Rapid Analysis of Cheddar Cheese and Nonfat Dry Milk Using Mid Infrared Spectroscopy

Abstract

The first objective of this work was to develop methods for the creation of liquid Cheddar cheese calibration standards and evaluate the calibration set using a combination MIR transmittance analysis and an in-line conductivity sensor within the MIR milk analyzer for measuring fat, protein, moisture, and salt content. Annatto colored cheese samples were collected from one cheese factory. Each cheese sample was analyzed using reference chemistry and then blended into a particle free dispersion to run through the FT-MIR. The remaining cheese was combined and used to create an 8-sample calibration set with decreasing amounts of fat, protein, total solids, and salt. Validation samples were also run using the new calibration model. Standard error of prediction (SEP) values for fat, moisture, and salt of the validation samples on the MIR produced SEP values for fat A+B, moisture, and salt of 0.177, 0.176, and 0.022, respectively. These low SEP values indicate that MIR could be used as an effective alternative to cheese producers for the rapid analysis of cheese using equipment most dairy processors already have in their facility. Our second objective was to develop and evaluate the performance of the rapid determination of fat, protein, lactose, and moisture of nonfat dry milk powders using mid-infrared transmittance analysis. Nonfat dry milk powders were reconstituted and analyzed using reference chemistry and the FT-MIR to create a calibration model. Validation was done at a separate time using the same nonfat dry milk powders. The SEP values for the validation samples were low. Moisture, fat A, protein, and lactose had SEP values of 0.292, 0.023, 0.110, and 0.334, respectively. This indicates that MIR could be used as an easy and effective way for NFDM producers to measure the components of their product.