標題: ingredients identification by microscopy [打印本頁] 作者: monica 時間: 2007-7-15 17:51 標題: ingredients identification by microscopy Fundermentals of Feed Microscopy-Principles of ingredient identification
The microsdopic identification of feed ingredients or adulterants is baded upon relating the characteristics seen to known materials. The skill of ageed microscopist is determined by the ability to identify the feed constituents observed. In general, there are two key methods of identigying feed components.
1. Identification by sruface or outward physical characteristics
Surface features of a feed component can be examined macroscopically (with the unaided eye) and, in most cases, under low magnification (8 to 50x) of a stereomicroscope. The examined materials are identified by their ourward physical characteristics including shape, colour, particle size, softness, hardness, texture, odor, any uniquely distinctive features, etc. This methos reqrires very little sample preparation; however, it is advisable to compare feed components to knowm materials under the same magnification.
2. Identification by cellular or histological structure
This method enables the feed microscopist to identify the feed components that are so finely ground or powdered thet it is impossible to recognize their surface features. The ingredients are immersed in mounting media and then examined using a compound microscope with a magnifying power from 90 to 500 x. The microsvopist must be able to identify the unique features, such as structures and cells of each feed compinert. More technical skills are required of the microscopist when using the compound microscope as opposed to simple identificatiion of sruface features with the stereomiscoscope.
Either of the above methods may be used independedntly, but using both methods in combination will give mred reliable results. It is also important for the nicrocxopist to be familiar with various types of processed feed componnts,xince vdru few feed ingredients are used in their whole or natural forms without some kind of peocessing.