Steve Peck, Technical Manager, AXEON Water Technologies
The Reinheitsgebot (aka German Beer Purity Law) is perhaps the oldest food-quality regulation in the world. Dating back to 1516, the Reinheitsgebot decreed that only water, barley and hops can be used as ingredients in beer. Centuries later, yeast was added as the fourth ingredient (after it was recognized as the fermenting agent). Although beer is primarily composed of water, the impact of water on its flavor profile is often overlooked. The recent explosive growth in the craft beer industry particularly in the United States is due in part to the fraternal atmosphere of home brewers (turned commercial brewers) sharing recipes of their creative combination of malt, hops and yeast strains. Yet water is seldom mentioned in these recipes as the brewer relies on the chemical makeup of the municipal tap water.
Historically, the influence of local water supply on the brewing of beer had been known well before the chemistry of water composition was understood. The classic styles of beer known today have evolved around the regional differences in water quality. The soft water in Pilsen led to the light pilsner lager. The high concentration of calcium and alkalinity in Dublin water on the other hand is well suited to dark beers such as stouts. With very high sulfate concentrations in its well waters, Burton on Trent, north of London, became known for its pale ales (and the IPA’s exported by the East India Company).
From a technical standpoint, the most important effect of brewing water is establishing proper pH when mashing the malt. The performance of the enzymes that breakdown the malt (into the sugars digestible by the yeast) greatly depends on both pH and temperature. The differing styles of beer result in part from balancing the acidity of the malt and the alkalinity of the water. The flavor profile of beer is also directly related to the mineral levels in the water. For example, chlorides and sulfates impact strong flavors but do not affect pH the same way as calcium and alkalinity. Chloride adds sweetness and fullness to malty beers; whereas, sulfate accentuates the bitterness of hoppy beers.
Modern craft brewers enjoy brewing a broad range of beer styles using a single water supply. The advancement of source water treatment technologies such as the availability of affordable reverse osmosis filtration allows the brewer to design a water profile that best suits each of these beer styles. Reverse osmosis removes the minerals in the water providing the brewer with an empty canvas to compose the desired mineral profile from scratch by adding brewing salts such as calcium chloride, gypsum (calcium sulfate) and baking soda (sodium bicarbonate).
Reverse osmosis systems filter water through semi-permeable membrane elements that employ thin-film technology to separate the salts from the water. These systems are designed to use RO membranes which can vary from high rejection elements such as the AXEON HR3-Series Membranes, which are capable of removing up to 99.5% of the salts and minerals in the water to ultra low energy elements such as AXEON HF5-Series Membranes, which can operate at lower pressures.
AXEON manufactures a range of pre-engineered Reverse Osmosis Systems with water production capacities of 50 gallons per day for home brewer use, up to 100,000 gallons per day for commercial brewer use and 500,000 gallons per day for industrial beer processing plants.
A standard pre-treatment setup prior to reverse osmosis includes the removal of suspended solids, iron and chlorine. Suspended solids are removed using media filtration such as an AXEON Zeolite System or AXEON Sediment Filter. AXEON Filox Systems are typically used for iron, manganese and hydrogen removal. The AXEON media filter systems are available in various size media tanks and have easy to program electronic control valves.
Municipal water supplies use free chlorine or chloramine to disinfect the water supply; however, they impart an off-flavor in beer. In addition, removal of chlorine and chloramines is an important pre-treatment step to prolong the life of RO membranes. AXEON Carbon Systems or AXEON Carbon Block Filter Cartridges are an effective choice in removing chlorine. The removal of chloramines, however, requires longer contact time with carbon compared with the removal of chlorine. Catalytic carbon is specially-treated carbon used for chloramine removal.
Since chlorination of the water is unacceptable, ultraviolet (UV) light is becoming a popular alternative method of disinfection. UV light is capable of killing 99.99% of bacteria and viruses and completely breaking down total organic carbon (TOC).
Some commercial brewers opt to blend the permeate water from the reverse osmosis with pre-treated water that is bypassed around the reverse osmosis unit. Changing the ratio of this blend allows the brewer the flexibility to modify the total dissolved minerals in the water as needed. Another increasingly popular option is the use of nanofiltration. Nanofiltration is also known as “membrane softening” as its greater permeability reduces hardness and alkalinity while allowing some sodium chloride to remain in the water. AXEON Nanofiltration Systems reject 75% to 80% of the salts and minerals in the water (compared to the 95% to 99% rejection achieved by reverse osmosis). AXEON Nanofiltration Membranes fit within the same commercial equipment manufactured for reverse osmosis.
With reverse osmosis and nanofiltration, the craft brewer has the advantage of custom designing water suitable to any beer style of choice instead of troubleshooting a water supply that is either inconsistent or unsuitable.
A micro-brewery is classified by the number of beer barrels it produces in a year, which is a limit of 15,000 beer barrels a year or 460,000 US gallons and at least 75 percent of that beer must be sold outside of the brewery. There are no strict guidelines set on the techniques or ingredients a micro-brewery uses to produce their beer
A craft brewery brews no more than 2 million gallons of beer per year and is owned independently. Unlike a micro-brewery, a craft brewery has set limitations on the techniques of their beer production. A craft brewery’s beer must contain at least 50 percent traditional malt, rather than adjuncts such as oats, barley and wheat and there lies one distinction
For an in depth read on the subject, the John Palmer and Colin Kaminski book “Water: A Comprehensive Guide for Brewers” is highly recommended. The title was recently added to the Brewers Publications’ Brewing Elements series. John Palmer is also the author of “How to Brew”, the top selling book on home brewing.