Near-Infrared Spectroscopic Analysis of Heme and Nonheme Iron in Raw Meats

Near-infrared (NIR) spectroscopy scanning from 1100 to 2500 nm was applied for the determinations of heme and nonheme iron in raw muscle meats. Ground meat samples were divided into two sets of 30 and 15 samples as a calibration and a prediction set, respectively. The multiple regression equations (MREs) established for the calibration set between the chemical analysis reference data and the second derivative data of the NIR spectra gave the multiple correlation coefficients of 0.966 and 0.923 for heme and nonheme iron contents, respectively. The best MREs were obtained with the NIR data recorded at wavelengths where NH groups in protein molecules and C–C and CH in the porphyrin ring of heme give absorption. The correlation coefficients between the data calculated from these MREs and the reference data for the prediction set were 0.991 and 0.906 for heme and nonheme iron contents, respectively. The results indicate that the NIR diffuse reflectance procedure is a technique which serves the need for rapid and simple heme and nonheme iron determinations, thereby allowing an in vitro estimation of bioavailability of iron in muscle meats.