Phenolic and furanic compounds of Portuguese chestnut and French, American and Portuguese oak wood chips

Factors in Modulating the Potential Aromas of Oak Whisky Barrels: Origin, Toasting, and Charring

In this study, the effects of origin (Chinese, France, and America), intensity of toasting, and degree of charring on the volatiles of oak whisky barrels were comprehensively investigated via liquid-liquid extraction-gas chromatography-mass spectrometry (LLE-GC-MS) combined with multivariate statistical analysis. Results of principal component analysis (PCA) showed that the main oak-derived volatiles in oak were more influenced by origin and toasting than by charring. French oak had a higher content of volatile compounds than the other two origins, and this difference decreased with toasting and charring. The process of toasting and charring was important for the release of volatile compounds from oak. The content of most oak-derived volatiles increased with deeper toasting intensity, and the degree of charring promoted or inhibited the release of oak-derived volatiles. The volatile components in oak blocks were affected by the two-factor interaction of toasting and charring. Continuing the process of the charring of oak at a certain level of toasting may have an enhancing or diminishing effect on the content of different volatile compounds, depending on the circumstances.

Bioactive Properties and Phenolic Composition of Wood-Aged Beers: Influence of Oak Origin and the Use of Pale and Dark Malts

Ageing beer in contact with wood is a common technological procedure that has been used for centuries to improve colour, structure, and certain flavours. Herein, the impact of the addition of French and American oak wood to two beer styles, pale and dark, on beer phenolic composition (total phenolics, total flavonoids, and HPLC-DAD) and bioactivity (FRAP, DPPH, anti-inflammatory activity in RAW 264.7, and antiproliferative in Caco-2 cells) was assessed. Thirteen phenolics were quantified with values according to previous reports. Dark malt resulted in higher values of total phenolics, to which m-hydroxybenzoic, syringic, p-coumaric acids, and xanthohumol contributed considerably; the exception was (+)-catechin and salicylic acid, which were found to be higher in pale beers. American oak significantly increased 3,4-dihydroxyphenylacetic, vanillic, and syringic acids up to roughly 3, 2, and 10 times, respectively, when compared with French wood. FRAP and DPPH values varied between pale and dark beers, with a less pronounced effect after wood addition. All samples presented considerable cellular antioxidant and anti-inflammatory as well as antiproliferative activity, but differences were found only for the antiproliferative activity, which was higher for the dark beers, which reached about 70% inhibition. Overall, the influence of malts was more pronounced than that of wood, in the studied conditions, highlighting the overwhelming impact of malts on the bioactivity of beer.

Phenolic and Antioxidant Compound Accumulation of Quercus robur Bark Diverges Based on Tree Genotype, Phenology and Extraction Method

Oak bark is a rich niche for beneficial bioactive compounds. It is known that the amount of the compounds found in plant tissues can depend on species, genotype, growth site, etc., but it is unclear whether oak phenology, i.e., late or early bud burst, can also influence the amount of phenols and antioxidants that can be extracted. We tested two Quercus robur populations expressing different phenology and five half-sib families in each population to see how phenology, genotype, as well as extrahent differences (75% methanol or water) can determine the total phenol, total flavonoid content, as well as antioxidant activity. Significant statistical differences were found between half-sib families of the same population, between populations representing different oak phenology and different extrahents used. We determined that the extraction of flavonoids was more favorable when using water. So was antioxidant activity using one of the indicators, when significant differences between extrahents were observed. Furthermore, in families where there was a significant difference, phenols showed better results when using methanol. Overall, late bud burst families exhibited higher levels in all parameters tested. Thus, we recommend that for further bioactive compound extraction, all these factors be noted.

Acetic Acid Bacteria in Sour Beer Production: Friend or Foe?

Beer is the result of a multistep brewing process, including a fermentation step using in general one specific yeast strain. Bacterial presence during beer production (or presence in the beer itself) is considered as bad, since bacteria cause spoilage, produce off-flavors, and/or turbidity. Although most problems in the past related to lack of hygiene and/or cleaning, bacteria do still cause problems nowadays. Despite this negative imago, certain bacteria play an irreplaceable role during fermentation and/or maturation of more unique, funky, and especially refreshing sour beers. The term sour beers or sours is not restricted to one definition but covers a wide variety of beers produced via different techniques. This review proposes an uncluttered sour beer classification scheme, which includes all sour beer production techniques and pays special attention to the functional role of acetic acid bacteria. Whereas their oxidation of ethanol and lactate into acetic acid and acetoin usually spoils beer, including sour beers, organoleptically, a controlled growth leads to a desirable acidic flavor in sour beers, such as lambic-style, lambic-based, and red-brown acidic ales.

