Countdown to zero ... The search for perfect alcohol-free beer. Written by Stuart Howe. First published April 2019, Brewer and Distiller International magazine.
Inside:
A simple message to the IBD Community
In these uncertain times all of us will have differing levels of anxiety and concern for ourselves and our family and friends, particularly if they are far away or more vulnerable. You may be struggling with the new and difficult demands of your personal and business life. You may also feel like you are being bombarded with information from every angle in which messages similar to this one are likely to use the word 'unprecedented'. Yet despite the difficulties that we may face today, we can all share in the certainty that there will be an end to this. Once we are on the other side, stronger, more resilient and inspired by a fresh perspective, it will be vital that we support the industry to recover as quickly as possible. Education and training will continue to play a key role in assuring the quality and consistency of the products that bring friendship and enjoyment to many around the world. The IBD will do what we can to support this recovery and to bring our members and wider community together in this aim. This publication is just one small part of that and is available to all, whether to enjoy as a brief respite or to learn something new, we want you to be a part of it. If you have entered your email address, we'll ensure you receive a copy of this publication on Tuesdays and Thursdays, and you can unsubscribe any time. We want to create content through collaboration and to tell the stories that champion the good work of our great community. Whether you are a colleague, a peer, or know a company that is doing something extraordinary during this time, we want to hear from you. Let us know what you would like to learn about and what information might help you now or when the industry starts its recovery.
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Jerry Avis, CEO
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Countdown to zero... The search for the perfect alcohol-free beer
can be up to 0.5% ABV whereas the Fins enjoy a 2.8% ABV limit. Non- alcoholic is generally the term applied to drinks for the purposes of licensing its sale, whereas alcohol-free tends to relate to the labelling and the consum- er’s expectation and has a lower upper limit. Alcohol free beer in Iran and the US must have no detectable ethanol whereas the EU de ne it as 0.5% ABV. Alcohol-free beer is of course not a new phenomenon and early versions of low alcohol beer were made in the US during prohibition. In the UK in the 1980s the availability of suitable technology saw the rst attempt to take alcohol-free beers (AFBs) to the mass-market. Those old enough and unlucky enough will remember the wonders of beers such as Kaliber and Barbican which may as well have contained alcohol as they were so undrinkable consumption of any volume with the potential for harm was impossible.
By Stuart Howe
Reading current media articles, you could be forgiven for believing that everyone under 40 is teetotal and sales of alcohol-free versions of beer, wine and gin are outselling their conventional counterparts by ten to one. Alleged growth in demand is being driven by the concerns over the safety of alcohol consumption and its prohibition by certain religions. The truth is, the actual numbers are slightly more modest – but the search goes on for a delicious alcohol-free beer…
I n the UK, the sales growth estimated by GlobalData Consumer Intelligence Centre was 30,000 hL so less than a single suc- cessful national brand of a standard beer would enjoy. Perhaps the most persuasive argument for brewing a non-alcoholic beer is that in a crowded and stagnant market- place it is a category in growth.
But we, ladies and gentlemen, are brewers – so shall not bother ourselves with the vagaries of marketing. We merely have the simple task of making alcohol-free beer cost effective to pro- duce and delicious to consume. Legal de nitions differ across the world. A non-alcoholic beer in the US
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minimise thermal load on the beers. MIS is a contract processor and packager and uses the system to produce beers and wines for contract customers down to 0% ABV. Luc feels that thermal systems and the SIGMATEC in particular represent the lowest operating cost technology available to produce such beers. Vacuum distillation Mechanical versions of vacuum distilla- tion are available which use the move- ment of the machine and hence the beer to increase the surface area for evapora- tion and thus reduce the contact time of the beer and the heating surface. In the Centriferm from Flavourtech the beer is sprayed via a nozzle onto the top side of a cone spinning in a cen- trifuge and the beer is rapidly distributed across the surface of the cone to form a thin lm (circa 0.1mm). Steam is passed through the machine into the underside of the cone causing evaporation of the ethanol and other volatiles. Because the liquid lm is so thin temperatures as low as 35 ° C can be used and it claimed the machine has minimal thermal impact on the beer. The vapour from the Centriferm requires condensation and recti cation before the aroma volatiles can be returned to the dealcoholised beer. The system is principally marketed as an evaporative drier for food and there are concerns over DO 2 pick up through its operation. Another mechanical vacuum distilla- tion option from Flavourtech is the spin- ning cone column (SCC). The SCC has upward fanning cones xed to a rotating column. Another series of cones are xed to the chamber wall surrounding
250
200
150
100
50
0
2014
2015
2016
2017
2018F
Year UK AFB sales 2014-2018 (source: GlobalData)
