Species identification of gelatines in yoghurt and dairy desserts by UPLC-ESI-Q-TOF-MS

Nessen, M.A.; Zoontjes, P.W.; Wubs, K.L.; Blokland, M.H.; Alewijn, M.; Ruth, S.M. van


Introduction: The use of unspecified gelatines in food products is a problem for people with specific diet wishes, such as people with an allergy, a specific religious background or a vegetarian diet. Accurate and truthful labelling of the source of gelatin is therefore needed and this requires a robust method that can identify and discriminate between the gelatines derived from different animal species. Methods: In this study a generic ultra performance liquid chromatography - electrospray - time of flight mass spectrometry (UPLC-ESI-QToF-MS) method for protein identification was used to identify gelatines in fruit yogurt and (dairy) desserts. The amino acid sequence of collagen differs between species, which allows identification of the source of the gelatin used in food products. Gelatin was extracted and enriched from the dairy products and subjected to trypsin digestion. After reversed solid phase extraction of the peptide mixture, samples were analysed by UPLC-ESI-QToF-MS/MS. Identification of the gelatines was done by data analysis using Mascot. Results: Fifteen yogurts, obtained from various retailers in the Netherlands, declared with and without gelatin, were analysed for gelatin content. It was found that six products did contain the gelatin as was declared on the product: two contained bovine gelatin, one contained porcine gelatin and three did not contain gelatin. Out of the nine products with unspecified gelatin, six contained gelatin from bovine source, two from porcine source and in one product no gelatin could be detected. Conclusion: This study shows the applicability of an LC-MS/MS method for the identification of gelatin from porcine or bovine source in dairy products. Further research on the gelatin extraction from different (processed) food products might allow extension of the method to other gelatin containing (food) products, such as different types of candy, (canned) meat products or pharmaceuticals, allowing accurate control of product authenticity.