Fire and smoke assessment

In Australia, the threat of fire is a reality faced by many regional communities.

In our wine regions, fires present danger to vineyards, wineries, plant and equipment. Smoke from fires also brings with it a risk that fruit may be affected by the free volatile phenols that are produced when wood is burnt.

Fire damage

Following a fire event, the impact within the vineyard can present itself in different ways. Some damage is obvious, such as dehydrated leaves and burnt bark, while some are more difficult to identify, such that from radiant heat.

Grapevines are very tough, and most will push new shoots from even seriously burned stumps.

Depending on the extent of the fire damage, vines may be able to be rehabilitated or they may need to be replaced. The resources at the Australian Wine Research Institute, available via links on this page will help you to assess damage.  

Rehabilitation can include training new growth up into a new vine, which in most cases will lead to a full crop in two to three years. If a vineyard needs to be completely replanted, it can take four to five years to achieve a full crop.

Recovery of vineyards after fire – a case study

Our case study on fire recovery discusses the actions that Greg Horner of Mount Bera Vineyards took following the Sampson Flat bushfire in 2015. Please note that this is one way to approach the vineyard rehabilitation process.

Download case study

Listen to our podcast below with Greg Horner

Assessing and managing fire damaged grapevines

The Australian Wine Research Institute (AWRI) held a webinar in January 2020, that outlined the immediate responses to be taken to maximise vine recovery after a vineyard fire event. A PDF case study is also available on the AWRI website here

The AWRI also has a number of resources on its website

 

Smoke exposed fruit

With fire comes smoke. However, research has shown that just because smoke may be visible or be able to be smelt doesn’t necessarily mean that there is a high risk of smoke affecting the grapes.

Smoke exposure has the highest chance of affecting the grapes from about a week after veraison through to harvest.

If grapes have tested positive to smoke effects, its impact can be reduced by minimising extraction from skins by hand harvesting, keeping fruit cool and whole bunch pressing, or using oak to add complexity and mask some of the smokiness. 

If the wine is showing high levels of the volatile smoke phenols, we refer to this as smoke tainted wines. The volatile phenols can leave flavours in the wine including smoked meat, disinfectant, leather, char, salami or even an ashtray.

These compounds come from smoke and they are absorbed directly by grapes exposed to smoke. Some of these compounds get converted by the grapevine into glycosylated precursors but can convert back, they act as a pool of compounds waiting to be released. The conversion back occurs in wine, which means that smokiness gets worse with time. Smokiness can be enhanced in the mouth of the wine drinker due to release of the volatile phenols from the glycosylated precursor by resident microbial population.

Grape samples can be sent to designated laboratories for chemical analysis and identification of any volatile compounds and glycosylated precursors. This coupled with a small-lot fermentation a few weeks before harvest allows for a comprehensive assessment of the likelihood of wines being affected by smoke.

See the resource links on the right hand side of this page for details on how to assess grapes and wine for smoke taint.

For further information about fire damage or smoke affects, please contact the AWRI helpdesk on (08) 8313 6600 or helpdesk@awri.com.au.

Australian laboratory services for smoke assessment 

Australian Wine Research Institute Commercial Services

Vintessential Laboratories

 


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