Terroir 1996 banner
IVES 9 IVES Conference Series 9 Ripening characterization and modelling of Listan negro grape in Spain using a regression analysis

Ripening characterization and modelling of Listan negro grape in Spain using a regression analysis

Abstract

The professional winegrower usually selects the harvest date considering several elements, such as the vine stem and berry colour, the flavour, appearance and grain elasticity. Nowadays these elements have turned old fashioned.
Other professionals take into account the weather or even manpower availability, so it is mainly random which determines wine quality, as this depends on the raw material (quality) characteristics.
In order to palliate these practice posible negative effects, this work was based on the simple mathematical equation obtention which characterized the ripening of the most common grape variety at Tacoronte-Acentejo vineyard area to give both the winegrower and the oenologist a simple instrument to find out the best harvest date or to know the value of each traditional parameter according to the weather.
This work was done during the season from 1994 to 1998, in the period that starts with the verasion and ends with the ripening process. During this period samples were taken weekly. About ten grains by vine stem were taken from a whole of fifty, which were previously selected in vineyards grown in different parts of the wine region.
Once they were in the laboratory and after getting the sample ready to obtain the grape must, multiple physicochemical analyses were done, from which we stand out the following ones: one hundred berry weight, total sample weight, total volume, grape must yield, soluble solids, probable alcoholic rate, pH, total acidity, tartaric acid, malic acid, bound and free volatile compounds (free and potentially volatile monoterpene grape flavourings), sodium, potassium, copper, iron, colour indicator parameters, from which only three have been used in this experiment, the sugar content given as probable alcoholic rate, pH and total acidity analysed using the Standard Methods.
After the systematic observation of the ripening curve lines, similar evolutive tendencies are found in the three analysed parameters. This tendency has been studied by comparing the curved line behaviour to a straight line, using a computerized calculation programme obtaining like this the slope, the ordinate in the origin and the coefficient of correlation r2 in each case. The equations found are of the type y = a + bx, were “y” represents the value of the physicochemical studied parameter and “x” the day from the verasion. The ordinate in the origin “a” will be the studied parameter value at the moment in which the first sample was taken, that is to say, in the verasion. Slope “b” indicates the studied parameter daily increase.
We have also found regression lines which allow the harvest date calculation for the probable alcoholic rate determined with 0,12 alcoholic / day slope for 500 m high vineyards areas or even higher. We have also established a linear pH relationship with the days up to the harvest, which depends on the vineyard height and a similar regression for the acidity has also been found.
Thus, knowing each parameter prediction equation, the winegrower will be able to know his harvest conditions. He will also be able to know the time left to obtain each analytical parameter wished value and so, the best optimum harvest date with more than a 90 % reliability.

DOI:

Publication date: February 24, 2022

Issue: Terroir 2000

Type: Article

Authors

García Fernández, M.J., González Mendoza, L.A., Pomar García, M.

Departamento de Ingeniería Química y Tecnología Farmacéutica
Facultad de Química. Universidad de La Laguna
Avda. Astrofísico Francisco Sánchez, s/n

Tags

IVES Conference Series | Terroir 2000

Citation

Related articles…

Downscaling of remote sensing time series: thermal zone classification approach in Gironde region

In viticulture, the challenges of local climate modelling are multiple: taking into account the local environment, fine temporal and spatial scales, reliable time series of climate data, ease of implementation and reproducibility of the method. At the local scale, recent studies have demonstrated the contribution of spatialization methods for ground-based climate observation data considering topographic factors such as altitude, slope, aspect, and geographic coordinates (Le Roux et al, 2017; De Rességuier et al, 2020). However, these studies have shown questions in terms of the reproducibility and sustainability of this type of climate study. In this context, we evaluated the potential of MODIS thermal satellite images validated with ground-based climate data (Morin et al, 2020). Previous studies have been encouraging, but questions remain to be explored at the regional scale, particularly in the dynamics of the massive use of bioclimatic indices to classify the climate of wine regions. The results at the local scale were encouraging, but this approach was tested in the current study at the regional scale. Several objectives were set: 1) to evaluate the downscaling method for land surface temperature time series, 2) to identify regional thermal structure variations. We used weekly minimum and maximum surface temperature time series acquired by MODIS satellites at a spatial resolution of 1000 m and downscaled at 500 m using topographical variables. Two types of analyses were performed:

