The content ratio of whey proteins to casein can serve as an indicator of milk quality as well as criterion for the presence of milk proteins adulteration, if it exceeds 0.25. The actual task is to produce an effective and portable sensor for the named ratio. The applicability of an inexpensive portable near infrared spectrometer for the specified task was tested in this work. The streams of backscattering and transmission light in the samples of the restored milk were acquired in the form of optical density spectra for a wavelength range of 800-1065 nm using a new two-channel CCD spectrometer. It was calibrated on the content of fat, casein and whey proteins using partial least squares regression. Another objective was to develop a cost-effective way to obtain a set of reference samples with various concentrations of three components that are needed to create the calibration models or to test them. Testing the calibration designed for the measurement of fat, casein and whey proteins in drinking milk showed root mean squared errors of prediction of 0.09% wt, 0.12% wt and 0.06% wt, and correlation coefficients of 0.90, 0.82 and 0.89, respectively. The value of the 95th percentile for the ratio of whey proteins to casein was found to be ± 0.06, which is sufficiently low for practical use of the method. A comparison of models, one of which was built using the proposed "custom" set of 35 samples and the other which was based on a random set of 81 samples, showed similar acceptable results. Thus, the proposed method is suitable for cost reduction without loss of calibration quality.

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The use of ultraviolet radiation in the treatment of milk and other liquid foods is a very promising field of study since it reduces their bacterial load. It is rarely used to increase the vitamin D content and modify the protein and fatty acid composition of milk. The paper describes how different parameters of ultraviolet radiation influence such characteristics of raw and pasteurized milk as the mass fraction of total protein, nonprotein nitrogen content, active and titratable acidity, general bacterial load (QMA&OAMO), fatty acid composition, and vitamin D content. Low-pressure gas-discharge lamps were used to treat a 400 µm moving layer of milk with ultraviolet radiation. The radiation time, its doses, and the milk flow rate changed in the ranges of 5–25 min, 5.1–102 mJ/cm2, and 0.04453- 0.13359 m3/s, respectively. We identified optimal radiation ranges that lead to both a lower microorganism content and a higher vitamin D content. Our study also determined specific correlations in the mutual changes of the given parameters. The treatment ranges did not produce any significant changes in other physico-chemical properties of milk. We also found that vitamin D was synthesized in raw and pasteurized milk in a similar way. Moreover, there was an insignificant decrease in the vitamin D content in milk treated with ultraviolet radiation during storage for up to 48 hours. On the whole, the results indicate that the treatment of milk with ultraviolet radiation in the dosage range from 5.1 to 102 mJ/cm2 has a complex effect on the total bacterial load (QMA&OAMO) and vitamin D content, whereas it has almost no effect on the protein and fatty acid composition.

The aspects of component visualization of the antimicrobial triterpenoids (betulin) additive, both on the surface and in the bulk of the polymer, constituting food film packaging, are considered. This paper presents new knowledge about the morphology and surface structure of modified films using three independent methodological approaches: optical microscopy; a histological method adapted to packaging materials; and a method of attenuated total internal reflection (ATR) spectroscopy in the infrared region with Fourier transform. The use of these methods shows the betulin granules, individual or forming chains. To visualize the antimicrobial additive in the polymer bulk, a modified histological method adapted for film materials and attenuated total internal reflection (ATR) spectroscopy in the infrared region were used with Fourier transform using a Lumos Bruker microscope (Germany) (ATR crystal based on germanium). Sample sections were analyzed using Leica 818 blades at an angle of 45 degrees. The histological method consists of the study of a biological object thin section, in the transmitted light of a microscope, stained with contrast dyes to reveal its structures, and placed on a glass slide. In the method modified for the present study, instead of a biological one, a synthetic object was used, namely the developed film materials with the addition of natural organic origin. Individual granules are about 2 µm long; chains can be up to 10 µm long. The thickness of the granules ranged from 1 to 1.5 microns. It can be seen that the depth distribution of granules in the film from the inner surface to the outer one is rather uniform. Spectroscopic studies using the method of automatic ATR mapping in the region of 880 cm−1 made it possible to evaluate the distribution of an antimicrobial additive based on triterpenoids on the surface and in the polymer bulk.

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