Use of Microwave Maceration in Red Winemaking: Effect on Fermentation and Chemical Composition of Red Wines

The objective of this study was to evaluate the effect of microwave treatment of crushed grapes on the yeast population of the must and on the development of alcoholic fermentation, as well as on the extraction of different compounds from the grapes such as polysaccharides and amino acids that can affect the organoleptic quality and stability of the wine. This study demonstrated for the first time the effect of the microwave treatment of grapes on native yeast species and their diversity, producing an increase in fermentation kinetics and a decrease in the lag phase. The microwave treatment produced a positive effect on the extraction of amino acids and polysaccharides from the grapes, resulting in significantly higher amounts of the main amino acids of the must and some major volatile compounds in the treated samples. The polysaccharides most affected by the microwave treatment were the PRAGs, the main polysaccharides liberated from grapes during the maceration.     

Influence of Must Clarification Technique on the Volatile Composition of Albariño and Treixadura Wines

Clarification of the musts is carried out to remove particles that cause turbidity, oxidizable polyphenols, and eliminate excess of proteins. However, an excessive clarification of the musts can lead to the reduction of volatile compound concentrations and, as a consequence, modify the sensorial properties of the wines. Therefore, in this study, the influence of two pre-fermentation clarification techniques (static settling and flotation) on the concentrations of volatile compounds has been assessed in Albariño and Treixadura wines. Fermentations were performed at an industrial scale. Volatile compounds have been identified and quantified by gas chromatography (FID and mass spectrometry detection) and expert panelists assessed the sensory properties of the final wines. The results showed effects of the clarification techniques on the volatile composition of wines from both varieties. Flotation significantly increased the concentrations of benzyl alcohol in Treixadura wines, whereas this technique increased the concentration of 1-hexanol, octanoic acid, and furfural in Albariño wines, but without exceeding the corresponding perception thresholds. Panelists tended to score higher the wines coming from flotation, which, together with the shorter application time, makes this technique suitable for clarifying the musts of these two white varieties.     

Effect of Must Hyperoxygenation on Sensory Expression and Chemical Composition of the Resulting Wines

This paper evaluates the effect of must hyperoxygenation on final wine. Lower concentrations of caftaric acid (0.29 mg·L⁻¹), coutaric acid (1.37 mg·L⁻¹) and Catechin (0.86 mg·L⁻¹) were observed in hyperoxygenated must in contrast to control must (caftaric acid 32.78 mg·L⁻¹, coutaric acid 5.01 mg·L⁻¹ and Catechin 4.45 mg·L⁻¹). In the final wine, hydroxybenzoic acids were found in higher concentrations in the control variant (gallic acid 2.58 mg·L⁻¹, protocatechuic acid 1.02 mg·L⁻¹, vanillic acid 2.05 mg·L⁻¹, syringic acid 2.10 mg·L⁻¹) than in the hyperoxygenated variant (2.01 mg·L⁻¹, 0.86 mg·L⁻¹, 0.98 mg·L⁻¹ and 1.50 mg·L⁻¹ respectively). Higher concentrations of total flavanols (2 mg·L⁻¹ in hyperoxygenated must and 21 mg·L⁻¹ in control must; 7.5 mg·L⁻¹ in hyperoxygenated wine and 19.8 mg·L⁻¹ in control wine) and polyphenols (97 mg·L⁻¹ in hyperoxygenated must and 249 mg·L⁻¹ in control must; 171 mg·L⁻¹ in hyperoxygenated wine and 240 mg·L⁻¹ in control wine) were found in both the must and the control wine. A total of 24 volatiles were determined using gas chromatography mass spectrometry. Statistical differences were achieved for isobutyl alcohol (26.33 mg·L⁻¹ in control wine and 32.84 mg·L⁻¹ in hyperoxygenated wine), or 1-propanol (7.28 mg·L⁻¹ in control wine and 8.51 mg·L⁻¹ in hyperoxygenated wine), while esters such as isoamyl acetate (1534.41 µg·L⁻¹ in control wine and 698.67 µg·L⁻¹ in hyperoxygenated wine), 1-hexyl acetate (136.32 µg·L⁻¹ in control wine and 71.67 µg·L⁻¹ in hyperoxygenated wine) and isobutyl acetate (73.88 µg·L⁻¹ in control wine and 37.27 µg·L⁻¹ in hyperoxygenated wine) had a statistically lower concentration.     

