Macrowine 2021
IVES 9 IVES Conference Series 9 Extraction of pathogenesis-related proteins and phenolics in Sauvignon Blanc as affected by different

Extraction of pathogenesis-related proteins and phenolics in Sauvignon Blanc as affected by different

Abstract

The composition of wine is largely determined by the composition of pre-fermentation juice, which is influenced by extraction of grape components. Different grape harvesting and processing conditions could affect the extraction of grape components into juice. Among these grape components, pathogenesis-related (PR) proteins are of great concern for white wine maker as they are the main cause of haze formation in finished white wine. If not removed before bottling, these PR proteins may progress into haze through the formation of complex with phenolics under certain conditions. Thaumatin-like proteins (TLPs) and chitinases are the main constituents of PR proteins found in protein haze. The aim of this study was to investigate the effects of grape harvesting and processing conditions on extraction of haze-forming PR proteins and phenolics, and the consequent impact on protein stability of wine. Sauvignon Blanc grapes were harvested by hand and by machine in 2011 and 2012 in Marlborough, New Zealand. Hand harvested grapes were processed by two different treatments: whole bunch pressing without skin contact, and pressing after destemming and crushing followed by 3 h skin contact; machine harvested grapes were processed by pressing after destemming and crushing followed by 3 h skin contact. For each treatment, the juice pressing procedure was carried out by gradually increasing the pressing pressure to three different levels (0.4 MPa, 0.8 MPa and 1.6 MPa), and juice samples were collected at each pressure point and bottle-fermented separately. Results of this study showed that pressing after destemming and crushing followed by 3 h skin contact can result in greater extraction of proteins and phenolics from grapes into juice compared with whole bunch pressing. Juice and wine obtained from machine harvested grapes showed a tendency of having lower concentration of proteins, as well as, PR proteins. Juice and wine obtained from higher pressing pressure showed the highest concentration of phenolics but the lowest concentration of proteins, suggesting that proteins in grapes are easily extracted at low pressing pressure, but greater extraction of phenolics in grapes requires higher pressing pressure. Analysis of wine protein stability showed a linear correlation between bentonite requirement and the concentration of chitinases in wine, indicating the importance of removal of chitinases to achieve protein stabilization. The findings presented here contribute to an improved understanding of the variable concentration of haze-forming PR proteins in juice as affected by grape harvesting and processing conditions, and hence the variation in bentonite requirement for resultant wine.

Publication date: May 17, 2024

Issue: Macrowine 2016

Type: Article

Authors

Bin Tian*, Claire Grose, James Morton, Marlene Jaspers, Mike Trought, Roland Harrison

*Lincoln University

Contact the author

Tags

IVES Conference Series | Macrowine | Macrowine 2016

Citation

Related articles…

Dissecting the polysaccharide‐rich grape cell wall matrix during the red winemaking process, using high‐throughput and fractionation methods

Limited information is available on grape wall-derived polymeric structure/composition and how this changes during fermentation. Commercial winemaking operations use enzymes that target the polysaccharide-rich polymers of the cell walls of grape tissues to clarify musts and extract pigments during the fermentations. In this study we have assessed changes in polysaccharide composition/ turnover throughout the winemaking process by applying recently developed cell wall profiling approaches to both wine and pomace polysaccharides. The methods included gas chromatography for monosaccharide composition (GC-MS), infra-red (IR) spectroscopy and comprehensive microarray polymer profiling
(CoMPP) using cell wall probes.

Impact of industrial-scale serial filtration on macromolecules in red wines

Filtration is a critical step in ensuring the clarity and microbial stability of wine prior to bottling. However the process of filtering potentially reduces red wine quality by removing some of the macromolecules that contribute to the texture of the wine. Commercial red wines, Cabernet Sauvignon (CAS) and Shiraz (SHZ), of two vintages and two grades (premium grade wines from the older vintage: CAS13 and SHZ13; and standard grade wines from a younger vintage: CAS14 and SHZ14) were filtered through industrial-scale commercial filtration units prior to bottling. Samples were taken before and after cross-flow filtration, lenticular filters, 0.65 µm and 0.45 µm pore size nylon membrane filters. The concentration and composition of macromolecules, including tannins and polysaccharides, were measured in all samples as well as particle size distribution and wine colour.

Moscatel vine-shoot extracts as grapevine biostimulant to increase the varietal aroma of Airén wines

There is a growing interest in the exploitation of vine-shoots waste, since they are often left or burned. Sánchez-Gómez et al. [1] have shown that vines-shoots aqueous extracts have significant contents of bioactive compounds, among which several polyphenols and volatiles are highlighted. Recent studied had demonstrated that the chemical composition of vine-shoots is enhanced when vine-shoots are toasted
[2,3]. The application of vegetable products in the vineyards has led to significant changes towards a more “Sustainable Viticulture”. An innovative foliar application for Airén vine-shoot extracts have been carried out to the vineyard. It has been shown that they act as grape biostimulants, improving certain wine quality characteristics [4].

Glutathione content evolution during spontaneous alcoholic fermentations of Sangiovese grapes

Glutathione is a tripeptide (γ-Glu-Cys-Gly), which can occur in grapes, in must and in wine prevalently in the reduced form as well as in the oxidized form as glutathione disulfide. The importance of the reduced form of glutathione lies in its antioxidant activity. In must, it limits browning by reducing o-quinones produced by polyphenol oxidase activity on hydroxycinnamic acids; in wine, it exerts a protective effect on various aromatic compounds. Glutathione concentration in wine is lower than in grape juice and variable as it depends on several factors, ranging from the native content of grapes to winemaking technique.

The influence of soil management practices on functional traits and biodiversity of weed communities in Swiss vineyards

Green cover in vine rows provides many ecological services, but can also negatively impact the crop, depending on the weed species. The composition of a vineyard weed community is influenced by many parameters. Ensuring an evolution of the vine row flora into a desired direction is therefore very complex. A key step towards this goal is to know which factors influence the establishment of the weed community and which types of communities are best suited for vineyards. In this study, we analysed the weed communities of several vineyards in the Lake Geneva region (379 botanical surveys on 117 plots), with the aim to highlight the links between soil management practices (chemical and mechanical weeding, mowing, mulching roll) and phytosociological profiles, biodiversity and selected functional traits (growth forms, life strategies, root depth). T