By Mackenzie Brisbois
Oxygen is complicated. It can help, hinder, destroy, build!
To simplify, let’s look at three main stages and investigate oxygens relationship with winemaking. Then, lets look at how we use oxygen in winemaking at Trail Estate.
Fermentation
Exposing juice to oxygen can either help or hinder, depending on style. Fruity white wines like Sauvignon Blanc are protected against oxygen contact, whereas my Chardonnay is actually hyperoxidized at the juice stage (and it turns this cool orange colour like in the image above!). The Barrel-Ferment Riesling juice is also hyperoxidized, meaning many phenolic compounds are oxidized and the resulting finished wine is longer-lived and more resistant to oxidation.
During fermentation the yeast need a fair amount of oxygen to grow and carry out the conversion of sugar to alcohol. During the initial days of fermentation, we conduct pump-overs and punchdowns to wet the cap and to incorporate oxygen. Towards the end of fermentation, we limit the amount of contact with oxygen as the wine is much more fragile.
Aging Wine
Too much oxygen as a wine ages can cause oxidation – reducing fruity flavours and replacing them with oxidize flavours like bruised apple or sherry. Wines can oxidize easily if we leave them open for days or expose them to too much oxygen when moving wine from vessel to vessel. An addition of sulphur dioxide and the use of inert gases, like Argon, can help protect a wine from oxygen.
Many winemakers use a little bit of oxygen to help their wine smooth out. In barrels the wines are exposed to slow amounts of oxygen. This small amount can help soften the wine over time, but too much and you’ll get a flat, brown drink.
In the Bottle; In the Glass
This topic should really be called bottling, bottle ageing prior to sale and customer storage and consumption! When bottling a wine, I need to consider the techniques and the oxygen contact across all these steps:
• Transporting wine from tank to bottle filler
• The amount of headspace in the bottle filler
• The time I take to bottle
• The amount of headspace I leave in a
For each of those steps, there are considerations in technique, equipment, temperature and logistics! Needless to say, room for improvement each year is easy to find!
Wine ageing must be done at the right temperature and with as little exposure to temperature swings and light. One trial measured storage of the same wine under different closures at different temperatures. The study found that all wines stored at high temperatures showed oxidative characters.
I cannot stress enough, store your wine somewhere cool, without a lot of fluctuations and let it be somewhere dark. Otherwise, DRINK IT!!!
Riesling at Trail Estate
Throughout my career at Trail Estate, I have crafted Riesling in many different styles:
• Dry
• Sweet
• Filtered
• Unfiltered
• Barrel-fermented
• Stainless steel
• Whole cluster
• Skin contact
• Direct press
We’ve harvested from several vineyards across Ontario and have really given it our best shot. My favourite wines have been our 2017 Heaven and Earth Series and our Barrel-Ferment Rieslings from 2016-2018 and 2020 (2019, still being a work-in-progress).
Foxcroft Barrel-Ferment Riesling 2017
Winemaking: Pressed and cold settled without the use of any enzymes. The 2016 Riesling was pulled from barrel and the 2017 was put to barrel to keep the same yeast and malolactic culture alive. Fermentation did not reach dryness until the summer of 2018. Malolactic completed soon after. Aged in oak for 10 months. Multiple rackings of this wine were used to combat reduction (hydrogen sulphide, which we will have to cover in another wine club). Bottled unfined and unfiltered with less than 20 ppm sulphur.
Tasting note: This wine boasts an energetic nose of citronella entwined with fresh peaches and wet rocks. The palate is luscious from extended time on lees and carried through to the finish with lively acidity.
Foxcroft Barrel-Ferment Riesling 2020
Winemaking: Grapes were hand harvested and pressed whole cluster. Settled in tank at 10°C for two days before racking to neutral 500L barrels. Taking about 10 days for the yeast population to build up this wine did not finish ferment until August of 2021. It was racked and put to bottle with minimal sulphur addition. A small amount of ferment completed in bottle giving this wine a spritz. In an ideal world I would have waited to bottle this, but I was worried about oxidation so decided to get it into bottle.
Tasting note: Such a happy, balanced wine. Aromatics of apricot, peach blossom and honey around a solid citrus core. Finishes near-dry with zippy acidity and ... refreshing spritz!
Earth (Hughes Vineyard) Skin-Fermented Riesling 2017
Winemaking: Harvested on October 19th, 2017 from the Hughes Vineyard in Niagara. Fermented naturally on skins for 13 days prior to pressing. As the wine fermented, the skins were punched down daily for gentle extraction. Aged in a neutral oak barrel before bottling using gravity without any filtration or fining.
Tasting note: This wine is lush and rich with hints of marmalade and juicy acidity.
Finally…
Further, to see how oxygen affects the wine as you swirl and drink these wines. What temperature are you conducting your ‘experiments’ at and how is this affecting your drinking?
Riesling 2017
Taste through this wine and note what oxidative flavours you taste. The increased racking gave this wine a LOT of oxygen right before bottling.
Riesling 2020
Pour two glasses of this wine.
glass #1: Taste immediately without swirling. Note flavours and texture of this wine. I find it has an effervescence at first, but over time this dissipates.
glass #2: Swirl aggressively. Note any differences in flavours and texture.