Anthocyanins HPLC-DAD and MS Characterization,Total Phenolics,and Antioxidant Activity of Some Berries Extracts

Extracts of indigenous wild blackberries, mulberries, bilberries, and blackthorns were analyzed for anthocyanin composition, anthocyanin content, total phenolics, and antioxidant capacity. Anthocyanins extraction with acidified methanol in ultrasonic condition (59 kHz, 60 min., 25°C) was carried out. The extracts were analyzed by high-performance liquid chromatography (HPLC) using a Dionex Ultimate 3000 apparatus equipped with photodiode array detector for qualitative characterization of the anthocyanins. The chromatograms revealed the presence of a large number of anthocyanins in fruits extracts: blackberries, 4 compounds; mulberries, 3 compounds; bilberries, 18 compounds; and blackthorns, 5 compounds. The most abundant anthocyanins were cyanidin-3-glucoside in blackberry, mulberry, and bilberry, and cyanidin-3-rutinoside in blackthorn extract. Structural information about anthocyanins was obtained by using a mass spectrometric method based on fully automated chip-nanoelectrospray ionization (nanoESI) high capacity ion trap (HCT). Anthocyanin content was quantified by the pH differential method and total phenolics were determined by Folin-Ciocalteu method. A Jasco V 530 UV-VIS spectrophotometer was used for absorbance measurements. The free radical scavenging activity of the berries extracts was performed by using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. The reduction of DPPH was followed by a spectrophotometric method. Also, a correlation of the antioxidant capacities of the extracts with their anthocyanin content and total phenolics was attempted.     

Electroanalytical Approach to Evaluate Antioxidant Capacity in Honeys: Proposal of an Antioxidant Index

A novel electrochemical route to estimate the antioxidant capacity in honey samples is proposed just using flow injection analysis. The analytical strategy involved the selective oxidation of polyphenolic compounds using two different target potentials, +0.8 and +0.5 V, at two different pHs. An oxidation current obtained at the fixed potential was used as an analytical guide of the antioxidant activity of the target honeys. Chemometrics (correlation and principal component analysis, PCA) demonstrated the significance of the electrochemical protocol versus the traditional spectrophotometric ones in the evaluation of antioxidant capacity and revealed the role of detection potential as a screening variable. The proposed protocol is very simple and fast. However, the most relevant merit of the electrochemical procedure is its inherent versatility which allows the evaluation of the antioxidant activity under predesigned controlled oxidation conditions. In addition, since intercept was statistically zero, its corresponding antioxidant content using just a calibration factor is proposed thus simplifying the calibration‐analysis process. As a result, an electrochemical antioxidant index (EAI) is proposed.     

Effect of processing on the release of phenolic compounds and antioxidant activity during in vitro digestion of hulless barley

