What is the difference between Mid-IR and ultrasound?

Mid-IR is an indirect physical method that measures the fat, protein, and carbohydrate content of milk through the absorption of energy of unique functional groups in the molecules. Ultrasound technology measures the speed of sound in milk depending on a density characterization of fat and estimates the fat content from this.  Content of protein and carbohydrate, etc. are calculations.

What makes Miris HMA better than NIR instruments?

The evaluation of NIR instruments has been on-going for at least 20 years without much success. One major drawback with NIR is that it is very sensitive for variation in particle size (fat globule diameter). Mid-IR uses the absorbance of radiation of functional chemical groups (CH2, C=O, CONH, -OH), which highly are correlated to fat, protein and carbohydrates. With NIR absorbance spectra, the peaks from fat, protein and carbohydrates overlap which makes them difficult to detect.

At what wavelengths in the infrared spectra does the HMA measure? 

The instrument has different filters for specific milk components and uses four different wavebands. The wavebands used are specific for the functional carbonyl groups (5.7µm) for fat determination; amide groups (6.5 µm) for protein determination, and hydroxyl groups (9.6 µm) for carbohydrate determination.

How does the technique work? 

Miris Milk Analyser is based on mid-infrared (MIR) transmission spectroscopy. A thin fluid film (50 µm) of sample is exposed to MIR radiation and the transmitted MIR wavelengths are detected at specific wavebands within the infrared spectrum. The reduced transmissions at the different wavebands are proportional to the concentration of milk components in the sample.