The effect of barrel temperature, added moisture, flow rate and steam pressure on pellet quality
of expander extruder processing of two sunflower heads based complete diet varying in roughage
proportion was studied. The product physical characterization was made by measuring moisture
content in hot pellets, maximum load force in a puncture test and physical evaluation. The two
complete diets were containing 40 and 50% sunflower heads (SFH) in a roughage concentrate ratio
of 40:60 and 60:40, respectively. Smooth, soft and shiny pellets were obtained from 40% SFH
based diet when steam was added at a pressure of 0.6kg/cm2 to the mash having moisture of 13.0%,
with the barrel temperature of 85oC. The moisture content in resulting hot pellets was 17.8% and
pellet strength of 74.67 N. Increasing the steam pressure beyond 1.0kg/cm2 increased the moisture
content in pellets and was of poor quality. Compared to the pelleting of 40% SFH based diet, higher
steam pressure (1.0-1.2 kg/cm2) was required for getting good pellets from pelleting of 50% SFH
diet. The pellets extruded at the above steam pressure were smooth, shiny with moisture content
between 15.76 and 17.0% and pellet strength between 63.2 and 74.3N. But further increasing the
steam pressure in mash resulted in pellets with high moisture and poor strength with rough surface. Feeding of expander extruder processed SFH diets to adult buffaloes indicated that DM and CP intakes were higher when fed 40% SFH diet compared to 50% SFH diet. The study indicated that the flow rate, steam pressure, temperature affected the pellet quality of SFH based diets. The proportion of roughage in the complete diets affected the processing conditions, the 50% SFH diet required higher steam pressure (1.0-1.2kg/cm2) than 40% SFH diet (0.6-1.0kg/cm2).