Laboratory Experiments with a New Infrared (IR) Milk Analyzer, the Milko-Scan 605

A new single-cell, dual-wavelength infrared milk analyzer, the Milko-Scan 605, has been introduced. The instrument is based on the same principle as the Milko-Scan 100 series. Various parts, however, have been modified (e.g., the detector, pump unit, and homogenizer), and the instruments has been supplied with a micro-processor. A number of critical points can be monitored and various possibilities for calibration and calibration control schemes can be preprogrammed. During the three-month trial, a traditional laboratory evaluation was performed at the Swedish Dairies Association. Performance characteristics such as repeatability, carry-over effects for different sample volumes, sample temperature effects, and so on were studied. Accuracy was calculated for fat (5.7 μm and 3.5 μm wavelengths), protein, and lactose determinations on bulk milk samples as well as samples from individual cows. The relative accuracies (coefficient of variation, CV) were estimated at 2.3% for fat (5.7 μm), 1.4% for fat (3.5 μ), 1.4% for protein and 1.3% for lactose. Interfering factors such as refractive index, free fatty acids, citric acid, and non-protein nitrogen were measured and statistically evaluated.