The technology of high-power ultrasound and its effect on the color and aroma of rosé wines.

BACKGROUND: The application of high-power ultrasound (US) has been studied extensively to obtain value-added red wines using short maceration times. It is a technique of wide interest for the extraction of aromatic compounds and compounds responsible for color, so it could also be an important tool to use in the elaboration process of rosé wines. Thus, this study focused on the effect of the application of US on the phenolic, aromatic, and sensorial profile of rosé wines. For this, three different types of rosé wine were produced: a control with direct pressing after crushing, another wine obtained from a 4 h macerated must, and a wine whose crushed and destemmed grape was sonicated and subsequently pressed. RESULTS: The results showed a higher color intensity and a higher total polyphenol and anthocyanin content in the wine obtained from sonicated grape compared to both control wine and that obtained from grape macerated for 4 h. Ultrasound treatment enhanced the extraction of varietal volatile compounds in must, especially the free faction of terpenes and norisoprenoids. It also gave rise to wines with a higher concentration of C6 alcohols and other compounds such as guaiacol and 4-vinylguaiacol, but led to fewer fatty acids, especially C6, C4 and C8 acids. Sensorially these wines showed intense aromas of red fruits and flowers, while no defects in aroma or astringency were found. CONCLUSIONS: The color and sensory profile of the resulting wines indicate that the US may be an interesting tool for obtaining quality rosé wines, replacing the maceration stage and reducing potential oxidation problems. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Rapid and Non-Destructive Analysis of Corky Off-Flavors in Natural Cork Stoppers by a Wireless and Portable Electronic Nose.

This article discusses the use of a handheld electronic nose to obtain information on the presence of some aromatic defects in natural cork stoppers, such as haloanisoles, alkylmethoxypyrazines, and ketones. Typical concentrations of these compounds (from 5 to 120 ng in the cork samples) have been measured. Two electronic nose prototypes have been developed as an instrumentation system comprise of eight commercial gas sensors to perform two sets of experiments. In the first experiment, a quantitative approach was used whist in the second experiment a qualitative one was used. Machine learning algorithms such as k-nearest neighbors and artificial neural networks have been used in order to test the performance of the system to detect cork defects. The use of this system tries to improve the current aromatic defect detection process in the cork stopper industry, which is done by gas chromatography or human test panels. We found this electronic nose to have near 100 % accuracy in the detection of these defects.

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.

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.

Effect of Power Ultrasound Treatment on Free and Glycosidically-Bound Volatile Compounds and the Sensorial Profile of Red Wines.

This study presents the effect of the application of high-power ultrasound to crushed grapes, at a winery-scale, on the content of varietal volatile compounds (free and glycosidically-bound) in musts and on the overall aroma of wines. Two different frequencies (20 kHz and 28 kHz) were tested and the combination of grape sonication and different maceration times on wine aroma was also evaluated. The volatile compounds were isolated by solid phase extraction and analyzed by gas chromatography-mass spectrometry, carrying out a sensory evaluation of wines by quantitative descriptive analysis. Sonication produced an increase in the concentration of free varietal compounds such as C6 alcohols, terpenes and norisoprenoids in musts and also in wines made by 48 h of skin maceration, being less efficient in the extraction of the bound fraction. Fermentation compounds were also positively affected by ultrasound treatment, although this effect was variable depending on the frequency used, the maceration time and the type of compound. All the wines made from sonicated grapes had better scores in the evaluated olfactory attributes with respect to the control wines. Our results indicate that sonication could produce an increase in the content of some volatile compounds of sensory relevance, obtaining wines with an aroma quality similar or higher than those elaborated with longer maceration times.

Effects of the pre-fermentative addition of chitosan on the nitrogenous fraction and the secondary fermentation products of SO2 -free red wines.

BACKGROUND: Different red winemaking were carried out to evaluate the effects of the prefermentative addition of chitosan, as an alternative to the use of SO2 , on the secondary products of alcoholic fermentation, yeast available nitrogen (YAN), biogenic amines and ethyl carbamate. RESULTS: The wines made with chitosan presented higher total acidity and higher content of tartaric and succinic acids than those made only with SO2 . The use of chitosan in winemaking resulted in wines with higher glycerol and diacetyl content without increasing the concentration of ethanol, acetic acid, acetaldehyde or butanediol. YAN was lower in wines made with chitosan, which may mean an advantage for the microbial stability of the wines. Furthermore, the use of chitosan at the beginning of alcoholic fermentation did not increase the concentration of biogenic amines or the formation of ethyl carbamate in SO2 -free red wines. CONCLUSION: The total or partial substitution of SO2 for chitosan at the beginning of the alcoholic fermentation gives rise to quality red wines without negatively affecting their nitrogen fraction or their very important secondary fermentation products such as acetic acid or acetaldehyde. © 2020 Society of Chemical Industry.

