OnTap Magazine

G iven enough time virtually all but the most un-flocculant yeasts will sediment out and other colloidal particles will either succumb to gravity or be taken out of suspension by the sinking yeast, leaving a clear ‘bright’ - and well-matured - beer, in good condition, ready to package. However, any brewer enjoying the luxury of this method of beer clarification, will, in all probability, face sceptical shareholders objecting to such luxuries. Since time is money brewers, therefore, have to use their ingenuity to accelerate the sedimentation and clarification process and create a shelf-stable beer. Filtration offers speedy solutions but requires capital investment and all filter materials are cost- ly and create waste. So, what are the op- tions for other forms of ‘natural’ clarification without filtration? LOOKING OUT TO SEA For most of its history beer was dark and cloudy. Served in earthenware pots, its appearance did not matter; but looks began to change with advancing malting andbrewing techniques and theuseof clear glass. Beer got brighter and clearer. While gypsum (calcium sulphate) was added to the brewing water to give the beer some clarity, the real stars for removing colloidal particles came from an unlikely source: the sea and the beach. For hundreds of years UK brewers achieved beer clarity by using marine- derived polymers, which were given the collective name: ‘finings’. At that time la- gering or filtration were not available op- tions for cask conditioned beer. The local climate did not allow natural ‘lagering’ (from the German lagern, ‘to store’), which is what the Bavarian brewers were doing in the early nineteenth century: storing their beers in cold cellars for prolonged periods, using bottom-fermenting yeast. The yeast and large particles would set- tle leaving a clean, pale, and carbonated lager beer. Considering beer brewing’s 6,000-year history, filtration is a relatively new development; the first beer filter de- signed by Lorenz Adalbert Enzinger was presented at a brewing exhibition in Mu- nich in 1880. The first filter medium was of paper leaves, then pulp cakes prepared from cotton fibres mixed with asbestos, and from the 1930’s, Diatomaceous Earth. INTO THE SEA The fining or clarifying agent that UK brewers were using for cask ales, and brewers worldwide still do, is known as Irish Moss. It is the name commonly given to the Atlantic redseaweed Chondrus crispus . The active ingredient is k (kappa)-carrageenan , a polysaccharide, which has since been discovered in a greater concentration in the Pacific seaweed Eucheuma cottonii . Irish Moss is added to the kettle or copper (hence ‘kettle finings’) just before the end of the wort boil, where the negatively charged carrageenan interacts with the positively charged protein, forming an insoluble complex which precipitates out and sediments. The other clarifying agent from the sea is isinglass, derived from the swimbladders of tropical and sub-tropical fish. When added to beer, isinglass's collagen protein attracts and combines with the negatively charged yeast and polyphenols (tannoids), forming large particles that sediment. Isinglass has long been used for cask-conditioned ales, where casks often moved, and the beer requires settling time before serving. It works similarly to gelatine or egg white. In recent years fish-based isinglass finings have attracted ethical and environmental criticism, which means that vegan friendly and even kosher finings are now increasingly applied. MOVING ONTO LAND Since sand is plentiful, easy to mine and relatively easy to process, it is the primary source of silicon dioxide (SiO 2 ), also known as silica. Silica sols (colloidal solution of SiO 2 ) and silica gels (xerogel, hydrogel, and hydrated xerogel) are widely used in the protein clarification and stabilisation of beer, where they are highly effective at reducing haze-active proteins, thereby increasing colloidal stability and prolonging beer shelf life. They are by far the easiest, cleanest, cost-effective and vegan-friendly clarification and stabilisation products, with minimal beer losses, little to no impact on filterability and are available in formulations, subject to local regulation, which do not require removal by filtration. One such clarifying agent derived from a natural source is gallotannin or tannic acid. It is extracted from the galls of the Aleppo oak ( Quercus infectoria ) and the Chinese nutgall ( Rhus chinensis ) using Aleppo Oak Irish Moss ontapmag.co.za | Spring 2024 | 25