Increasing the added value of vine-canes as a sustainable source of phenolic compounds: A review

Grapes represent one of the most produced fruit crops around the world leading to the generation of large amounts of vine-canes as a side product, with no current economically profitable application. However, vine-canes have been demonstrated to be natural sources of phenolic compounds with numerous health benefits associated, with several potential applications. Therefore, new ambitious applications focused on their re-use are needed, targeting a sustainable process that simultaneous produces functional products and mitigates the waste generation. This review gives to the readers a complete summary about the state of the art regarding the vine-canes extracts research. Vine-canes phenolic composition is addressed and related to the health benefits exhibited. This review comprises studies from the past two decades reporting the extraction processes to recover vine-cane phenolic compounds, including conventional and environmentally friendly technologies and discussing their advantages and disadvantages. The conditions that favour the extraction process for vine-cane polyphenols for each technique were also deeply explored for the first time, enabling to the reader apply only the best parameters to achieve the highest yields without huge investment in optimizations procedures. Furthermore, a correlation between the bioactive properties of the vine-cane extracts and their applications in multiple fields is also critically presented.

Identification of gallotannins and ellagitannins in aged wine spirits: A new perspective using alternative ageing technology and high-resolution mass spectrometry

This research was focused on identifying gallotannins and ellagitannins degradation pathways to better understand their behavior in complex media such as wine spirits (WS). A WS was aged with chestnut wood staves with three levels of micro-oxygenation, nitrogen, and using wooden barrels. Gallotannins and ellagitannins were identified by LC-ESI-HRMS/MS using a Q-TOF in samples collected at 8, 21, 60, 180, 270, and 365 days of ageing, allowed comparing their relative abundances according to the ageing technology. It was established for the first time, the importance of oxygen in gallotannins and ellagitannins formation/degradation pathways in WS and shading light into the explanation for the steady increase of gallic and ellagic acid contents on WS during ageing. The results also highlighted the presence of penta-O-galloyl-β-d-glucose, tetra-O-galloyl-β-d-glucose, tri-O-galloyl-β-d-glucose, di-O-galloyl-β-d-glucose, and mono-O-galloyl-β-d-glucose, 2,3-(S)-hexahydroxydiphenoyl-β-d-glucose, pedunculagin, isomers vescalagin/castalagin and two products stemming from ethanol-promoted oxidation of castalagin/vescalagin and vescalin/castalin, in the composition WS aged with chestnut wood.

The Application of Wood Species in Enology: Chemical Wood Composition and Effect on Wine Quality

Aging wine is a usual practice in winemaking, as the wine quality improves due to the compounds extracted from wood barrels or chips, cubes, blocks, or staves used. The wood species used are traditionally oak, namely from Quercus petraea, Q. alba, or Q. robur species. In the last years, the increasing request for oak wood has caused a significant increase in environmental and production costs. Therefore, heartwood from several alternative species has been considered a potential wood source for winemaking and aging. Thus, the main purpose of this review is the application of these alternative wood species on wine production and to discuss the advantages and disadvantages of its use compared with the traditional wood species, namely oak wood. In addition, a brief chemical characterization of several wood species with possible application in enology is also discussed in this review.

Application of Hanseniaspora vineae Yeast in the Production of Rosé Wines from a Blend of Tempranillo and Albillo Grapes

Hanseniaspora vineae is an apiculate yeast that can be used for the production of interesting commercial wines, due to its contribution of fermentative volatiles. This paper presents a detailed comparative study of the use of H. vineae, compared to pure fermentations of S. cerevisiae in Tempranillo and Albillo rosé wines. Fermentations were carried out in oak barrels and stainless steel barrels. The results indicated that fermentation with H. vineae resulted in wines with residual sugars below 3.4 g/L and similar general characteristics, compared to S. cerevisiae. However, H. vineae wines contain up to 44% more total anthocyanins, resulting in an appreciable improvement in colour. In addition, H. vineae produced up to 65% more 2-phenylethyl acetate in stainless steel barrels and 2.5 times more terpene alcohols in oak barrels. Therefore, the use of H. vineae results in a more attractive colour, as well as fruity and floral organoleptic characteristics of rosé wines.

