Chemical and Sensory Evaluation of Magnetic Polymers as a Remedial Treatment for Elevated Concentrations of 3-Isobutyl-2-methoxypyrazine in Cabernet Sauvignon Grape Must and Wine

Amelioration of Smoke Taint in Wine via Addition of Molecularly Imprinted Polymers during or after Fermentation

The adsorbents used to remove taint compounds from wine can also remove constituents that impart desirable color, aroma, and flavor attributes, whereas molecularly imprinted polymers (MIPs) are tailor-made to selectively bind one or more target compounds. This study evaluated the potential for MIPs to ameliorate smoke taint in wine via removal of volatile phenols during or after fermentation. The addition of MIPs to smoke-tainted Pinot Noir wine (for 24 h with stirring) achieved 35-57% removal of guaiacol, 4-methylguaiacol, cresols, and phenol, but <10% of volatile phenol glycoconjugates were removed and some wine color loss occurred. Of the MIP treatments that were subsequently applied to Semillon and Merlot fermentations or wine, MIP addition post-inoculation of yeast yielded the best outcomes, both in terms of volatile phenol removal and wine sensory profiles. Despite some impact on other aroma volatiles and red wine color, the findings demonstrate that MIPs can ameliorate smoke-tainted wine.

A Review on Wine Flavour Profiles Altered by Bottle Aging

The wine flavour profile directly determines the overall quality of wine and changes significantly during bottle aging. Understanding the mechanism of flavour evolution during wine bottle aging is important for controlling wine quality through cellar management. This literature review summarises the changes in volatile compounds and non-volatile compounds that occur during wine bottle aging, discusses chemical reaction mechanisms, and outlines the factors that may affect this evolution. This review aims to provide a deeper understanding of bottle aging management and to identify the current literature gaps for future research.

Methoxypyrazine concentrations in the grape bunch rachis of Vitis vinifera L. Cv Shiraz: Influence of rootstock, region and light

Vitis vinifera L. cv Shiraz appears unable to synthesise 3-alkyl-2-methoxypyrazines (MPs) in the berry, but can still produce significant concentrations in rachis. MPs are readily extracted from rachis during fermentation, producing Shiraz wines with uncharacteristic "green" flavours. Recently, rootstocks were shown to significantly alter MP concentrations in Cabernet Sauvignon rachis compared to own-rooted varieties, but whether Shiraz followed a similar trend required investigation. This study considered the effect of thirteen rootstocks on the concentrations of 3-isobutyl-2-methoxypyrazine (IBMP), 3-isopropyl-2-methoxypyrazine (IPMP), and 3-sec-butyl-2-methoxypyrazine (SBMP) in the rachis of Shiraz bunches sampled during multiple vintages across several Australian growing regions. Although IBMP was the most abundant, all measured MP concentrations were significantly affected by vintage, rootstock, and region. In addition, vine vigour showed positive correlations with IBMP, which were attributed to changes in canopy coverage impacting rachis light exposure. This hypothesis was explored with light exclusion trials, which significantly increased rachis IBMP concentrations.

Direct Visualization of Homogeneous Chemical Distribution in Functional Polyradical Microspheres

It is demonstrated that the postfunctionalization of solid polymeric microspheres can generate fully and throughout functionalized materials, contrary to the expectation that core-shell structures are generated. The full functionalization is illustrated on the example of photochemically generated microspheres, which are subsequently transformed into polyradical systems. Given the all-organic nature of the functionalized microspheres, characterization methods with high analytical sensitivity and spatial resolution are pioneered by directly visualizing the inner chemical distribution of the postfunctionalized microspheres based on characteristic electron energy loss signals in transmission electron microscopy (TEM). Specifically, ultrasonic ultramicrotomy is combined successfully with electron energy loss spectroscopy (EELS) and electron spectroscopic imaging (ESI) during TEM. These findings open a key avenue for analyzing all-organic low-contrast soft-matter material structures, while the specifically investigated system concomitantly holds promise as an all-radical solid-state functional material.

GC-MS Untargeted Analysis of Volatile Compounds in Four Red Grape Varieties (Vitis vinifera L. cv) at Different Maturity Stages near Harvest

Grape volatile compounds directly determine the aroma quality of wines. Although the aroma profile of grapes evolved greatly at different maturity stages, there were less considerations for aroma status when determining grape harvest time. In the present study, several maturation indicators, namely, sugars/acids ratio, free volatile compounds, bound volatile compounds and IBMP (3-isobutyl-2-methoxypyrazine) content were monitored in four red wine grape varieties (Vitis vinifera L. cv Cabernet Sauvignon, Cabernet Gernischet, Cabernet Franc and Merlot) near harvest time (42 days) in Ningxia, China. The results showed that the highest sugars/acids ratio was reached on day 21 and day 28 for Merlot and the other three varieties, respectively. For both free and bound volatile compounds, the content of carbonyl compounds decreased continuously in the process of ripening. The contents of free alcohols, esters and terpenes increased in the ripening stage and decreased in the stage of over-ripening. The accumulation of favorable bound aroma compounds peaked at day 35. The content of IBMP presenting a green smell in all four varieties descended continuously and kept steady from day 28. Therefore, the present findings revealed that the best aroma maturity time of four studied grape varieties was later than the sugars/acids ratio in Ningxia region. Aroma maturity should be taken into account during harvest time determination.