Hulless barley contains phenolic compounds and possesses various antioxidant activities. To clarify the effects of thermal processing and in vitro digestion on the release of phenolic compounds in hulless barley, we studied the phenolic components and antioxidant activities of hulless barley after steaming, roasting processes, and in vitro digestions. Both total phenolic content (TPC) and total flavonoid content (TFC) in raw hulless barley (HB, 4.14 mg/g DW and 1.53 mg/g DW, respectively) were higher than that of steamed hulless barley (SHB) and roasted hulless barley (RHB). In vitro digestion significantly released more ferulic acid from its bound form, but hydrolyzed some amount of flavonoid (luteolin). Chrysoeriol-7-O-glucouronide was significantly detected (412.13 µg/g DW in HB, 382.19 µg/g DW in SHB, and 396.91 µg/g DW in RHB) in all three hulless barley. The total released content of phenolic compounds obtained from each phase after digestion reached to 46% and 45% for SHB and RHB, which was higher than that in the HB (41%). The antioxidant assay (via DPPH and ABTS free radical scavenging assays) indicated that the capacity of HB was obviously higher than that of SHB and RHB in undigested group. For digested group, the ABTS⁺ assay order was following, undigested > oral > small intestine > gastric > large intestine. The DPPH assay results indicated the antioxidant capacity as the order of undigested > oral > gastric > large intestine. Correlation analysis showed that ferulic acid, chrysoeriol-7-O-glucouronide, luteolin, chrysoeriol, and luteolin-7-O-glucouronide contributed to the antioxidant activities. Hierarchical cluster analysis (HCA) grouped samples accordingly. Roasting process could be considered as a better daily thermal treatment for hulless barley than steaming in terms of phenolic compounds and their antioxidant activities.     

Phenolic Composition and Total Antioxidant Capacity by Electrochemical,Spectrophotometric and HPLC‐EC Evaluation in Portuguese Red and White Wines

Phenolic composition and in vitro total antioxidant capacity have been evaluated, in red and white Portuguese wines, by electrochemical methods, spectrophotometric methods, and reverse‐phase high performance liquid chromatography with electrochemical detection (HPLC‐EC). The different phenolic compounds present in seventeen red and white wines, with different grape varieties, and from different geographical locations, were successfully identified and detected. The wines in vitro total antioxidant capacity, using the method of capture of diphenilpicrilhydrazil (DPPH^.) free radical “efficient concentration” (EC₅₀), and the electrochemical quantitative index (EI), was determined. The wine with the highest total antioxidant capacity exhibited the lowest antioxidant power, and the EI and EC₅₀ assays had a very good correlation.     

An Electrochemical Method for Sensitive Determination of Antioxidant Capacity

A simple and sensitive electrochemical method for the determination of antioxidant capacity has been studied. 4‐hydroxybenzoic acid (4‐HBA) was used as a trapping agent for photogenerated ^.OH radicals, leading to 3,4‐dihydroxybenzoic acid (3,4‐DHBA). Square‐wave voltammetry was used to quantify the amount of 3,4‐DHBA formed from the reaction between 4‐HBA and ^.OH. Addition of antioxidants induced the competition between 4‐HBA and antioxidants toward ^.OH elimination, resulting in a decrease of the measured current. The IC₅₀ for different standard antioxidants was calculated and expressed in Trolox equivalent antioxidant capacity (TEAC). The proposed method was successfully compared to a fluorimetric one.     

A comparative study of phytochemical metabolites and antioxidant properties of Rhodiola

Rhodiola crenulata (RC) and Rhodiola fastigiata (RF) are representative species of Rhodiola with well-accepted health benefits; the roots are the medicinal part. However, prior to this study, the differences in phytochemicals between these two species and different parts of the same species remained unclear. Using LC-ESI-MS/MS, HS-SPME-GC–MS, chemical and sensory analyses, volatile compounds and non-volatile compounds, and antioxidant activities of the roots of Rhodiola crenulata and Rhodiola fastigiata and four parts (roots, leaves, flowers, and above-ground stems) of RC were investigated. The volatile compounds and non-volatile compounds of RC roots exhibited upregulation overall compared to those of RF roots, and the odorousness, phenolic content, and antioxidant activity were more pronounced in the RC roots. The phenolic content and antioxidant activity of roots and leaves, alongside the odorousness of roots and flowers, were more significant among the four parts of RC, and the RC roots and RC flowers exhibited similar odorousness. Comparison of non-volatile differential metabolites between RC roots and RC leaves showed upregulations of saccharides and phospholipids, and minor upregulations of flavonoids and phenylpropanoids in the roots; in addition, amino acids, organic acids, and vitamins were upregulated in the leaves. These results revealed the following: 1) RC roots are superior to RF roots regarding volatile compounds and non-volatile compounds, and antioxidant activity; 2) it is more favorable to select RC roots for exploiting volatile compounds compared with RC flowers in consideration of the biomass available; 3) in terms of non-volatile compounds, and antioxidant ability, RC leaves are also of great value in addition to RC roots, though these two parts show distinct characteristics.     

