Over the years, there has been much confusion in defining molecular markers of mesenchymal stem cells (MSCs) for other than human species due to a lack of species-specific antibodies. Therefore, the aim of our study was to define rabbit amniotic fluid-derived mesenchymal stem cells (rAF-MSCs) and to reflect upon the current identification of AF-MSCs by providing a summary of detected surface markers in different species. The expression of rAF-MSC surface markers was analyzed at the protein and mRNA level. Flow cytometry analyses showed that rAF-MSCs were positive for CD29 and CD44, low positive for CD90, but negative for CD73, CD105, and CD166. Interestingly, RT-PCR (reverse transcription-polymerase chain reaction) exposed a discprepancy between transcribed mRNA and protein expression, as the cells expressed mRNA of all MSC markers: CD29, CD44, CD73, CD90, CD105, and CD166. Our results also confirmed the mesenchymal nature of isolated cells by morphology, ultrastructure, and intracellular marker expression profile. In addition, the expression of few pluripotency markers was also detected. We also found that passaging did not affect apoptosis and viability. Similarly, changes in karyotype were not observed during passaging. In conclusion, the provided characteristics may be used as a comprehensive set of criteria to define and characterize rAF-MSCs, required for the identification of these cells in preclinical investigations. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1601-1613, 2017.

Slovak bryndza" is a traditional Slovak cheese manufactured by milling a lump of matured ewe's cheese or by milling a mixture of lump ewe's cheese and lump cow's cheese. The percentage of lump ewe's cheese is greater than 50% w/w dry matter. Differences in the purchase prices of ewe's and cow's milk create the potential for adulteration. The detection of cow's milk compounds by isoelectric focusing of γ-caseins after plasmolysis is a suitable method for the determination of adulteration of this traditional cheese. The analysis and final results may be affected by factors affecting laboratory activity and biological factors. Biological factors are manifested primarily as variations in the casein content of ewe's and cow's milk. Despite this variation, this method may also be used for quantification purposes. We were able to establish a reliable calibration line from the internal reference materials prepared in our laboratory. The mean composition of Slovak bryndza cheese determined in our research was protein 18.7 ± 1.9 g 100 g −1 , fat 24.0 ± 1.8 g 100 g −1 , lactose 1.5 ± 1.9 g 100 g −1 , ash 4.5 ± 0.3 g 100 g −1 , fat in dry matter 49.3 ± 2.6 g 100 g −1 , casein 18.4 ± 1.9 g 100 g −1 , gamma casein 0.60 ± 0.19 g 100 g −1, and bovine-to-ovine gamma casein ratio 0.65 ± 0.12 g 100 g −1 .

Milk testing and quality control should be carried out at all stages of the dairy chain. Milk can be tested for quantity, organoleptic characteristic, compositional characteristic, physical and chemical characteristics, hygienic characteristics, adulteration or drug residues. The content of the major constituents of raw milk is important for milk payment system. Enzymes naturally present in the milk can change the chemical composition of raw milk. Also, enzymes secreted by bacteria or enzymes from somatic cells can degrade the raw milk composition. Products of these degradation reactions can have undesirable effects on milk structure, smell and taste. It is very important that farm-fresh raw milk be cooled immediately to not more than 8 °C in the case of daily collection, or not more than 6 °C if collection is not daily. During transport the cold chain must be maintained. An authorized person, properly trained in the appropriate technique, shall perform sampling of bulk milk in farm. Laboratory samples should be dispatched immediately after sampling to the dairy company and consequently to the testing laboratory. The time for dispatch of the samples to the testing laboratory should be as short as possible, preferably within 24 h. Laboratory samples shall be transported and stored at temperature 1 to 5 °C. Higher temperatures may adversely affect the composition of the laboratory sample and may cause disputes between the farmer, the dairy company and the laboratory. The effect of refrigerated storage at temperature 4 °C during 24 h on the composition of raw milk were investigated in this work, because we wanted to know how the milk composition will be changed and how the laboratory results will be affected. In many cases, the samples are not preserved with chemical preservants like azidiol, bronopol, potassium dichromate or Microtabs. We found, that the composition of raw cows' milk after 24 was changed significantly (p >0.005). We found an average decrease in the fat content of -0.04 g/100g, increase in the protein content of +0.02 g/100g, increase in the lactose content of +0.02 g/100g, increase in the solid-not-fat content of +0.02 g/100g and decrease in the total solid content of -0.02 g/100g. It is necessary to cool the raw cows' milk after the milking to decrease the changes in milk composition caused mainly due to the lipolytic activity of lipase.

Milk is a food of high nutritional value processed by heat treatment. Heat treatment of milk is a technological process designed to inhibit the growth of microorganisms and extend the shelf life of products. The heating process directly affects the molecular structure of whey proteins by the process of denaturation. It leads to the formation of a whey protein–casein polymer complex. Based on these facts, milk heat-treatment conditions should be controlled during milk processing. This work focuses on describing the whey protein denaturation process and formation of the complex of whey protein with casein. The effect of heat treatment on individual milk protein fractions alpha-casein (α-cas), beta-casein (β-cas), kappa-casein (κ-cas), beta-lactoglobulin (β-lg) and alpha-lactalbumin (α-la) was studied by SDS-PAGE. Formation of the whey protein–casein polymer complex increased significantly (p < 0.05) on increasing the temperature and duration of the heat treatment.

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