Milk protein content is an important component of milk, especially from a nutritional point of view and also for payment purposes. The aim of work was to draw up an overview on reference and routine methods for protein determination. Reference methods perform accurate analyses comply according to the International Standard ISO whereas routine methods perform analyses using routine instrumental techniques for faster and cheaper results with acceptable accuracy and a large number of processed samples. In most of cases, using of routine indirect methods for milk protein analysis requires their specific calibrations according to biological kind of measured milk (cow’s, goat’s or sheep’s milk) or specific conditions of milk technology treatment. Also, the quality control measures have a significant role for result determination reliability.

Milk fat content is an important indicator of milk quality because of nutritional and technological aspects of dairying. In this sense the milk fat determination is important practice procedure. The work goal was to do an effective overview and comparison of reference and routine methods of fat determination during their development. Nowadays, there exist a number of methods for determining milk fat content. Reference methods require accurate analysis in compliance with the International Standard ISO, whereas routine methods perform analysis using routine instrumental techniques for faster and cheaper results with acceptable accuracy. Quality control measures have a significant role for result determination reliability and they include internal quality controls, external quality controls, precision of evaluation, and blank samples. In conclusion, due to continuous development and improvement, routine methods will be used more often.

Rapid analytical methods can contribute to the expansion of milk fatty acid determination for various important practical purposes. The reliability of data resulting from these routine methods plays a crucial role. Bulk and individual milk samples (60 and 345, respectively) were obtained from Czech Fleckvieh and Holstein dairy cows in the Czech Republic. The correlation between milk fatty acid (FA) proportions determined by the routine method (infrared spectroscopy in the mid-region in connection with Fourier transformation; FT-MIR) and the reference method (gas chromatography; GC) was evaluated. To validate the calibration of the FT-MIR method, a linear regression model was used. For bulk milk samples, the correlation coefficients between these methods were higher for the saturated (SFAs) and unsaturated FAs (UFAs) (r = 0.7169 and 0.9232; p < 0.001) than for the trans isomers of UFAs (TFAs) and polyunsaturated FAs (PUFAs) (r = 0.5706 and 0.6278; p < 0.001). Similar results were found for individual milk samples: r = 0.8592 and 0.8666 (p < 0.001) for SFAs and UFAs, 0.1690 (p < 0.01) for TFAs, and 0.3314 (p < 0.001) for PUFAs. The correlation coefficients for TFAs and PUFAs were statistically significant but too low for practical analytical application. The results indicate that the FT-MIR method can be used for routine determination mainly for SFAs and UFAs.

Evaluation of fatty acids (FAs) stability in dairy products undergoing technological milk processing is important for subsequent determinations of nutritional value. The aim of the study was to assess FA composition in milk and its dairy product and to explore differences in the FA profile found in yoghurt compared to raw material (goat milk). In the present study, a reduced proportion of volatile FAs (VFA) that cause “goat flavor” was reported in goat yoghurt in comparison to the FA profile of milk. Conversely, an increase of medium-chain as well as beneficial long-chain and unsaturated FAs (UFA) was reported in yoghurt compared with milk. In all cases, the differences in the FA composition between milk and yoghurt were not significant; therefore, it was found that manufacturing of yoghurt had no major influence on FA composition.

78 individual milk samples (IS) were taken in the Czech Fleckvieh and Holstein dairy cow herds and 33 bulk milk samples (BS) were taken in 13 Holstein dairy cow herds to compare two methods for the determination of fatty acids (FAs) – routine/indirect (infrared (IR) spectroscopy, MIR-FT) and reference/direct (gas chromatography, GC). The IS results show that the fatty acids C16:0 and C18:1 and the group of saturated (SFA) and unsaturated (UFA) FAs can be determined using routine method with a relatively high reliability (correlations (r) 0.7543, 0.7607, 0.8424 and 0.9492; P < 0.001). In case of polyunsaturated FAs is the r lower (0.2891; P < 0.05). In BS the tightness of relations is stronger in the case of the SFA and UFA (r 0.7094; 0.9389; P < 0.001), while for the group of TFA (trans isomers of unsaturated FAs) and PUFA (polyunsaturated FAs) are lower r (0.5897 and 0.5931; P < 0.001 respectively). Routine method for fatty acids profile determination is efficient for selection of raw milk to guarantee the production of specific dairy products with increased content of healthful fatty acids.