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Effects of Soya Bean Meal Feed Properties on Extrusion Failures and Implementing a Solution. Case Study Monmouth Path's Inves

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Effects of Soya Bean Meal Feed Properties on Extrusion Failures and Implementing a Solution. Case Study Monmouth Path's Inves International Journal of Nutrition and Food Sciences 2013; 2(2) : 60-69 Published online March 10, 2013 (http://www.sciencepublishinggroup.com/j/ijnfs) doi: 10.11648/j.ijnfs.20130202.16 Effects of soya bean meal feed properties on extrusion failures and implementing a solution. Case study Monmouth Path’s Investments (Pvt) Ltd, Harare, Zimbabwe P. Muredzi 1, M. Nyahada 2, B.W. Mashswa 2 1School of Industrial Sciences and Technology, Harare Institute of Technology, Ganges Rd, Belvedere, Harare, Zimbabwe 2Department of Food Processing Technology, Harare Institute of Technology, Ganges Rd, Belvedere, Harare, Zimbabwe Email address: [email protected] (P. Muredzi), [email protected] (M. Nyahada), [email protected] (B.W. Mashswa) To cite this article: P. Muredzi, M. Nyahada, B.W. Mashswa. Effects of Soya Bean Meal Feed Properties on Extrusion Failures and Implementing a Solution. Case Study Monmouth Path’s Investments (Pvt) Ltd, Harare, ZimBabwe, International Journal of Nutrition and Food Sciences . Vol. 2, No. 2, 2013, pp. 60-69. doi: 10.11648/j.ijnfs.20130202.16 Abstract: This research was a contribution on the optimization of extrusion process by determining the effects of feed properties on extrusion failures and implementing a solution. The objectives of the research were to increase the set soy meal to chunk conversion standard from 65% to 80%; to determine the effects of feed properties on extrusion failures; to determine the best conditions of the feed properties that promote an effective extrusion cooking process; and to determine a solution of optimizing these feed properties for successful extrusion. The research was company based and it followed the failures of extrusion experienced at Monmouth Path Investment (Pvt) Ltd in Waterfall, Harare. This research was limited to feed properties such as fat content, moisture content and particle size as the factors that cause extrusion failures. The determination of moisture content was done by using a moisture analyzer, fat content was determined through the Soxhlet method and the particle size of the feed was determined through sieve analysis. The results revealed that extrusion process was most suc- cessful when the soy meals fat content was greater than 6.0%, with a moisture content less than 6.0% and particle size range of 0.95-1.0mm. The process of optimization of extrusion process was solved by designing an extrusion calculator and blending ratio factors. The objective of determining the effects of feed properties on extrusion failures was achieved as well as that of implementing a solution. The objective of increasing Monmouth Path’s standard soy meal/chunk conversion was partially achieved since the implemented solution is not yet measurable. Keywords: Extrusion; Feed Material; Feed Rate, Soy Meal Size; Moisture Content; Correlation The company’s prime raw material is soybeans and it is 1. Introduction processed into soy based products (cooking oil, soy chunks Extrusion is a process of central importance and wide- and oil). One of the main problems this company was facing spread application in the food industry in Zimbabwe. The was that of failures in chunk extrusion. They believed it was extensive development of extrusion technology represents caused by the feed properties and according to literature one of the most significant achievements in food process extrusion failures are caused by feed properties and extru- engineering in the last fifty years. Extrusion is done in the sion parameters (www.extrusionfactors.edu). Monmouth’s production of such products as expanded snacks, source of income is mainly boosted by soy chunks and their ready-to-eat cereals, pellets and texturized proteins products set standard soy meal conversion to chunks per each pro- for example, soy chunks (which is the main focus of this duction batch is 65%. Considering the fact that soybeans research). This research was focused on the evaluation of the cannot be grown all year round in Zimbabwe therefore any factors that cause extrusion failures and the implementation failures on chunk production will result in a depreciation of of a solution. funds throughout the phases of the end season. The com- The research was industrial based for a company called pany’s probability of sustenance went down as 0.30 in No- Monmouth Path Investment (Pvt) Ltd located in Waterfall. vember and in December and considering the fact that the International Journal of Nutrition and Food Sciences 2013, 2(2) : 60-69 61 company has experienced losses of approximately 60% due trusion cooking is a high-temperature, short -time process in to extrusion failures since it was founded. If such ope ration which moistened, expansive, starc hy and/or protenacious losses continue the company is likely to co llapse in the long food materials are plasticized and cooked in a tube by a run. combination