Physico-chemical characterisation of Slovak wines

The aim of the present study was characterisation of selected varieties of still wines produced in Slovak Republic in vintage year 2013 and one 2012. There were tested ten samples of nine varieties of wines originated from Malokarpatská "Lesser Carpathian" and Južnoslovenská "Southern Slovakia" wine regions of Slovak Republic, Dornfelder, Frankovka modrá, Svätovarinecké, Zweigeltrebe, Müller Thurgau, Veltlínské zelené, Rizling rỳnsky, Rizling vlašskỳ and Sauvignon wines. There were studied selected physico-chemical properties of tested wines as a total contents of anthocyanins and polyphenols by means of spectrophotometry, titratable acidity, density and chromatic characteristics. The highest content of anthocyanins (TAC) was found in red wine Frankovka modrá, 183 mg.L-1 and the lowest for sample rose wine St. Laurent 19 mg.L-1. The content of total phenolic compounds as a gallic acid was in range 2833 to 1961 mg.L-1 for red wines, 1016 and 1013 mg.L-1 for rose wines, 1085 to 549 mg.L-1for white wines. Total acidy was average 6.3 0.3 g.L-1 only for Ryzling rỳnskỳ, 8.2 g.L-1 and Sauvignon rose 8.0 g.L-1 and was expressed as the amount of tartaric acid. Quality of wines can be expressed by colour intensity too. Was evaluated and compared intensity of colour in wines by CIE Lab method and the total differences between red, rose and white wine Δ E was calculated. The most differences was found for Svätovarinecké a Frankovka modrá (2.5) - red wines ("clearly perceptible") and 4.9 for Veltlỳnské zelené and Müller Thurgau - white wine ("moderating effect"). © 2017 Potravinarstvo Slovak Journal of Food Sciences

The effect of conformational transition of gelatin-polysaccharide polyelectrolyte complex on its functional properties

The blends of gelatin and shear-thinning hydrocolloids (guar gum, kappa-carrageenan and xanthan gum) were examined to determine the effect of the conformational change on the functional properties of the solutions. The polyelectrolyte complexes of 0.5% gelatin/0.5% polysaccharide in 70 mM KCl or 70 mM NaCl were investigated by the laboratory rheometer and conductivity meter in the temperature range 25 - 45 °C. The rheological data were fitted by the power-law and Herschel-Bulkley model to obtain the flow parameters. The functional properties of the samples were substantially affected by the conformational change of the polysaccharide, as well as by the type of the hydrocolloid and salt solution. There was an evident change of viscosity and conductivity of the solutions upon heating, corresponding to the helix-coil transition of the polysaccharide at temperature about 35 °C. The type of the salt solvent had an effect on the gelation properties of the samples. Gelatin/kappa-carrageenan blend in NaCl provided a gel of high consistency at ambient temperature (20 - 25 °C), whereas the blend in KCl did not gel in the studied temperature range. The potential stability of the blends was determined by zeta-potential analysis. The low values of ζ-potential indicate that the gelatin/polysaccharide blends are electrically unstable systems which tend to coagulate. The mixtures of gelatin/polysaccharide electrostatic complexes may have a great potential in many food applications. © 2017 Potravinarstvo Slovak Journal of Food Sciences

Effect of cocoa fat content on wetting and surface energy of chocolate

The aim of this study was the quantification of the effect of the cocoa fat content on the wetting characteristics and surface free energy of different chocolate compositions. On the market, there are many different types of chocolate products which differ both in the sensory and physico-chemical properties together with their raw material compositions and the contents of the individual components. This paper focuses on differences in the use of different types of fats - cocoa butter, milk fat, equivalents or cocoa butter substitutes in chocolate products. Studied samples (prepared at Carla, Ltd. Company) were followed by static contact angles of wetting measurements and by calculated surface free energies. There were investigated the effects of fat content and used fat types of the chocolate products on their final wettabilities and resulting surface free energies. There was found a linear dependence between total fat content and the surface free energy, which was gradually increasing with increasing fat content. Additionally, there were performed TG DTG and NIR spectrometry measurements of the tested materials with the aim to determine the melting point of studied fats used, as well as to determine and identify individual fat components of chocolate products which may affect the resulting value of surface free energy. © 2017 Potravinarstvo Slovak Journal of Food Sciences

