The objectives of the study were to evaluate the accuracy and the repeatability of ultrasonic milk analyzers compared to reference methods. At the same time, milk composition was assessed using an ultrasonic analyzer, Fourier transform mid-infrared milk analyzer, and standard methods. The results obtained by the different analytical methods for fat, protein, and lactose contents were compared using different statistical parameters. The repeatability and reliability of the results obtained with the calibrated ultrasonic analyzer were comparable with those obtained using mid-infrared, Gerber method, and Kjeldahl method. The ultrasonic method underestimated the fat concentration by about 1 g/L and overestimated protein content by about 1.2 g/L, while the mid-infrared method showed results very close to the direct methods for all milk components. Well calibrated ultrasonic analyzers might be an alternative to conventional methods of milk analysis in small dairy processing units and milk collection centers in Tunisia because Fourier transform mid-infrared instruments are very expensive and need highly trained technicians.