Molecular mechanism of Mare Nectaris and magnetic field on the formation of ethyl carbamate during 19 years aging of Feng-flavor Baijiu

Ethyl carbamate (EC) is carcinogen occurring naturally in fermented foods, while the EC formation pattern in Feng-flavor Baijiu during Mare Nectaris storage and magnetic field treatment remains controversial. In this work, variation of EC in Mare Nectaris and magnetic field were investigated for the first time through ultra high performance liquid chromatography quadrupole-orbitrap high resolution mass spectrometry (UHPLC-Q-Orbitrap). Quantification results revealed that EC decreased significantly in the stage of 3-9 years and kept at 12.4 μg L-1 after 10 years of aging. Arginine succinate synthase (ASS) and urease were deemed as vital factors for EC decomposition. Degradation effetc of EC in 250 mT is simillar to that of EC in Baijiu stored in Mare Nectaris for 8 years. This is due to that aging process was accelerated by magnetic field and the content of total acid in Baijiu was increased, creating a favorable environment for decomposition of EC and urea.

Comparison of Methoxypyrazine Content and Expression Pattern of O-Methyltransferase Genes in Grape Berries and Wines from Six Cultivars (Vitis vinifera L.) in the Eastern Foothill of the Helan Mountain

Methoxypyrazines (MPs) are a unique class of volatile compounds containing nitrogenous heterocyclics that impart green bell, vegetal and herbal odors to red grape berries and wines. In this study, the quality and MPs levels of grape berries from six representative red wine grape varieties were determined in the two consecutive years. The results showed that, at maturity, the highest total soluble solid was observed in Petit Verdot grape berries in the two consecutive years. While the anthocyanin content showed the highest in Marselan berries in 2018, in 2019, Petit Verdot berries had the highest anthocyanin content. Moreover, 2-methoxypyrazine (MOMP), 3-methyl-2-methoxypyrazine (MEMP) and 3-ethyl-2-methoxypyrazine (ETMP) levels were relatively lower, with almost no detectable in berries at maturity. The relative higher 3-isobutyl-2-methoxypyrazine (IBMP) content was observed in Cabernet Sauvignon, Marselan, Merlot, and Malbec berries. However, 3-sec-butyl-2-methoxypyrazine (SBMP) and IBMP were only detected in six wines, and their levels were higher than those in the grape berries. Furthermore, correlation analysis showed that there was a statistically positive correlation between the expression levels of VvOMT1 and VvOMT3 and MPs content in grape berries, while the lowest association was found in the VvOMT2. These findings provide a basis for selecting the most suitable grape varieties to improve wine quality.

Rootstock, Vine Vigor, and Light Mediate Methoxypyrazine Concentrations in the Grape Bunch Rachis of Vitis vinifera L. cv. Cabernet Sauvignon

Ramsey rootstock has previously been implicated in an approximate 8-fold increase of 3-isobutyl-2-methoxypyrazine (IBMP) levels in the rachis (grape bunch stem) of Vitis vinifera L. cv. Shiraz scions over own-rooted Shiraz vines at harvest. IBMP extracted from rachis during red wine fermentation can contribute potent "green" flavors. Methoxypyrazines (MPs) are normally present in Cabernet Sauvignon grapes, rachis, and wines, but it is unknown whether rootstocks can influence the MP concentration in the rachis. This study considered the effect of eight rootstocks including Ramsey and own roots on the concentrations of IBMP, 3-isopropyl-2-methoxypyrazine (IPMP), and 3-sec-butyl-2-methoxypyrazine (SBMP) in the rachis and grapes of Cabernet Sauvignon over two seasons. IBMP predominated, and its concentration in rachis and berries at harvest was significantly affected by rootstock and growing season. In the 2020 vintage, light exclusion, vine vigor, and spatial variation in vine vigor were shown to significantly affect MP concentrations in rachis.

