Macrowine 2021
IVES 9 IVES Conference Series 9 Influence of short-time skin maceration combined with enzyme treatment on the volatile composition of musts from fresh and withered fiano winegrapes

Influence of short-time skin maceration combined with enzyme treatment on the volatile composition of musts from fresh and withered fiano winegrapes

Abstract

AIM: The increasing market competitiveness is promoting the production of special dry wines with distinctive characteristics, obtained either from minor winegrape varieties and/or the inclusion of partially dehydrated grapes. With the aim of taking advantage of the grape quality traits in terms of aroma potential, short-time skin contact prior pressing in combination with the use of exogenous enzymes can facilitate the release of volatile organic compounds (VOCs) into the grape must. In addition, the possible presence of glycosidase activity enhances the hydrolysis of odourless glycosidically-bound precursors, which have a particular importance for non-aromatic grape varieties. [1,2] In this study, the effect of eight enzyme treatments with different single activity during short-term pre-fermentative maceration was investigated on the volatile composition of musts, obtained from both fresh and withered winegrapes cv. ‘Fiano’.

METHODS: The study was carried out on fresh or partially dehydrated (20% of weight loss) ‘Fiano’ white winegrapes from Campania region (southern Italy). For each sample, twenty-seven berry sets of 500 g each were randomly selected and crushed in presence of 10 mg/kg of potassium metabisulphite. Then, three berry sets were individually treated with pectin lyase (PL), polygalacturonase (PG), pectin methylesterase (PME), xylanase (XYL), arabinase (ARA), protease (PRO), β-glucanase (GLN), or β-glucosidase (GLU) enzymes at a dose of 10 mg/kg, homogenized and subjected to pre-fermentative maceration for 13 h at 12 °C. The other three berry sets were treated similarly but without enzyme addition (control). Subsequently, the musts obtained were separated from the skins and used for the determination of free and glycosidically-bound VOCs using solid-phase extraction followed by GC-MS analysis [3].

RESULTS: Regarding the free volatile fraction of musts, few compounds were influenced by the different enzyme treatments tested. This effect appeared to be more evident for glycosylated volatile compounds, for which the concentration of total compounds, aromatic alcohols, C6 alcohols, and certain terpenes (nerol and geraniol) significantly prevailed in musts from fresh grapes treated with PG. Moreover, samples from withered Fiano grapes treated with PG and ARA were characterized by higher contents of terpenes (cis-8-hydroxylinalool, nerol, geraniol, and α-terpineol), C6 alcohols (trans-2-hexenol and 1-hexenol), and benzenoids (eugenol).

CONCLUSIONS: 

 The addition of enzymes during short-term pre-fermentative maceration resulted to have effect mainly on the glycosylated volatile fraction of the musts obtained from fresh and withered grapes. In particular, exogenous enzyme activities such as PG exhibit major influence on the volatile profile of musts derived from fresh and withered ‘Fiano’ grapes, which could contribute to enhance the sensory perceived aroma of the resulting wines.

DOI:

Publication date: September 10, 2021

Issue: Macrowine 2021

Type: Article

Authors

Stefano Boz

University of Torino, Italy,Susana RÍO SEGADE, University of Torino, Italy Stefano BOZ, University of Torino, Italy Mattia MALABAILA, University of Torino, Italy Domen ŠKRAB, University of Torino, Italy Maria Alessandra PAISSONI, University of Torino, Italy Simone GIACOSA, University of Torino, Italy Luca ROLLE, University of Torino, Italy

Contact the author

Keywords

 volatile compounds; enzymes; pre-fermentative maceration; fiano winegrapes

Citation

Related articles…

Influence of agronomic practices in soil water content in mid-mountain vineyards

In the context of LIFE project MIDMACC (LIFE18 CCA/ES/001099), several pilots have been installed in vineyards in mid mountain areas of Catalonia (NE Spain) to test well stablished agronomic practices to increase the adaptation of Mediterranean mid mountain to climate change. Soil water content (SWC) at three different depths (15, 30 and 45cm) was measured in continuum from August 2020. One pilot (WC) included a well-established green cover (GC), a new GC (NC) and a conventional soil management (CM, tilling+herbicides). NC presented an intermediate state between WC and CM, responding similarly to CM in autumn but quickly reaching similar SWC to WC, then following the same evolution till next spring, with CM presenting lower values along autumn and winter. Then vegetation activation decreased SWC in all plots, (much slower in CM, lacking GC). Sensibility to spring rains is again intermediate for NC, which joins SWC evolution of CM by the end of spring till next autumn. It is expected that NC will resemble WC more and more as its GC develops. In the pilot combining vine training (VSP vs Gobelet) and hillside management (slope vs terrace), no clear pattern could be related with these conditions. However, both terraces seem to be more sensitive to spring rains. A third pilot included new vineyards (7 and 1 year old). In the new vineyard (N), higher canopy development, a spontaneous green cover and row straw resulted in a slower SWC dynamic, not so sensitive to rains but conserving more soil water in spring and most of summer, even with presumably a higher water extraction by vines. In the newest vineyard (VN) the deepest sensor is still sensitive to rain events all over the year and SWC is always highest at this depth, revealing small water capture by vines.

