 IVES 9 IVES Conference Series 9 Desorption of phenolic compounds bound to lees by combining hydrolytic enzymes and ultrasounds

Desorption of phenolic compounds bound to lees by combining hydrolytic enzymes and ultrasounds

Abstract

The final concentration of phenolic compounds in the wines is usually lower than what might be expected given the phenolic concentration measured in grapes. One possible cause of this low concentration is the interactions between the suspended mesocarp and skin cell walls and phenolic compounds during the maceration process of red wine [1]. Most of these aggregates that are formed by these interactions are insoluble and end up precipitating forming, together with the yeast cell walls, the lees. Maceration enzymes have the ability to degrade the polysaccharides that represent the major components of the cell wall, which it is why these enzymes could lead to the release of phenolic compounds previously absorbed by the cell walls. Ultrasound (US) has been used in oenology as a technology to break cell structures through cavitation and facilitates the release of compounds of interest from the cell interior [2,3], and, precisely because of this capacity, US could also promote the desorption of phenolic compounds precipitated with lees.The objective of this work is to determine the capacity of two different techniques, the use of enzymes and/or the application of high power ultrasounds (US) to release those anthocyanins and tannins adsorbed in the lees. Both techniques seek the degradation (enzymes) or disruption (US) of the structures of the cell walls, to facilitate the desorption of the phenolic compounds.The lees from a red wine vinification were recovered, dissolved in a model ethanolic solution and treated, at laboratory scale, with enzymes and/or ultrasounds. Three different commercial enzymes were used: two different pectolytic enzymes and glucanase. The best sonication conditions were previously tested in order to find the optimal treatment conditions. The chromatic characteristics of the model solution and anthocyanins and tannins recovery were analyzed after the treatments. Anthocyanins and tannins were quantified and characterized by liquid chromatography. In addition, the soluble polysaccharides and tannins extracted from the lees after the treatments were analyzed by size exclusion chromatography.The results of this study could be of interest for the valorization of the lees, as a winery byproduct, by recovering the adsorbed compounds but also we add light into possible enological procedures for facilitating and accelerating the aging on lees, through the liberation, first of all, of polysaccharides from the lees but also those phenolic compounds lost during vinification.

DOI:

Publication date: September 7, 2021

Issue: Macrowine 2021

Type: Article

Authors

Andrea Osete Alcaraz

Department of Food Science and Technology, Faculty of Veterinary Sciences, University of Murcia, 30100 Murcia, Spain.,Ana Belen, BAUTISTA-ORTÍN, Department of Food Science and Technology, Faculty of Veterinary Sciences, University of Murcia, 30100 Murcia, Spain. Encarna, GÓMEZ-PLAZA, Department of Food Science and Technology, Faculty of Veterinary Sciences, University of Murcia, 30100 Murcia, Spain. Paula, PÉREZ-PORRAS, Department of Food Science and Technology, Faculty of Veterinary Sciences, University of Murcia, 30100 Murcia, Spain. Raquel, SANCHEZ-BERNAL, Department of Food Science and Technology, Faculty of Veterinary Sciences, University of Murcia, 30100 Murcia, Spain.

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Keywords

anthocyanins, tannins, ultrasound, enzymes, lees

Citation

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Sustaining wine identity through intra-varietal diversification

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Better understand the soil wet bulb formation with subsurface or aerial drip irrigation in viticulture

The gradual change in rainfall patterns experienced in the south of France vineyards, especially around the Mediterranean sea, means that the vines are increasingly subject to summer drought. The winegrowers developped the use of irrigation techniques to ensure the maintenance of competitive yields in the production of wines under Protected Geographical Indication label. In practice, drip irrigation pipes can be installed above the ground or buried into the soil as well as at different distances from the vine row. The objective of this study was to examine the profiles of the wet bulbs of the soil obtained from two drip irrigation systems : aerial drip located under the vine row and subsurface drip placed in the middle of the inter-row. This experiment took place over two consecutive seasons (2020-2021) on a 3.4 ha Viognier plot in the Mediterranean region (PGI Oc, France) on sandy clay soil. The annual rainfalls were less than 400 mm. Soil water content probes were installed at different depths (20 – 40 – 60 – 80 cm) and at different lateralities from the vine row (30 – 60 – 90 – 120 cm) to control the formation of the soil wet bulb during irrigation. The mapping and the analysis of the data allowed a better understanding and differentiation of the water percolation when irrigating with subsurface or aerial drip. For the same amount of water and without differences of vine water status, it is shown that in a subsurface drip irrigation situation, the size of the wet bulb formed is larger than in aerial drip irrigation system.

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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.