rectifying column. Rising through the stripping column as a counter current ow are vapours produced by heating dealcoholised beer which selectively remove ethanol from the beer. Although there is some selectivity, other important volatile components are removed from the beer into the distillate so the system undertakes further recti - cation in an aroma recovery unit. These volatiles are then added back to the beer under pressure after cooling with glycol. Although this element of the system adds back some of the aroma removed through evaporation, some 70-90% of the higher alcohols and esters are lost during processing according analysis undertaken in 2005. Luc De Baerdemaeker, Operations Director at MIS SA in Courcelles, Belgium, operates the SIGMATEC system. Luc uses a process temperature of 30 ° C to
Modern versions are a great deal more palatable and, in this article, I will discuss today’s technologies for producing AFBs and technical options for achieving a product with the best possible value, avour and stability. The methods for producing AFBs can be split neatly into two approaches. Removing the alcohol from an alcoholic beer (physical) and producing a beer with little or no alcohol in (biological). Physical methods can be further split into membrane technology and thermal technology. Thermal dealcoholisation When AFBs rst started to look like a nice little earner the volatility of ethanol in comparison with water and solutes led brewers/chemical engineers to employ heat to evaporate the ethanol. It is important to note that evaporation is not boiling so we are not talking about sim- mering the beer gently over a low ame. Thermal systems are the only deal- coholisation technology which can ef - ciently remove all the ethanol from beer. Another signi cant bene t of thermal systems is the production of food-grade ethanol which can be sold on for use in other drinks. Applying heat to beer, unless you are making mulled ale, is substantially deleterious to avour, so modern thermal systems are designed to be as non-thermal as possible. Use of a vacuum increases the rate of evap- oration of ethanol thus enabling removal at a lower temperature. Vacuum recti cation In the SIGMATEC system manufac- tured by API Schmidt, beer is heated to 42-46 o C in a heat-exchanger and fed to the top of the stripping section of a
Parameter
Unit
Pre VR Beer
Post VR AFB
OG
% Weight
11.59
2.46
Ethanol
% v/v
4.99
0.48
Bitterness
EBU
24.9
25.5
1-propanol
mg/l
6.7
0.8
2-methyl propanol
mg/l
11.2
0
2-methyl 1-butanol
mg/l
15.2
0
3-methyl 1-butanol
mg/l
52.8
0
Total higher alcohols
mg/l
104.7
38.3
Ethyl acetate
mg/l
16.9
0
Iso amyl acetate
mg/l
1.9
0
2-phenyl ethyl acetate mg/l
0.4
0.03
Total esters
mg/l
19.6
0.04
Table 1: Beer attributes before and after vacuum recti cation (adapted from Branyik et al. 2012)
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aroma recovery step is not undertaken so practically all aroma volatiles are lost. To overcome or at least ameliorate this loss of avour Flavourtech have devel- oped the Resin Adsorbing Column (RAC) which uses a charged polymer to adsorb the aroma compounds and ethanol. The ethanol is then washed out using water before the aroma com- pounds are desorbed into water for adding back to the dealcoholised beer. The production of AFBs down to <0.05% ABV is possible using the SCC and RAC. Rothaus Brauerei in Grafenhausen, Germany, have used the SCC to make its 0.4% ABV Pilsner and Hefeweizen and is pleased with the avour of the beer produced. Falling lm evaporators CENTEC GMBH produces the DeAlco- Tec dealcoholisation unit based around the falling lm evaporator. In this system the feed beer is passed through a heat-exchanger counter currently to the warmed dealcoholised beer leaving the column and on to degassing. The CO 2 driven off during degassing carries with it aroma volatiles – so this is passed to the falling lm column for processing. The heated beer is then fed into the top of the evaporation
the unit. This gives alternate spinning and stationary cones down the length of the chamber. In SCC the beer to be processed is fed in the top and ows down over cones. The centrifugal force generated by the rotation causes the beer to ow up the rotating cone as a thin layer (circa 1mm) and weir over onto the xed cone where it runs down due to gravity. Deionised water vapour is fed up through the unit and mixes with the beer at each of the weir points at the ends of the cones. On the underside of the rotat- ing cones are ns which act to promote turbulence between the liquid and vapour streams thus dramatically increasing mass transfer between the two. A two-stage operation is utilised for beer dealcoholisation with a rst pass removing aroma volatiles and some eth- anol at a maximum temperature of 30 ° C and then a second pass for ethanol removal at 45 ° C. The condensate from the rst pass is recombined with the dealcoholised portion to return the aroma volatiles. When used on a feed beer with an ABV of 4.8% the fraction containing the vola- tiles is 75% ABV so addition back to the dealcoholised fraction gives a beer of 0.5%ABV.
Spinning cone shaft
Spinning cone
Stationary cone Liquid/slurry inlet
Vapour plus volatiles outlet
Gas vapour inlet
Pulley for drive belt
Liquid outlet
Liquid vapour ow
Spinning cone shaft
Liquid and vapour mixing
Downward liquid ow
Elements of SCC (image courtesy of Flavourtech)
As with the SIGMATEC unit there is a net loss of aroma volatiles of around 80% through the process even after the recovery of the aroma fraction. If a beer of less than 0.05% is required the
Heineken 0.0 is twice brewed and fermented with Heineken’s unique A-yeast from natural ingredients with gentle alcohol removal and blending to achieve a fruity avour and slight malty note. In the most challenging brewing process of his career, Willem van Waesberghe, Global Craft and Brew Master at Heineken, stated; “Removing alcohol from regular 5% Heineken would have been easy, but it wouldn’t deliver the same premium beer taste that Heineken is known for. Heineken 0.0 is brewed from scratch and has a perfectly balanced taste with refreshing fruity notes and soft, malty nish.”
