3. Results
The extrusion process characteristics are based on the measurements of the basic parameters of extrusion during its optimal operation. The results presented here are the outcomes of a series of preliminary tests with various parameters. Similar parameters was tested during extrusion of pasta and wheat flour by other authors (Abecassis etal. 1994, Andersson, Hedlung 1990, Arhaliass et al. 2009, Chinnaswamy , Hanna 1988).
The resulting extrudates were characterized by final moisture content below 8%. The highest hardness was obtained by subjecting to extrusion a mixture of unhulled soya bean meal with corn, while introducing meal of hulled soya bean resulted in extrudates with about 70% lower hardness. A similar correlation was obtained when measuring the cutting strength in relation to the respective meal compounds. The value of the cutting strength decreased by circa 50%.
From the analysis of the results obtained for the extrudates of mixtures with wheat and corn with addition of soya bean grains, it can be concluded that both the cutting strength and the hardness of the extrudates was higher in the case of corn compound.
The greatest ratio of expansion was achieved for the extrudates of wheat and unhulled soyabean compound.
The extrudates with admixture of wheat were characterized by the lowest kinetic strength of 50.4% for hulled soya bean and 45% for unhulled soya bean. At the same time, the extrudates with corn admixture had kinetic strength of 82%, regardless of whether hulled or unhulled soya bean has been added.