Melánia Feszterová

Dr. Melánia Feszterová

orcid

Research Focus & Metrics

Academic Career Length

14Years (2013-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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25 September 2023 in Applied Sciences
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MFMelánia Feszterová
Melánia Feszterová
Małgorzata Katarzyna KowalskaMałgorzata Katarzyna Kowalska
Małgorzata Katarzyna Kowalska
MMMargaréta Mišiaková
Margaréta Mišiaková
The effect of environmental variables on vitamin C degradation in the analysed plant and vegetable juice samples was investigated. The study focused on samples from chives, dandelion, and nettle, as well as tomato, carrot, cucumber, red and white peppers, and cabbage. The aims of the study were to summarise the impact of storage time, temperature, and packaging materials on antioxidants (using vitamin C as an example) in processing plant and vegetable juices. The vitamin C concentration was tested iodometrically at 0 to 21 days intervals. Storage was carried out at different temperatures (4 °C, 23 °C, −18 °C) and in two selected packaging materials (glass and plastic). The analyses showed that low temperatures (t = 4 °C) and storage in glass containers are best for preserving vitamin C content. Storage time influenced the decrease in vitamin C values, with higher losses accompanying longer storage times. Plastic containers had a shorter shelf life for vitamin C compared to glass containers. In general, high temperatures during processing and storage have a negative effect on the preservation of vitamin C. Therefore, storing juices in the refrigerator and glass containers intended for food applications to minimise vitamin C degradation is important.

1 June 2023 in Gels
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AŻAnna Żbikowska
Anna Żbikowska
Sylwia Onacik-GürSylwia Onacik-Gür
Sylwia Onacik-Gür
Małgorzata Katarzyna KowalskaMałgorzata Katarzyna Kowalska
Małgorzata Katarzyna Kowalska
KZKatarzyna Zbikowska
Katarzyna Zbikowska
MFMelánia Feszterová
Melánia Feszterová
The natural properties of oils and fats do not always allow for their direct use in industry (e.g., for food, cosmetics, and pharmaceuticals). Furthermore, such raw materials are often too expensive. Nowadays, the requirements for the quality and safety of fat products are increasing. For this reason, oils and fats are subjected to various modifications that make it possible to obtain a product with the desired characteristics and good quality that meets the needs of product buyers and technologists. The modification techniques of oils and fats change their physical (e.g., raise the melting point) and chemical properties (e.g., fatty acid composition). Conventional fat modification methods (hydrogenation, fractionation, and chemical interesterification) do not always meet the expectations of consumers, nutritionists, and technologists. In particular, Hydrogenation, while it allows us to obtain delicious products from the point of view of technology, is criticised for nutritional reasons. During the partial hydrogenation process, trans-isomers (TFA), dangerous for health, are formed. One of the modifications that meets current environmental requirements and trends in product safety and sustainable production is the enzymatic interesterification of fats. The unquestionable advantages of this process are the wide spectrum of possibilities for designing the product and its functional properties. After the interesterification process, the biologically active fatty acids in the fatty raw materials remain intact. However, this method is associated with high production costs. Oleogelation is a novel method of structuring liquid oils with small oil-gelling substances (even 1%). Based on the type of oleogelator, the methods of preparation can differ. Most oleogels of low molecular weight (waxes, monoglycerides, and sterols) and ethyl cellulose are prepared by dispersion in heated oil, while oleogels of high molecular weight require dehydration of the emulsion system or solvent exchange. This technique does not change the chemical composition of the oils, which allows them to keep their nutritional value. The properties of oleogels can be designed according to technological needs. Therefore, oleogelation is a future-proof solution that can reduce the consumption of TFA and saturated fatty acids while enriching the diet with unsaturated fatty acids. Oleogels can be named “fats of the future” as a new and healthy alternative for partially hydrogenated fats in foods.

22 June 2021 in Sustainability
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MFMelánia Feszterová
Melánia Feszterová
LPLýdia Porubcová
Lýdia Porubcová
Anna TirpakovaAnna Tirpakova
Anna Tirpakova
This study assisted in identifying and preventing the increase in heavy metals in soil and winter wheat. Its accumulation can affect cultivated crops, quality and crop yields, and consumers’ health. Selected heavy metals were analyzed using the GTAAS method. They were undertaken on selected heavy metals content (Cd, Cu, Pb, and Zn) in arable soils at three sites in Slovakia and their accumulation in parts of cultivated winter wheat. Our study showed that the limit value of Cd in soil samples was exceeded in the monitored arable soils from 2017–2019. The average content values of Cu and Zn did not exceed the limit values, even in Pb values (except for the spring period). The analyses also showed that the heavy metals content for plants bioavailable in soil did not exceed the statutory critical values for Cd, Cu, and Zn’s average content values. However, Pb content exceeded permitted critical values. Heavy metals bioaccumulation (Zn, Cu) was within the limit values in wheat. Analyzed Cd content in wheat roots and Pb content were determined in all parts of wheat except grain. The study showed that grain from cultivated winter wheat in monitored arable soils is not a risk for consumers.