HPLC-DAD-MS Determination of Colored and Colorless Phenolic Compounds in Kalecik Karasi Wines: Effect of Different Vineyard Locations

Phenolic composition of wines from Kalecik karasi, a native grape variety grown in Turkey, and influence of different vineyard locations on these compounds were investigated. High performance liquid chromatography-diode array detector (HPLC-DAD) and mass spectrometry (MS) were used for the phenolic compound analysis. Fourteen anthocyanins, six flavanols, twelve phenolic acids, and six flavonols were identified and quantified. It was observed that total phenolic content in wine from Ankara region was clearly higher than in wine from Nevsehir. Sensory analysis was also used to investigate the influences of the vineyard location. Based upon sensory analysis, the wines obtained from Ankara region had higher color, harmony, astringency aftertaste, astringency, flavor, and body character than wine from Nevsehir.     

Evaluation of the Storage Conditions and Type of Cork Stopper on the Quality of Bottled White Wines

The effects of different storage conditions, light exposure, temperature and different commercially available cork stoppers on the phenolic, volatile and sensorial profile of Verdejo wines were studied. Two natural corks of different visual quality and a microgranulated cork stopper were investigated over one year at two different storage conditions. One simulating light exposure and temperature in retail outlets and the other simulating optimal cellar conditions (darkness and 12 °C). The wines stored under commercial conditions showed greater losses of total and free SO₂ and higher levels of brown-yellowish tones, related to the oxidation of flavan-3-ols. Although these wines underwent a decrease in the total content of stilbenes, a significant increase in trans-piceid was observed. In addition, these wines suffered important changes in their volatile and sensory profile. Volatile compounds with fruity and floral aromas decreased significantly, while volatile compounds related to aged-type characters, as linalool oxides, vitispirane, TDN or furan derivatives increased. Wines stored in darkness at 12 °C underwent minor changes and their sensory profiles were similar to wine before bottling. The high-quality natural corks and microgranulated corks better preserved the quality of the white wines from a sensory point of view. These results showed that temperature and light exposure conditions (diffuse white LEDs and 24 ± 2 °C) in retail outlets considerably decrease the quality of bottled white wines and, consequently, their shelf life, due to the premature development of aged-type characters.     

Comparative analysis of phytochemical profile,antioxidant and anti-inflammatory activity from Hibiscus manihot L. flower

Hibiscus manihot L. is a kind of healthy plant with edible value and health benefits, which possesses multiple pharmacological activities that are closely related to antioxidant and anti-inflammatory activities. The dynamic changes of main active components and biological activities in Hibiscus manihot L. flower (HMLF) during its flowering period were systematically studied to determine the appropriate harvest time. Chemopreventive efficacies of the investigated HMLF extracts, by means of their anti-inflammatory and antioxidant activities, were assessed. The sample harvested on early August had the supreme total flavonoid content, total phenolic content and the strongest antioxidant activity (DPPH radical scavenging activity (IC₅₀ 0.160 mg/mL), ABTS radical scavenging activity (1.570 mmol/g Trolox), reducing power (IC₅₀ 0.101 mg/mL) and FRAP (3.644 mmol FeSO₄/g)). The results of principal component analysis indicated that the primary active components included hyperin, isoquercetin, hibifolin and quercetin-3′-O-glucoside, which were strongly associated with the antioxidant activity in the early August sample, while neochlorogenic acid, chlorogenic acid and caffeic acid were associated with the anti-inflammatory activity. The extracts significantly inhibited lipopolysaccharide-induced nitric oxide production in RAW264.7 cells, especially the samples harvested around August, which was only 3.569 μΜ with the inhibition ratio of>50%. This study indicated that HMLF harvested on the early August possessed the highest antioxidant and anti-inflammatory potential and could be used as high bioactive resources for healthy production.     

