Laser-induced breakdown spectroscopy for food authentication

With the globalisation of food markets, food authentication has become a significant concern worldwide to ensure food safety and to avoid origin and quality fraud. A multi-elemental fingerprint is a powerful tool for detection of adulterants and geographical origin of foods. Laser-induced breakdown spectroscopy (LIBS) is a promising technique that can provide a mineral fingerprint of food products. LIBS allows a rapid, high-throughput, micro-destructive and multi-elemental analysis of a wide range of samples type. It has already been demonstrated by several authors that LIBS can be successfully used for food authentication. Although LIBS shows excellent potential for at-line or portable applications, improvement in sensitivity of trace elements detection, sample preparation, data analysis and instrument miniaturisation are needed

Rapid analysis of magnesium in infant formula powder using laser-induced breakdown spectroscopy

Laser-induced breakdown spectroscopy (LIBS) was investigated to determine magnesium (Mg) content in infant formula powder. To predict Mg content in the range established by the Codex Alimentarius, a partial least squares regression (PLSR) model was developed using a calibration data set (n = 30) based on full cross-validation and validated using an independent validation data set (n = 21). The prediction model performance was evaluated using the regression coefficients of determination (Rcv2 = 0.94 and Rp2 = 0.85) with the root mean square errors on cross-validation and prediction (RMSECV = 60 mg kg−1 and RMSEP = 80 mg kg−1). The limit of detection (150 mg kg−1) was also calculated. In addition, LIBS successfully predicted the Mg content distributed within a pellet. This study demonstrated that LIBS is suitable as a rapid reagent-free method for the quantification of Mg in powdered infant formula and can provide spatial information with acceptable accuracy

Sampling effects on the quantification of sodium content in infant formula using laser induced breakdown spectroscopy (LIBS)

Laser-induced breakdown spectroscopy (LIBS) was employed to predict the sodium content of infant formula (IF) over the range 0.5–4 mg Na g−1. Calibration models were built using partial least squares regression (PLS), correlating the LIBS spectral data with reference Na content quantified by atomic absorption spectroscopy (AAS). The main aim of this study was to demonstrate the ability of LIBS as a rapid tool for quantifying sodium in IF, but also to explore strategies concerning the acquisition and pre-processing of LIBS spectra. A range of different pre-processing techniques, measuring depths (repetition of laser shots) and accumulations were conducted and evaluated in terms of PLS performance. The best calibration model was developed using the third-layer spectra normalised by the H I 656.29 nm emission line, yielding a coefficient of determination (R2) of 0.93, and root-mean-square errors (RMSE) of 0.37 and 0.13 mg g−1 for cross-validation and validation, respectively

Quantification of calcium in infant formula using laser-induced breakdown spectroscopy (LIBS), Fourier transform mid-infrared (FT-IR) and Raman spectroscopy combined with chemometrics including data fusion

peer-reviewedLaser-induced breakdown spectroscopy (LIBS), Fourier transform mid-infrared (FT-IR) and Raman spectroscopy combined with chemometrics were investigated to quantify calcium (Ca) content in infant formula powder (INF). INF samples (n = 51) with calcium content levels (ca. 6.5–30 mg Ca/100 kJ) were prepared in accordance with the guidelines of Commission Directive 2006/125/EC. Atomic absorption spectroscopy (AAS) was used as the reference method for Ca content determination. To predict Ca content in INF samples, partial least squares regression (PLSR) models that developed based on LIBS, Raman and FT-IR spectral data, respectively. The model developed using LIBS data achieved the best performance for the quantification of Ca content in INF (R2 (cross-validation (CV))-0.99, RMSECV-0.29 mg/g; R2 (prediction (P))-1, RMSEP-0.63 mg/g). PLSR models that developed based on data fusion of Raman and FT-IR spectral features obtained the second best performance (R2CV-0.97, RMSECV-0.38 mg/g; R2P-0.97, RMSEP-0.36 mg/g). This study demonstrated the potential of LIBS, FT-IR and Raman spectroscopy to accurately quantify Ca content in INF.Department of Agriculture, Food and the Marine, Irelan

Application of Laser-Induced Breakdown Spectroscopy Technique for Studying Salt Diffusion in Model Cheese Matrices

Salt dissolved in the aqueous phase of cheese, plays vital roles during cheese manufacture by manipulating protein-protein and protein-water interaction and during ripening by contributing to the flavor of cheese, controlling the growth of microorganisms, and helping with enzymatic breakdown of cheese. Salt diffusion in the cheese moisture phase is a slow process. Conventional methods used for tracking salt migration within cheese matrices involve wet chemistry, tedious sample preparation and longer estimation times. Laser-induced breakdown spectroscopy (LIBS) is a novel technique which is currently used for mineral analysis in different food materials. The technique gives spatial distribution (at macroscopic level) of minerals (Na, K, Ca) on a surface; it requires no sample preparation; it is a non-invasive and quick method and it doesn\u27t involve hazardous chemicals and procedures. The current work examined the ability of LIBS technique to capture sodium/salt migration in cheese systems. Cheese samples with different contact time (0, 30, 60 min) with brine (23%) solution were cut into half cubes (2.5x2.5x2.5 cm3). Spatially distributed LIBS spectra were collected from interior cut surfaces/cross sections by applying laser shots in 45x45 square grid patterns. The emission peaks of plasma light at 589.05, 393.339 and 769.826 nm in each spectral data moment were used to generate sodium, calcium and potassium distribution images, respectively. A clear difference in spatial distribution of Na was observed in the control as compared with brined model cheeses dipped for 30 and 60 min. With brining time, the relative area of pixels indicating higher Na concentration levels increased significantly. Progressive diffusion of salt within model cheese matrix was clearly evident in spatial distribution mapping plots for Na. This work highlights a novel application of LIBS technique for generating spatially distributed salt concentration maps within cheese matrices. This technique may be applied for studying salt diffusion kinetics