Raman-spectroscopy-based chemical contaminant detection in milk powder

Abstract

Addition of edible and inedible chemical contaminants in food powders for purposes of economic benefit has become a recurring trend. In recent years, severe health issues have been reported due to consumption of food powders contaminated with chemical substances. This study examines the effect of spatial resolution used during spectral collection to select the optimal spatial resolution for detecting melamine in milk powder. Sample depth of 2mm, laser intensity of 200mw, and exposure time of 0.1s were previously determined as optimal experimental parameters for Raman imaging. Spatial resolution of 0.25mm was determined as the optimal resolution for acquiring spectral signal of melamine particles from a milk-melamine mixture sample. Using the optimal resolution of 0.25mm, sample depth of 2mm and laser intensity of 200mw obtained from previous study, spectral signal from 5 different concentration of milk-melamine mixture (1%, 0.5%, 0.1%, 0.05%, and 0.025%) were acquired to study the relationship between number of detected melamine pixels and corresponding sample concentration. The result shows that melamine concentration has a linear relation with detected number of melamine pixels with correlation coefficient of 0.99. It can be concluded that the quantitative analysis of powder mixture is dependent on many factors including physical characteristics of mixture, experimental parameters, and sample depth. The results obtained in this study are promising. We plan to apply the result obtained from this study to develop quantitative detection model for rapid screening of melamine in milk powder. This methodology can also be used for detection of other chemical contaminants in milk powders.

Rapid Detection of Nonprotein Nitrogen Adulterants in Milk Powder Using Point-Scan Raman Hyperspectral Imaging Technology

“…Due to the adulteration of milk powder with illegal additives, the quality and safety of dairy products has become a hot topic of public concern . There are many methods of detecting illegal additives in milk powder, such as the fluorescence probe method, , colorimetry, , ultra-performance liquid chromatography/liquid chromatography-tandem mass spectrometry (UPLC/LC-MS), − nuclear magnetic resonance (NMR) spectroscopy, − and electrochemical methods. , These methods are generally time-consuming and complex, and the instruments are bulky and immobile; thus, these techniques are not suitable for rapid real-time screening of large batches of samples at port sites. Spectral imaging is a rapid nondestructive testing method that combines spectroscopy, computers, digital image processing, and other technologies.…”