Determination of Copper in Wine by Anodic Stripping Voltammetry with Rotating Glassy Carbon and Microfiber Carbon Electrode

Anodic stripping voltammetry (ASV) with rotating glassy carbon electrode (RGCE) and microfiber carbon electrode (µFCE), both filmed with mercury, were used to determine copper content in wine. Influence of phenolics on in situ mercury film formation was studied. Wine and quercetin were added gradually into solution of Hg(II) in acetic acid-sodium acetate buffer (pH = 4.60). Reduction of Hg(II) was observed in both cases. In situ filmed electrode was found unsuitable. Results obtained using ex situ filmed RGCE and µFCE were found in good agreement with ASV using hanging mercury drop electrode. Thus, ASV with ex situ mercury filmed electrodes can be recommended for accurate quantification of copper in complex samples containing phenolics, without any special pretreatments. This work is licensed under a Creative Commons Attribution 4.0 International License

Serbian aromatized wine “Bermet”: Electrochemical, chemiluminescent and spectrophotometric determination of antioxidant activity

Serbian aromatized wine “Bermet” from grapes grown on Fruška Gora Mountain has been in production since the 15th century. Ten commercial Bermets produced according to the traditional procedure by different manufacturers, and six prepared within the scope of this study were assessed for antioxidant (AO) activity using electrochemical, chemiluminescent and spectrophotometric AO assays. Direct current polarographic assay based on the decrease of anodic current of [hydrogen(peroxido)(1-)]hydroxidomercury(II) complex formation in alkaline H2O2 solution at potential of mercury oxidation, chemiluminescent H2O2 scavenging assay, as well as commonly used spectrophotometric assays (2,2’-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) based Trolox equivalent antioxidant capacity (TEAC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP)) were used. Total phenolic content (TPC) was determined by Folin–Ciocalteu assay. The results obtained were correlated using regression analysis, ANOVA and F-test. An integrated approach to AO capacity determination allowed a more comprehensive comparison between samples. The approach is based on the introduction of the relative antioxidant capacity index, calculated by assigning each AO assay equal weight, and by PCA analysis. In addition, the introduction of phenolic antioxidant coefficients, calculated as the ratio between individual AO capacity and TPC, enabled a better understanding of their relation

Antioxidant Capacity of Nettle Leaves During Osmotic Treatment

Osmotic treatment (OT) of nettle leaves was assessed in various osmotic solutions (sugar beet molasses – SBM and ternary aqueous solution – TAS), at temperatures of 20, 35 and 50 °C, under the atmospheric pressure. The influence of the kind of utilized osmotic solution, process temperature and osmotic time on the antioxidant activity (AOC), expressed with the spectrophotometric assays (ABTS, FRAP and DPPH), as well as two direct current polarographic assays, Hydroxo Perhydroxo Mercury (II) complex assay, based on the decrease of anodic current and assay based on the decrease of a cathodic current of Hg (II) reduction. For determination of the total phenolic content Folin-Ciocalteu assay was used. The Relative Antioxidant Capacity Index (RACI), obtained by setting equal weight for every involved assay was applied in order to get an extensive comparison among analyzed samples and between the used assays. Based on these results, after the OT of nettle leaves in TAS, the AOC decreased, while the OT in SBM increased AOC values. The phenolic antioxidant coefficients (PAC), calculated as the ratio between particular AO capacity and TPC, were used to achieve a more comprehensive comparison between analysed samples, as well as applied assays. The results of RACI evaluation revealed that the most favorable osmotic treatment is the one performed for 5h at 35 °C

Formulation of novel liqueurs from juice industry waste: Consumer acceptance, phenolic profile and preliminary monitoring of antioxidant activity and colour changes during storage

Research background. Apple juice is one of the most popular and liked beverages worldwide. Due to the increased health consciousness among consumers, beetroot and chokeberry juices have also rising consumption trends. Despite representing a consider-able percentage of the processed fruit and rich source of bioactive compounds, fruit pom-ace, remaining after juice production, has still been underutilised. Here, the possibility of using apple, beetroot and chokeberry pomace in liqueur formulations is investigated. Experimental approach. Apple and chokeberry liqueurs were produced from apple and chokeberry pomace extracts, respectively. Apple/chokeberry and apple/beetroot liqueurs were obtained by combining apple pomace with chokeberry and beetroot pomace extracts in ratios 50:50 and 70:30, respectively. The sensory quality and acceptability of freshly prepared liqueurs were evaluated by experts and consumers. Sugars and phenolics were identified and quantified by high-performance anion-exchange chromatography with pulsed-amperometric detection (HPAEC-PAD) and high-performance liquid chromatog-raphy–diode array detection–tandem mass spectrometry (HPLC–DAD–MS/MS), respec-tively. Storability was preliminarily evaluated based on monitoring of total phenolic con-centration, antioxidant activity and colour each month during 6 months of storage at 4 and 22 °C. Results and conclusions. The expert and the consumer testing indicated that apple and chokeberry pomace could be used as raw materials without any flavour corrections while apple/beetroot pomace liqueur would require modification. High total phenolic content and antioxidant activity were found in all freshly prepared liqueurs, with chokeberry liqueur being by far superior. Among identified phenolics, ellagic acid and phlorizin were quantified as the most prominent, except in chokeberry liqueur, where phlorizin was not quantified. Despite the decrease in total phenolic concentration and antioxidant activity after 6 months, liqueurs still represented a rich source of phytochemicals. The highest phenolic compound retention and antioxidant activity maintenance were observed in chokeberry liqueur. Also, the appealing colour was retained despite the changes detected in chromatic characteristics. Novelty and scientific contribution. The possibility of apple, beetroot and chokeberry pomace restoration into the food chain by the production of liqueurs has been demon-strated for the first time. Functional and sensorial properties of newly developed liqueurs indicated that the selected pomace represents the promising raw material for liqueur pro-duction. The applied approach represents a contribution to the circular economy in juice production

