Прегледај по Аутор "Malešević, Zoranka"

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    A Comparative Analysis of Thin-Layer Microwave and Microwave/Convective Dehydration of Chokeberry
    (MDPI, 2023) Petković, Marko; Filipović, Vladimir; Lončar, Biljana; Filipović, Jelena; Miletić, Nemanja; Malešević, Zoranka; Jevremović, Darko
    Due to high water content, chokeberries (Aronia melanocarpa L.) are perishable. Therefore, energy-saving, combined drying technologies have been explored to improve the chokeberry drying. The combined microwave and the traditional convective drying method (MCD) have significantly enhanced the drying effectiveness, efficiency, and energy utilization rate and improved product quality. The MCD method, which implies the microwave power (MD) of 900 W for 9 s and the convective dehydration (CD) at 230 C for 12 s, has the shortest dehydration time t (24 2 min), has the maximum coefficient of diffusion (Deff = 6.0768 10􀀀9 5.9815 10􀀀11 m2 s􀀀1), and represents the most energy effective for dehydration process (Emin = 0.382 0.036 kWh). A higher waterholding capacity (WHC) characterized the chokeberries obtained by the MCD method compared to the regular microwave method (MD). The mildest MCD (15 s of MD on 900 W, 7 s of CD on 180 C) could dehydrate chokeberries with the highest WHC (685.71 40.86 g H2O g􀀀1 d.m.) and the greatest evaluations for sensory attributes in terms of all properties. The results of this study provide the drying behavior of chokeberries that can help develop efficient drying methods and improve existing ones.
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    Comparative analysis of phenolic, flavonoid and antioxidant content in root vegetables from organic and conventional production
    (Czech Academy of Agricultural Sciences, 2023) Malešević, Zoranka; Jovović, Mirjana; Govedarica-Lučić, Aleksandra; Petković, Marko
    Vegetables and their products have a low caloric value. Root vegetables are rich in bioactive compounds such flavonoids, polyphenolic acids, carotenoids. It also contains a some percentage of other functional components that can significantly affect human health.In order to achieve a high yield, excessive fertilization with nitrogen fertilizer is performed, which worsens the quality of vegetables. The aim of this paper is to analyze the impact cultivation system on the content of total phenolics and flavonoids, as well as a comparative assessment of their antioxidant activity in selected samples of vegetables. The antioxidant activity was studied using DPPH, and ABTS assays. The total phenolic content (TPC) and total flavonoid content (TFC) of the extracts were determined using Folin-Ciocalteuand and Aluminium chloride colorimetric methods, respectively. The highest content of total phenolics was determined for parsley from conventional production (427.38 mg GAE/100 g fresh sample), parsley from organic production the richest source of flavonoids (54.92 mg GAE/100 g fresh sample). Other samples of vegetables from conventional production had a lower flavonoid content compared to organic production. It was confirmed that the antioxidant activity of the analyzed vegetables in the maximum correlation with the content of total phenolics (R2 = 1). Organic samples of vegetables were characterized by a significantly higher content of flavonoids compared to vegetables grown conventionally. Organic production could be a good method to increase the concentration of bioactive compounds with antioxidant properties in vegetables.