Application of Hand-Held and Portable Infrared Spectrometers in Bovine Milk Analysis

Abstract

A simple and fast method for the detection and quantification of milk adulteration was developed using portable and hand-held infrared (IR) spectrometers. Milk samples were purchased from local supermarkets (Columbus, OH, USA) and spiked with tap water, whey, hydrogen peroxide, synthetic urine, urea, and synthetic milk in different concentrations. Spectral data were collected using mid-infrared (MIR) and near-infrared (NIR) spectrometers. Soft independent modeling of class analogy (SIMCA) classification models exhibited tight and well-separated clusters allowing the discrimination of control from adulterated milk samples. Partial least-squares regression (PLSR) was used to estimate adulteration levels, and results showed high coefficients of determination (R(2)) and low standard errors of prediction (SEP). Classification and quantification models indicated that the tested MIR systems were superior to NIR systems in monitoring milk adulteration. This method can be potentially used as an alternative to traditional methods due to their simplicity, sensitivity, low energy cost, and portability.

Common milk adulteration and their detection techniques

“…In a case study performed in Brazil, urine was detected in all samples of UHT milk by following a chemometric approach (Souza et al 2011). Presence of synthetic urine up to the concentration of 0.78 mg/L of milk can be identified by a method using infrared microspectroscopy and chemometric analysis (Santos et al 2013b). Similar approach has been reported to be used in developing a portable and hand-held infrared spectrometer for milk analysis (Santos et al 2013c).…”

“…In a comparative experimental study between NIR and MIR (Medium Infra Red) spectroscopy, Santos et al (2013a) developed a portable spectrometer and commented that MIR performed better than NIR to detect the adulterants such as tap water, whey, hydrogen peroxide, synthetic urea and urine. Like urea, synthetic urine is also used in milk to increase the nitrogen content.…”

Detection and quantification of milk adulteration using time domain nuclear magnetic resonance (TD-NMR)

“…PLSR models developed using different NIR and MIR spectrometers showed RMSEP values ranging from 0.83 to 4.74% [27]. Similarly, PLSR models obtained with digital image showed a RMSEP of 5.85% [28].…”

A Low-Cost Video-Based Reflectometer for Selective Detection of Cu2+ Using Paper-Based Colorimetric Sensors

“…1 These instruments are useful and advantageous, especially due to the low cost, simplicity of operation, convenience of fast in situ analysis and appropriate sensitivity and specificity to produce near realtime information used to solve specific problems which require rapid feedback of information. 2 Examples of portable instruments based on ion trap mass, 3 Raman, 4 near infrared 5 and mid-infrared 6 spectroscopies, capillary electrophoresis [7][8][9][10][11] and X-ray fluorescence 12 represent the tendency of instrument miniaturization for sensing applications. In case of miniature ion trap mass spectrometry, which represents a high breakthrough in portable analytical instrumentation, two approaches can be used to build this kind of instrument: the bottom-up approach in which the miniature instrument is assembled with the components built on a specific scale of interest; and the top-down approach, in which the component sizes of a macroscale instrument are reduced in an interactive way to maintain their performance.…”