Udjeli ukupnih fenola, flavan-3-ola i proantocijanidina te oksidacijska stabilnost i antioksidacijski kapacitet čokolade tijekom skladištenja

Antioxidant (AO) capacity of chocolates with 27, 44 and 75 % cocoa was assessed after production and during twelve months of storage by direct current (DC) polarographic assay, based on the decrease of anodic current caused by the formation of hydroxo-perhydroxyl mercury(II) complex (HPMC) in alkaline solutions of hydrogen peroxide at potentials of mercury oxidation, and two spectrophotometric assays. Relative antioxidant capacity index (RACI) was calculated by taking the average value of the AO assay (the sample mass in all assays was identical). Oxidative stability of chocolate fat was determined by differential scanning calorimetry. Measured parameters and RACI were correlated mutually and with the content of total phenols (Folin-Ciocalteu assay), flavan-3-ols (vanillin and p-dimethylaminocinnamaldehyde assay) and proanthocyanidins (modified Bate-Smith assay). During storage, the studied functional and health-related characteristics remained unchanged. Amongst applied AO assays, the DC polarographic one, whose validity was confirmed by two-way ANOVA and F-test, correlated most significantly with oxidative stability (oxidation onset temperature and induction time). In addition, principal component analysis was applied to characterise chocolate types.Antioksidacijski kapacitet čokolade s 27, 44 i 75 % kakaa ispitan je odmah nakon proizvodnje te tijekom dvanaest mjeseci skladištenja, i topolarografskom metodom praćenja smanjenja anodne struje uslijed nastajanja kompleksa žive(II) s hidroksilnim i perhidroksilnim radikalima u alkalnim otopinama vodikovog peroksida pri elektrodnom potencijalu žive, te dvjema spektrofometrijskim metodama. Relativni antioksidacijski kapacitet čokolade izračunat je iz prosječnih rezultata dobivenih pojedinom metodom. Oksidacijska je stabilnost masti u čokoladi određena diferencijalnom pretražnom kalorimetrijom. Dobiveni rezultati uspoređeni su s ukupnim udjelom fenola (određenim pomoću metode Folin-Ciocalteu), flavan-3-ola (određenim pomoću vanilina i p-dimetilaminocinamaldehida) i proantocijanidina (određenim pomoću modificirane Bate-Smith metode). Funkcionalna svojstva i antioksidacijski kapacitet čokolade nisu se mijenjali tijekom skladištenja. Rezultati dobiveni polarografskom metodom uz pomoć jednosmjerne struje, obrađeni dvosmjernim ANOVA testom i F-testom, pokazali su najveću korelaciju s oksidacijskom stabilnosti, tj.temperaturom na kojoj započinje oksidacija i indukcijskim vremenom oksidacije. Analizom glavnih komponenata okarakterizirani su svi uzorci čokolade

Food Waste (Beetroot and Apple Pomace) as Sorbent for Lead from Aqueous Solutions—Alternative to Landfill Disposal

This article presents studies, whose main goal was to minimize food waste. To achieve this goal, it is necessary to expand the scope of their application, for example, for the purification of polluted water from heavy metals. Millions of tons of waste from the fruit and vegetable industry, including pomace of apples and beetroots, are thrown into landfills, posing a danger to the environment. In order to solve the problems with the disposal of these wastes, the authors investigated their sorption potential for the removal of lead from wastewater. The sorbents, dried apple (AP), and beetroots (BR) pomaces were characterized by various methods (study of composition, zeta potential, FTIR-ATR, and SEM-EDX). Various models of sorption kinetics and sorption isotherms were analyzed. Kinetical studies under optimal conditions showed that the sorption process occurs through complexation and ion exchange and the determining stage limiting the rate of sorption is the diffusion of lead ions in the sorbent. The maximum sorption capacity was 31.7 and 79.8 mg/g for AP and BR, respectively. The thermodynamic data revealed the spontaneous sorption of lead ions by sorbents. The temperature rise contributes to the sorption increase by the AP sorbent, while for the BR sorbent, the opposite effect is observed. The obtained results showed that apple and beetroots pomaces can serve as effective renewable materials for the preparation of sorbents, contributing to the solution of complex environmental problems