Examination of non-volatile organic compounds in red wines made in Eger

At present the analytical investigation of human consumption products, with special regard to the environmental and health connections, is basically important all over the world. Recently in several countries it was almost impossible to sell wine without a certificate of quality, based on modern, instrumental analytical methods. There is well-known medical–biological evidence, which has proved the antioxidant and vein wall-protecting effects of the wines in the case of frugal ingestion. On the other hand, they also play a part in the prevention of heart attacks. Regarding these biological effects the most important constituents of wines are the flavonoids, anthocyanidins, and their glycosides. Anthocyanins can be identified first of all in red wines. The organic constituents have characteristic antioxidant effects, which can play an important role in health protection. During our investigation we have studied the volatile and non-volatile organic compounds in different types of wines made in Eger and Tokay (Hungary). In our opinion these types of research projects have unique importance, from the economic viewpoint and in that they are not negligible in a national context. The separation and determination of volatile compounds was carried out by applying a Finnigan GSQ GC-MS apparatus and the non-volatile ones with HPLC-DAD and FAB MS techniques.     

Nanoemulsions for the Determination of the Antioxidant Capacity of Oils by an Electrochemical Method

The paper describes a rapid and simple method for the evaluation of the antioxidant capacity in oil in water nanoemulsion. This procedure does not require extensive sample treatment and, most important, does not use any organic solvent for dissolution of the fatty matrix. The nanoemulsions were directly injected in a flow injection (FI) system with an electrochemical detector equipped with a glassy carbon working electrode operating amperometrically at a potential of +0.8 V (vs. Ag/AgCl). Results obtained were compared with those obtained by the Oxygen Radical Absorbance Capacity (ORAC) assay.     

Effect of Hanseniaspora uvarum–Saccharomyces cerevisiae Mixed Fermentation on Aroma Characteristics of Rosa roxburghii Tratt,Blueberry, and Plum Wines

Hanseniaspora uvarum, a non-Saccharomyces cerevisiae species, has a crucial effect on the aroma characteristics of fruit wines, thus, attracting significant research interest in recent years. In this study, H. uvarum–Saccharomyces cerevisiae mixed fermentation was used to ferment Rosa roxburghii Tratt, blueberry fruit wine, and plum fruit wines using either a co-inoculated or a sequentially inoculated approach. The three fruit wines’ volatile aroma characteristics were analyzed by headspace–solid-phase microextraction–gas chromatography-mass spectrometry (HS–SPME–GC–MS). The results showed that the mixed inoculation of H. uvarum and S. cerevisiae reduced the alcoholic content of Kongxinli fruit wine. Moreover, H. uvarum–S. cerevisiae fermented Rosa roxburghii Tratt, blueberry, and plum fruit wines and further enriched their flavor compounds. The overall flavor characteristics of sequentially inoculated fruit wines differed significantly from those fermented with S. cerevisiae alone, although several similarities were also observed. Sequential inoculation of H. uvarum and S. cerevisiae positively affected the mellowness of the wine and achieved a better harmony of the overall wine flavors. Therefore, H. uvarum–Saccharomyces cerevisiae mixed fermentation can improve the complexity of the wines’ aromatic composition and empower them with a unique identity. In particular, H. uvarum–Saccharomyces cerevisiae blueberry wine produced by mixed fermentation had the widest variety and content of aroma compounds among the fermented wines. Therefore, H. uvarum–Saccharomyces cerevisiae mixed-fermentation inoculation in the three fermented fruit wines significantly increased the aroma compound variety and content, thus, enriching their aroma richness and complexity. This study is the first comparative evaluation of the aroma characteristics of different fruit wines fermented with a mixed inoculation of H. uvarum and S. cerevisiae and provides a preliminary guide for these fruit wines produced with non-Saccharomyces yeast.     