Inhibition of Oenococcus oeni during alcoholic fermentation by a selected Lactiplantibacillus plantarum strain

The use of selected cultures of the species Lactiplantibacillus plantarum in Oenology has grown in prominence in recent years. While initial applications of this species centred very much around malolactic fermentation (MLF), there is strong evidence to show that certain strains can be harnessed for their bio-protective effects. Unwanted spontaneous MLF during alcoholic fermentation (AF), driven by rogue Oenococcus oeni, is a winemaking deviation that is very difficult to manage when it occurs. This work set out to determine the efficacy of one particular strain of Lactiplantibacillus plantarum(Viniflora® NoVA™ Protect), against this problem in Cabernet Sauvignon must. The work was carried out at commercial scale and in a winery environment and compared the bio-protective culture with the more traditional approach of reducing must pH by the addition of tartaric acid. The combination of both was also investigated. The concentration of both Oenococcus oeni and Lactiplantibacillus plantarum was determined using qPCR. The adventitious Oenococcus oeni showed the most growth during AF in the control wine, whereas in the wines treated with Lactiplantibacillus plantarum a bacteriostatic effect against this species was observed. This effect was comparable to the wines treated with tartaric acid. This has particular commercial relevance for controlling the flora in musts with high pH, or when the addition of tartaric acid is either not permitted or is prohibitive for other reasons.

Extreme canopy management for vineyard adaptation to climate change: is it a good idea?

Climate change constitutes an enormous challenge for humankind and for all human activities, viticulture not being an exception. Long-term strategic changes are probably needed the most, but growers also need to deal with short-term changes: summers that are getting progressively warmer, earlier harvest dates and higher pH in musts and wines. In the last 10-15 years, a relevant corpus of research is being developed worldwide in order to evaluate to which extent extreme canopy management operations, aimed at reducing leaf area and, thus, limiting the source to sink ratio, could be useful to delay ripening. Although extreme canopy management can result in relevant delays in harvest dates, longer term studies, as well as detailed analysis of their implications on carbohydrate reserves, bud fertility and future yield are desirable before these practices can be recommended.

How can historical cultivars mitigate the effects of climate change?

IFV, INRAe and the national network “Partenaires de la Sélection Vigne” representing 37 organizations from the different wine regions, have been working increasingly closely over the last 2 decades towards the preservation of the French varietal patrimony. There are approximately 600 patrimonial varieties according to INRAe and SupAgro Montpellier experts, including ancient cultivars (400) and intravarietal crossbreeds obtained since the 19th century. In the context of a drastic reduction in such varieties from the mid 1980’s in favor of mainstream varieties, it was essential to carry out an inventory of old vines and vineyards. INRAe Vassal collection plays a key role here as it holds the largest diversity available, along with a rich bibliography and herbariums, offering us the opportunity to document and double check the identity of a cultivar, consolidating the expertise of ampelographers. The work is carried out in several stages, from verifying the existence of a variety in a small region, through to rehabilitation. During this session, the authors present the process that leads to the official registration of a variety. After this, IFV selection center takes over to initiate the process of selection and propagation. A specific focus within regions such as the Alps, Champagne and the South-West will provide details of the full procedure. Bia, Bouysselet, Chardonnay rose, Mecle and the aptly named Tardif, are some of the cultivars that have followed this procedure. Furthermore, a recent regulation established by INAO on “varieties of interest for adaptation purposes” might boost uptake by growers. Since 2006, 36 historical cultivars have been registered. Most of these have been neglected in the past due to late maturity, lack of sugar and high titratable acidity at harvest time. Such characteristics are today considered as positive qualities, not only in mitigation of the effects of climate change, but also as an opportunity for restoring diversity…

Projected changes in vine phenology of two varieties with different thermal requirements cultivated in La Mancha DO (Spain) under climate change scenarios

The aim of this work was to analyze the phenology variability of Tempranillo and Chardonnay cultivars, related to the climatic characteristics in La Mancha Designation of Origin, and their potential changes under climate change scenarios. Phenological dates referred to budbreak, flowering, veraison and harvest were analyzed for the period 2000-2019. The weather conditions at daily time scale, recorded during the same period, were also evaluated. The thermal requirements to reach each of these phenological stages were calculated and expressed as the GDD accumulated from DOY=60. Changes in phenology were projected by 2050 and 2070 taking into account those values and the projected temperatures and precipitation, simulated under two Representative Concentration Pathway (RCP) scenarios –RCP4.5 and RCP8.5– using an ensemble of models. The average phenological dates during the period under study were, April 16th ± 6.6 days and April 5th ± 6.0 days for budbreak, May 31st ± 6.0 days and May 27th ± 5.3 days for flowering, July 26th ± 5.6 days and July 25th ± 5.8 days for veraison, and Ago 23rd ± 10.8 days and Ago 17th ± 9.0 days for harvest, respectively, for Tempranillo and Chardonnay. The projected changes in temperature imply an average change in the maximum growing season (April-August) temperatures of 1.2 and 1.9°C by 2050, and 1.6 and 2.6°C by 2070, under the RCP4.5 and RCP8.5 scenarios, respectively. A reduction in precipitation is predicted, which vary between 15% for 2050 under RCP4.5 scenario and up to 30% by 2070 under RCP8.5. The advance of the phenological dates for 2050, could be of 6, 7, 7, and 8 days for Tempranillo and 4, 6, 6 and 9 days for Chardonnay, respectively for budbreak, flowering, veraison and harvest under the RCP4.5 scenario. Under the RCP8.5 emission scenario, the advance could be up to 30% higher.