Characterization of benzenemethanethiol in sesame-flavour baijiu by high-performance liquid chromatography-mass spectrometry and sensory science

Chinese sesame-flavour baijiu (CSB) is one of aroma types discovered after the founding of China. Sulfur-containing compounds have low content in CSB but play an important role. This study developed a quantitative method by derivatization reaction combined LC-MS/MS for the determination of benzenemethanethiol (BM), which has a roasted aroma in CSB. Under the optimized conditions, the LOD and LOQ of BM were 11.73 ng L^-1 and 39.09 ng L^-1, respectively. The recovery yield of the derivatization product ranged from 82.12% to 93.99%. The content of BM in 4 CSBs were 150.22-860.40 ng L^-1. To confirm the contribution of BM to the overall aroma of CSB, aroma recombination experiments and omission experiments were carried out. Compared with that of the simulated baijiu sample without BM, the roasted aroma of the simulated baijiu sample containing BM was enhanced. Omission experiments showed that BM made important contributions to the overall aroma of CSB.

Influence of pre-fermentative addition of aqueous solution tannins extracted from oak wood (Quercus petraea) on the composition of Grillo wines

In this research, the chemical characterization of fixed and volatile compounds of two different tannins in aqueous solution (Pratiko® L-Harvest and L-Fruit) extracted from oak wood, has been studied. The influence of the above tannins, at different concentrations, on the alcoholic fermentation kinetics and on the composition and sensorial characteristics of a white wine were then evaluated. The wines added tannins in aqueous solution compared to control wines showed significant differences in fixed compounds (colloids, polyphenols and ellagitannins) and volatile compounds (phenolic aldehydes, volatile phenols, furanic and piranic compounds). The differences of aqueous solution tannins extracted from oak wood were partly due to the drying/maturing and roasting methods used in barrel production. Alcoholic fermentation was partially facilitated by the addition of tannins in aqueous solution. The wines obtained showed a higher content of ethyl esters of medium-chain fatty acids (from 22 to 31%) and, in some cases, higher acetate alcohols (from 15 to 28%), relevant to the olfactory sensations provided to the wines. The tannins added to the must before fermentation also made it possible to obtain an additional supply of polyphenols (from 25 to 85%) able to induce more complex sensory profiles in the wines, with increased persistent taste notes.

Accelerating Aging of White and Red Wines by the Application of Hydrostatic High Pressure and Maceration with Holm Oak (Quercus ilex) Chips. Influence on Physicochemical and Sensory Characteristics

BACKGROUND

The use of holm oak (Quercus ilex) chips as a potential alternative wood and the application of hydrostatic high pressure (HHP) as an alternative technique to accelerate the release to the wine of wood-related compounds within a short processing time were evaluated.

METHODS

Five treatments were investigated: (i) bottling without any treatment (B); (ii) and (iii) bottling after maceration (5 g/L) of holm oak chips with HHP treatments (400 MPa, 5 and 30 min) (HHP5, HHP30); (iv) bottling after maceration during 45 days with chips (M), and; (v) maceration in tanks without chips (T). The effects of treatments on general parameters, polyphenols, color, and sensorial characteristics of red and white wines were investigated over 180 days.

RESULTS

HHP5, HHP30, and M increased the polyphenols content, thus modified the chromatic characteristics regarding B and M treatments of white wines, also the tasters differentiated HHP5, HHP30, and M from B and T. However, these effects were not observed in red wines. Thus, the effect of the wood depends on the type of wine in which it is used.

CONCLUSIONS

This research contributes to better knowledge about these chips as a new alternative wood species and the use of HHP as a useful technology to accelerate the aging of wines.

RP-HPLC Analysis of Phenolic Lignin Monomers with DAD and Coulometric Array Detection

An high performance liquid chromatography (HPLC) method, applying diode array (DAD) and coulometric array detection simultaneously, was developed to determine monomeric phenolic compounds in lignin hydrolysates. To allow for additional mass spectrometric detection, a formic acid gradient was designed as an alternative to the non-volatile phosphate buffer gradient. Within a total run time of 28 min, 10 out of 14 analytes were baseline separated by the formic acid gradient, and 8 compounds were completely resolved by the phosphate gradient. The dependence of the coulometric detection on cell potential, potential step width, eluent pH and eluent composition was comprehensively tested. Detection limits ≤20 μg/L were achieved by DAD detection for nine analytes and by coulometric array detection for all analytes, demonstrating the superior sensitivity of electrochemical detection. DAD offered better linearity and reproducibility. Inter-day precision of peak heights spanned from 0.26 to 2.00% (formic acid gradient) and from 0.75 to 2.85% (phosphate buffer gradient) operating the DAD detector, but it exceeded 10% for several compounds applying the coulometric array detector. The simultaneous operation of both detectors offered an enhanced certainty of substance identification. The appropriateness of the method was confirmed by the analysis of various hydrolysates of lignin-containing materials.

