Understanding wine sorption by oak wood: Modeling of wine uptake and characterization of volatile compounds retention

Application of toasted vine-shoot chips and ultrasound treatment in the ageing of Primitivo wine

Ageing wine in barrels is an historical practice used to improve the aromatic complexity of wine, but due to the high cost and the long ageing period, alternative approaches have been developed, such as the use of wood chips and ultrasound treatment. The present paper reports the results of an investigation performed on wine (cv. Primitivo). Three treatments were investigated: a) control wine untreated; b) wine with toasted vine-shoot chips (10 g/L); c) wine with toasted vine-shoot chips (10 g/L) and treated by ultrasound. Wines were analysed after 7, 14, 21, and 28 days. The application of ultrasound combined with vine-shoot chips promoted tannin evolution, thereby accelerating the ageing process of wine. The chips addition decreased the total anthocyanins content and increased the stilbenes (trans-resveratrol and trans-piceid) and wood-related aromas (i.e., furfural, 5-methylfurfural) concentration. Finally, wines added with chips were richer in woody, vanilla, oak, and chocolate notes and more preferred by the tasters.

Toasted Vine Shoots as an Alternative Enological Tool. Impact on the Sensory Profile of Tempranillo Wines during Bottle Aging

The use of toasted vine shoots (SEGs) as an enological tool is a new practice that seeks to improve wines by differentiating between them and encouraging sustainable wine production. The sensorial impact during bottle aging of wines treated with SEGs is a key factor to consider. This paper studies the influence of SEGs on Tempranillo wines treated with their own SEGs in two different doses (12 and 24 g/L) at two differences moments (during alcoholic fermentation and after malolactic fermentation) throughout 1 year of bottle aging. The results indicate that addition moment is the factor that most affects the evolution of sensorial descriptors. The greatest evolution in the wines was observed during the first 4 months, wherein improved integration of the notes related to addition of SEGs occurred. A reduction in the perception of dryness and bitterness was observed in the treated wines, therefore, SEGs could be considered accelerators to eliminate these initial sensations from wines.

Metabolomics of Red Wines Aged Traditionally, with Chips or Staves

Traditionally and alternatively aged wines' odour activity values (OAVs) are investigated to differentiate and highlight the differences between the selected methods. An analysis of the volatile aroma compounds of wines derived from ageing in barrels, oak chips, and staves was performed using stir bar sorptive extraction chromatography-mass spectroscopy (SBSE-GC-MS). The results showed that alcohols, esters, and oak compounds were the main contributors to aroma, and their OAVs were higher in the stave samples after 3 months than in the samples from the other two systems of ageing. Furthermore, wines aged with staves have stronger fruity, spiced, and woody aromas, while samples aged in barrels present more chemistry-driven, floral, caramelly, and creamy aromas. The staves-medium plus toast (SMPT at 3 months > 225) and chips-medium plus toast (CMPT at 3 months > 170) showed the highest levels of aromatic series, suggesting that alternative systems provided more powerful aromas than traditional systems, such as barrels-medium plus toast (BMPT at 3 months > 150). A principal component analysis (PCA), orthogonal partial least squares (OPLS) analysis, and cluster analysis allowed for a clear differentiation to be made between red wines according to ageing systems and ageing times. The odour activity values fingerprint in winemaking is a feasible approach to characterise and distinguish wines. Moreover, OAVs provide important information on the effects of production methods on wine quality and aroma profile.

Chemical exchange in the vine shoots-wine system when used as an innovative enological procedure

BACKGROUND

Pruned vine shoots prepared as toasted fragments (SEGs) have recently been proposed as enological additives capable of producing differentiated quality wines. In this work, the composition of phenolic and volatile compounds of SEGs, before and after contact with wines, has been studied.

RESULTS

SEGs from Tempranillo and Cabernet Sauvignon were used, which were kept in contact for 30 days with red wines made with the same varieties. Phenolic compounds were the ones with the highest sorption in SEGs, but a variety-dependent behavior was observed in anthocyanins and flavonols, with an increase in some malvidin derivatives only in Tempranillo wine and an increase in (-)-epicatechin in SEGs and Cabernet Sauvignon wine. trans-Resveratrol was transferred from SEGs to wine but also increased in SEGs regardless of the variety used. The volatile compounds that were most retained in SEGs were phenylethyl alcohol and ethyl lactate, but in lower proportions than the phenolic compounds and without important changes in wines.

