GiESCO 2019 banner
IVES 9 IVES Conference Series 9 GiESCO 9 The impacts of frozen material-other-than-grapes (MOG) on aroma compounds of red wine varieties

The impacts of frozen material-other-than-grapes (MOG) on aroma compounds of red wine varieties

Abstract

Context and purpose of the study – An undesirable note called “floral taint” has been observed in red wines by winemakers in the Niagara region caused by large volumes of frozen leaves and petioles [materials-other-than-grapes (MOG)] introduced during mechanical harvest and subsequent winemaking late in the season. The volatiles, which we hypothesized are responsible, are primarily terpenes, norisoprenoids, and specific esters in frozen leaves and petioles. The purpose of this study was to investigate the volatile compounds which may cause the floral taint problem and explore how much of them (thresholds) may lead to the problem. Also, the glycosidic precursors of some of these compounds were analyzed to see the changes happening during frost events.
Materials and methods – Research winemaking was conducted in 2016, 2017 and 2018. All fermentations were based on 40-kg replicated ferments of Cabernet Franc (CF) and Cabernet Sauvignon (CS). MOG Treatments were (by weight): 0, 0.5%, 1%, 2% and 5% petioles, and 0, 0.25%, 0.5%, 1%, and 2% leaf blades. In 2017 and 2018, different yeast strains and harvest strategies were also included in the CF treatments. Yeast treatments included CSM, EC1118 and FX10. Harvest strategies involved conventional machine harvesting (MH), Braud-New Holland Opti MH, Gregoire 8 MH, MH + optical sorting, and MH with pre-harvest leaf removal. Concentrations of key odor-active compounds were quantified by gas chromatography-mass spectrometry with stir bar sorptive extraction.
Results – Several compounds including cis- and trans-rose oxides, β-ionone, citronellol, linalool, eugenol, methyl and ethyl salicylate were higher in MOG treatments for both CF and CS and their concentrations increased linearly with the accumulative levels of petioles or leaves. Principal components analysis showed petiole and leaf treatments were separated apart from the control sample with the 5% petioles and 2% leaves as the extremes. Petiole and leaf treatments were spread out on different axes, which indicated their large differences in volatile compositions. Interestingly, eugenol and rose oxides and many other compounds followed linear curves with the addition of petioles and leaves in the 2016 vintage, which could be potentially used as a tool to communicate with winemakers on potential floral taint risk based on their sensory thresholds. Preliminary results from 2017 showed that more terpene compounds were found in the standard MH treatment than the hand-harvested control, and the yeast EC1118 produced the least terpenes out of three different yeasts among all leaf and petiole addition treatments in most cases, while yeast strain FX10 produced the highest terpene concentrations. In general, petiole additions contributed more to the floral taint problem than leaf additions. Specifically, petioles contributed terpenes and salicylates (floral notes) to the wines, and leaves contributed norisoprenoids and C6 alcohols (green notes).

DOI:

Publication date: March 12, 2024

Issue: GiESCO 2019

Type: Poster

Authors

Jiaming WANG1, Emilie AUBIE2, Yi-Bin LAN1, Marnie CROMBLEHOLME1, Andrew REYNOLDS1*

1 Cool Climate Oenology & Viticulture Institute, Brock University, St. Catharines, ON, L2S 3A1, Canada. 2Andrew Peller Winery, 697 S Service Rd, Grimsby, ON L3M 4E8, Canada

Contact the author

Keywords

MOG, floral taint, yeasts, harvest strategies, leaves, petioles, GC-MS, terpenes

Tags

GiESCO | GiESCO 2019 | IVES Conference Series

Citation

Related articles…

Understanding the complexity of grapevine winter physiology in the face of changing climate

The vast majority of our understanding of grapevine physiology is focused on the processes that occur during the growing season. Though not obvious, winter physiological changes are dynamic and complex, and have great influence on the survival and phenology of grapevines. In cool and cold climates, winter temperatures are a constant threat to vine survival. Additionally, as climate changes, grapevine production is moving toward more traditionally cool and cold climates, either latitudinal or altitudinal in location. Our research focuses on understanding how grapevines navigate winter physiological changes and how temperature impacts aspects of cold hardiness and dormancy. Through these studies, we have gained keen insight into the connections between winter temperature, maximum cold haridness, and budbreak phenology, that can be used to develop prediction models for viticulture in a changing climate.

The use of pulsed fluorescence detector to quantify free SO2 in wines via the headspace

Pulsed fluorescence SO2 analyzers are widely used for atmospheric monitoring. They are accurate, portable, sensitive and their price are reduced compared to advanced techniques like gas chromatography with sulfur chemiluminescence detection (GC-SCD).

An online training tool for wine professionals around the world: from responsible service to a sustainable consumption of wine

Most consumers enjoy wine in moderation, however, there remains a minority that may develop risky drinking habits, potentially harming themselves and those around them. For the last fifteen years, a prime objective of the wine in moderation programme has been to educate and empower the wine sector and now for the first time, a central education tool has been developed, integrating the topic of moderate consumption horizontally in all wine activities. The entire wine value chain – from the producer to the salesperson to the restaurant service staff – can contribute to reduce harmful consumption and encourage responsible drinking patterns.

Mannoproteins from oenological by-products as tartaric stabilization and color agents in white and red wines

Climate change is drastically modifying grape composition and wine quality. As consequence, must and wines are becoming unbalanced, with high sugar concentration, increased alcohol content, lower acidity, excessive astringency, color instability and also a rise in the incidence of tartaric instability is being showed.

Effect of interspecific yeast hybrids for secondary in-bottle alcoholic fermentation of english sparkling wines

In sparkling winemaking several yeasts can be used to perform the primary alcoholic fermentation that leads to the elaboration of the base wine. However, only a few Saccharomyces cerevisiae yeast strains are regularly used for the secondary in-bottle alcoholic fermentation 1. Recently, advances in yeast development programs have resulted in new breeds of interspecific wine yeast hybrids that ferment efficiently while producing novel flavours and aromas 2. In this work, sparkling wines produced using interspecific yeast hybrids for the secondary in-bottle alcoholic fermentation have been chemically and sensorially characterized.METHODS: Three commercial English base wines have been prepared for secondary in-bottle alcoholic fermentation with different yeast strains, including two commercial and several novel interspecific hybrids derived from Saccharomyces species not traditionally used in sparkling winemaking. After 12 months of lees ageing, the 14 wines produced were analysed for their chemical and macromolecular composition 3,4, phenolic profile 5, foaming and viscosity properties [6]. The analytical data were supplemented with a sensory analysis.