Preparation And Quality Evaluation Of Aspergillus Niger Phytase Pellets

Phytase serves as a biological feed additive for elevating the utilization level of phosphorus in feed, improving performance of animal production, and reducing environmental water pollution caused by the high-phosphorus dejection of animal. But the application and spread of phytase have been limited in China because of its poor antireversion force, especially its poor thermal stability. In this thesis, we prepared a kind of pellet of phytase of Aspergillus niger with good thermal stability using advanced technology of pharmaceutical preparations, and evaluated its quality. This study was designed to prepare a kind of phytase pellets of Aspergillus niger which have a good thermal stability by applying of advanced technology of pharmaceutical preparations.The activity of phytase pellets were quantified by vanadium-ammonium molybdate method. The results of intra-day and inter-day precision, recovery and sample determination were satisfying, proving that this method is a scientific, reliable and simple method for quantitative analysis of phytase, and can be used for activity determination of the phytase pellets during inspection of preparation and stability.We prepared phytase prime pellets possessing smooth surface, good roundness, small-friability, uniform particle size by using extrusion-spheronization method with high yield. The good liquidity of the obtained pellets was in favor of its mixing into feed pellets and applying into actual production. Liquidity of pellets was good, so it is conducive to mixing into feed pellets and applying into actual production.Phytase coated pellets were prepared by coating phytase prime pellets using bottom-spray type fluidized bed. The relative residual activity of phytase coated pellets treated with steam heat-moisture at 100℃for 2min served as the main inspection indicators. We determined the coating prescription by selecting the manner of coating, coating material of every layer and the total weight as well as weight ratio of coating layer according to actual production requirements and studied the effect of process factors on thermal stability of phytase coated pellets. The results showed that quality and character study of phytase coated pellets met the requirements, the phytase coated pellets had uniform activity, suitable particle size, high yield and good process reproducibility, and preparation process of phytase pellets of Aspergillus niger was stable, reliable and could be applied to the actual production.The quality of phytase coated pellets was evaluated by referring the method of drug stability in pharmaceutical preparations. A more detailed inspection of the heat resistance of phytase was carried out including the resistance to dry heat, damp heat and stability of feed processing condition test. Heat resistance tests showed that the resistance of phytase coated pellets against dry and damp, especially anti-damp-heat ability was excellent and the relative activity was significantly higher than that of uncoated pellets in the stability of feed processing condition test. Results of the tests of stability including influence factors indicated that phytase coated pellets should be stored in the airtight container and in dark under low temperature.