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…

Phenolic profiles of minor red grape cultivars autochthonous from the Spanish region of La Mancha

The phenolic profiles of little known red grape cultivars, namely Garnacho, Moribel and Tinto Fragoso, which are autochthonous from the Spanish region of La Mancha (ca. 600,000 ha of vineyards) have been studied over the consecutive seasons of years 2013 and 2014. The study was separately performed over the skins, the pulp and the seeds, and comprised the following phenolic types: anthocyanins, flavonols, hydroxycinnamic acid derivatives (HCADs), total proanthocyanidins (PAs) and their structural features. The selected grape cultivars belong to the Vine Germplasm Bank created in this region in order to preserve the great diversity of genotypes grown in La Mancha.

Effect of post-harvest ozone treatments on the skin phenolic composition and extractability of red winegrapes cv Nebbiolo and Barbera

Wine industry is looking forward for innovative, safe and eco-friendly antimicrobial products allowing the reduction of chemical treatments in the grape defense and the winemaking process that can affect negatively the quality of the product. Ozone has been tested in food industry giving good results in preventing fungi and bacteria growth on a wide spectrum of vegetables and fruits, due to its oxidant activity and ability to attack numerous cellular constituents. Ozone leaves no chemical residues on the food surface, decomposing itself rapidly in oxygen. Gaseous ozone has been already tested for table grapes storage and on wine grapes during withering.

Update knowledge about the presence of condensed tannins in grapes and their contributions to astringency perception

Condensed tannin is a principle group of polyphenol compounds derived from grape, greatly contributing to the bioactivity and the sensory perception of wine. Condensed tannins present as a heterogeneous mixture in nature involving various degrees of both polymerization and galloylation. Even though multiple attempts focusing on fractionation of grape condensed tannins by solid-phase have been conducted over the past decades, few individual tannins have been purified and identified. Hence, our knowledge on grape and wine condensed tannin moleculars has to be limited at the several known monomeric, dimeric and trimeric proanthocyanidins

Microbial life in the grapevine: what can we expect from the leaf microbiome?

The above-ground parts of plants, which constitute the phyllosphere, have long been considered devoid of bacteria and fungi, at least in their internal tissues and microbial presence there was long considered a sign of disease. However, recent studies have shown that plants harbour complex bacterial communities, the so-called “microbiome”[1]. We are only beginning to unravel the origin of these bacterial plant inhabitants, their community structure and their roles, which in analogy to the gut microbiome, are likely to be of essential nature. Among their multifaceted metabolic possibilities, bacteria have been recently demonstrated to emit a wide range of volatile organic compounds (VOCs), which can greatly impact the growth and development of both the plant and its disease-causing agents.

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