Department of Animal Science, College of Veterinary Science, Tirupati517502, India
Online published on 20 January, 2012.
Trials were conducted to optimise conditions for Salurea-90 production in S-40 L cooker extruder in two experiments. In experiment 1, six products were extruded at three exit temperature ranges from 116 to 120, 121 to 125 and 126 to 130°C, and two die sizes 4 to 6 mm. Die size (P < 0.05) or die size x exit temperature (P < 0.01) showed significant effect on swelling potential of the product. In experiment 2, twenty seven extruded products were produced at moisturisation levels (M) of 14, 16 or 18 per cent; screw speeds (S) at 300, 350 or 400 rpm and feeder rate (F) of 6, 8 or 10 rpm to further optimise the conditions for extrusion cooking. The factors M (P < 0.01), F (P < 0.01) and the interactions of M X F (P < 0.05), S x F (P < 0.01) and M x S x F (P < 0.01) had a significant effect on swelling potential. The NH3-N production was significantly influenced by M (P < 0.01), S (< 0.10) and F (P < 0.01) and the first and second order interactions (P < 0.01). Synthesis of microbial protein was also significantly influenced by the main effects, M, F and the interactions M x F, M x S and M x S x F (P < 0.01).
A moisture level of 16 per cent, screw speed of 350 rpm and the feeder rate of 10 rpm with a die size of 6 mm and an exit temperature of 116-120°C were found to be optimum for extrusion cooking deoiled salseed meal (DOSSM) and urea mix (Salurea-90). The product on extrusion cooking showed increased swelling potential (P < 0.05) by 1.8-fold, reducing activity (P < 0.05) by 2.79-fold, microbial protein synthesis (P < 0.01) by 3,4-fold and significantly lowered (P < 0.01) in vitro NH3-N production.
