Prediction of bovine milk true protein content by mid-infrared spectroscopy

Abstract

The aim of this study was to estimate the concentration of milk true protein (TP) by mid-infrared absorbance method (MIR) in samples from bulk tank of dairy herds, and to determine the correlation between the results ofThe reference methodology for crude protein determination in milk is the Kjeldahl method, which measures the total nitrogen (TN) content in milk. By this method, the nitrogen released from protein and other components is converted to ammonia nitrogen by acid digestion. Once quantified the TN amount, milk concentration of crude protein (CP) is obtained by multiplying TN by 6.38 (TOUFEILI, 2007). Thus, the CP content determined by this method refers to nitrogen arising from TP and other sources of nonprotein N (NPN) in milk. Since about 95-97% of CP is TP, the difference is represented by non-protein components such as ammonia, urea, creatine, creatinine, uric acid, orotic, hippuric, amino acids and other nitrogen compounds (FOX;MCSWEENEY, 2003). The concentration of milk casein comprises about 75-85% of CP and 85-95% of TP, while the whey proteins consist of 10-15% of TP (ROUCH et al., 2006).

Dielectric Properties of Raw Milk as Functions of Protein Content and Temperature

“…They are just used in laboratory and are not capable of real-time or situ detection. The spectroscopy analysis methods, including the visible (Bogomolov et al 2012), infrared (Rutten et al 2011), midinfrared (Bonfatti et al 2011;Botaro et al 2011), near-infrared (Bogomolov and Melenteva 2013;Feng et al 2013;Kalinin et al 2013), and ultraviolet (Dziuba et al 2001;Rukke et al 2010), have been used to determine protein content in milk widely; however, too complex instruments are needed. Moreover, most of them are difficult to be used in real-time detection.…”

Milk Protein Analysis: an Overview of the Methods - Development and Application

“…Currently, the protein content of milk is analysed through automated flow analysers (Silveira et al, 2004) which are based on the mid-infrared (MIR) spectroscopy (Biggs, 1978;Coleman and Moss, 1989;Botaro et al, 2011). These analysers use optical filter technology (MIR) or whole infra-red spectrum scan in mid-range (MIR-FT, Fourier transform).…”