Harvesting and fruit intake

Smoke has been reported in my source vineyard – now what?

The good news is that even if you can smell or see smoke in your source vineyard, it doesn’t mean that your grapes have been affected. 

The extent of smoke compounds picked up by your grapes will depend on a few factors, the most important being:

• Stage of fruit development
  
  

• Intensity of the fire – smoke compounds from a large amount of freshly burnt vegetation is most likely to cause smoke taint in the final wine. The longer the smoke lingers, the greater the possible impact.
• Proximity to fire and weather conditions – vineyards close to the fire are more likely to be impacted. Conditions like wind direction also affect how much smoke the grapes are exposed to.
• Grape variety - some varieties appear to more readily take up smoke than others. For example, thicker-skinned grapes, like Chardonnay and Shiraz, are less susceptible to damage while Pinot Noir’s delicate skins do little to protect the fruit. You can’t assume that a poor result from testing from one variety in your vineyard will apply to all. To further complicate matters, grapes naturally contain low levels of smoke compounds and these levels vary from one variety to another.

How bad is the damage - grape testing options before vintage

Before you can make any decisions about what to do with your source fruit at harvest, at intake and during processing, you need to know if, and how badly, the grapes have been affected.

Currently, your only option is laboratory testing of samples taken 2-3 weeks before your scheduled harvest date.

Grapes and juice can be tested for the level of smoke compounds and you can also test for smoke ‘taint’ in finished wine. Laboratories can test grapes or juice and provide advice on the likely effect on wine made from it. Or alternatively, the laboratory (or you) can make a small ‘bucket’ batch of wine from the affected grapes to assess the damage in the final product. They can do this using scientific analysis and/or tasting.

If and how the grapes can still be processed into something saleable, will depend on the level of smoke taint, the grape variety and any magic the winemaker can work back at the winery.

Taking and preparing pre-vintage grape samples for testing

If you decide to get your source fruit tested, the way you (or your vineyard team) collect and transport the grape samples may vary, depending on the phylloxera classification of your source vineyard, as well as the laboratory you choose.

However, to give you a general idea of what to expect if this is your first smoke analysis request, here are some generic guidelines:

• Test no more than 2-3 weeks before your planned harvest date.
• Plan your sampling date around opening times for collection points or laboratories and courier services to ensure freshness.
• Take grape samples early in the morning, before it gets hot and vines are stressed.
• Take approx. 30 random bunches from across the whole vineyard. No more than one bunch per vine.
• Keep different grape varieties separate.
• Keep samples cool.
• Consider keeping different blocks and vineyards separate.

After collecting all your samples:

• Pull about half of the grapes off each bunch and mix them thoroughly in a large container.
• Take about 500g of grapes from the mix and double-bag them into 2 labelled zip-lock bags.
• Put in the freezer for at least 24 hours before packing on cold packs and sending to the laboratory.
• The labels on both bags should include the grower’s name and address, variety and block details.

Where do I get my grapes tested?

There is currently only ONE commercial laboratory that offers smoke compound and taint testing.

Fortunately, there are multiple drop-off points across the regions.

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How to make a bucket ferment from unharvested vineyard samples

If you believe your source grapes may have been affected by smoke, one option is to make a bucket ferment from a sample of the potentially affected grapes, followed by sensory and/or analytical assessment. If you can ‘taste’ smoke taint in your small batch of wine, its highly likely that your intended consumers will as well.

This bucket ferment will take about a week, so the sooner you get onto it the better – ideally, 2-3 weeks before your scheduled harvest date. Having your data will allow you to make informed decisions about which grapes you’ll accept and how you’ll manage them back at the winery.

Step by step instructions (PDF)

The most cost-effective option is to conduct a sensory evaluation of bucket ferments in house, using your own ‘consumer style’ industry panel. Alternatively, commercial laboratories offer sensory panel testing and/or analytical testing of your ferment for smoke compounds.

Whilst sensory evaluation of bucket ferments may provide an indication of the degree of smoke taint, the only objective testing option is still analytical analysis.

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Harvesting options to minimise smoke transfer to grape juice

If you have decided to keep the smoke-affected fruit for processing, there are some harvesting techniques you can use which may reduce the transfer of smoke ‘taint’ producing compounds to the grape juice. Whilst these suggestions work best when applied in combination, it is unlikely that anything you change during harvesting or in the winery will totally eliminate smoke taint in badly affected grapes.

Adding new techniques or technology to your usual routines may also add additional costs: you’ll need to estimate these and weigh them up against any benefits you hope to achieve by including them.

• Exclude leaves and stalks – Anything you can do to keep Material Other than Grape (MOG), which will also be coated in smoke, away from the grapes and juice, the better.
• Consider how and when to harvest your fruit
  • Machine harvest quickly - 
    • It is now thought that you may typically have a 48-hour ‘window’ before the vine starts attaching sugars to volatile smoke molecules. Consequently, if your vines are ripe enough to harvest when the smoke hits, taking them off the vine quickly by machine may be more useful in reducing smoke taint.
  • Hand-picking - reduces grape splitting and juice contact with smoke particles on skins and MOG.
• Keep your fruit cool during harvest – to slow down smoke-related reactions.

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Skin contact choices

Skin to juice contact increases the chance of smoke flavour in the resulting wine. Smoke compounds tend to accumulate in grape skins and are extracted during periods of skin contact. Consider using the management options below to reduce the transfer of smoke molecules to the juice and must.

• Minimise time between harvesting and pressing.
• Minimise or (preferably) eliminate skin contact time between crushing and pressing.
• Keep fruit cool (AWRI found fruit processed at 10⁰C transferred less smoke related molecules than at 25⁰C)
• Whole bunch press and void fruit maceration as much as possible.
• Separate free juice and press fractions from each other (to assess smoke flavour later). AWRI found there is less extraction of smoke-related phenols in the first 400L/t fractions.
• Use white processing protocols, even for red varieties.
• Opt for a lighter press and/or making a rosé style that requires less skin contact.

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Take care of yourself

Dealing with smoke damaged fruit can be challenging.

A calmer, clearer head will help you see a way forward. Talk to your friends and colleagues, and if you’re not sure where to turn next please reach out for professional support.

• Lifeline 13 11 14
• Beyond Blue 1300 224 636
• SANE Australia 1800 187 263