Papers by Ivana Redovnikovic
Applied sciences, Oct 13, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Separations
In this work, the solid–liquid extraction of bioactive molecules from grape skin was performed us... more In this work, the solid–liquid extraction of bioactive molecules from grape skin was performed using water as the extraction solvent. The effects of extraction time (t = 60, 75, and 90 min), extraction temperature (T = 40, 60, and 80 °C), solid–liquid phase ratio (S/L = 10, 20, and 30 g/L), and mixing speed (rpm = 250, 500, and 750 1/min) on the total dissolved solids, extraction yield, concentration of total polyphenols, and antioxidant activity were determined using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) methods. According to response surface modeling, the optimal extraction conditions were t = 75 min, T = 80 °C, S/L = 30 g/L, and rpm = 750 1/min, and under optimal process conditions, 8.38 mgGAE/gd.m. was obtained. Furthermore, the potential of near-infrared (NIR) spectroscopy coupled with artificial neural network (ANN) modeling for prediction of the physical and chemical properties of prepared extracts was also analyzed. The use of ...
International Journal of Electrochemical Science
Electrochemical investigations show that aluminium and AA5754 alloy have certain corrosion activi... more Electrochemical investigations show that aluminium and AA5754 alloy have certain corrosion activity in 1% acetic acid solution. Results indicate that aluminium has better corrosion resistance to the action of 1% acetic acid than its AA5754 alloy. The addition of ethanol solution of laurel oil in acetic acid decreases the values of corrosion current densities and increases the polarization resistance. Corrosion inhibition effect of laurel oil is confirmed by SEM examination.
Foods
The recovery of valuable bioactive compounds from the main underutilised by-products of the food ... more The recovery of valuable bioactive compounds from the main underutilised by-products of the food industry is one of the greatest challenges to be addressed in circular economy. Potato peels are the largest waste generated during potato processing. However, they could be a potential source of valuable bioactive compounds, such as polyphenols, that can be reused as natural antioxidants. Currently, environmentally benign enabling technologies and new types of non-toxic organic solvents for the extraction of bioactive compounds may dramatically improve the sustainability of these processes. This paper focuses on the potential inherent in the valorisation of violet potato peels (VPPs) by recovering antioxidants using natural deep eutectic solvents (NaDES) under ultrasound (US)- and microwave (MW)-assisted extraction. Both the enabling technologies provided performances that were superior to those of conventional extractions in terms of antioxidant activity determined by the DPPH· (2,2-di...
Applied Sciences
The implementation of a suitable and ecologically friendly solid waste management plan is accepte... more The implementation of a suitable and ecologically friendly solid waste management plan is accepted as an essential need. Given that organic matter constitutes the majority of solid waste, composting has gained popularity as an alternative way of organic refuse recycling. Compost quality is defined by its stability and maturity, both of which must be assessed by measuring a large number of physical–chemical parameters, microbiological variables, and enzymatic activities. These procedures are complex and time-consuming, making it difficult to assess compost quality correctly. Spectroscopy methods could be used as an efficient alternative. In this work, general information about composting processes and near-infrared spectroscopy (NIRS) is given. A discussion and comparison of the different approaches of coupling NIRS and chemometric tools for the monitoring and/or control of composting processes are presented in this work.
Plants
Mediterranean forest ecosystems in Croatia are of very high significance because of the ecologica... more Mediterranean forest ecosystems in Croatia are of very high significance because of the ecological functions they provide. This region is highly sensitive to abiotic stresses such as air pollution, high sunlight, and high temperatures alongside dry periods; therefore, it is important to monitor the state of these forest ecosystems and how they respond to these stresses. This study was conducted on trees in situ and focused on the four most important forest species in the Mediterranean region in Croatia: pubescent oak (Quercus pubescens Willd.), holm oak (Quercus ilex L.), Aleppo pine (Pinus halepensis Mill.) and black pine (Pinus nigra J. F. Arnold.). Trees were selected and divided into two groups: trees with defoliation of >25% (defoliated) and trees with defoliation of ≤25% (undefoliated). Leaves and needles were collected from selected trees. Differences in chlorophyll content, hydrogen peroxide content, lipid peroxidation and enzyme activity (superoxide dismutase, catalase, ...
Sustainable Chemistry and Pharmacy
Foods
Valorisation of grape pomace, a by-product of the winery industry, has been pushed into the spotl... more Valorisation of grape pomace, a by-product of the winery industry, has been pushed into the spotlight in recent years since it can enable lower environmental impact, but it can also bring an added value to the wine production process by recovering several grape pomace biologically active compounds. The first step that allows for grape pomace reuse is its drying, which should be carefully performed in order to preserve the biologically active compounds’ stability. In this study, the effects of different drying methods on the stability of polyphenols, tannins and tartaric acid in grape pomace (Vitis vinifera) cv. Graševina were investigated. In particular, vacuum drying (at different temperatures: 35, 50 and 70 °C), conventional drying at 70 °C and open sun drying were performed and the drying kinetics was described using Peleg’s model. Considering the processing time and thermodynamics, vacuum drying at 70 °C was the most convenient processing method. Polyphenols were highly stable d...
