Stabilisation and encapsulation studies on xylanase for animal feed improvement

Pig and poultry feeds contain materials that are derived from plant and animals. Most of the plant materials are indigestible because they contain non-starch polysaccharides and as a result the animal suffers from anti-nutritional effects. To reduce the anti-nutritional effects, a number of enzymes, including xylanase, are added to the feed to break down the non-starch polysaccharides. Prior to ingestion, the feed must be processed to destroy any microbial contaminants. As a consequence of this action, the enzymes become inactivated due to the high temperatures of processing. The aim of this project was to improve the quality of the feed by preventing the degradation of enzymes during processing. In order to carry out a thorough investigation to improve the stability of xylanase, a full characterisation profile was determined first. The denaturation of xylanase when exposed to stressful conditions was monitored by circular dichroism spectroscopy. In most occasions, in the presence of low molecular weight additives, xylanase had enhanced activity and improved structural stability. Stabilisation by immobilisation on two support materials such as modified silica and chitosan improved the thermal stability of xylanase. Conditions typically reproduced within a processing cycle were used to investigate the stability of the immobilised xylanase. Microencapsulation of xylanase was also carried out by spray drying with stabilising polymers and by phase separation methods. The enzyme activities following each formulation were determined. The morphology of the microspheres produced was examined using scanning electron microscopy.