Mango by-products as a natural source of valuable odor-active compounds.

BACKGROUND: The aromatic potential of mango by-products was evaluated to seek natural and cheap sources of odor-active compounds. Volatile compounds in mango peel and seed were chemically characterized and compared with those in mango pulp using headspace solid-phase microextraction coupled to gas chromatography-mass spectrometry (HS-SPME/GC-MS). RESULTS: More than 60 volatile compounds were detected in mango by-products, whose aromatic activity was estimated using odorant activity values (OAVs). The results indicated that mango peel was a valuable matrix of odor-active compounds, which were found in even larger quantities than in edible mango fractions. 3-Carene was the predominant compound, although other compounds such as decanal, 1-octen-3-one, nonanal, limonene, ß-damascenone, and 2-nonenal were the most odor-active compounds in mango peel. The greatest aromatic impact was obtained from mango peel, with sensorial features described as fresh / herbaceous, fruity, floral and resinous. CONCLUSION: The exceptional flavoring potential of mango peel by-product opens a door for its use and revalorization as a natural flavoring ingredient in the food and cosmetic industries. © 2020 Society of Chemical Industry.

Effect of Microwave Maceration and SO2 Free Vinification on Volatile Composition of Red Wines.

This study evaluates the effect of microwave treatment in grape maceration at laboratory scale on the content of free and glycosidically bound varietal compounds of must and wines and on the overall aroma of wines produced with and without SO2. The volatile compounds were extracted by solid phase extraction and analyzed by gas chromatography-mass spectrometry, carrying out a sensory evaluation of wines by quantitative descriptive analysis. Microwave treatment significantly increased the free and bound fraction of most varietal compounds in the must. Wines from microwave maceration showed faster fermentation kinetics and shorter lag phase, resulting in an increase in some volatile compounds of sensory relevance. The absence of SO2 caused a decrease in concentration of some volatile compounds, mainly fatty acids and esters. The sensory assessment of wines from microwave treatment was higher than the control wine, especially in wines without SO2, which had higher scores in the "red berry" and "floral" odor attributes and a more intense aroma. This indicates that the pre-fermentative treatment of grapes with microwaves could be used to increase the wine aroma and to reduce the occurrence of SO2.

Analysis of cyclitols in different Quercus species by gas chromatography-mass spectrometry.

BACKGROUND: The carbohydrate profile of some woods used for aging wines and spirits has been recently studied using a pressurized liquid extraction method, the main differences found being related to cyclitol content. The aim of this study was to perform a detailed study of these compounds in woods of different Quercus species in order to identify two unknown compounds which appeared in the extracts and to verify whether the obtained profile was homogeneous for other Quercus species. RESULTS: Besides the known monosaccharides and five cyclitols previously described, three deoxy-inositols (epi-, vibo- and scyllo-quercitol) were identified. The presence of these eight cyclitols was confirmed in all subgenera and species of Quercus analyzed, allowing a characteristic cyclitol profile. CONCLUSIONS: Three deoxy-inositols (quercitols) have been identified in the carbohydrate profile of oak wood. All examined Quercus species displayed a common profile consisting of four inositols and four quercitols, which represent a good dataset for characterization of this genus.

Effect of Wine Lees as Alternative Antioxidants on Physicochemical and Sensorial Composition of Deer Burgers Stored during Chilled Storage.

Wine lees from two grape varieties (Vitis vinifera L. Cv. "verdejo" and "palomino") were studied as natural preservatives in deer burgers compared with the traditional additive sodium ascorbate. Burgers packed in modified atmosphere packaging and stored in refrigeration were analyzed at 0, 4, 8, and 12 days. The addition of lees (2.5% and 5%) produced a reduction of pH and variations in color (L* and a*), higher antioxidant capacity and phenolic content, lower lipid and protein oxidation, and the inhibition of psychotrophic aerobic bacteria and enterobacteria during the storage time. Likewise, burgers with lees kept the aldehydes concentration (volatile compounds indicators of lipid oxidation) over storage time, while esters, acids, and other compounds, previously present in lees, increased. These changes provided new odor and taste attributes like wine, bakery, and raisin notes. Therefore, the addition of wine lees had an antioxidant and antimicrobial effect and produced new sensory attributes in deer burgers.

