A Fishy Tale – Isinglass Finings in Brewing

Isinglass FiningsIsinglass finings you wouldn’t think that it would be the subject of heated political argument.  However, to label or not to label, that was the difficult decision facing the brewing industry when new European Commission food labelling directives were introduced in 2003. The EC wanted to tighten the labelling legislation surrounding food and drink. What they wanted to achieve was to provide the consumer, especially those with food allergies, with a greater level of information about not only all of the ingredients present in food and drink but also those ingredients or processing aids that were used in a food or drink’s production.

It is widely accepted that the prevalence of food allergies is increasing and with there being no cure for the condition, those who suffer sensitivity to particular foods have to adopt management strategies to ensure that they do not consume even small amounts of the foods to which they react. To be able to do that food allergy sufferers need precise information about the ingredients contained in the food and drink that they are likely to consume.

The labelling of most food and drink in the UK is governed by the provisions of the Food Safety Act 1990 and The Food Labelling Regulations 1996. In addition to these provisions the European directive 2000/13/EC set out more general requirements for the listing of ingredients used in food. However, this legislation contained a number of exemptions that meant that the consumer with food allergies would not have access to the relevant information to make an informed decision about whether a particular product was safe to consume. A particular shortfall was a provision known as the 25% rule which meant that if a compound food, such as a sponge cake used in a trifle, made up less than 25% of the finished food the manufacturer was not legally obliged to label the ingredients that made up that compound food. Understandably there was a high degree of dissatisfaction from a number of consumer groups representing food allergy sufferers who felt that this labelling practice should be changed. Thus a new EC directive was introduced in 2003 requiring full ingredient listings for common food allergens. In all 12 common food allergens were identified as having to be labelled and these included things such as nuts, milk, eggs, and cereals containing gluten. However, also included in the list of food allergens that had to be labelled were ingredients derived from fish which presented the brewing industry with a labelling dilemma.

Beer which is ready to be racked into casks typically contains around one million yeast cells per millilitre. This creates a visible haze in the beer which many drinkers would associate with a beer that is past its best. Therefore the yeast has to be separated from the beer. If the beer is to be brewery conditioned, where secondary fermentation is carried out in conditioning tanks in the brewery, there are a number of methods that can be employed to remove the yeast prior to packaging such as centrifugation and filtration. However, for cask conditioned beer, yeast must remain in the cask after it leaves the brewery to enable secondary fermentation to occur. If a cask of beer is left for long enough yeast will eventually sediment naturally leaving the beer bright and clear. However, thirst breeds impatience, and of course economic realities facing the busy pub landlord require that this sedimentation has to be a lot quicker. To achieve cask conditioning, but also allow the landlord to serve a clear pint of beer, brewers add a wonderful processing aid known as finings, and in particular isinglass finings, to the cask.

Over the years a wide variety of substances have been employed to aid the clarification of beer including oyster shells, chalk and fullers earth. However, before the advent of earthenware, beer and wine was often stored in dried animal skins as well as containers derived from other animal sources such as stomachs and fish swim bladders. It was the Romans who noted that wine stored in just such vessels was much less opaque than wine stored in other vessels. In a more purified form Isinglass finings , the product of fish swim bladders, was found to be particularly effective at clarifying wine and beer and so when commercial brewing expanded at the end of the 18th century its use became routine to clarify beer in the cask.

At that time isinglass finings were sourced from the sturgeon, a common large fish found in many of the rivers surrounding the major brewing cities. Today isinglass is generally obtained from the swim bladders of fish such as catfish, drumfish and threadfins caught in tropical and sub-tropical waters. The swim bladder, located in the dorsal portion of the fish allows the fish to control its depth without having to expend energy by swimming. The size of the swim bladder and its quality as a fining agent varies between fish species and can also be affected by where the fish are caught. Thus the dried bladders have gained rather exotic names such as Long Saigon, Pennang and Brazil Lump and some brewers may insist on using isinglass finings made from a particular type of swim bladder.

So how are isinglass finings prepared and how do they work?

To prepare isinglass finings suitable for brewery use the isinglass is removed from the fish and dried naturally, if dried too quickly a lot of the clarification potential can be lost. Once dried the finings are cleaned, sterilised and “cut” in acid. The “cutting” process results in a white liquid or emulsion of isinglass which is ready to add to beer.

The mechanism by which the action of fining beer works can be explained by a mathematical formula derived by George Gabriel Stokes in 1851. Stokes was interested in how particles moved in fluids, particularly how they settled or sedimented at the bottom of a liquid. Rather unsurprisingly Stokes observed that one of the key factors that determined how quickly particles settled was their size. The bigger the particle the quicker it would settle. Therefore if you can get small particles to somehow coalesce and form bigger particles they will settle quicker. That is the principle that underpins how isinglass works in beer.

The important constituent of isinglass that makes it effective as a fining agent is collagen. Collagen is a protein that has a helical shape rather like the structure of DNA but whereas DNA has a double helix collagen has a triple helix. The triple helix of collagen winds itself together to form a complex mesh or net like structure. Furthermore Collagen contains numerous sites within that helical structure which are electrically positively charged in beer and are a key factor as to why isinglass is so effective at clarifying beer.

When added to beer, it has been proposed, that isinglass passes through beer, if you can pardon the analogy, rather like a fishing net. The yeast cells simply become enmeshed in the net like structure and an electro-static interaction between the positively charged sites on the collagen molecule and the negatively charged surface of the yeast cell creates a tight bond between yeast and isinglass. This newly created particle has a vastly increased size and so sediments out of the beer far quicker than the yeast would naturally and the pub landlord now has a cask of clarified ale ready for serving.

Isinglass finings are a tried and tested method of clarifying beer and so it came as a great relief to traditional cask ale brewers when the EC, last year, introduced an amendment to the 2003 labelling directive. The brewing industry successfully argued that as a processing aid, not an ingredient that would be consumed, and with a long history of use with no recorded incidents of an allergic reaction there was a good case for isinglass to be exempt from the directive and the future of isinglass finings as a brewing aid secured.

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