Molecules
The aim of this work was to develop a simple and easy-to-apply model to predict the pH values of ... more The aim of this work was to develop a simple and easy-to-apply model to predict the pH values of deep eutectic solvents (DESs) over a wide range of pH values that can be used in daily work. For this purpose, the pH values of 38 different DESs were measured (ranging from 0.36 to 9.31) and mathematically interpreted. To develop mathematical models, DESs were first numerically described using σ profiles generated with the COSMOtherm software. After the DESs’ description, the following models were used: (i) multiple linear regression (MLR), (ii) piecewise linear regression (PLR), and (iii) artificial neural networks (ANNs) to link the experimental values with the descriptors. Both PLR and ANN were found to be applicable to predict the pH values of DESs with a very high goodness of fit (R2independent validation > 0.8600). Due to the good mathematical correlation of the experimental and predicted values, the σ profile generated with COSMOtherm could be used as a DES molecular descripto...
Kemija u industriji, 2021
Otapala se svakodnevno upotrebljavaju u brojnim industrijskim procesima zbog presudne uloge u ota... more Otapala se svakodnevno upotrebljavaju u brojnim industrijskim procesima zbog presudne uloge u otapanju krutih komponenti, prijenosu tvari i topline te u koracima izdvajanja i pročišćavanja produkta. Procjenjuje se da hlapljiva organska otapala čine gotovo 60 % svih industrijskih emisija te 30 % svih emisija hlapljivih organskih spojeva u svijetu, uzrokujući brojne negativne učinke na okoliš (promjena klime na globalnoj razini, onečišćenje zraka, narušavanje ozonskog omotača, narušavanje ljudskog zdravlja i sl.). Povrh toga, većina tradicionalno uporabljenih organskih otapala je toksična, zapaljiva i korozivna, a njihova regeneracija i ponovna uporaba povezana je s energetski zahtjevnom destilacijom uz znatne gubitke te unakrsno onečišćenje.1 Godine 1991. kemičar P. T. Anastas je kroz program nazvan zelena kemija, koji se zasniva na prihvatljivom usuglašavanju ekonomskih i ekoloških zahtjeva tijekom proizvodnje različitih industrijski značajnih kemikalija, ukazao na potrebu za smanje...
Separations, 2022
Olive leaves are a rich source of polyphenols that have beneficial antihypertensive, hypocholeste... more Olive leaves are a rich source of polyphenols that have beneficial antihypertensive, hypocholesterolemic, cardioprotective, and anti-inflammatory effects. The aim of this study was to compare the efficiency of conventional extraction (CE), microwave-assisted extraction (MWE), and microwave–ultrasound-assisted extraction (MWUE) for the extraction of bioactive molecules from olive leaves using water as a solvent and to define the optimal extraction conditions for all three methods used. CE conditions (temperature, time, magnetic stirrer rotational rate and particle diameter) and MWE extraction and MWUE conditions (microwave power, time, particle diameter, and temperature) were optimized using response surface methodology (RSM) based on the Box–Behnken experimental design. The total polyphenol content and antioxidant activity of all prepared extracts was analyzed and compared. The results showed that MWUE provided the highest amount of total polyphenols (Total Polyphenolic Content (TPC...
Processes, 2022
Composting is a more environmentally friendly and cost-effective alternative to digesting organic... more Composting is a more environmentally friendly and cost-effective alternative to digesting organic waste and turning it into organic fertilizer. It is a biological process in which polymeric waste materials contained in organic waste are biodegraded by fungi and bacteria. Temperature, pH, moisture content, C/N ratio, particle size, nutrient content and oxygen supply all have an impact on the efficiency of the composting process. To achieve optimal composting efficiency, all of these variables and their interactions must be considered. To this end, statistical optimization techniques and mathematical modeling approaches have been developed over the years. In this paper, an overview of optimization and mathematical modeling approaches in the field of composting processes is presented. The advantages and limitations of optimization and mathematical modeling for improving composting processes are also addressed.