Natural extracts from fresh and oven-dried winemaking by-products as valuable source of antioxidant compounds.

Winemaking by-products are a natural source of antioxidant components; however, due to their highly perishable and seasonal nature, they may require a prior conservation step before being processed. Natural extracts from fresh and oven-dried red grape agro-industrial by-products were obtained by ultrasound assisted extraction (UAE), using a hydroalcoholic solution as extracting solvent. Extracts were analyzed by HPLC-DAD-ESI-MS, to know the feasibility of winemaking by-products as natural sources of phenolic compounds, as well as the effect of the oven-drying treatment on the phenolic composition. Oven-drying at 45°C caused a significant decrease on the total phenolic content, which implied a reduction of the antioxidant capacity of the extracts. Also, it produced a decrease in total and individual flavan-3-ols, stilbenes, and flavonols, being greater in those extracts from stems. Respect to anthocyanins, which were only identified in grape pomace extracts, oven-drying caused an important decrease, being the peonidin-3-O-glucoside the more thermosensitive compound. Natural extracts from fresh or oven-dried winemaking by-products could be used in other food industries as a valuable source of phenolic compounds with antioxidant properties. However, further studies on other drying methods are required for addressing the preservation of phenolic compounds from winery by-products successfully.

Bioactive Flavonoids, Antioxidant Behaviour, and Cytoprotective Effects of Dried Grapefruit Peels (Citrus paradisi Macf.).

Grapefruit (Citrus paradisi Macf.) is an important cultivar of the Citrus genus which contains a number of nutrients beneficial to human health. The objective of the present study was to evaluate changes in bioactive flavonoids, antioxidant behaviour, and in vitro cytoprotective effect of processed white and pink peels after oven-drying (45°C-60°C) and freeze-drying treatments. Comparison with fresh grapefruit peels was also assessed. Significant increases in DPPH, FRAPS, and ABTS values were observed in dried grapefruit peel samples in comparison with fresh peels, indicating the suitability of the treatments for use as tools to greatly enhance the antioxidant potential of these natural byproducts. A total of thirteen flavonoids were quantified in grapefruit peel extracts by HPLC-MS/MS. It was found that naringin, followed by isonaringin, was the main flavonoid occurring in fresh, oven-dried, and freeze-dried grapefruit peels. In vivo assay revealed that fresh and oven-dried grapefruit peel extracts (45°C) exerted a strong cytoprotective effect on SH-SY5Y neuroblastoma cell lines at concentrations ranging within 0.1-0.25 mg/mL. Our data suggest that grapefruit (Citrus paradisi Macf.) peel has considerable potential as a source of natural bioactive flavonoids with outstanding antioxidant activity which can be used as agents in several therapeutic strategies.

Accelerated aging against conventional storage: effects on the volatile composition of chardonnay white wines.

The effects of time (storage period) and temperature (accelerated aging) on Chardonnay white wines have been evaluated. Attention was focused on a large extent of individual volatile compounds, scarcely previously reported in that kind of wines. On the one hand, several volatile compounds (mainly esters, benzenic compounds, C13 -norisoprenoids, acids, and terpenes) showed the same behavior when temperature and time were applied separately. Therefore, the effect of 1 y of storage could be predicted by temperature application during short time, just analyzing those volatile compounds. Moreover, the formation of some volatile compounds (such as dioxanes, dioxolanes, and 1,2-dihydro-1,1,6-trimethylnaphtalene (TDN)) and the disappearance of some alcohols, terpenes, and furanic compounds occurred in both conventional stored and accelerated-aged wines. On the other hand, wines submitted to high temperature differed from 1-y stored wines on several volatile compounds, such as ß-damascenone, C6 -alcohols, dioxolanes, γ-butyrolactone, and TDN. Therefore, it is possible to assert that the analysis of these compounds could allow checking the possible inadequate handling by employing an excessive temperature.

Improvement of Cencibel red wines by oxygen addition after malolactic fermentation: study on color-related phenolics, volatile composition, and sensory characteristics.