Nanotechnology: recent advances in viticulture and enology

Nowadays, nanoscience is a leading modern science that has a major impact on the food, pharmaceutical, and agriculture sectors. Several nanomaterials show a great potential for use during vine growing and winemaking processes. In viticulture, nanotechnology can be applied to protect vines against phytopathogens and to improve grape yield and quality. Thus, nanotechnology may allow the use of lesser amounts of phytochemical compounds, reducing environmental impact and promoting a more sustainable agriculture. And in winemaking, nanomaterials and nanodevices can be used to control the growth of spoilage microorganisms and to reduce or remove undesirable compounds, such as ethyl phenols (4-ethylphenol and 4-ethylguaiacol), biogenic amines, and tartaric acid, and so on, as well as to facilitate some technological processes (i.e. in wine filtration to eliminate microorganisms). This review summarizes recent studies with applications of nanotechnology in viticulture in order to facilitate agronomic management and optimize grape production and in enology to improve wine quality and safety. © 2021 Society of Chemical Industry.

Yeast race effect on the quality of base and young sparkling wines

Introduction. A disadvantage of the ancestral method (la méthode ancestrale), which is widely used in the production of sparkling wine, is that it is difficult to control fermentation. We aimed to identify the optimal yeast race for obtaining high-quality young sparkling wines with varietal aroma without yeast tones. Study objects and methods. Our study objects were base and young sparkling wines from Cabernet-Sauvignon prepared on various yeast races. Organic acids, sugars, and ethanol contents were determined by high performance liquid chromatography. Phenolic and coloring substances were measured by colorimetric method. Foaming properties were determined by air barbotage of a wine sample in a measuring cylinder; sparkling properties, by measuring the CO2 desorption rate; CO2 content, by volumetric method; viscosity, with a viscometer. Sensory evaluation was carried out according to standard methods. Results and discussion. The wines produced on the Odesskiy Chernyi-SD13 yeast race received the highest tasting scores of 7.82 and 9.05 points for base wine and young sparkling wines, respectively. They contained larger amounts of phenolic substances (1103 mg/dm3) and coloring agents (275 mg/dm3) and had higher color intensity (1.614). The panelists rated them highly on their complex varietal aroma and harmonious, velvety flavor, as well as their foaming and sparkling properties. This yeast race ensured intensive fermentation of sugars and a great amount of bound CO2 (up to 24.93%). Conclusion. The Odesskiy Chernyi-SD13 yeast race is optimal for making base and young sparkling wines by the bottle method. This technology can be used to produce high-quality sparkling wines in the crop year by large and small enterprises.

Untargeted foodomics reveals molecular mechanism of magnetic field effect on Feng-flavor Baijiu ageing

Ageing is a time-consuming step in Baijiu manufacture, stimulating an urgent requirement of optimization. Variation of artificial aged Feng-flavor Baijiu by inhomogeneous alternating magnetic field was investigated through quantitative foodomics combined with confirmed ultra high performance liquid chromatography quadrupole-orbitaltrap high resolution mass spectrometry (UHPLC-Q-Orbitrap). A total of 153 substances were identified with significant variables (p < 0.05, VIP > 1) and 16 metabolic pathways related to Feng-flavor Baijiu functions were obtained. The method showed good accuracy with recovery values between 80.4% and 117.4% and precision lower than 9.8% for all characteristic substances. Limit of detection (LOD) was ranging between 1.6 and 10.0 μg/L with R² ≥ 0.99. Factor analysis demonstrated that ageing degree of magnetized samples increased with rise of magnetic field intensity and the maximum effect was equivalent to 12.81 years of natural ageing. The results of stoichiometric analysis revealed that regulation of magnetic field on proportion in Baijiu was mainly performed through entropy and the hydrogen bond strength of Baijiu molecules. Sensory evaluation illustrated that score of Baijiu samples reached the highest at 150 mT, demonstrating that magnetic field treatment can be considered as an optimized ageing means for Feng-flavor Baijiu.

Dummy Molecularly Imprinted Polymers Using DNP as a Template Molecule for Explosive Sensing and Nitroaromatic Compound Discrimination

This work reports a rapid, simple and low-cost voltammetric sensor based on a dummy molecularly imprinted polymer (MIP) that uses 2,4-dinitrophenol (DNP) as a template for the quantification of 2,4,6-trinitrotoluene (TNT) and DNP, and the identification of related substances. Once the polymer was synthesised by thermal precipitation polymerisation, it was integrated onto a graphite epoxy composite (GEC) electrode via sol–gel immobilisation. Scanning electron microscopy (SEM) was performed in order to characterise the polymer and the sensor surface. Responses towards DNP and TNT were evaluated, displaying a linear response range of 1.5 to 8.0 µmol L−1 for DNP and 1.3 to 6.5 µmol L−1 for TNT; the estimated limits of detection were 0.59 µmol L−1 and 0.29 µmol L−1, for DNP and TNT, respectively. Chemometric tools, in particular principal component analysis (PCA), demonstrated the possibilities of the MIP-modified electrodes in nitroaromatic and potential interfering species discrimination with multiple potential applications in the environmental field.

