Vranac, an old autochthonous red grapevine variety of Montenegro, was first mentioned in a historical document published in the 15th century. As currently the study of indigenous varieties is of particular importance, the subject of this work was detailed characterization of phenolic compounds in the autochthonous grapevine variety Vranac, from the Montenegrin Podgorica subregion. Phenolic profiles of leaves, berries (skin, seeds, and pulp were examined separately) and young monovarietal wine were determined using ultra-high performance liquid chromatography (UHPLC) with linear trap quadrupole (LTQ)—Orbitrap XL mass spectrometry (MS). Total phenolic content (TPC) and radical scavenging activity (RSA) were higher for the grape seeds extracts, followed by extracts of grape skins and pulps. As expected, the total anthocyanin content (TAC) was higher in grape skin than in wine. A total of one hundred twenty nine compounds (forty two phenolic acids and their derivatives, twenty three flavan-3-ols, twenty one flavanols, five stilbenes and thirty eight anthocyanins) were identified in the investigated extracts. To our best knowledge, this is the first report of tentative identification of (epi)catechin 3-O-coumarate in grape seed and chalcan-flavan 3-ol dimers in wine and grape seed.

This paper studies the corrosion inhibition of X52 5L carbon steel in 0.51 mol dm-3 sodium chloride solution in the presence of propolis extract. The inhibition efficiency of propolis extract in a chloride solution was tested by its adding to the working solution and by making a solid propolis coating on the electrode surface. The possibility of corrosion inhibition in the presence of propolis in flow conditions as well as at different temperatures was investigated by electrochemical methods: potentiodynamic polarization method and electrochemical impedance spectroscopy. It was shown that propolis extract acts as a corrosion inhibitor of anodic type whose efficiency increases with increasing of temperature and with stirring of solution. The best protection is achieved by applying propolis coating in flow systems. The EIS method confirmed formation of a protective layer by adsorption of propolis extract on the electrode surface. The results of the FTIR, SEM and EDX surface tests are consistent with the results of electrochemical testing and suggest that propolis extract acts as a corrosion inhibitor of steel by forming a protective film on the electrode surface.

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This paper studies the corrosion inhibition of carbon steel in a 0.51 mol × dm−3 sodium chloride solution in the presence of honey. The tests were carried out using the potentiodynamic polarization method, scanning electronic spectroscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and Fourier-transform infrared spectroscopy (FTIR). Electrochemical parameters which indicate the corrosion behavior of the steel in the sodium chloride solution in the absence and in presence of honey were calculated based on the experimental results. It was shown that honey acts as a mixed corrosion inhibitor whose efficiency increases with an increasing concentration. The maximum efficiency of inhibition (77.68 %) was maintained through a 1200 ppm concentration of honey. The adsorption of the tested inhibitor is described by Langmuir's isotherm, and the calculated value of free adsorption energy indicates the physical adsorption of the organic components of honey on the steel surface. The results of the SEM, FTIR and EDX analysis show that the honey covers the steel surface and prevents the influence of the aggressive medium.