Functionality and Palatability of Yogurt Produced Using Beetroot Pomace Flour Granulated with Lactic Acid Bacteria

Following the idea of sustainability in food production, a yogurt premix based on beetroot (Beta vulgaris) pomace flour (BPF) was developed. BPF was granulated with lactose solution containing lactic acid bacteria (LAB) by a fluidized bed. Particle size increased ~30%. A decrease in Carr Index from 21.5 to 14.98 and Hausner ratio from 1.27 to 1.18 confirmed improved flowability of granulated BPF, whereas a decrease in water activity implied better storability. Yogurts were produced weekly from neat starters and granulated BPF (3% w/w) that were stored for up to one month (4 °C). High viability of Streptococcus thermophilus was observed. Less pronounced syneresis, higher inhibition of colon cancer cell viability (13.0–24.5%), and anti-Escherichia activity were ascribed to BPF yogurts or their supernatants (i.e., extracted whey). Acceptable palatability for humans and dogs was demonstrated. A survey revealed positive consumers’ attitudes toward the granulated BPF as a premix for yogurts amended to humans and dogs. For the first time, BPF granulated with LAB was used as a premix for a fermented beverage. An initial step in the conceptualization of a novel DIY (do it yourself) formula for obtaining a fresh yogurt fortified with natural dietary fiber and antioxidants has been accomplished

Investigation of antioxidant capacity of several luting cements processes by HPMC method

Background: Free radicals (FR) occur in oral cavity where lot of food was transferred to through entire life under specific saliva conditions. Many enzymes, microorganism, alcohol beverages, nicotine and other harmful or indifferent substances when in contact to oral tissues might provoke oxidation process under specific condition creating FR's. The similar role might have various dental materials. Aim of the study was to record the level of antioxidant (AO) activity of several permanent (P) luting cements alone or combined with quercetin AO substance. Materials/Methods: P cements were Zn-phosphate, Zn-polycarboxilate, GIC and composite resin cement. They were prepared as original prescription and their variant by 1% weight addition of quercetin. AO activity of cements was measured by HPMC test evaluated by Student t test. Results: There were statistically significant differences among Zn-phosphate, Zn-polycarboxilate and resin dental cements (p gt 0,05). GIC displayed significantly higher AO values (p lt 0,01) versus other three cements. There were no difference in AO capacity between sample of original P cements and their corresponding quercetin variants (p gt 0,05). Conclusions: Conventional GIC displayed the most powerful AO activity among P luting cements. Addition of 1% antioxidant quercetin did not improve AO capacity of investigated cements

Content of Total Phenolics, Flavan-3-Ols and Proanthocyanidins, Oxidative Stability and Antioxidant Capacity of Chocolate During Storage

Antioxidant (AO) capacity of chocolates with 27, 44 and 75 % cocoa was assessed after production and during twelve months of storage by direct current (DC) polarographic assay, based on the decrease of anodic current caused by the formation of hydroxo-perhydroxyl mercury(II) complex (HPMC) in alkaline solutions of hydrogen peroxide at potentials of mercury oxidation, and two spectrophotometric assays. Relative antioxidant capacity index (RACI) was calculated by taking the average value of the AO assay (the sample mass in all assays was identical). Oxidative stability of chocolate fat was determined by differential scanning calorimetry. Measured parameters and RACI were correlated mutually and with the content of total phenols (Folin-Ciocalteu assay), flavan-3-ols (vanillin and p-dimethylaminocinnamaldehyde assay) and proanthocyanidins (modified Bate-Smith assay). During storage, the studied functional and health-related characteristics remained unchanged. Amongst applied AO assays, the DC polarographic one, whose validity was confirmed by two-way ANOVA and F-test, correlated most significantly with oxidative stability (oxidation onset temperature and induction time). In addition, principal component analysis was applied to characterise chocolate types

Polarographic study of hydrogen peroxide anodic current and its application to antioxidant activity determination

Behavior of hydrogen peroxide in alkaline medium has been studied by direct current (DC) polarography with dropping mercury electrode (DME) aiming to apply it in antioxidant (AO) activity determination. Development of a peroxide anodic current having form of a peak, instead of common polarographic wave, has been investigated. As a base for this investigation the interaction of H(2)O(2) with anodically dissolved mercury was followed. Formation of mercury complex [Hg(O(2)H)(OH)] has been confirmed. The relevant experimental conditions, such as temperature, concentration and pH dependence, as well as time stability of hydrogen peroxide anodic current, have been assessed. Development of an AO assay based on decrease of anodic current of hydrogen peroxide in the presence of antioxidants (AOs) has been described. Under optimized working conditions, a series of benzoic acids along with corresponding cinnamate analogues have been tested for hydrogen peroxide scavenging activity. In addition, the assay versatility has been confirmed on various complex samples. (C) 2011 Elsevier B.V. All rights reserved