12 March 2023 in Applied Sciences
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MFMelánia Feszterová
Melánia Feszterová
MMMargaréta Mišiaková
Margaréta Mišiaková
Małgorzata Katarzyna KowalskaMałgorzata Katarzyna Kowalska
Małgorzata Katarzyna Kowalska
The content of vitamin C in fruit juices can be lowered by alterations in storage and temperature. This study compared storage circumstances (temperature, duration, and packaging type) to determine which variable had the biggest influence on changes in the vitamin C content of juices (grapefruit, mandarin, peach, apple, pear, plum). Fruit juices held in glass (plastic) containers at 4 °C saw vitamin C losses in the range of 0.0–10.9% (2.4–17.4%) in 24 h, 1.4–22.6% (5.2–25.3%) in 48 h, and 2.8–37.0% (6.0–39.0%) in three days. By raising the storage temperature to 23 °C, vitamin C losses in glass (plastic) containers were found to be 1.4–19.1% (5.2–22.2%), 2.8–20.9% (5.9–25.9%), and 4.5–43.5% (6.0–38.7%) of the value after 24 h, 48 h, and three days, respectively. When decreasing the temperature to −18 °C in fruit juices stored in glass (plastic) containers, there were losses of vitamin C in 24 h in the range of 1.5–19.6% (3.0–20.0%), in 48 h, 4.5–26.1% (4.5–26.1%), and in three days, 6.0–43.1% (5.8–43.5%) of the value. The effect of temperature on vitamin C concentration has been proven. Fruit juice’s vitamin C is more stable when kept in glass containers as opposed to plastic ones, which have a limited shelf life.

5 January 2023 in Applied Sciences
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Małgorzata Katarzyna KowalskaMałgorzata Katarzyna Kowalska
Małgorzata Katarzyna Kowalska
JKJustyna Konopska
Justyna Konopska
MFMelánia Feszterová
Melánia Feszterová
AŻAnna Żbikowska
Anna Żbikowska
BKBarbara Kowalska
Barbara Kowalska
The purpose of the study was to analyse and update consumers’ changing preferences in the choice of citrus fruit juices and to evaluate the sensory and physicochemical characteristics of two kinds of juices: juice squeezed from raw fruit and a commercial juice indicated by respondents as best matching their preferences. The survey was conducted in the form of an online survey posted on app.ankieteo.pl. The survey was also sent via a link through social networks. A total of 862 people took part in the survey. Consumers are most likely to consume juices one to three times a week (28.3%). Orange juice was the most popular among respondents (52.4%). The main factors influencing decisions to purchase citrus fruit juices are the type of fruit from which the juice was made, the vitamin content and the product’s price. In choosing juices, respondents were also guided by favourable health qualities and the presence of minerals. From the physicochemical determinations of orange juices obtained from a juicer and squeezer and commercial juice “O”, it was found that the quality of commercial orange juice indicated by consumers in the survey is comparable to juices made with a squeezer or a juice.

27 March 2024 in Applied Sciences
Verified
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MFMelánia Feszterová
Melánia Feszterová
Małgorzata Katarzyna KowalskaMałgorzata Katarzyna Kowalska
Małgorzata Katarzyna Kowalska
MHMichal Hudec
Michal Hudec
This study examined the sorption of heavy metals in selected soils (e.g., Andosol, Cambisol, Planosol) in Slovakia, focusing on the kind and quantity of humic materials as well as the soil’s characteristics. Heavy metals were detected using GT AAS, while UV-Vis spectroscopy was used to determine humic substances’ colour quotients. The impact of the total organic carbon on the total cadmium, bioavailable lead, and cadmium was highlighted. The results reveal positive correlations among humic substances and bioavailable forms of Cd (r = 0.692) and Pb (r = 0.709). A relationship was discovered between FAs and the bioavailable forms of Pb (r = 0.743) and Cd (r = 0.700) and between the level of HSs and the bioavailable content of Cd (r = 0.499). Bioavailable heavy metals showed a positive correlation with clay fraction and a negative correlation with heavy metal content. Correlations were found between the bioavailable heavy metal forms and the colour quotients of humic substances and humic acids. Heavy metals in bioavailable forms decreased with the levels of the condensation and dispersion of humic substances. From clay to silt, the amounts of Cd and Pb increased. This study’ results provide insights into the relationships between soil properties, humic substances, and the sorption of the studied elements.