Effect of the extrusion process of corn semolina and pea hulls blends on chemical composition and selected physical properties of the extrudate
A. Sobota 1
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Engineering and Cereals Technology Department, University of Life Sciences, Skromna 8, 20-704 Lublin, Poland
Int. Agrophys. 2009, 23(1): 67–79
A study was conducted on the process of extrusion of blends of corn semolina and pea hulls to determine the effect of the share of high-fibre material and of parameters of the process of extrusion eg extruder barrel temperature and material moisture content, on the solubility of dry matter, viscosity, and content of fundamental chemical components – proteins, fats, and dietary fibre in the extrudates. Detailed analysis were performed for changes taking place in the dietary fibre fractions. Also analyzed were changes in the content of total dietary fibre as determined with the enzymatic method, including the fractions of soluble dietary fibre and insoluble dietary fibre. The study showed that extrusion cooking leads to a reduction in the content of crude fibre and free fats, and to a slight reduction in the level of proteins in the processed material. No significant changes were observed in the content of ash. Extrusion cooking resulted in decreased content of neutral-detergent fibre, acid-detergent fibre and cellulose fractions; at the same time a reduction was observed in the content of insoluble dietary fibre and an increase in the content of soluble dietary fibre fractions. It was found that intensive parameters of the process of extrusion (low moisture content of material and high process temperature) resulted in increased water solubility index values for the extrudates. The highest viscosity (after heating and cooling of suspension to 20°C) was characteristic of products obtained with the application of process temperature of 125°C.