Detection of recombinant bovine somatotropin in milk and effect of industrial processes on its stability.
A LC-MS/MS method has been developed for the direct detection of recombinant bovine somatotropin (rbST) in milk and dairy products. The sample preparation protocol is based on a solid phase extraction step followed by precipitation with cold methanol and enzymatic digestion. The analysis is focused on the tryptic N-terminal peptide, specific of the recombinant form of the hormone and the detection is performed by LC-ESI(+)-MS/MS. This method has been validated according to the European Union criteria described in the Directive 2002/657/EC. Acceptable performances, with a decision limit (CCalpha) of 1.24 ng mL(-1) and detection capability (CCbeta) of 1.92 ng mL(-1) were obtained. Calculation of repeatability and intermediate reproducibility of the signal at 100 ng mL(-1) lead to relative standard deviations lower than 20%, showing the robustness of the method. Samples subjected to various industrial processes namely, heating, freezing, defatting, pasteurization and spray-drying were then analysed in order to determine the consequences of these treatments on the stability of the hormone. Results showed that temperature related processes, such as pasteurization and spray-drying induce a loss of the hormone up to 95%.
Le Breton
Marie-Hélène
MH
Nestlé Research Center, Nestec Ltd., P.O. Box 44, CH-1000 Lausanne 26, Switzerland. marie-helene.le-breton@rdls.nestle.com
Beck-Henzelin
Andrea
A
Richoz-Payot
Janique
J
Rochereau-Roulet
Sandrine
S
Pinel
Gaud
G
Delatour
Thierry
T
Le Bizec
Bruno
B
D000818:Animals; D002417:Cattle; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D013006:Growth Hormone / Q000032:analysis*; D013058:Mass Spectrometry / Q000379:methods*; D008892:Milk / Q000737:chemistry*; D055550:Protein Stability
D013006:Growth Hormone