Devising barrier technologies to ensure the stability of microbiological and organoleptic quality indicators of meat semi-finished products

Ways to ensure the quality and safety of meat processing products are being devised at an intensive pace. To solve these tasks, various "barriers" are used: chemical, physical, microbiological, as well as their combinations. When performing this research, a critical analysis of existing "barriers" as techniques to stabilize the quality of meat products with long shelf life was carried out. It has been revealed that the main preferences of consumers are associated with natural additives that ensure the safety of products. The introduction of modern barrier technologies is a relevant issue as it could ensure the stability of quality indicators during storage. An important task is to use natural raw materials as barriers. To this end, an analysis of the antioxidant activity of extracts from various plant-based raw materials was carried out. The results make it possible to devise technologies for creating film coatings with bioprotective properties. The dynamics of changes in the microbiological contamination of large-piece semi-finished products from beef in the process of storage at different temperatures were studied. It was found that the use of film barrier coatings leads to a restraining of the growth of microflora and has a bacteriostatic effect, which helps extend the shelf life of semi-finished products compared to control samples. The implementation of this study's results could significantly prolong the shelf life of meat semi-finished products, including at positive temperatures, without the risk of microbiological spoilage and loss of quality and functional-technological characteristics.

Synthesis and properties of vinyl benzyl alcohol copolymers with styrene

Objectives. Synthesis and study of the properties of copolymers of vinyl benzyl alcohol (VBA) with styrene with antimicrobial properties.Methods. The study employed infrared (IR) and nuclear magnetic resonance (NMR) spectroscopy, thin-layer chromatography, viscometry, and elemental analysis. The sessile drop method and the pencil method were respectively utilized to determine the contact angles and hardness of the films. The process of testing the film coatings’ resistance to the effects of molds consisted of contaminating the film coatings applied to the glass with mold spores of the All-Russian Collection of Microorganisms in a solution of mineral salts without sugar (Czapek–Dox medium).Results. Homopolymers of vinyl benzyl acetate and its copolymers with styrene were synthesized in this study. Homo- and copolymers of VBA were obtained by saponification. IR and proton NMR (1H NMR) spectroscopy determined the composition of the copolymers. Employing IR spectroscopy, the degree of saponification was monitored by the appearance of the hydroxyl group absorption band and the disappearance of the ester group absorption band. According to the IR spectroscopy data, only an insignificant (~3%) amount of ester groups remains in the saponified copolymers. The influence of the copolymers’ composition on their solubility in various solvents is demonstrated. IR spectroscopy of the copolymers revealed hydrogen-bond formation between the unreacted ester groups and hydroxyl groups formed due to the saponification. The viscometry of the solutions of mixtures of saponified and unsaponified copolymers, solutions of mixtures of saponified copolymer with polyvinyl acetate, and viscometry of saponified copolymers in various solvents all support this conclusion. These bonds’ concentration depends on the copolymer’s composition and can be controlled by the nature of the solvent from which these copolymers’ films are formed. Saponified copolymer solutions form smooth, transparent film coatings with excellent adhesion to metals and silicate glass surfaces. The contact angle of these films, like the hardness, decreases as the VBA units’ concentration in the copolymers increases and depends on the solvent polarity used to form the films. It has been demonstrated that increasing the VBA units concentration suppresses the microorganisms’ growth.Conclusions. Film coatings made of copolymers of styrene with VBA have been shown to have high biocidal activity against molds; can be used to protect structural materials and products from the effects of microorganisms.

Towards a Better Understanding of Verapamil Release from Kollicoat SR:IR Coated Pellets Using Non-Invasive Analytical Tools

The aim of this study was to gain deeper insight into the mass transport mechanisms controlling drug release from polymer-coated pellets using non-invasive analytical tools. Pellet starter cores loaded with verapamil HCl (10% loading, 45% lactose, 45% microcrystalline cellulose) were prepared by extrusion/spheronization and coated with 5% Kollicoat SR:IR 95:5 or 10% Kollicoat SR:IR 90:10. Drug release was measured from ensembles of pellets as well as from single pellets upon exposure to acetate buffer pH = 3.5 and phosphate buffer pH = 7.4. The swelling of single pellets was observed by optical microscopy, while dynamic changes in the pH in the pellet cores were monitored by fluorescence spectroscopy. Also, mathematical modeling using a mechanistically realistic theory as well as SEM and Raman imaging were applied to elucidate whether drug release mainly occurs by diffusion through the intact film coatings or whether crack formation in the film coatings plays a role. Interestingly, fluorescence spectroscopy revealed that the pH within the pellet cores substantially differed upon exposure to acetate buffer pH = 3.5 and phosphate buffer pH = 7.4, resulting in significant differences in drug solubility (verapamil being a weak base) and faster drug release at lower pH: from ensembles of pellets and single pellets. The monitoring of drug release from and the swelling of single pellets indicated that crack formation in the film coatings likely plays a major role, irrespective of the Kollicoat SR:IR ratio/coating level. This was confirmed by mathematical modeling, SEM and Raman imaging. Importantly, the latter technique allowed also for non-invasive measurements, reducing the risk of artifact creation associated with sample cutting with a scalpel.

The Influence of Sample Preparation Techniques on Aluminium Alloy AA2024-T3 Substrates for Sol-Gel Coating

Sol-gel coatings provide environmentally friendly surface protection for metals and can replace toxic pre-treatments such as those based on hexavalent chromium on metal alloys. This project ultimately aims to develop silica-based organic–inorganic sol-gel derived thin film coatings possessing anti-corrosion and anti-fouling properties on aluminium alloy substrates. As with any coating, sample preparation plays a significant role in the performance of a sol-gel coating. Therefore, it was necessary to define a preparation method that combines the removal of contaminants and surface roughening to improve adhesion and reproducibility. Four techniques were investigated: fine abrasive sandpaper cleaning, acetone degreasing only and cleaning with an industrial-available alkaline cleaner for 5 min and 30 min.

Thin film coatings material particles creation by pulsed methods in vacuum

Thin film materials particles creation pulsed methods such as magnetron sputtering HiPIMS, pulsed laser deposition PLD, vacuum arc pulsed discharge, high-intensity pulsed ion beam impact HIPIB, as well, were described. It was shown that the stream of material, created by means of an explosion action such as ablation, avalanche paired impacts and microsecond electrical disruption as well creates preconditions for nanocrystalline thin film coating manufacture.