of moisture, pressure, temper ature and me- The aim of the research was to invest igate on the effect of chanical shear, resulting in molecular tran sformation and feed properties on extrusion failures and implemen ting a chemical reactions (Havck& Huber, 1989; Castells et al., solution. The objectives of the research were to increase the 2005). set soy meal to chunk conversion standard from 65% to 80%; Extrusion is done by an extruder which is a machine to determine the effects of feed properties on e xtrusion which shapes materials or a thermostatically co ntrolled cooking process; to determine the best conditions of the feed cylinder or conical body which contains a polished, r otating properties that promote an e ffective extrusion coo king screw with a gradually decreasing pitch. According to Ha r- process; and to design a device that will help to optimize per (1979), [3] a food extruder consists of a flighted Arc- these feed properties for successful extrusion process. The himedes screw, which rotates in a tightly fitting cylindrical research was done in the favour of Mo nmouth as way of barrel. Raw ingredients are pre -ground and blended before increasing its extrusion success operations. being placed in the feeding system of the extrusion screw. This resea rch was limited to fat, moisture content tests The action of the flights on the screw push the fo od products and size of feed particles, physical extrusion operation p a- forward and in so doing, work and mix the constituents into rameter (feed rate) and not on soybean varieties and the viscous dough-like mass. chemistry behind. There are two main types of extruders namely single Extrusion screw extruders and twin-screw extruders (co -rotating and The verb "to extrude" derives from Latin word ex (out) counter rotating). At Monmouth Path they use sing le screw and trud ere (to thrust), and means to force, as through a extruders and these extruders they only have one parameter small opening or to shape a material under pressure by of control and that is feed rate. The screw seed remains forcing it through a specially designed openi ng [4] or Ex- constant and the temperature that is friction generated [14]. Figure 1 . Single Screw Extruder. Extrusion cooking is a continuous pr ocess by which food cooking, lowering water content of the feed material (soy biopolymers and ingredients are mixed, plasticized, cooked meal) results in higher viscosity, which causes throughput and formed by combination of moisture, tempe rature, rate to decrease, pressure drop to increase, and power co n- pressure, and mechanical shear. The extr usion-cooking sumption to increase. However, in extrusion of starch, gel a- process combines the effect of heat with the action of ex- tinization o ccurs more readily at higher moisture contents. trusion [5] All combinations that promote the occurrence of Soybeans are harvested at 11 to 13% moisture content and extrusion can however affect the rate of extrusion if they are can be placed directly into ordinary storage bins equipped not attained, for example, because of the temperature and with simple aeration systems [www.soybeans.umn.edu]. A moisture conditions in this extrusion process a post die e x- modern way of obtaining moisture cont ent is by using a pansion of extrudate takes place resulting in a light and moisture content analyzer. crispy product (Harper, 1979). Type of Feed Properties Extrusion cooking process is affected by two classified The type and nature of feed material, in term of protein, groups of factors which are: starch, lipid, and moisture plays a significant role on the Feed properties nature of extruded products. In addition to di fferences in Moisture Content viscosity between materials made from different grains, the Moisture is one of the key factors that affect extrusion internal structure of the extruded products is also caused by 62 P.Muredzi M. Nyahada et al .: Effects of soya bean meal feed properties on extrusion failures and implementing a solution. Case study Monmouth Path’s Investments (Pvt) Ltd, Harare, Zimbabwe different constituents. For example, adding whey proteins to range of configurations are numerous. Parameters that can grain-type extruded products will significantly alter the gel be varied in a twin-screw extruder include pitch of the screw, structure during extrusion cooking and, hence a different number of flights, root diameter, angle of pitch of the screw, product exiting the die [www.extrusionfactors.edu]. degree of intermeshing of the two screws, and the type of pH of Ingredients mixing device (www.extrusionfactors.edu). Adjusting the pH of the feed material may influence the Screw Speed state of proteins during extrusion and thus influence physical Screw speed affects the degree of fill within the screw, characteristics of the final product. Study has shown that residence time distribution of product flowing through the increasing pH in the 5.5-7.5 range results in an increase in extruder, heat transfer rates and mechanical energy input in volatile compounds in cystein/reducing sugar/starch mixture the extruder, and the shear forces exerted on the materials.
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