Effect of Bentonite Addition to Pedro Ximénez White Grape Musts before Their Fermentation with Selected Yeasts on the Major Volatile Compounds and Polyols of Wines and Tentative Relationships with the Sensorial Evaluation

In this work, we study the effect of bentonite addition to the grape must before alcoholic fermentation on the chemical composition and sensorial profile of the obtained wines. Fermentations were carried out with two Saccharomyces cerevisiae commercial active dry yeasts treated or not with bentonite and were compared with a control wine obtained by spontaneous fermentation (using the grape must microbiota). Several significant effects on the chemical and sensorial attributes were established by statistical treatments. The selection by multiple variable analysis of seven volatile molecules (ethyl acetate; methanol; 1-propanol; isobutanol; 2-methyl-1-butanol; 3-metyl-1-butanol and 2-phenylethanol) provided several footprints that provide an easy visualization of bentonite effects on wine volatile compounds. A Principal Component Analysis carried out with all the compounds quantified by Gas-Chromatography revealed that the first two Principal Components explain 60.15 and 25.91%, respectively, of the total variance and established five groups that match with the five wines analyzed. Lastly, predictive models at p ≤ 0.05 level for the attributes sight, smell and taste were obtained by Partial Least Squared regression analysis of selected chemical variables.     

树状桥联半受阻酚类抗氧剂的合成与抗氧化性能

从端基为胺基树状大分子出发, 合成了一种具有多个半受阻酚抗氧化基团、 结构对称的树状桥联半受阻酚类抗氧剂. 元素分析、 傅里叶变换红外光谱(FTIR)、 氢核磁共振波谱(¹H NMR)、 质谱(MS)和冰点降低法证实合成的树状桥联半受阻酚类抗氧剂的化学结构与理论结构一致, 纯度较高. 采用1,1-二苯基-2-苦基肼(DPPH)法和差热扫描量热(DSC)法研究了树状桥联半受阻酚类抗氧剂的抗氧化性能, 并与相应的树状桥联全受阻酚类抗氧剂进行了对比. 研究结果表明, 树状桥联半受阻酚类抗氧剂清除DPPH自由基的活性不仅与清除体系中抗氧剂的浓度有关, 而且与清除时间有关; 清除时间为30 min时的抗氧化能力是清除时间为400 min时抗氧化能力的近2倍. 树状桥联半受阻酚类抗氧剂的半受阻效应使其在DPPH体系和HDPE树脂中的抗氧化能力均优于其相应的树状桥联全受阻酚类抗氧剂.     

3D Tungsten Trioxide Nanosheets as Optoelectronic Materials for On-chip Quantification of Global Antioxidant Capacity

The photoelectrochemical properties of semiconductors mainly depend on the size and shape of the corresponding nanoparticles. Herein, 3D WO₃ nanosheets were controllably synthesized with the aid of polyethyleneimine, which presents enhanced photocurrent responses. Based on this excellent photoelectrochemical property, a photoelectrochemical chip was prepared by lithography technology for the smart monitoring of the antioxidant capacity(AC) in red wine and exhibits a series of advantages inclu-ding rapid response time, high sensitivity, and long-lasting stability. The mechanism of the present photoelectrochemical sensing was explored and shows a single electron transfer reaction. Furthermore, only 200 μL of samples are required for one testing, which demonstrates that the present photoelectrochemical chip can be potentially integrated with a portable commercial device(such as a mobile phone) for further research and development of food and drug supervision.