Characterization of the biochemical variability of bovine milk using metabolomics

Abstract

Bovine milk contains a complex mixture of metabolites, which were identified by liquid and gas chromatography mass spectrometry methods. With the aid of new software methods, spectral assignment was carried out, enabling the identification of 223 metabolites. Those included amino acids, lipids, carbohydrates, nucleotides, energy metabolites, vitamins, cofactors and short peptides. Metabolite concentrations were compared between 10 bovine milk varieties, differing in brand, fat content, expiry date, package type and farming method. Principal components analysis showed a clear separation of the different milk varieties. Whole milk could be distinguished from reduced fat and fat free milk by higher lipid metabolites like free fatty acids, cholesterol and 1,2-dipalmitoylglycerol. But also, the reduced fat varieties had lower levels of vitamin E. In comparing organic to conventional milk, 14 named metabolites were statistically different between the two farming methods. This shows the potential of identifying farming-method-specific biomarkers upon analysis and validation of a larger sample size. Finally, high biochemical variability was shown in conventional whole milk derived from different producers. The distinct biochemical profiles of milk varieties shows the utility of metabolic profiling for authentication of milk varieties, and for deriving potential markers that can serve as signatures for a particular milk.

Using metabolomics to describe food in detail

“…The aforementioned study from Boudonck et al (2009) found further differences in milk due to the reduction of fat content. Nowadays, more and more food products are subject to many transformation steps and processes, which might alter their nutritional, sensory, and biochemical properties.…”

“…The impact of different rearing conditions on the quality of bovine milk was investigated by Boudonck et al (2009), through the use of GC-MS and LC-MS/MS metabolomics, followed by unsupervised data analysis (PCA). Ten different types of bovine milk were analysed.…”

Metabolomics reveals unhealthy alterations in rumen metabolism with increased proportion of cereal grain in the diet of dairy cows

“…To our knowledge, only a few studies have used modern metabolomics techniques to address nutritional issues in ruminant animals. One study looked at the effects of intra-ruminal infusion of SCFA in non-lactating heifers (Bertram et al 2005), another study investigated the metabolism of rumen epithelial tissue of newborn calves (Bertram et al 2009), and a third study used metabolomics to look at the quality of marketed milk (Boudonck et al 2010). Recent research has also shown that metabolomics can be used to characterize metabolic profiles at the gut level.…”

Recipe for revealing informative metabolites based on model population analysis

“…Up to date, the statisticians or chemometricians or biologists have developed a large number of methods (Golub et al 1999;Madsen et al 2010;Tibshirani 1996;Wongravee et al 2009;Zou and Hastie 2005) which can be utilized to reveal the informative metabolites, of which the changes may reflect the potential metabolic disorder in the living systems (Bertram et al 2009;Boudonck et al 2009;Crews et al 2009;Graham et al 2009). To identify the informative metabolite, a criterion will usually be first defined and then employed to assess the importance of the metabolite under investigation.…”