MALDI-TOF mass spectrometry for the monitoring of she-donkey’s milk contamination or adulteration

Donkey’s milk (DM), representing a safe and alternative food in both IgE-mediated and non-IgE-mediated cow’s milk proteinallergy, can be categorized as precious pharma-food.Moreover, an economically relevant interest for the use ofDMin cosmetologyis also developing. The detection of adulterations and contaminations of DM is a matter of fundamental importance from both aneconomic and allergenic standpoint, and, to this aim, fast and efficient analytical approaches to assess the authenticity of thisprecious nutrient are desirable. Here, a rapid matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry(MALDI-TOF MS)-based method aimed to the detection of bovine or caprine milk in raw DM is reported. The presence of theextraneous milks was revealed by monitoring the protein profiles of the most abundant whey proteins, a-lactalbumin (a-LA)and b-lactoglobulin, used as molecular markers. The possibility of obtaining a quantitative analysis of the level of cow or goatmilk in DMbased on theMALDI-TOF peak areas of a-LAs was also explored. The results showed that the experimental quantitativevalues were in good agreement with the real composition of each mixture. As pretreatment of the milk samples is not required,and owing to the speed and the high sensitivity of MALDI-MS, the protocol here reported could represent a reliable method forroutine analyses aimed to assess the absence of contamination in rawfresh DM samples.