The objective of this paper was to check whether a micro-oxygenation technique applied after malolactic fermentation could improve the quality of Cencibel red wines. For that purpose, the color-related phenolics, volatile composition, and sensory characteristics during the micro-oxygenation treatment have been considered. The phenolic compounds more affected by the oxygen addition were hydroxycinnamic acids and their derivatives [(+)-catechin and (-)-epicatechin], flavonols (glycosilated forms), and anthocyanins-related pigments. The fact that the concentration of pyranoanthocyanins and hydroxyphenyl-pyranoanthocyanins was higher in treated red wines is closely related to their color stabilization. As a consequence, higher values of the yellow and red component of the color (b* and a*, respectively) were also observed in micro-oxygenated red wines. Red wine aroma quality was also improved in treated wines. A significant decrease in herbaceous notes, bitterness, acidity, and astringency was found, as well as higher scores of red fruits, plum, liquorice, and spicy attributes in oxygen-added red wines.

Combined effects of prefermentative skin maceration and oxygen addition of must on color-related phenolics, volatile composition, and sensory characteristics of Airén white wine.

The effects of the joint prefermentative maceration and hyperoxygenation of Airén white must and wine on the phenolic content, chromatic characteristics, volatile composition, and sensory characteristics, not previously described in combination, have been evaluated. A total of 20 phenolic and 149 volatile compounds have been identified and quantified for that purpose. As a consequence of the oxygen addition, the concentrations of hydroxycinnamic acid derivatives and flavan-3-ols decreased (above all t-GRP and (+)-catechin), leading to color stabilization, but also the concentrations of several volatile compounds with a great importance for quality aroma decreased. Prefermentative skin maceration, previously applied to the hyperoxygenation of Airén musts, provided the aforementioned color stabilization in the respective wine but also increased the content of short-chain fatty acid esters and terpenes and decreased the concentration of C(6) alcohols. That combination of prefermentative treatments (skin maceration followed by must hyperoxygenation) produced an improvement of the global impression of the final wine based on significantly better scores of tropical fruit, body, and herbaceous notes.

Hyperoxygenation and bottle storage of Chardonnay white wines: effects on color-related phenolics, volatile composition, and sensory characteristics.

The effects of hyperoxygenation on Chardonnay white musts and the influence of subsequent storage on the corresponding wines have been evaluated. Attention was focused on the color characteristics, phenolic and volatile composition, and sensorial analysis, not previously reported in conjunction. On the one hand, the hyperoxygenation treatment provoked a significant decrease in the concentration of virtually all phenolic compounds in musts, young wines, and one-year-stored wines. In addition, a higher resistance to browning was observed in stored wines derived from hyperoxygenated musts. Different storage conditions (light and dark) produced significant differences in the 2-S-glutathionylcaftaric acid derivatives amounts. On the other hand, significant differences were observed in the volatile composition of wines due to the hyperoxygenation treatment, such as a decrease in the isoamylic alcohols concentration, acetaldehyde, and ß-damascenone, even after storage under different conditions. Finally, Chardonnay white wines derived from hyperoxygenated musts had higher banana odor and lower herbaceous and flowery notes.

Identification of new derivatives of 2-S-glutathionylcaftaric acid in aged white wines by HPLC-DAD-ESI-MS(n).

Glutathione, a natural occurring antioxidant, is a thiol-containing peptide present in grape must and wine. It is able to regenerate the o-diphenol group of enzymatically oxidized trans-caftaric acid, giving rise to 2-S-glutathionyl-trans-caftaric acid (also known as grape reaction product, GRP) and thus inhibiting the browning of wine. The amount of GRP present in a wine provides information on the oxidation history of the wine over its elaboration and aging. GRP has been proved to suffer hydrolysis in model solutions and wines. To know the actual content of glutathione involved in white wine browning inhibition as GRP, the GRP-derived products have been studied in 1-year-aged white wines by HPLC-DAD-ESI-MS(n). Online UV-vis spectra and pseudomolecular ions [(M + H)(+)] obtained by LC-MS supported the formation of some of the expected GRP hydrolysis products, mainly 2-S-glutathionyl-trans-caffeic acid (trans-GSCf), together with minor 2-S-(cysteinylglycyl)-trans-caftaric acid, 2-S-(γ-glutamylcysteinyl)-trans-caftaric acid, and 2-S-cysteinyl-trans-caftaric acid. On the basis of UV-vis and LC-MS(2) spectra, new GRP derivatives in aged white wines have been tentatively characterized for the first time as three monoethyl esters of GRP (GRP-Et) and also the cis isomers of GRP, GSCf, and some of the GRP-Et.