Rapid Liquid AP-MALDI MS Profiling of Lipids and Proteins from Goat and Sheep Milk for Speciation and Colostrum Analysis.

Cristian Piras,Carlotta Ceniti,Nicola Costanzo,Paola Roncada,Domenico Britti,Rainer Cramer,Evita Hartmane,Valeria Maria Morittu

doi:10.3390/proteomes8030020

Abstract

Rapid profiling of the biomolecular components of milk can be useful for food quality assessment and for food fraud detection. Differences in commercial value and availability of milk from specific species are often the reasons for the illicit and fraudulent sale of milk whose species origin is wrongly declared. In this study, a fast, MS-based speciation method is presented to distinguish sheep from goat milk and sheep colostrum at different phases. Using liquid atmospheric pressure (AP)-matrix-assisted laser desorption/ionisation (MALDI) MS, it was possible to classify samples of goat and sheep milk with 100% accuracy in one minute of data acquisition per sample. Moreover, an accuracy of 98% was achieved in classifying pure sheep milk samples and sheep milk samples containing 10% goat milk. Evaluating colostrum quality and postnatal stages represents another possible application of this technology. Classification of sheep colostrum samples that were collected within 6 hours after parturition and 48 hours later was achieved with an accuracy of 84.4%. Our data show that substantial changes in the lipid profile can account for the accurate classification of colostrum collected at the early and late time points. This method applied to the analysis of protein orthologs of different species can, as in this case, allow unequivocal speciation analysis.

Highlights

Production and consumption of goat and sheep milk are increasing worldwide due to their nutritional and antiallergenic properties [1]
This work demonstrates the efficacy of liquid atmospheric pressure (AP)-matrix-assisted laser desorption/ionisation (MALDI) mass spectrometry (MS) profiling for the fast classification of milk from different species and of mixtures through the recording of the milk’sprotein MS
Profiles as well as the detected orthologs of single proteins within these profiles. This profiling method has the potential to be applied in several areas of the food and zootechnical industry, from the detection of adulterations to food quality and nutritional assessment

Summary

Introduction

Production and consumption of goat and sheep milk are increasing worldwide due to their nutritional and antiallergenic properties [1]. Increasing demand, differences in commercial value and the (seasonal) availability of milk originating from different species can promote the fraudulent sale of adulterated products both for direct consumption and for cheesemaking [2,3]. Analyses of proteins and proteoforms for profiling purposes employing capillary electrophoresis [6], two dimensional electrophoresis [7] and HPLC [8] have previously been reported. These methods, are quite time consuming (at least 1 hour) due to the electrophoretic or chromatographic separation. Colostrum tends to be richer in proteins and lipids than milk

Methods

Discussion

Conclusion