Speciation and milk adulteration analysis by rapid ambient liquid MALDI mass spectrometry profiling using machine learning

Abstract

Growing interest in food quality and traceability by regulators as well as consumers demands advances in more rapid, versatile and cost-effective analytical methods. Milk, as most food matrices, is a heterogeneous mixture composed of metabolites, lipids and proteins. One of the major challenges is to have simultaneous, quantitative detection (profiling) of this panel of biomolecules to gather valuable information for assessing food quality, traceability and safety. Here, for milk analysis, atmospheric pressure matrix-assisted laser desorption/ionization employing homogenous liquid sample droplets was used on a Q-TOF mass analyzer. This method has the capability to produce multiply charged proteinaceous ions as well as highly informative profiles of singly charged lipids/metabolites. In two examples, this method is coupled with user-friendly machine-learning software. First, rapid speciation of milk (cow, goat, sheep and camel) is demonstrated with 100% classification accuracy. Second, the detection of cow milk as adulterant in goat milk is shown at concentrations as low as 5% with 92.5% sensitivity and 94.5% specificity.

LAP-MALDI MS coupled with machine learning: an ambient mass spectrometry approach for high-throughput diagnostics

“…Positive ions were recorded over an m/z range of 100-2000. External TOF calibration was performed manually by AP-LDI MS as previously described, 23 using sodium iodide, an acquisition time of 3 min with an m/z range of 100-2000 and Intellistart soware (MassLynx™; Waters). All samples were analysed with an acquisition time of 1 min.…”

Automated Milk Quality Analyzer with Billing System

“…https://dx.doi.org/10.22161/ijeab.74. 17 157 temperature in air. Then, free electrons from tin oxide are influenced by the oxygen, thus arresting the current flow.…”

“…https://dx.doi.org/10.22161/ijeab.74. 17 155 change in resistance produced by the fat content in milk.…”

Identification of milk from different animal and plant sources by desorption electrospray ionisation high-resolution mass spectrometry (DESI-MS)

“…Innovation in new ionisation sources, and the ongoing development of existing technologies provide ever more possibilities for the identification of milk fraud. Matrix-assisted laser desorption/ionisation-time of flight mass spectrometry (MALDI–TOF MS) has been adapted to profile differences in milk chemical compounds from different mammalian species 34 – 36 and for the discrimination of plant-based milk from cow milk. However, sample pre-treatment and MALDI matrix chromophore preparation procedures are complex, which is an issue when attempting to develop rapid MALDI screening workflows.…”