Modification of Sensory Expression of 3-Isobutyl-2-methoxypyrazine in Wines through Blending Technique

Sensory interactions exist between 3-alkyl-2-methoxypyrazines and various volatiles in wines. In this study, the binary blending of Cabernet Franc wines containing high levels of MPs and three monovarietal red wines with two proportions was conducted after fermentation. Volatiles were detected by gas chromatography-mass spectrometry (GC-MS), and wines were evaluated by quantitative descriptive analysis at three-month intervals during six-month bottle aging. Results showed blending wines exhibited lower intensity of ‘green pepper’, especially CFC samples blended by Cabernet Sauvignon wines with an even higher concentration of 3-isobutyl-2-methoxypyrazine (IBMP). Based on Pearson correlation analysis, acetates could promote the expression of ‘tropical fruity’ and suppress ‘green pepper’ caused by IBMP. Positive correlation was observed among ‘green pepper’, ‘herbaceous’, and ‘berry’. The concentration balance between IBMP and other volatiles associated with ‘green pepper’ and fruity notes was further investigated through sensory experiments in aroma reconstitution. Higher pleasant fruity perception was obtained with the concentration proportion of 1-hexanol (1000 μg/L), isoamyl acetate (550 μg/L), ethyl hexanoate (400 μg/L), and ethyl octanoate (900 μg/L) as in CFC samples. Blending wines with proper concentration of those volatiles would be efficient to weaken ‘green pepper’ and highlight fruity notes, which provided scientific theory on sensory modification of IBMP through blending technique.

Polylactide-Based Stent Coatings: Biodegradable Polymeric Coatings Capable of Maintaining Sustained Release of the Thrombolytic Enzyme Prourokinase

The novelty of the study is the development, creation, and investigation of biodegradable polymeric membranes based on polylactide, that are capable of directed release of large molecular weight biomolecules, particularly, prourokinase protein (MW = 46 kDa). Prourokinase is a medication with significant thrombolytic activity. The created membranes possess the required mechanical properties (relative extension value from 2% to 10%, tensile strength from 40 to 85 MPa). The membranes are biodegradable, but in the absence of living cells in a water solution they decompose by less than 10% in half a year. The created membranes are capable of controlled prourokinase release into intercellular space, and the total enzymatic activity of prourokinase does not decrease by more than 12%. The daily release of prourokinase from one square centimeter of the membrane ranges from 1 to 40 μg per day depending on the technique of membrane preparation. The membranes have no acute toxic effect on cells accreting these surfaces de novo. The number of viable cells is at least 96%-97% of the overall cell count. The mitotic index of the cells growing on the surface of the polymeric films comprised around 1.5%. Histological examination did not reveal any disorders in tissues of the animals after the implantation of polymer membranes based on polylactide, both alone and as components of stent cover. Implantation of stents covered with prourokinase-containing polymers led to the formation of a mature connective tissue capsule that is thicker than in the case of uncovered stents. Thus, various polylactide-based biodegradable polymeric membranes possessing the required mechanical properties and capable of prolonged and directed release of prourokinase macromolecules are developed and investigated in the study.

Magnetic Separation in Bioprocessing Beyond the Analytical Scale: From Biotechnology to the Food Industry

Downstream processing needs more innovative ideas to advance and overcome current bioprocessing challenges. Chromatography is by far the most prevalent technique used by a conservative industrial sector. Chromatography has many advantages but also often represents the most expensive step in a pharmaceutical production process. Therefore, alternative methods as well as further processing strategies are urgently needed. One promising candidate for new developments on a large scale is magnetic separation, which enables the fast and direct capture of target molecules in fermentation broths. There has been a small revolution in this area in the last 10–20 years and a few papers dealing with the use of magnetic separation in bioprocessing examples beyond the analytical scale have been published. Since each target material is purified with a different magnetic separation approach, the comparison of processes is not trivial but would help to understand and improve magnetic separation and thus making it attractive for the technical scale. To address this issue, we report on the latest achievements in magnetic separation technology and offer an overview of the progress of the capture and separation of biomolecules derived from biotechnology and food technology. Magnetic separation has great potential for high-throughput downstream processing in applied life sciences. At the same time, two major challenges need to be overcome: (1) the development of a platform for suitable and flexible separation devices and (2) additional investigations of advantageous processing conditions, especially during recovery. Concentration and purification factors need to be improved to pave the way for the broader use of magnetic applications. The innovative combination of magnetic gradients and multipurpose separations will set new magnetic-based trends for large scale downstream processing.