Posts Tagged ‘yeast lees’

Breathe Magazine requested for me to rewrite my original “Something Fishy” article for their Hunter Valley Wine Show edition.

Something fishy… What’s the Story of Fish in Wine?

I often get asked why there are warnings on wine labels pertaining to fish, milk and egg products. Aren’t the basic ingredients of wine just grapes and yeast? Sometimes we need a little help to optimise our basic ingredients.

In the Fermentation process, yeast converts the grape sugars (glucose and fructose) into alcohol (and carbon dioxide). Yeast can be found naturally on the skins of the grapes, or it can be introduced. The type of yeast can also affect the flavour, aroma, texture and body of the final wine.

The winemaker may also choose to put the wine through secondary fermentation. Malolactic Fermentation (or Malo for short – pronounced “May-Low”) would usually occur after the primary ferment. During Malo, Lactic Acid Bacteria get busy converting Malic acid from the grapes into Lactic acid in the wine. Lactic acid is not as sharp and acidic to taste, resulting in a wine that has a smoother mouth feel. Malo can result in a buttery, creamy Chardonnay, but if not done skilfully can end up causing faults in the wine.

It is a sad ending for the yeast as after primary ferment, it dies. Unfortunately, the yeast is a casualty of our consumption. Making matters worse, all the residual and dead yeast cells or “lees” are now floating around in our wine. There may also be natural proteins, bacteria and other particles suspended in the wine. I don’t like “floaties” in my Shiraz or Chardonnay. What is the solution to this problem?

Winemakers use a fining agent to flocculate at various stages during wine production, ensuring your Hunter Valley Semillon is crystal clear. Clarity, brightness and transparency are important for both the wine judge, and us wine drinkers.

Flocculation: [verb] forced removal of sediment from a liquid through addition of a flocculating agent. Gravity controlled flocculation precipitates solids within a liquid.

Now for the science lesson: as the diagram suggests, the fining agent is added to the top of the tank, weighs down on the dead yeast cells (and other “floaties”) and drags everything to the bottom of the tank where it can be siphoned off.

Fining agents can improve haze, phenolics, astringency, colour, flavour and even off-odour in wine. Therefore, fining is a process which results in a wine created with finesse, which may also have attractive qualities not present in unfined wine.

Stabilisation can be used to prevent wine faults caused by environmental changes to temperature, humidity and movement. Unstable wines can be subject to haze, tartrates and premature ageing. For example, Cold stabilisation encourages liquid tartaric acid to solidify. “Wine Diamonds” (tartrate crystals) form when the wine is very cold. They develop in small crystals or long shards and can be removed prior to bottling. Sometimes these form in the finished bottle – they may look like glass but are completely harmless.

So where does fish come into this? Not to worry – winemakers are certainly not throwing seafood medley into the tank!

Below are some common fining agents:

Isinglass (pronounced eye-sin-glass) is a gelatin derived from the air bladder of a fish – especially and traditionally the sturgeon. Isinglass is expensive, delicate, will not strip flavour and often used with white wines.

Gelatin has been used to fine wine since Roman civilisation. It can remove harsh tannins, bitter flavours, and improve astringency.

Casein. Casein is an active protein in skim milk or powdered skim milk. It can be used to nullify astringency and bitterness in white wines, sometimes lightening the colour.

PVPP or polyvinyl-polypyrrolidone is a synthetic polymer chain that behaves like a natural protein.

Albumin is the fining agent relating to eggs. Only the whites are used (sometimes powdered) – so never sunny side up! This is usually reserved for red wines and believe it or not it’s only 1-2 egg whites for 100 Litres of wine.

There are natural proteins present in grapes that may cause a cloudy haze if the wine is subject to higher temperatures. Bentonite is a naturally occurring clay or mineral derivative that stabilises the wine, preventing cloudy protein haze in the wine.

Did you know? Bulls blood was commonly used as a fining agent in many European countries including France, until 1997 when the EU banned this practice as a measure to curb Mad Cow’s Disease.

If I’m allergic to seafood do I have to avoid wine?

No. Not even with wines fined with Isinglass. The protein in fish which commonly causes allergic reactions is called parvalbumin. It’s not normally found in isinglass.

Modern manufacture of isinglass ensures no residual parvalbumin remains. The European Food Safety Commission led the way and granted isinglass exemption from allergen labelling laws. In 2009, Food Standards Australia New Zealand (FSANZ) also granted food labelling exemption for isinglass in beer and wine. Even if trace parvalbumin snuck into the wine with the isinglass, it would settle with the isinglass when flocculated and be removed in the filtration process.

This doesn’t sound kosher!

Well technically, isinglass that is derived from a sturgeon isn’t. However isinglass from a kosher fish is. Other un-kosher fining agents include gelatin, casein.

I’m a vegetarian /vegan?

A lot of wines on the market are still unfined or use vegetarian-friendly fining agents. Synthetic fining agents are increasingly popular, and Bentonite is one of the most common fining agents. It is important to consider that some wines and many beers may not be suitable.

Vegans can look for wines that boast “unfined” or “unfiltered” or Bentontite/clay. Some wineries are cleverly labelling for vegetarian and vegan consumption determined by their winemaking processes. Just because some wines are labelled as vegetarian-friendly doesn’t mean that the wines that don’t specify aren’t already suitable for vegetarians or vegans. Continue enjoying Hunter Valley wines and if you are concerned – read the label and ask the friendly folks at the winery.

Testing has shown that there is limited capacity for wines to absorb fining agents and when they have been detected, only in negligent proportions. Fining is considered more natural and delicate a process than filtration which can rapidly strip a wine of colour and flavour. It’s also an important part of traditional winemaking practice that Australian winemakers have inherited from our old world wine countries.

So now you know more about the processes behind some of our proud award winning wines– celebrate quality Hunter Valley wines and appreciate the complexity of the science and skill it took to produce them.

Cheers to that!


This article was published in Breathe Magazine – Issue 30, Spring 2011  “Hunter Valley Wine Show edition” – see link.

Read Full Post »

Lighter in colour and style than I expected. A refined wine with a modest structure, but good varietal character. Energetic and lively when first poured, the colour is brick red with a chestnut hue. The label mentions “time spent on yeast lees” – but the size of the bubbles tells me they are not likely talking about bottle fermentation. All the same it is a gracious example of a Sparkling Red, and I have no qualms about Charmat sparkling wines. 

Rich in flavour, leather, smokiness and blackberries with a sweet oven roasted  red capsicum and cinnamon spice. Sweeter breadth of fruits add a real plumminess sweep over the palate, enhanced by the tantalising bubbles. The firmness of the slight tannins compose the mouth feel and it finishes balanced and dry. A good structured wine but not overly intense, and a nice wine to compliment poultry such as turkey or duck. I served it with Roast portuguese styled chicken and baked winter veg, and this highlighted the intense fruit in the wine.

A good light hearted take on a Sparkling Red and a great example of why we should all break the old world wine rules.

13% al/vol, Cork seal, Ashamedly, I have no idea how this came to be in my collection. On http://www.oliomio.com.au/Stormy_Ridge_Wine.html it is listed as $29 per bottle.

Read Full Post »


Get every new post delivered to your Inbox.

Join 700 other followers