Development of FTIR spectroscopy in combination with chemometrics for analysis of rat meat in beef sausage employing three lipid extraction systems

Abstract

The substitution of rat meat (non-halal meat) in beef-based sausage products is illegal practice. This study was aimed to develop Fourier transform infrared (FTIR) spectroscopy in combination with chemometrics for analysis of rat meat in sausage employing three different lipid extraction techniques. Lipid was extracted from the sausages using Bligh and Dyer, Folch, and Soxhlet methods. The lipid extracted was then analyzed using FTIR spectroscopy combined with chemometrics of principal component analysis (PCA) and partial least square (PLS) calibration. The absorbance values at wavenumbers region of 750–1800 cm−1 were selected in PCA for classification and PLS modeling for quantification. PCA was successfully used to classify rat meat and beef lipids extracted by the three lipid extraction methods. The coefficient of determination (R2) and root mean square error of calibration (RMSEC) during PLS calibration modeling on lipid extracted from beef–rat meat sausages using Bligh and Dyer, Folch, and Soxhlet method were 0.945 and 2.73%; 0.991 and 1.73%; 0.992 and 1.69%, respectively. The validation study showed that R2 and root mean square error of prediction values for the correlation between actual value of rat meat and FTIR predicted value using lipids extracted by Folch and Soxhlet method were 0.458 and 18.90%, and 0.983 and 4.21%, respectively. Statistical analysis using independent t-test (p = 0.95) showed that there were significant differences on the content of some fatty acids of beef lipid and rat lipid as determined using gas chromatography. The contents of fatty acids of C12:0, C16:0, C16:1 cis 9, and C18:0 in rat lipid were higher than those in beef lipid, and the otherwise was observed for fatty acids of C14:1 cis 9, C15:0, C17:0, C17:1 cis 10, unsaturated C18, and C21:0. The difference in lipid composition, as indicated in FTIR spectra profiles and fatty acid composition, can be used as fingerprint technique for analysis of rat meat in beef sausage for halal authentication purpose.