Milk analysis authenticity

Fatty acid analysis of a fat is nowadays a relatively routine analytical operation. After methylation of the fat using reaction with boron trifluoride/methanol, boron trichloride/methanol, methanolic hydrogen chloride solution, diazomethane or, if free fatty acids are not present, alkaline catalysts such as sodium methoxide/methanol, the prepared methyl esters are then analysed by GC on a polar column such as CpSil 88, BPX70 or SP2340. The high polarity of the column is necessary to separate the saturated and unsaturated fatty acids fully. The fatty acid composition of a milk fat sample is thus relatively easily obtained, and was therefore one of the first techniques investigated for authentication purposes. 

Lercker, G., Frega, N., Bocci, F. and Bertacco, G. (1992) Milk fat. Gas chromatographic analysis of triglycerides in assessment of authenticity of butter. Scienza Tecnica Lattiero Casearia, 43, 95-110. 

Different protein-based methods have been reviewed for species identification in milk and dairy products, and for characterization of cheese maturity, such as electrophoretic, chromatographic, and immunological techniques (11, 12). In addition to new developments in these techniques, the interdisciplinary and dynamic nature of milk product analysis is being enhanced by the application of disciplines already used to analyze other foodstuffs. Among them, capillary electrophoresis (CE), polymerase chain reaction, and isotope ratio mass spectrometry are just gaining popularity for solving dairy authenticity problems (13-15). 

The separation of dairy proteins by CE has been generally carried out by CZE and has been exhaustively covered in several review papers, - - thus Table 30.8 only presents the key methodologies that offer the reader an overview of their most distinctive features. Basically, dairy protein analysis has been performed in whole milk for the simultaneous determination of caseins and whey proteins, or in fractions isolated from milk after casein precipitation. The first approach being used when the quantitative determination of the major proteins is required for the calculation of casein/whey protein ratios or for authentication purposes where an analysis of the whole protein profile is required. In both cases, accurate quantitative data must be derived. However, few studies have addressed the analysis of both groups of proteins in a single run by presenting quantitative data based on calibration curves constructed with analytical standards and good recovery of all proteins from milk samples. 

Authentication and the detection of adulteration are serious problems within the citrus juice industry. Traditional multicomponent analysis methods are limited by the time required to perform the individual analyses and to construct the database required. Py-MS rapidly provides fingerprints of the original juice, which facilitates the use of multivariate pattern recognition procedures to detect potentially adulterated samples and to confirm authentication, as weU as helping in quality control. More recently, the combination of Py-MS and ANNs has been applied to problems of adulteration within the olive oil industry, shellfish, and milk. ... 

Hrbek V Vaclavik L, Elich O, et al. Authentication of milk and milk-based foods by direct analysis in real time ionization-high resolution mass spectrometry (DART-HRMS) technique a critical assessment. Food Control. 2014 36 138 5. 

Louren o, M., G. Van Ransl, B. Vlaeminck, S. De Smet and V. Fievez, 2008. Influence of different dietary forages on the fatty acid composition of rumen digesta as well as ruminant meat and milk. Anim. Feed Sci. Technot 145,418-437. Spangenberg, J.E., S.A. Macko and J. Hunziker, 1998. Characterization of olive oil by carbon isotope analysis of individual fatty acids bnpUcations for authentication. J. Agric. Food Chem. 46,4179-4148. 

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