Physico-chemical study of steroids from different matureness corn silk material

This study shows an ultrasonic assisted extraction procedure of steroids from corn silk (CS). The total steroids contents were positively correlated with the ultrasonic assisted extraction time. The extracted steroids contents varied according to the different maturity stages of CS. There were three tested CS maturity stages: silking stage (CS-S), milky stage (CS-M) and mature stage (CS-MS). The β - sitosterol standardization method with 530 nm wavelength colorimetric measurements were applied to determine the content of extracted steroids. Measured steroids concentrations range were from 38.3 × 10-3 mg.mL-1 to 368.9 × 10-3 mg.mL-1 in different extraction time and CS maturity stages. The highest concentration of steroids, 368.9 × 10-3 mg.mL-1 was found in CS-MS sample with the 75 minutes ultrasonic extraction time. The fluorescence mapping techniques were used to confirm the existence of steroids. The thermal analysis illustrated a typical multistep decomposition process for the CS-S, CS-M and CS-MS samples. Two endothermic peaks were found: The first one was 54.3 °C for CS-S and CS-MS, 60.2 °C for CS-M, the second one, 397 °C (CS-MS), 415.1 °C (CS-M) and 419.7 °C (CS-S) attributed to the total thermal decomposition. The observed exotheric process found at 524 °C corresponded to CS-MS sample decomposition. The optimal ultrasonic-assisted extraction time for all samples under study CS-S, CS-M and CS-MS was about 75 minutes and the optimal steroids extraction contents obtained were 92.8 × 10-3 mg.mL-1 (CS-S), 124.2 × 10-3 mg.mL-1 (CS-M) and 368.9 × 10-3 mg.mL-1 (CS-MS) respectively. © 2019 Potravinarstvo Slovak Journal of Food Sciences

Physico-chemical study of flavonoids from different matureness corn silk material

There was tested a simple extraction procedure of flavonoids separation from the original corn silk (CS) material. It was found, that the total flavonoids content differs with the extraction time and extraction temperature. There were found different flavonoids contents in extracts prepared from different maturity stages of the original corn silk material (silking stage (CS-S), milky stage (CS-M)). Extracted flavonoids content was quantified by the lutin standardization method by means of colorimetry at 510 nm wavelength. Obsreved flavonoids concentration was ranging from 2×10-3 mg.mL-1 to 7 ×10-3 mg.mL-1 dependent on the extraction time period and extraction temperature. The highest flavonoids concentration of 7.5×10-3 mg.mL-1 was found for CS-M after 20 minutes extraction time and 80 °C extraction temperature. There was confirmed the presence of flavonoids by fluorescence mapping experiments. There was found a typical multistep decomposition process for both CS-S and CS-M materials by TG analysis. There was found a melting temperature of flavonoids of 54.3 °C for corn silk silking stage material exhibiting 58.9 J.g-1 heat of fusion and 60.2 °C for corn silk milky stage material with 112.9 J.g-1 heat of fusion. The optimal conditions of corn silk flavonoids extraction were 40 °C, 50 minutes for CS-S, the optimal flavonoids extraction content was (6.8 ±2.1)×10-3 mg.mL-1, 80°C, 20 minutes for CS-M and the optimal extraction content was (7.2 ±0.3)×10-3 mg.mL-1. © 2018 Potravinarstvo Slovak Journal of Food Sciences

Thermal aging of edible oils: spectrophotometric study

The aim of the present study was to determine the spectrophotometric and thermal aging properties of various edible oils (olive, peanut, rapeseed, soybean and sunflower oils) which are commonly available in the Czech market. The samples were measured by UV/VIS absorption spectrometry and fluorescence spectroscopy. Detected substances of UV/VIS spectra were compared to expected oil composition; the highest absorbance values were detected in a wavelength range 300-550 nm which can be related to the presence of unsaturated fatty acids. The mixtures of oils were characterized by fluorescence spectroscopy; the individual oils were successfully distinguished according to their excitation-emission profiles. This method was also used to detect the samples of adulterated oils, i.e., the adulteration of high-quality oils with soybean oil. From a physicochemical point of view, the influence of temperature on the compounds of extra virgin olive oil was examined by thermal stress simulation. This thermal aging analysis demonstrated that the amount of oxidation products in olive oil increased during the heating whereas the chlorophyll content decreased. The results showed the ability of the techniques used, UV/VIS absorption spectrometry and fluorescence spectroscopy, to characterize the quality and composition of oils, and to distinguish individual oils in blends. UV/VIS spectrometry was also successfully employed for the evaluation of olive oil qualitative parameters according to the standard quality parameters by the "International Olive Council" (EEC 702/2007). </span

