Tropentag, October 5 - 7, 2004 in Berlin "Rural Poverty Reduction through Research for Development and Transformation"

Effect of Extrusion and Microwave Techniques on Nutrient Quality of Soybean in Piglet Diets

Chiang Mai University, Department of Animal Science, Thailand

Abstract

This study was conducted in Thailand to investigate the effect of microwave and extrusion techniques on nutrient quality of soybean. Soybeans were treated by microwave at 55 and 85ºC. Extrusion was also carried out at 110ºC. There were no treatment differences on dry matter, ash, crude protein, ether extract, crude fibre and nitrogen free extract. Microwave heat treatment did not affect the fatty acid composition. However, the microwave heat treatment activated the peroxidase, which resulted in an increase in lipid splitting enzymes as shown by the higher content of malondialdehyde compared to the extrusion treatment. Increasing the temperature from 55 to 85ºC by microwave and using 110ºC by extruder technique resulted in decreased trypsin inhibitor content (24.12, 19.61 and 9.54 TIU mg^-1 respectively). The results of feeding trial with 24 piglets at the University farm indicated that the temperatures at 55 and 85ºC of microwave treatment were not high enough to destroy all the trypsin inhibitor in soybean. The production performance based on average daily gain and feed conversion ratio of the piglets fed with microwave treated soybean at 55 and 85ºC were less (P<0.01) than those of the piglets fed extruder soybean treated at 110ºC and soybean meal supplemented with soybean oil (0.20, 0.23, 0.40, 0.43 kg d^-1 and 3.68, 3.26, 2.01 and 1.73 respectively). As it can seen out of the results microwave technique can be used as a source of energy to destroy trypsin inhibitor in soybean but the temperature should be increased to that of the extrusion technique.

Keywords: Extrusion, microwave, oil quality, performance, piglet, production, trypsin inhibitor

Contact Address: Therdchai Vearasilp, Chiang Mai University, Department of Animal Science, Huay Kaew Road, 50200 Chiang Mai, Thailand, e-mail: agitvrslchiangmai.ac.th