Comprehensive analysis of goat milk oligosaccharides

Resumen del trabajo presentado al XVI Scientific Meeting of the Spanish Society of Chromatography and Related Techniques, celebrado en Sevilla (España) del 2 al 4 de noviembre de 2016.Goat milk is known to contain oligosaccharides (OS) structurally similar to those present in human milk and in higher concentrations than milks from other mammals. Different beneficial properties, such as prebiotic and anti-inflammatory effects or modulation of the immune system have been attributed to these carbohydrates. It is know that goat milk oligosaccharides (GMO) are complex structures with different glycosidic linkages, degrees of polymerization and monomeric composition. Since bioactive properties are directly related to the chemical structure, there is a high interest in the study of these OS. However, little information about their detailed structures, concentrations and evolution during different lactation stages is available. Hydrophilic interaction liquid chromatography (HILIC) is a powerful technique for the analysis of OS, providing an appropriate resolution and good peak shapes. Also, in recent years, the use of nano-liquid chip-based technologies mainly coupled to mass spectrometry (MS) or tandem MS (MS/MS) techniques have demonstrated to be extremely helpful for OS identification and it has been applied to milk characterization due to its high sensitivity and ability for compositional verification. In this work, a methodology for the comprehensive characterization of GMO was developed. Goat colostrum samples were initially selected for methodoptimization since they are expected to have higher OS amounts than mature goat milk. Defatted and deproteinized milk samples, previously treated by size exclusion chromatography (SEC) to remove lactose, were analyzed by nanoflow liquid chromatography-quadrupole-time of flight mass spectrometry (Nano-LC-Chip Q-TOF MS). Up to 78 oligosaccharides were identified. As a second step, a hydrophilic interaction liquid chromatography coupled to mass spectrometry (HILIC-MS) methodology was developed for the separation and quantitation of the main OS, both acidic and neutral carbohydrates. The developed methodology was used for a detailed study of the evolution of GMO at different stages of lactation and different trends were observed depending on the type OS (acidic or neutral). To the best of our knowledge, this is the first time that a comprehensive characterization of GMO has been carried out.Peer Reviewe