Effect of regulated deficit irrigation regime on amino acids content of Monastrell (Vitis vinifera L.) grapes

Irrigation is an important practice to influence vine quality, especially in Mediterranean regions, characterized by hot summers and severe droughts during the growing season. This study focused on deficit irrigation regime influence on amino acids composition of Monastrell grapevines under semiarid conditions (Albacete, Southeastern of Spain). In 2019, two treatments were applied: non-irrigation (NI) and regulated deficit irrigation (RDI), watered at 30% of the estimated crop evapotranspiration from fruit set to onset of veraison. Grape amino acids content was analyzed by HPLC. Berries from non-irrigated vines showed higher concentration of several amino acids, such as tryptophan (73%), arginine (70%), lysine (36%), isoleucine (27%), and leucine (21%), compared to RDI grapes. Arginine is, together with ammonium ion, the principal nitrogen source for yeasts during the alcoholic fermentation; while isoleucine, tryptophan, and leucine are precursors of fermentative volatile compounds, key compounds for wine quality. Moreover, NI treatment increased in a 14% the total amino acids content in grapes compared to RDI treatment. The reported effects might be because yield was 70% higher in RDI vines than in the NI ones and, therefore, the sink demand was increased in the irrigated vines. In addition, NI vines suffered more severe water stress and it is known that the amino acids synthesis and accumulation can be influenced by the plant response to stress. According to the results, the irrigation regime showed effect on amino acids concentration in Monastrell grapes under semiarid conditions. Grapes from non-irrigated vines showed a higher content of several amino acids relevant to the fermentative process and to the wine aroma compounds formation. It is demonstrated that the final content of nitrogen-related components in grapes is influenced by the irrigation regime. The convenience of the irrigation strategy to suggest will depend on the desired wine style and the target yield levels.

A predictive model of spatial Eca variability in the vineyard to support the monitoring of plant status

[lwp_divi_breadcrumbs home_text="IVES" use_before_icon="on" before_icon="||divi||400" module_id="publication-ariane" _builder_version="4.19.4" _module_preset="default" module_text_align="center" module_font_size="16px" text_orientation="center"...

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.

Pruned vine biomass exclusion from a clay loam vineyard soil – examining the impact on physical/chemical properties

The wine industry worldwide faces increasing challenges to achieve sustainable levels of carbon emission mitigation. This project seeks to establish the feasibility of harvesting winter pruned vineyard biomass (PVB) for potential use in carbon footprint reduction, through its use as a renewable biofuel for energy production. In order to make this recommendation, technical issues such as the potential environmental impact, chemical composition and fuel suitability, and logistical challenges of harvesting biomass needs to be understood to compare with the results from similar studies. Of particular interest is the role PVB plays as a carbon source in vineyard soils and what effect annual removal might have on soil carbon sequestration. A preliminary trial was established in the Waite Campus vineyard (University of Adelaide) to test current management strategies. Vines are grown in a Eutrophic, Red Dermosol clay loam soil with well managed midrow swards. A comparison was undertaken of mid-row treatments in two 0.25 Ha blocks (Shiraz and Semillon), including annual cultivation for seed bed preparation, the deliberate exclusion of PVB (25 years) and incorporation of PVB (13 years) at an average of 3.4 and 5.5 Mg/Ha-1 for Shiraz and Semillon respectively. In both 0-10cm and 10-30cm soil core sample depths, combined soil carbon % measures in the desired range of 1.80 to 3.50, were not significantly different between treatments or cultivars and yielded an estimated 42 Mg/ha-1 of sequestered soil carbon. Other key physical and chemical measures were likewise not significantly different between treatments. Preliminary results suggest that in a temperate zone vineyard, managed such as the one used in this study, there is no long term negative impact on soil carbon sequestration through removing PVB. This implies that growers could confidently harvest PVB for use in several end fates including as a bio fuel.