MilkoScan™ 7 is based on Fourier Transform InfraRed (FTIR) analysis. It works with the mid-Infrared region of the spectrum from 3 - 10 µm corresponding to 1000 – 5000 cm -1.
The FTIR interferometer scans the full infrared spectrum, collecting data simultaneously and allowing measurement of new parameters even in complex dairy products. Analysis of an additional parameter simply becomes a matter of calibration.
The fact that FTIR instruments are standardised offers a great advantage. A calibration developed on one instrument may be transferred to other instruments, which due to the standardisation will provide identical readings. Standardisation is achieved by comparing spectra of a specially developed FTIR equalizer sample, collected on a newly installed instrument (slave) to the spectra of a similar sample using a master instrument at FOSS.
The main infrared wavelengths
The fat molecule consists of a glycerol backbone to which three fatty acids are bound. Two different fat wavelengths are mainly used in the IR instruments, Fat A and Fat B.
Fat A absorption is due to stretching vibrations in the C=0 bond of the carbonyl group in fat. This filter counts the number of fat molecules regardless of the length and the weight of the individual fatty acids. This is a drawback if the length of the fatty acids changes.
Fat B absorption is due to stretching vibrations in the C-H bonds of fatty acid chains. The measurement is therefore related both to the size and the number of fat molecules in the sample.
The lactose molecule is a disaccharide consisting of two monosaccharides glucose and galactose joined together. The hydroxyl group, (OH) is characteristic of carbohydrates and the lactose absorption is due to the C-OH bond.
The protein molecule consists of amino acid units joined together with peptide bonds. Protein absorption is due to stretching vibrations in the N-H bonds within the peptide bonds.
In addition to these four main wavelengths, up to 1000 other wavelengths can be selected from the full spectrum to give unprecedented possibilities for new parameters and accurate analysis. For the measurement of freezing point depression a conductivity cell is included.