Identifying Wine Faults
Summary:
What do “volatile acidity” and “reduction” smell like? What is the difference between a taint and an off-flavour? Find out at this webinar with sensory scientist Sietze Wijma.
Hundreds of different flavour and aroma compounds have been identified in wine. These can be traced back to different grape varieties, winemaking techniques and microorganisms. However, sometimes things don’t go according to plan. The unintentional appearance of wild yeast and bacteria can result in undesirable flavours. Taints can come from various external sources in the vineyard and the winery.
During this webinar, you will learn the flavour characteristics of 10 compounds that are related to wine faults. Examples of these compounds are TCA, acetaldehyde and guaiacol. Join Justin Martindale MW and Sietze Wijma as they taste through wine samples that have these compounds added. We will discuss the origins of the fault and what preventive and corrective measures are available.
N.B This webinar will be slightly longer than our standard format, and is expected to last around 90 mins.
About the Speaker:
Sietze is a wine and beer enthusiast, based in the Netherlands. With his company The Art of Tasting he shares his knowledge about flavour chemistry and helps people become better tasters, through unique masterclasses and tasting kits. He has previously worked in England for a producer of flavour compounds. Sietze has a MSc in Sensory Science, is a student for the WSET Diploma and is an Advanced Cicerone®️.
@artoftasting
Timestamps:
Introduction to the Webinar (00:00)
Host welcomes the audience and introduces the guest speaker, Sietze Wijma, and the session's focus on wine faults.
Overview of Wine Faults (00:01)
Sietze Wijma explains the two components of the session: identifying faults and understanding their origins.
Defining Wine Faults (00:02)
Discussion on what constitutes a wine fault and its dependence on wine style and concentration.
First Sample: Cork Taint (00:03)
Participants smell a reference wine to identify the characteristic of cork taint, described as wet cardboard.
Origins of Cork Taint (00:05)
Exploration of how TCA forms from molds on corks and the impact of environmental contaminants.
Detection Thresholds of TCA (00:09)
Explanation of the minuscule quantities of TCA that can spoil wine and the human sensitivity to it.
Comparing Human and Machine Detection (00:11)
Discussion on the challenges of detecting TCA using machines versus human sensory perception.
Second Sample: Bruised Apple (00:12)
Participants explore the smell of bruised apple, linked to acetaldehyde, and its fermentation implications.
Understanding Acetaldehyde (00:14)
Sietze Wijma explains acetaldehyde's role in fermentation and oxidation, highlighting its detection in wines.
Third Sample: Brown Sugar (00:16)
Introduction of the brown sugar flavor, associated with oxidation and its detection in various wine styles.
Historical Context of Oxidation (00:20)
Discussion on premature oxidation in white Burgundy and factors contributing to this phenomenon.
Introduction to Wine Faults (00:22)
Discussion on the context of wine faults and the impact of inappropriate flavors.
Blending Wines (00:23)
Instructions on blending wines to identify oxidation components.
Taints vs. Off Flavors (00:24)
Distinction between taints from external sources and off flavors present in all wines.
Specific Anosmia (00:25)
Explanation of genetic differences in aroma sensitivity among wine tasters.
Yeast Stress and Reduction (00:26)
How stressed yeast leads to reductive wine faults and associated flavors.
Nitrogen and Sulfur Compounds (00:28)
Impact of nitrogen deficiency on yeast and the production of sulfur-related aromas.
Oxygen's Role in Reduction (00:29)
Discussion on how oxygen affects reductive problems in wine.
Decanting Wine Faults (00:31)
Unique ability to correct certain faults through decanting.
Cooking with Corked Wine (00:32)
Using corked wine in cooking and its flavor masking effects.
Smoke Taint Introduction (00:33)
Overview of smoke taint and its origins from wildfires.
Handling Smoke-Tainted Grapes (00:37)
Techniques winemakers use to manage smoke taint in grapes.
Phenolic Compounds Overview (00:41)
Introduction to volatile phenols and their role in aroma.
Brettanomyces and Its Impact (00:43)
Description of brettanomyces and its characteristic aromas.
Brettanomyces Flavors (00:47)
Discussion on the various compounds produced by Brettanomyces and their differing impacts on wine.
Preventing Brettanomyces (00:48)
Insights on managing Brettanomyces through yeast selection and sugar levels in winemaking.
Identifying Volatile Acidity (00:51)
Introduction to acetic acid and its association with volatile acidity in wine.
Sensory Properties of Acetic Acid (00:53)
Exploration of the trigeminal nerve's role in detecting the stinging sensation of acetic acid.
Ethyl Acetate and Its Aroma (00:57)
Description of ethyl acetate's fruity and glue-like aromas, produced alongside acetic acid.
Ladybird Beetle Fault (00:59)
Discussion on how ladybird beetles can impart potato skin flavors in wine.
Mousy Flavor in Wine (01:03)
Explanation of the mousy flavor caused by lactic acid bacteria, detectable on the palate.
Natural Wines and Mousy Flavor (01:07)
Connection between natural wines and the increased occurrence of mousy flavor faults.
Sulfur Dioxide Sensory Threshold (01:09)
Information on the sensory detection threshold for sulfur dioxide in wine.
Introduction to Sulfur Dioxide (01:10)
Discussion on the effects of sulfur dioxide when opening wine and its potential to dissipate.
Volcanic Soil and Wine Aroma (01:10)
Exploration of how volcanic sulfur soil can impart onion-like and smoky aromas in wines.
Terroir vs. Winemaking (01:11)
Debate on whether flavors in wine are due to terroir or winemaking practices.
Methoxy Resins in Wine (01:13)
Explanation of methoxy resins and their association with specific wine varieties like Cabernet Sauvignon.
Unusual Wine Aromas (01:14)
Inquiry into a scent resembling canned peaches and the speakers' unfamiliarity with it.
Grape Varieties and Faults (01:15)
Discussion on how certain grape varieties are more prone to specific faults and flavor characteristics.
Species vs. Varieties in Wine Faults (01:15)
Clarification on how different grape species and varieties relate to faults in wine production.
Conclusion and Wrap-Up (01:17)
Final thoughts on the session, expressing gratitude and interest in future discussions on wine chemistry.
