Has a wine ever smelled or tasted fishy to you?  And by fishy, I don’t mean causing doubt or suspicion.  Rather, I’m talking about the distinct and rather unpleasant odour of fish in your glass of wine.  Believe it or not, the story of fishiness in wine goes back to the 16th century at least and has its origins from areas near the Caspian and Black Seas.  Before we uncover the possible causes of fishiness in wine, perhaps a more pressing question is:  Should fish smell fishy?

It turns out that the fishy smell occurs as the flesh of the fish is broken down by bacteria after it dies, even if the fish has been well refrigerated since it was caught.  Of course, a slight fishy smell may be ok and may be completely disappear after cooking.  However, if the fish is truly stinky, it is best avoided.  Trust your senses, but if there is any doubt, throw it out!  So how does fishiness get into wine?

For the answer, we turn to the most famous of all the fish used for harvesting roe or fish eggs, the salt-cured version of which we know as caviar.  The Sturgeon fish, native to waters of the Caspian and Black seas, has long been held as the ultimate source for caviar.  Many a glass of fine Champagne has been guzzled along with this particular fruit of the sea, in what many consider to be a truly classic food and wine pairing.  But it is to the swimbladder of the sturgeon that we now turn our attention.

As I write these words, my mind is thrown back to my childhood, where my dad would often spend hours in his shed, the ultimate man-cave of the 80’s, melting down lead from scrap metal and pouring this silver sludge into small square forms.  He was in fact making home-made lead weights for his diving belt.  As an avid snorkeller and diver, he needed to overcome the natural tendency for his body to float, especially when wearing a wet suit and holding a breath of air.  These weights helped him to adjust his buoyancy so that he can dive down to explore the coral reefs and shipwrecks along the South Australian coast.  Fish have a special organ that helps them to do the exact same thing, and it is known as the swimbladder.  While dad was using lead to adjust his bouyancy, fish use a neat type of protein, that we probably all have consumed at some point or another.

This protein is a form of collagen and has been used for centuries in clarifying, or helping to make clear, wine and beer.  By the way, I would love to know how someone first discovered this.  The mind does boggle, so if you happen to know the answer, please do leave a comment under this blog post.  These days, isinglass is also sourced from the much cheaper Cod fish and in terms of wine, it often gets used to “bring out or unmask fruit character without large changes in phenolic levels responsible for wine astringency (the drying, mouth-puckering sensation you get from red wines) and body”, according to the Australian Wine Research Institute (AWRI).  “Excess isinglass can impart a fish odour to the wine” according to the AWRI, especially when a specific form of the fining agent is used which needs to be rinsed to remove fish odours before being added to the wine.

This accounts for the label warning seen in many countries:  “May contain trace amounts of fish” on the label.  As a known allergen, such a warning is absolutely necessary as the symptoms produced in those allergic to fish can range from a rash to anaphylaxis – a life threatening condition that impairs breathing and can send people into shock.  It should be noted that having a fish allergy does not automatically mean you are also allergic to shellfish such as lobster, oysters or crab.

It can be frightening to think that the small residue left over after a gentle clarification step could lead to the untimely death of some poor, unfortunate wine consumer.  Thankfully another wine label term  comes to the rescue.  It is:  “unfined” although it often appears as:  “unfined and unfiltered”.  This label clue indicates that the producer is perhaps more of the artisanal type of wine producer. This lack of processing is seen by many as a higher benchmark of quality as it puts the responsibility squarely on the wine producer to make an acceptably clear wine without the use of additives or machines.  This is often achieved through numerous rackings, where clear wine is separated from the natural sediment that forms during the winemaking process. The upside should be a wine with less of the aromas, flavours and body removed by the fining and filtering processes.  Certainly its a term looking out for, not only for those with food sensitivities or allergies but also for vegetarians and vegans who are looking to actively exclude animal-based or animal products from their diets.

It should be noted though that fine and sterile filtration are often seen as necessary steps in removing all the possible micro-organisms in wine, especially in the making of sweet wines, where the residual sugar in the wine might easily be consumed by any viable microbes, causing a re-fermentation inside the bottle and leading to a general recall of the product.

Still, not all fishiness in wine necessarily comes from fish-based fining agents such as isinglass. Many wine consumers report noticing a fishy smell in their wine glasses when they have not been thoroughly rinsed after washing.  It seems that either detergent, or perhaps more likely, dirty dishwater, residue may also be causing some of the fishiness in your glass, so rinsing them with water, or wine if you are feeling extravagant will often remove this problem.  It also is a good reminder to smell your dry, empty glass before using it at home.

So the next time your wine tastes fishy, check the empty glassware first, then if the wine still tastes fishy, don’t hesitate to take it back for a full refund or reject it outright at a restaurant!

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