CONCLUSION

The high content of phenolic compounds in SEGs after their use as enological additives suggests that they could be considered as a source of anthocyanins and as raw materials for phenolic compounds with recognized antioxidant properties. © 2022 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Contribution of Starmerella bacillaris and Oak Chips to Trebbiano d'Abruzzo Wine Volatile and Sensory Diversity

In this study, six fermentation trials were carried out: co-inoculation and sequential inoculation of Saccharomyces cerevisiae and Starmerella bacillaris in the presence and absence of oak chips. Moreover, Starm. bacillaris strain was attached to the oak chips and co-inoculated or sequentially inoculated with S. cerevisiae. Wines fermented with Starm. bacillaris adhered to oak chips showed a higher concentration of glycerol (more than 6 g/L) than the others (about 5 g/L). These wines also showed a higher content of polyphenols (more than 300 g/L) than the others (about 200 g/L). The addition of oak chips induced an increase of yellow color (b* value of about 3). Oak-treated wines were characterized by a higher concentration of higher alcohols, esters and terpenes. Aldehydes, phenols and lactones were detected only in these wines, independently from the inoculation strategy. Significant differences (p < 0.05) were also observed in the sensory profiles. The fruity, toasty, astringency, and vanilla sensations were perceived as more intense in wines treated with oak chips. The white flower descriptor showed a higher score in wines fermented without chips. Oak surface-adhered Starm. bacillaris cells could be a good strategy to improve the volatile and sensory profile of Trebbiano d'Abruzzo wines.

Promoting Candida zemplinina adhesion on oak chips: A strategy to enhance esters and glycerol content of Montepulciano d'Abruzzo organic wines

In this study cell surface hydrophobicity and the ability to adhere on abiotic surfaces (polystyrene plates, stainless steel and oak chips) of 10 Candida zemplinina strains were assessed. Moreover, the impact of C. zemplinina cells adhered on oak surface on fermentation kinetics and volatile profile of Montepulciano d'Abruzzo organic wines was evaluated. All strains showed a hydrophobic nature with a certain affinity for the apolar solvents tested (hexadecane and decane). In agreement with this data strains were able to adhere on abiotic surfaces in a strain dependent way. On polystyrene plates all strains mainly grew as planktonic cells. On stainless steel surfaces sessile cells ranged from 2.6 Log CFU/mL (SB2) to 4.1 Log CFU/mL (SB8), while on oak chips were about 2 log higher ranging from 4.3 Log CFU/mL (SB8) to 6.1 Log CFU/mL (SB10). Candida zemplinina sessile state resulted in an increase of glycerol (from 6.98 g/L to 11.92 g/L) and esters amount (from 55.47 g/L to 91.5 mg/L), and a reduction of ethanol content (from 14.13% to 9.12% v/v). As for esters, methyl vanillate, ethyl isobutyrate, and ethyl isovalerate were present only when C. zemplinina was adhered on oak chips. This study revealed that changes of concentrations in esters and glycerol content reflected the fermentation bioactivity of yeast cells attached on oak chips. Surface-adhered behaviours should be considered in the improvement of strategies for the development of high-quality organic wines and eventually obtain novel wine styles.

Wood powders of different botanical origin as an alternative to barrel aging for red wine

Wood powders are produced in large quantity as by-product of barrel, staves and chips industry. Differently from larger particles (chips), the use of wood powders in winemaking is not admitted (Regulation (CE) n. 934/2019); however, it could represent a cheap and sustainable alternative for the accelerated aging of red wine. To evaluate their potential use in winemaking, a comparative study on the use of wood powders from oak, chestnut and acacia wood for the accelerated aging of red wine (cv. Aglianico) was conducted. This alternative aging was compared to the aging in wood barrels from the same botanical species. The wine aged in contact with powders underwent a quicker evolution of polyphenolic fraction. After 15 days of contact, the loss of total anthocyanins was higher than that observed after 6 months of aging in barrels (from 4 to 14% with respect to the corresponding kind of barrel). The amount of polymeric pigments tannins–anthocyanins–tannins in wines aged in contact with powders was higher respect to the wines aged in barrels (from 7 to 21% with respect to the corresponding kind of barrel), while the greatest loss of total tannins was detected in the oak barrels (28% less with respect to the control). There were several differences in wine phenolic acids due to wood botanical origin, with the clearest differences being between oak and the alternative wood species (chestnut and acacia). Also, there was a significant botanical effect on sensory profiles. Indeed, both among barrels and among powders, oak wood was the one that gave the strongest wood odor character. However, all the treatments with wood powders (oak, acacia and chestnut) preserved the fruity character of wine, conferring in the meanwhile non-dominant woody notes.