Evolution of the Phenolic Fraction and Aromatic Profile of Red Wines Aged in Oak Barrels

Various changes occur in red wine during aging in oak barrels. Among these, the variation of the polyphenolic fraction and the transfer of aromatic compounds to the wine from oak wood are of great importance. The aim of the present work is to compare the chemical composition of wines aged in different new oak barrels with similar commercial denominations. During 8 months, the total polyphenol index (TPI), color parameters, anthocyanins and pyranoanthocyanins, and wood aromatic compounds were periodically evaluated. The measurement of the TPI and color parameters was similar in all wines, but significant differences were found in total anthocyanin and vitisin content and in certain aromatic compounds belonging to volatile phenols, furanic compounds, and phenolic aldehydes. The results obtained indicate the need for the winemaker to carry out preliminary tests in order to be able to choose the wood that best suits the sensorial profile of the wine.

Use of Alternative Wood for the Ageing of Brandy de Jerez

The use of alternative types of wood has arisen for the aging of the Brandy de Jerez, on a pilot plant level. In particular, besides the use of American oak, two more types of oak have been studied, French oak and Spanish oak, allowed by the Technical File for the ID Brandy de Jerez, and chestnut, which, though it is not officially allowed, is a type of wood which had been traditionally used in the area for the aging of wines and distillates. All of them have been studied with different toasting levels: Intense toasting and medium toasting. The study of the total phenolic composition (TPI), chromatic characteristics, organic acids, and sensory analysis have proven that chestnut leads to distillates with a higher amount of phenolic compounds and coloring intensity than oak. This behavior is the opposite as regards the toasting of the wood. Among the different types of oak, Spanish oak produces aged distillates with a higher phenolic composition and a higher color intensity. Regarding tasting, the best-assessed samples were those aged with chestnut, French oak, and American oak, and the assessors preferred those who had used a medium toasting level to those with an intense level.

Effect of toasting on non-volatile and volatile vine-shoots low molecular weight phenolic compounds

Low molecular weight phenolic compounds (LMWPC), including non-volatile and volatile, of Airén and Moscatel vine-shoot cultivars waste submitted to different toasting conditions (light, 180°/15min; medium, 180°/30min; high 180°/45min) were studied in order to exploit them with oenological purposes. The LMWPC differences were mainly due to the toasting times rather than vine-shoot variety. In non-volatile LMWPC fraction, flavanols and almost all phenolic acids decreased by toasting. The presence of trans-resveratrol has a special relevance at light toasting: 14 times more concentrated in Airén and 6 times in Moscatel vine-shoots, than their respective non-toasted samples. The volatile LMWPC showed a significant increment with toasting, being vanillin the one with the highest difference respect to non-toasted samples at high conditions: more than 15 times in Airén and 11 in Moscatel. Although toasting reduced some LMWPC, particular characteristics of these vine-shoots must be taken into account when considering its future use.

Phenolic composition of vinegars over an accelerated aging process using different wood species (acacia, cherry, chestnut, and oak): effect of wood toasting

Wood shavings are widely employed in vinegar making to reduce aging time. Accordingly, this study aims to evaluate the effects of using shavings from different wood species (acacia, cherry, chestnut, and oak) and of toasting on the release of phenolic compounds into vinegar during the aging process. The study involved aging vinegars using previously toasted shavings and untoasted ones, at 0.5% and 1% (w/v), and collecting samples at 15 and 30 days. The phenolic compounds were analyzed by LC-DAD during the aging process. As a result, wood markers naringenin and kaempferol (cherry), robinetin and fustin (acacia), and isovanillin (oak) were identified for the first time in vinegars. The results also showed that toasting wood shavings decreases the concentration of most flavonoid wood markers (e.g., (+)-taxifolin, naringenin, and fustin) in vinegar, but that it is essential for the highest releases of aldehyde compounds (syringaldehyde, protocatechualdehyde, and vanillin). Remarkably, 15 days was sufficient to obtain the highest increases of most polyphenol compounds in the vinegar. Statistical analysis (linear discriminant analysis) proved that the phenolic compounds identified in vinegars are useful for discriminating vinegars regarding the wood species of the shavings used to accelerate aging.