Emulsion-based coatings for preservation of meat and related products

One of the biggest challenges faced by the meat industry is maintaining the freshness of meat while extending its shelf life. Advanced packaging systems and food preservation techniques are highly beneficial in this regard. However, the energy crisis and environmental pollution demand an economically feasible and environmentally sustainable preservation method. Emulsion coatings (ECs) are highly trending in the food packaging industry. Efficiently developed coatings can preserve food, increase nutritional composition, and control antioxidants' release simultaneously. However, their construction has many challenges, especially for meat. Therefore, the following review focuses on the essential aspects of developing ECs for meat. The study begins by classifying emulsions based on composition and particle size, followed by a discussion on the physical properties, such as ingredient separation, rheology, and thermal characteristics. Furthermore, it discusses the lipid and protein oxidation and antimicrobial characteristics of ECs, which are necessary for other aspects to be relevant. Lastly, the review presents the limitations of the literature while discussing the future trends. ECs fabricated with antimicrobial/antioxidant properties present promising results in increasing the shelf life of meat while preserving its sensory aspects. In general, ECs are highly sustainable and effective packaging systems for meat industries.Tomas Bata University in Zlin, TBU: IGA/FT/2023/007; Univerzita Palackého v Olomouci: IGA_PrF_2023_024Tomas Bata University in Zlin [IGA/FT/2023/007]; Palacky University in Olomouc [IGA_PrF_2023_024

Thermal aging of edible oils: Spectrophotometric study

The aim of the present study was to determine the spectrophotometric and thermal aging properties of various edible oils (olive, peanut, rapeseed, soybean and sunflower oils) which are commonly available in the Czech market. The samples were measured by UV/VIS absorption spectrometry and fluorescence spectroscopy. Detected substances of UV/VIS spectra were compared to expected oil composition; the highest absorbance values were detected in a wavelength range 300-550 nm which can be related to the presence of unsaturated fatty acids. The mixtures of oils were characterized by fluorescence spectroscopy; the individual oils were successfully distinguished according to their excitation-emission profiles. This method was also used to detect the samples of adulterated oils, i.e., the adulteration of high-quality oils with soybean oil. From a physicochemical point of view, the influence of temperature on the compounds of extra virgin olive oil was examined by thermal stress simulation. This thermal aging analysis demonstrated that the amount of oxidation products in olive oil increased during the heating whereas the chlorophyll content decreased. The results showed the ability of the techniques used, UV/VIS absorption spectrometry and fluorescence spectroscopy, to characterize the quality and composition of oils, and to distinguish individual oils in blends. UV/VIS spectrometry was also successfully employed for the evaluation of olive oil qualitative parameters according to the standard quality parameters by the "International Olive Council" (EEC 702/2007). © 2018 Potravinarstvo Slovak Journal of Food Sciences

Effect of conditioning on PU foam matrix materials properties

This article deals with the characterization of the thermal-induced aging of soft polyurethane (PU) foams. There are studied thermal and mechanical properties by means of thermal analysis, tensile, compression and dynamic mechanical vibration testing. It was found in this study, that the increasing relative humidity of the surrounding atmosphere leads to the initiation of the degradation processes. This is reflected in the observed decreased mechanical stiffness. It is attributed to the plasticization of the PU foams wall material. It is in agreement with the observed increase of the permanent deformation accompanied simultaneously with the decrease of Young's modulus of elasticity. The latter phenomenon is studied by the novel non-destructive forced oscillations vibration-damping testing, which is confirmed by observed lower mechanical stiffness thus indicating the loss of the elasticity induced by samples conditioning. In parallel, observed decreasing of the matrix hardness is confirming the loss of elastic mechanical performance as well. The effect of conditioning leads to the significant loss of the PU foam's thermal stability.European Regional Development Fund in Research Centre of Advanced Mechatronic Systems project within Operational Programme Research, Development and Education [CZ.02.1.01/0.0/0.0/16_019/0000867]; Internal Grant of Palacky University in Olomouc [IGA_PrF_2021_031]CZ.02.1.01/0.0/0.0/16_019/0000867; Univerzita Palackého v Olomouci: IGA_PrF_2021_03

Hemp-derived CBD used in food and food supplements

Cannabis sativa L., a plant historically utilized for textile fibers, oil, and animal feed, is progressively being recognized as a potential food source. This review elucidates the nutritional and functional attributes of hemp and cannabidiol (CBD) within the context of food science. Hemp is characterized by the presence of approximately 545 secondary metabolites, among which around 144 are bioactive cannabinoids of primary importance. The study looks in detail at the nutritional components of cannabis and the potential health benefits of CBD, encompassing anti-inflammatory, anxiolytic, and antipsychotic effects. The review deals with the legislation and potential applications of hemp in the food industry and with the future directions of cannabis applications as well. The paper emphasizes the need for more scientific investigation to validate the safety and efficacy of hemp components in food products, as current research suggests that CBD may have great benefits for a wide range of consumers.Tomas Bata University in Zlín, TBU, (IGA/FT/2023/007