Volatile compounds sorption during the aging of Chinese Liquor (Baijiu) using Pottery Powder

Pottery jar is the preferred storage vessel for aging baijiu, Chinese liquor, and it could sorb liquor micro-compounds. The objective of this work was to identify the sorption of liquor micro-compounds onto pottery powder, and gained insights regarding the sorption processes and mechanism. The sorption of liquor micro-compounds onto pottery powder of different sizes was studied using different kinetic models. The results showed that the sorption capacity varied among particle size of pottery powder, which also affected equilibrium time. The sorption process could be well described by the pseudo-second-order model, and the external diffusion was the rate-limiting step. Liquor volatiles in pottery powder at equilibrium were characterized, which detected alcohols, esters, acids, and furan by gas chromatography-mass spectrometry (GC-MS). These findings demonstrated pottery could not only cause subtractive changes that occur to liquor during the aging period, but also as a vector for transferring aromas sorbed when reused.

Production of a Distilled Spirit Using Cassava Flour as Raw Material: Chemical Characterization and Sensory Profile

Cassava plays a key role in the food production and economies of several countries worldwide. Due to its starch content, alcoholic fermentation is a promising transformation process for adding value to cassava. However, most of the existing cassava beverages are from traditional origin, with the yields and quality often poorly known or controlled due to the use of artisanal production processes. This work aims at the application of easily implementable biotechnological tools for the production of cassava spirits, in order to add value to this raw material. Cassava flour was liquefied and saccharified using enzymatic cocktails, generating a fermentable broth with ~184 g L⁻¹ of fermentable sugars. This was then fermented into an alcoholic product with ~10% ethanol by volume and distilled for spirit production. Cassava spirits with 40% ethanol by volume, with or without application of oak wood, were produced. For further valorization, volatile fractions of cassava spirits were characterized by gas chromatography–flame ionization detection (GC-FID) and GC–MS. These showed a predominance of yeast fermentation metabolites, complemented by wood extractives where oak chips were applied. Both produced spirits showed desirable sensory traits, receiving good acceptance by experienced tasters, demonstrating the feasibility of the proposed process to add value to cassava surplus.

Evaluation of multi-starter S. cerevisiae/ D. bruxellensis cultures for mimicking and accelerating transformations occurring during barrel ageing of beer

During beer ageing, endogenous barrel microbes grow spontaneously and transform wort/beer composition, being Dekkera bruxellensis and Saccharomyces cerevisiae among the main contributors to the chemical and sensory profile of aged beer. This work aims at the application of multi-starter cultures to mimic and accelerate biological modifications occurring during barrel ageing of beer, in controlled fermentation processes. Co-cultures of D.bruxellensis/S.cerevisiae were conducted under conditions commonly found in barrel aged beer production: different pitching rates, high glucose concentration and presence of ethanol and wood extracts. Selective pressures and competition between yeasts influenced microbial growth and metabolite production, namely ethanol, acetic acid and target volatile compounds (esters, alcohols, terpenols, volatile acids and volatile phenols). Metabolic profiles of co-cultures combined traits of both species, and differed from those of pure cultures. Lastly, multi-starters were successfully applied in combination with wood in a controlled and accelerated fermentation process for mimicking barrel ageing transformations.

Customized oxygenation barrels as a new strategy for controlled wine aging

The process of aging red wines in barrels is a common practice that aims to improve the quality of the wine. Oxygen, together with the compounds released by the oak wood, is responsible for this improvement through interaction with the wine compounds during the process. Wood as a natural product presents a series of highly significant discontinuities in its characteristics, not only between trees of the same species, but even between different areas of the same log. It is not surprising that, despite the homogenization of the characteristics of the wood due to the number of staves in a barrel (around 30 pieces), barrels made from the same batch of wood show very different behavior when aging the same wine. This work presents the results of applying a new way of classifying wood in cooperage by means of image analysis of the staves, based on its anatomical characteristics besides grain and handling of the staves, in order to achieve the production of barrels with a desired oxygen transfer rate (OTR) potential and also with great homogeneity between manufacturing batches. The two batches of barrels built with high and low OTR proved to be very homogeneous and the oxygen dosage of the high OTR barrels was more than twice that of the low OTR barrels, which confirmed the success of the system developed.