Studies On Extrusion Processing Technique For Blood Meal

Animal blood is rich in protein, containing up to 80%. There are such common methods to process blood as drum drying, spray drying and fermentation, which may have the disadvantages of low digestibility, high cost for processing and environmental pollution. Many efforts are made to have good use of blood into protein ingredients for feed in the world. The extrusion cooking (E-C), treating the powder blood with high temperature and short time (HTST), increases the digestibility of the blood. Studying the effects of E-C parameters on blood meal is the theory base of E-C practical production. It will have positive effects on exploitation of trash blood resource.The research studied on the effect of E-C parameters on quality of blood meal and the extruder performance characteristics, analyzed the change of main nutritional ingredient and microstructure of expanding blood meal, and gave the technologic parameters for practical production.The research result show that:l.The research studied the variety regularity of protein denaturation temperature of blood meal by Differential Scanning Calorimetry (DSC). The study shows that denaturation temperature is crucial factor. When the DSC' s calefactive speed is 5 degrees centigrade per minute, protein denaturation temperature is 76.9 degrees centigrade.2. We summarized the influence regularity of the extrusion parameters on the quality of expanding blood meal by single factor experimentation. The regularity shows that:Fixed other factors, the pepsin digestibility of expending blood meal firstly increases with the increase of moisture content, but when moisture content increase to maximum, the pepsin digestibility begins to descend.Fixed other factors, the pepsin digestibility descends with the increaseof screw speed.Fixed other factors, the pepsin digestibility increases with the increase of die diameter, but when die diameter increases to 13 millimeter, the pepsin digestibility begins to descend.3. The research studied the influence regularity of extrusion system parameters on quality of expanding blood meal and the extruder performance characterstics by the method of quadratic orthogonal rotation combinationdesign test of three factors and five levels, and evaluated the optimum solution of multi-objectives nonlinear programming problems by combining fuzzy integration order with frequency analysis. The study shows that:When the importance of four objectives is the same level, the optimized system parameters of extrusion are follows: the moisture of fed blood meal 23 +1.02%, the die diameter 14. 5 + 0. 65mm, the screw rotate speed 234.5+6.5 r/min-.When the pepsin digestibility and the electricity consumed of unit product are the main factors, the optimized system parameters of extrusion are follows: the moisture of fed blood meal 22. 57?. 18%, the die diameter 15?. 5mm, the screw rotate speed 207.1 + 7.5 r/min.4. The comparison of microstructure between expanding blood meal and common blood meal indicate that: The granule surface of expanding blood meal is loose, delaminatiorK ruleless and lustrous. The granule is built of countless holes that are conterminous each other. The structure is very crisp and insubstantial. One hand the structure increase the contact area of digestive enzyme and granule, on the other hand else nourishment ingredients fill the holt of granule, thereby avoiding the loss of these nourishment ingredients on transportation.5. The comparison of the expanding blood meal produced by our experimentation with common blood meal show that: the pepsin digestibility of the former increases 3.3 centesimal points. This may elucidate that the extrusion technology can improve the quality of blood meal and enhance the digestibility of nourishment ingredients. On the other hand the moisture content of expanding blood meal descend, thereby making for store.Graduate student: Ma Zhiyu Major: Environment and Energy Sources Engineering of Agricultural Biology Supervisor: Associate prof. chen li...