Calibration of Infrared Milk Analyzers: Modified Milk Versus Producer Milk

Abstract

Mid-infrared (MIR) milk analyzers are traditionally calibrated using sets of preserved raw individual producer milk samples. The goal of this study was to determine if the use of sets of preserved pasteurized modified milks improved calibration performance of MIR milk analyzers compared with calibration sets of producer milks. The preserved pasteurized modified milk sets exhibited more consistent day-to-day and set-to-set calibration slope and intercept values for all components compared with the preserved raw producer milk calibration sets. Pasteurized modified milk calibration samples achieved smaller confidence interval (CI) around the regression line (i.e., calibration uncertainty). Use of modified milk calibration sets with a larger component range, more even distribution of component concentrations within the ranges, and the lower correlation of fat and protein concentrations than producer milk calibration sets produced a smaller 95% CI for the regression line due to the elimination of moderate and high leverage samples. The CI for the producer calibration sets were about 2 to 12 times greater than the CI for the modified milk calibration sets, depending on the component. Modified milk calibration samples have the potential to produce MIR milk analyzer calibrations that will perform better in validation checks than producer milk-based calibrations by reducing the mean difference and standard deviation of the difference between instrument values and reference chemistry.

Effect of organic sources of minerals on fat-corrected milk yield of dairy cows in confinement

“…Milk yields were corrected for the fat content of 3.5%, according to Sklan et al (1994). Fresh milk samples were analyzed for crude protein, fat, lactose and total solids, according to the methodologies described by Kaylegian et al (2006).…”

Mid Infrared Spectroscopy and Multivariate Analysis Evaluation of Adulteration in Whey Protein Powder

“…For each model created to predict lactose, creatine and caffeine added to WPC, the samples were divided into calibration and validation datasets. The samples were randomly chosen within the range of 0 to 50% of substitution, where the calibration set consisted of 7 samples while the validation dataset consisted of the other 4 which were not part of the calibration set [19].…”

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

“…Currently, the protein content of milk is analyzed through automated analyzers (SILVEIRA et al, 2004), which are based on the principle of mid-infrared (MIR) energy absorbance of protein specific chemical group, amides, at the approximately wavelength of 6.7 m (LYNCH et al, 2006) peptide bonds to estimate the concentration of CP (BARBANO & LYNCH, 2006). The use of automated analyzers allows quick determination of milk composition at low cost in comparison with the reference method (KAYLEGIAN et al, 2006). MIR absorbance technique is an indirect method, which requires calibration of the equipment with reference values obtained by the reference methodology (ETZION et al, 2004).…”