Kinetic Study of Oxidation Degradation of Polyphenols in Sour Cherry and Blackberry Extracts During Storage

In this study was to investigate the influence of storage time, light and temperature on stability of polyphenols in sour cherry (Prunus cerasus) and blackberry (Rubus fruticosus), were harvested in western Serbia (Rasinski region). Total phenol content was monitored in the fruit extracts during 23 days stored at 7°C under darkness and 90 days storage at 23°C in oxygen. For analyzed extracts, first-order reaction kinetics was established for the degradation process of polyphenols. The temperature dependence of the polyphenols degradation rate constants was expressed by the temperature coefficients Q10 of the process. It is found that the Q10 values of polyphenols degradation in sour cherry and blackberry extracts were 1.247 and 3.239, respectively

Quality Red Wines: Changing the Content of Anthocyanins in the Process of Ripening Grapes

The content of anthocyanins in grape affects the color and sensory properties of red wine. This paper deals with the quality of Cabernet Sauvignon wines examining changes in the content of anthocyanins in the process of ripening grapes. The HPLC results show that the skin extracts obtained from the early defoliation plants showed up to 6 % and corresponding wine up to 24 % increase of the content of total anthocyanins as compared to the extracts from the control grape and corresponding wine samples. Partial early defoliation may be an excellent tool for control of anthocyanins in grapes and may be employed as a management practice as parameter for quality of red wines

Decomposition mechanism and kinetics of zinc–isophthalate complex with 2,2’-dipyridylamine as a precursor for obtaining nanosized zinc oxide

Studies related to the synthesis of nanosized ZnO as the antibacterial agent have become an interdisciplinary area gathering chemists, physicists, biologists, and medics. The broad scope of materials based on ZnO resulted in the development of various techniques for its preparation. Considering the dependence of particle shape and size onto physical and chemical properties of ZnO, the synthesis procedure is of major importance. In this work, an unconventional methodology of synthesis is proposed for obtaining nanosized ZnO. Polymeric zinc complex containing 2,2’-dipyridylamine (dipya) and dianion of 1,3-benzenedicarboxylic acid (ipht), [Zn(dipya)(ipht)]n, was used as precursor. Besides the crystal structure of [Zn(dipya)(ipht)]n which was already published [1], the luminescent properties are presented in this work. Also, the amazing antibacterial activity of this precursor prompted us to investigate the relationship between the crystal structure and thermal properties, especially if we bear in mind the lack of similar studies in the literature. Therefore, the mechanism and kinetics of its degradation was investigated under non isothermal conditions in nitrogen and air atmospheres. Degradation enthalpies, thermodynamic activation parameters, pre-exponential factor, A, and the apparent activation energy, Ea, were determined for each step using Kissinger’s and Ozawa’s equations. The complexity of degradation steps has been analyzed using isoconversional methods. TG/DCS data were collected at four different heating rates: 10, 15, 20 and 25 ºC min –1 , while the formation of nanosized ZnO was confirmed using XRPD and FESEM techniques. The influence of precursor on the crystallite size and morphology of the resulting ZnO along with its antibacterial activity was examined. The obtained results will be discussed and compared. [1] L. Radovanović, J. Rogan, D. Poleti, M. Milutinović, M.V. Rodić, Polyhedron 112 (2016) 18

Biljna ulja u ishrani riba

There has been a trend towards constant growth in fish farming. It is well known that fish meal (as a basic source of protein) and fish oil (as a source of fatty acids) provide feedstuffs for farmed fish. Increasing aquaculture requirements and limited natural resources call the attention of both practice and scientific research to alternative sources of these feed components. Certain vegetable oils have been increasingly used as a source of fatty acids. This study provides an outline of the potential use of linseed (Linum usitatissimum L.) and rapeseed (Brassica napus L.) oils as complete or partial substitutes for fish oil in the diet of cyprinids and trouts predominating in European aquaculture.Gajenje riba u akvakulturi ispoljava tendenciju stalnog porasta. Poznato je da se u kompletnim smešama za ishranu riba koriste riblje brašno (osnovni izvor proteina) i riblje ulje (izvor masnih kiselina). Rastuće potrebe akvakulture i ograničeni prirodni resursi uslovljavaju da se u praksi i naučnim istraživanjima velika pažnja posvećuje alternativnim izvorima ovih hranidbenih komponenti. Kao izvor masnih kiselina sve više se koriste pojedina biljna ulja. U radu je dat kratak osvrt na mogućnost korišćenja biljnih ulja iz semena lana (Linum usitatissimum L.) i uljane repice (Brassica napus L.) kao potpunih ili delimičnih supstituenata ribljeg ulja u smešama za ishranu šaranskih i pastrmskih riba koje su dominantne u evropskoj akvakulturi

Photocatalytic and antimicrobial effects of zinc oxide nanoparticles prepared by thermal decomposition of zinc benzenepolycarboxylato complexes

Zinc oxide nanoparticles (ZnO-NPs) have been a subject of numerous researches owing to their multifunctional properties in many applications, such as solar cells, UV light-emitting devices, gas sensors and photocatalysts. ZnO-NPs can be synthesized through various methods and their features can be tailored by shape and size, resulting in new applications relevant to their structural properties. The synthesis of ZnO-NPs via controlled thermal decomposition of the single-source precursors represents a novel synthetic methodology. The basic goal of this study was to investigate the influence of precursors on crystallite size and morphology of the resulting ZnO-NPs. Four structurally characterized Zn complexes with different benzenepolycarboxylato ligands [1] were used as precursors for investigation of photocatalytic and antimicrobial effects of thermally obtained ZnO-NPs. The XRPD and FESEM analysis of ZnO-NPs, prepared by thermolysis of Zn precursors at 450 °C in the air atmosphere, revealed hexagonal wurtzite structure (space group P63mc, a ≈ 3.25 and c ≈ 5.21 Å) with an average crystallite size in the range of 39–47 nm and similar morphology. The best photocatalytic activity for degradation of Reactive orange 16 dye has been observed for ZnO-NPs where crystallites form the smallest agglomerates. All obtained ZnO-NPs showed excellent inhibitory effect against Gram-positive bacteria Staphylococcus aureus and Gram-negative bacteria Escherichia coli