Sumarski List, 2015
Fitoremedijacija se smatra obecavajucom, jeftinom te estetski prihvatljivom, in situ tehnologijom... more Fitoremedijacija se smatra obecavajucom, jeftinom te estetski prihvatljivom, in situ tehnologijom za remedijaciju teskih metala iz oneciscenih t
Antioxidants, 2020
Interest in bioactive phytochemicals and sustainable processes is the driving force behind this s... more Interest in bioactive phytochemicals and sustainable processes is the driving force behind this study on two novel green extraction methods for the recovery of anthocyanins from the residues of blueberry processing. Five natural deep eutectic solvents (NADES) have been tested for anthocyanin extraction. Acidified hydroalcoholic solutions were used as benchmarks and the shelf life of eutectic systems was monitored. The most promising NADES was tested in microwave (MAE)- and ultrasound-assisted extractions (UAEs), and Peleg’s kinetic model was used. Both the enabling technologies provided performance that was superior to that of conventional extraction. MAE and UAE yielded up to 25.83 and 21.18 mg/gmatrix of total anthocyanin content, respectively, after 15 and 30 min. Moreover, a preliminary test for extract concentration and NADES recycling was performed using resin adsorption. Finally, the antiproliferative activity of the extracts was determined by a CellTiter 96® AQueous One Solu...
Applied Sciences, 2020
In the past few years, research efforts have focused on plant exploitation for deriving some valu... more In the past few years, research efforts have focused on plant exploitation for deriving some valuable compounds. Extraction has been usually performed using petrochemical and volatile organic solvents, but nowadays, increased recognition of environmental pollution has prompted the utilization of green solvents as alternatives. Therefore, the aim of the present study was to exploit deep eutectic solvents (DES) (choline chloride: citric acid and choline chloride: glucose) as solvents for extracting valuable phenolic antioxidants from grapes. Investigation was conducted on ten grape varieties, observing seeds and skin as different matrix. Total polyphenol content (TPC) was determined by Folin-Ciocalteu spectrophotometric microassay. Antioxidant activity was investigated using four different tests and results were combined in a unique Antioxidant Composite Index (ACI) to reveal comprehensive information about this biological activity. Polyphenol compounds were identified and quantified ...
Separation and Purification Technology, 2020
Development of continuously operated aqueous two-phase microextraction process using natural deep... more Development of continuously operated aqueous two-phase microextraction process using natural deep eutectic solvents, Separation and Purification Technology (2020), doi:
Molecular Biology Reports, 2019
Food proteins from different sources can provide beneficial effects on human health by releasing ... more Food proteins from different sources can provide beneficial effects on human health by releasing the bioactive peptides that are integral part of their native structure. In this study, we tested the biological potential of hempseed protein hydrolysates (HPHs) obtained from hempseed cake protein isolate. The HPHs were prepared by enzyme hydrolysis using three different proteases of microbial origin: Alcalase®, Neutrase® and Protamex®. The antioxidant activity of the obtained hydrolysates was determined by oxygen radical absorbance capacity (ORAC) assay, while the proliferative effects on normal (HaCaT) and cancer (HeLa) cells were determined by the CellTiter 96 ® AQ ueous One Solution Reagent (MTS) assay. HPHs showed dosedependent antiproliferative effects on HeLa cells and stimulatory effects on the proliferation of HaCaT cells. HPH obtained by Neutrase ® (HPH-N) showed the highest antioxidant activity expressed as an ORAC value. The protective effect of HPH-N on H 2 O 2-induced oxidative stress in normal and cancer cells was evaluated and 1 mg/mL of HPH-N significantly reduced the formation of intracellular reactive oxygen species (ROS) in both cell lines. The obtained results indicate the benefits of HPHs as potential natural antioxidants for the food industry and contribute to the growing trend of utilizing hempseed by-products.
Food Technology and Biotechnology, 2017
In this study, eight diff erent types of imidazolium-based ionic liquids (ILs) were applied as ne... more In this study, eight diff erent types of imidazolium-based ionic liquids (ILs) were applied as new solvents in the extraction of fl avonoids from grape skin, and compared to the conventional organic solvent extraction that was not reported earlier. The structure of anions, cations and concentration of ILs signifi cantly aff ected extraction yields. The highest mass fractions of proanthocyanidins and anthocyanins were obtained with 2.5 mol/L of 1-butyl-3-methylimidazolium bromide [C 4 mim][Br] and 2.5 mol/L of 1-ethyl-3-methylimidazolium bromide [C 2 mim][Br], respectively. The studied ILs provided an excellent preliminary result in the extraction of anthocyanins. Signifi cantly higher mass fractions of total and all free anthocyanins were extracted with 2.5 mol/L of [C 2 mim][Br] and 2.5 mol/L of 1-methylimidazolium hydrogen sulfate [mim][HSO 4 ] than with conventional solvent with the exception of anthocyanin-3-O-acetylmonoglucosides in the latt er. On the other hand, 2.5 mol/L of [C 4 mim][Br] and 2.5 mol/L of 1-(4-sulfobutyl)-3-methylimidazolium hydrogen sulfate [sC 4 mim][HSO 4 ] showed signifi cantly higher selectivity towards anthocyanin-3-O-acetylmonoglucosides and anthocyanin-3-(6-O-p-coumaroyl)monoglucosides.
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Papers by Ivana Redovnikovic