Chemical Analysis 101: Measurement Of Consituents In Food ProductsSource: Thermo Scientific Product Inspection
While having conversations with some of our representatives around the world there seems to be, in some cases, a lack of knowledge as to what primary methods the food industry presently uses to determine certain constituents and the TEV (Total Existing Variance) or lab precision of those primary methods. I will also touch on the accreditation of the methods that are discussed which is important.
Dairy foods are somewhat unique in the measurement of fat as the fat molecule or globule takes a special process to extract for the determination of the content of fat in a sample. Methods used are the Gerber method along with the more automated method using the basic premises, Mojonnier, are the primary methods approved by IDF (International Dairy Federation) NCIMS (National Conference on Interstate Milk Shipments, a US regulatory group associated with the FDA) and AOAC (Association of Official Analytical Chemists). The method uses ether extraction to separate the fat from the other constituents in the milk which takes several steps and from 15-20 minutes for a complete analysis. Most laboratories will have many tests run at once so the technician is processing new samples as the other samples are running through the hydrolysis. Accuracy or TEV for milk from skim or almost 0 fat to approximately 4% butterfat is 0.01%-0.02%. Cream at 40% fat the TEV would be around 0.2%-0.4%.