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Food systems

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Vol 1, No 3 (2018)
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https://doi.org/10.21323/2618-9771-2018-1-3

4-12 209
Abstract

The aim of this work was to study the effect of pressure (50; 90; 160; 250; 350 MPa) on a physical property of casein micelle: hydrodynamic radius, tyrosine and tryptophan fluorescence and IR spectra characteristics. According to photon-correlation spectroscopy, the average hydrodynamic radius of the casein micelle was 128 nm, increasing at 50 MPa to 467 nm with the formation of conglomerates. Further increase of pressure led to the formation of two fractions of particles, differing in hydrodynamic radius. At a pressure of 350 MPa, an average radius of 75 % of particles was 121 nm. Comparison of hydrodynamic radius and tyrosine fluorescence revealed a decrease in the intensity of the glow with an increase in the proportion of large particles and an increase in the radiation in the solution with a decrease of the micelles size. The increase of casein fluorescence by tryptophan and its decrease by tyrosine indicate a change in the conformation of protein molecules during pressure treatment. FTIR spectroscopy revealed a change in the intensity of the optical density in the range of amide I, amide II and valence bonds of tyrosine, confirming the absence of new bonds. The obtained physical data indicate a change in the structure of casein micelles with an increase in the proportion (25 %) of large particles after the action of high pressure (350mpa), which should be taken into account in milk processing. The fluorescence of casein during pressure treatment is a poorly investigated physical indicator and can be important for the processing of raw milk.

13-26 254
Abstract

In the experiment, beef samples were used with the marbling scores «moderate» and «good» (n = 4). Half of the samples were packaged in a plastic film under vacuum, while the rest ones were left unpackaged. Aging was carried out for 4, 16, and 28 days in a storage chamber at a temperature of 2 ± 1 °C and a relative humidity of not more than 90 %. During beef aging, pH, sensory indicators of quality and freshness, microstructural indicators, and shear force were evaluated. Regardless of the marbling score, on day 28, sensory indicators of unpackaged beef had the signs of non-fresh meat, while the packaged samples had no deviations. Regardless of the marbling score, sensory evaluation indicated the high quality of boiled meat and broth during the entire aging period for packaged beef and during 16 days for unpackaged beef. Histological studies found that with the increase in beef aging period, the destructive changes in tissues increased as well. On days 16 and 28, samples of packaged beef, both with marbling score «good» and «moderate», corresponded to the second and third stage of meat aging. Changes in unpackaged beef at the corresponding days of aging were less pronounced. The results of a shear force study indicated that, during the entire observed aging period, a gradual decrease in shear force occurred.

27-32 225
Abstract

Collection cultures of actinomycetes are mainly stored in a dried state on adsorbents. Practiced low-temperature storage of actinomycetes at minus 70°C. The article presents the results of investigations of the properties of the conidia of strains of the actinomycete Streptomyces lucensis VKPM Ac–1743 and Streptomyces violaceus VKPM Ac–1734 is in the process of storage at minus 12°C and minus 18°C in glycerin solution and in 0,9 % aqueous sodium chloride solution. It was found that the inhibitory activity in the native solution for the studied strains stored in the glycerin solution at minus 12°C and plus 4°C, as a result of their subsequent cultivation on the starch hydrolyzate for 120 h is at the level of (450 ± 10) IE/cm3. The indicator for crops stored at minus 18°C was higher (560 ± 10) IE/cm3. Low-temperature storage of conidia in saline solution is less effective. Pigmentation is more active in the cultivation of strains stored at minus 18°C.

33-37 189
Abstract

The article describes in vitro methods basic principles, authors analyzed cell and tissue cultures used to assess toxicity and specific biological activity, including metabolic processes, include antihypertensive and cytoprotective properties analysis, antioxidant activity (in vitro and ex vivo) used to study ingredients functional properties based on animal origin raw materials, as well as meat products.

38-43 347
Abstract

As studies by Russian and foreign scientists show, the breed and the cows genotype affects on their productivity and milk quality. In connection with this, the purpose of this research was to study the milk productivity and milk quality of the Tatarstan type Kholmogory cows with different complex genotypes on the milk protein genes, namely, alpha S1-casein, beta-casein, kappa-casein, beta-lactoglobulin, alpha-lactalbumin. The genotypes on the milk protein genes were determined by DNA analysis methods. Determination of quantitative and qualitative indicators of milk was carried out by control milking and on a milk analyzer «LAKTAN1–4». Better raw milk, that is, with the greatest amount of nutrients, such as milk fat and protein, was milk from cows with complex genotypes of milk proteins ВВ/АВ/АВ/АВ/АА, ВВ/АВ/АВ/АВ/АВ, ВВ/АВ/АВ/АВ/ВВ. In practical terms, it is possible to get more quality dairy products from such raw materials.

44-54 237
Abstract

In order to determine the nature of processes of the dynamic polymer flow with simple chemical reactions in two-dimensional cylindrical geometry, objects — a sugar melt and a high molecular weight fraction of glutenin of flour — were chosen in the hydrodynamic description, which were investigated on a rotational rheometer HAAKE RotoVisco 1 and the Moisture Analyzer OHAUS MB23. The nonlinear dynamics of a viscous flow of a compressible, homogeneous liquid with chemical reactions is considered. A nonstationary exact solution of the Poiseuille type is obtained. This solution is used to investigate the effect of viscosity and chemical reactions of the first order on the characteristics of the nonequilibrium dynamic states of the system. The present results of the joint research of the specialists of the All-Union Research Institute of the Confectionery Industry and the MEPhI are a continuation of the work on the formation of structures in food disperse systems and indicate that similar features can also be manifested in real flows of polymer liquids in various industrial installations.



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ISSN 2618-9771 (Print)
ISSN 2618-7272 (Online)