.95 k.cal).
2.5- Calcium content was found in higher amount in blend No. 5 (300 mg/ l00 g sample) followed by blends No. 4, No. 3 (280 mg, 250 mg/ 100 g sample). Blends No. 3 and No. 4 had the highest level of magnisum and Phosphorus content. The highest content of elements iron and manganese was found in blend No. 2 (300, 50 p.p.m respectively), followed by blends No. 1, No. 3 and No. 4, while blend No. 6 had the highest content of znic (55 p.p.m) followed blends No. 4, No. 5 and No. 3. In contrast the blend (No. 1) had the least amount of znic, the element copper was found in higher amount in blend No. 5
(156 p.p.m), while blend No. 1 had the lowest content of copper (5.5 p.p.m).
3- Effect of extrusion processing on the blends.
3.1- Chemical changes of blends :
The humidity content, NFE and protein content decreased as a result to the extrusion process, compared to the products with those in raw materials before extrusion.
3.2- The extrusion process, at 180°C for about 2 min., caused some destruction in the trypsin inhibitor. The decreasing percentage in these blends varied from 62.35% - 91.95%. The ratio of the reduction of the extruded blends depended on type of blend and raw material which using to formulate the blend. High reduction of trypsin inhibitor content of the extruded blends was noticed in blends fortified with full fat peanut or sesame flours.
3.3- Cooking by extrusion led to some reduction in the total amino acids in all extruded samples under study. This loss may be due to Maillard reaction during the heating process.
3.4- Extrusion process showed no marked changes on the mineral content of the extruded blends.
3.5- Extrusion process showed a remarkable decrease in the total count of bacteria and the disappearance of coliform bacteria and staphyllococcus content of the blends compared to before
processing. This decrease may be due to the high temperature which killed all these organisms.
4- The physical characteristics of the extrudates showed the water absorption index (WAI), water solubility index (WSI), bulk density and expansion ratio varied according to type of blend and the additive levels.
4.1- Blends No. 3, No. 4 and No. 1 had the highest percentage increase of WAI. Meanwhile, the other blends had a reduced the value of WAI.
4.2- Blends No. 1, No. 2, No. 3 and No. 4 also had the highest values of WSI. The WAI and WS1 were decreased with an increase in quantity of added protein and increased by increasing starchy materials.
4.3- The lowest bulk density was observed in blends No. 2, No. 5 and No. 6. On the contrary blends No. 1, No. 3 and No. 4 showed the highest bulk density. The BD was increased by increasing protein in blends.
4.4- The expansion ratio ranged from 1.1 to 3.62 depending on the type and concentration of the fortifying materials. The ER was increased by increasing by increasing starchy materials.
5- Sensory evaluation revealed that the lowest taste scores were noticed in the blends No. 1, No. 3 and No. 4 followed by the blends No. 2, No. 5 and No. 6.
5.1- Chewiness values of the same blends No. 1, No. 3 and No. 4 were found to be significantly better than the blends No. 2, No. 5 and No. 6. In general chewiness scores tended to decrease with increasing legume additives causing toughness in the texture of extrudates.
5.2- Extrudates color of blends No. 1, No. 3 and No. 4 were better than the other blends. The colour was darker by increasing added legumes as mung bean, soybean, cowpea and faba bean.
5.3- Pores distribution and porous texture showed no marked difference in the all blends under study.
5.4- Surface characteristics and general appearance of extruded blends No. 1, No. 3 and No. 4 were higher than blends No. 2, No. 5 and No. 6. Surface texture turned from smooth to tough in the product extrudates.
6- Effect of storage for six months at room temperature showed that:
All sensory evaluation scores, values of Hunter color measurements (L, a and b) of the extrudates decreased during storage for all extruded products especially the blends which containing full fat seeds like peanuts, sesame, soybeans, cowpeas and mung beans.
6.1- Humidity content for all the blends increased gradually During storage .
6.2- The thiobarbiutric acid value slightly increased during storage at room temperature especially the blends with a high content of fat.
6.3- Microbiological analysis showed that all blends were free of pathogenic microorganisms, so it can be concluded that all blends were suitable and safe for nutrition after processing even after storage at room temperature for six months .
Finally it might be recommended that :
1- It should be feasible to formulate many types of high protein, high fiber and high fiber/high protein extrudates at a lower cost by using local cereals and legumes to producing extrudates with good sensory characteristics. In addition to either fiber and protein sources are cheaper in cost and show lower energy consumption during process therefore used it is
economic.
2- It should be feasible to produce excellent extrudates with specific dietary characteristics depending on proper selection of ingredients and by processing variables and keeping on the biological value and sensory characteristics of the extrudates.