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This means that oxygen control around the dealcoholisation plant and throughout the brewing process must be as tight as possible so as to not damage avour and avour stability. Given that analytically thermally dealcoholised beer has signi cantly reduced levels of volatile aroma com- pounds and thermal load is placed on the beer during the process, it unsur- prising that the avour of the beer is sometimes reported as thin, lacking in fresh, fruity aromas and carrying more bready, caramel aromas than standard beers. In addition to this, thermally dealcoholised beers can suffer from an increase of off- avours. Membrane dealcoholisation A number of different membrane-based approaches for beer dealcoholisation have been proposed and operated exper- imentally. Dialysis and osmotic distillation have both been trialled commercially but only reverse osmosis and nano ltration have made it to the wider marketplace. For the purposes of this article reverse osmosis (RO) and nano ltration (NF) are effectively the same process. The only difference between the two is the pore size of the membrane and some pore sizes t both classi cations. Osmosis is the process whereby a solvent moves from an area of low-sol- ute concentration to an area of higher solute concentration across a semiper- meable membrane in order to achieve an equilibrium. The osmotic pressure is that which is required to hold the sol- vent back on the more solute concen- trated side of the membrane. Reverse osmosis reverses the process by applying a pressure greater
6
Ethyl acetate Isoamyl acetate Isoamyl alcohol
5
4
3
2
1
0
Feed beer
DeAlcoTec
Alternative
Volatiles in dealcoholised beer from CENTEC unit vs competition
into the dealcoholised beer stream once this is cooled. As some ethanol is also collected during this recovery, the beer produced from the blending cannot be below 0.05% ethanol unless made so by dilution. To adopt a thermal system, you have to be pretty serious about pro- ducing AFBs. Thermal plants are big beasts and require either a very high ceiling or one with a great big hole in it. The maintenance costs for mechanical systems are very high with a full strip down required annually. In addition you have the fact that you are making a highly ammable and in the right conditions, explosive liquid. Part of the plant will be subject to ATEX zoning considerations. Despite the use of the vacuum to enhance evaporation
column which is packed with ne sheet stainless-steel to increase the mass transfer surface. Vapours formed from the dealcoholised beer are fed into the bottom of the column. They rise upwards inside the column in counter current to the falling warm liquid beer absorbing the volatile ethanol from the product. The less volatile com- ponents fall to the column base and ow into the falling lm evaporator that generates the vapour for the dealcohol- isation of the warmed beer entering the column at the top. A vacuum ow through unit is maintained and controlled by a vacuum pump. Operating at a greater degree of vacuum than analogous technologies, the maximum temperature of operation is below 40 ° C. The volatiles from the original product can be separated in an aroma recovery system and added back to the nished product. With this system the option of a recti er is available allowing concentration of the ethanol up to 90% ABV. CENTEC claims its system is the gentlest available technology – work undertaken at Weihenstephan Univer- sity is used to support this. A unit has recently been installed in Gaffel Brauerei in Cologne, Germany who is reported to be very pleased with the alcohol-free version of its Kolsch. Alfa Laval makes an equivalent technology (the imaginatively named dealcoholisation module) which uses culinary steam as the ethanol stripping agent in a column based on those used in its ALDOX deaerated water produc- tion systems. In the Alfa Laval unit the volatiles are recovered by cooling after the degas- sing stage and can be blended back
thermal systems do increase the thermal load on the beer.
GEA AromaPlus (Courtesy of GEA)
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membrane housing. Dealcoholisation is carried out in three steps.
Step 1: Pre-concentration In pre-concentration the beer is pro- cessed through the membrane hous- ing removing ethanol and water. This step continues until a target volume reduction is achieved. This step will not reduce the ethanol concentration suf - ciently so a dia ltration step is employed Step 2: Dia ltration Dia ltration is the ltration under dilution and involves the addition of demin- eralised DAL to the feed stream. The process increases permeate ux and hence movement of the target solute across the membrane. Effectively you are washing the ethanol out of the beer. The volume of water added at the dia ltration step is equal to the volume of uid lost across the membrane as permeate so the volume in the system remains the same as after the precon- centration step. Step 3: Alcohol adjustment Dilution water is then added to the process tank to adjust the beer to the target ABV. The concentration of etha- nol in the permeate is not high enough (as low as 1% ABV) for sale without further processing but it can be used for alcoholic soft drinks. Operating costs for membrane systems tend to be higher than for thermal sys- tems. The water used to beer produced ratio is 2.5:1 all of which has to be chilled, deaerated, demineralised and ul- timately disposed of as process ef uent. Adnams mitigates this to a degree by using this cooled water for wort cooling and in its distillery. Energy costs are also signi cant with large motors on high- pressure pumps and cooling costs to keep beer temperature during processing. Additionally, membranes are relative- ly new technology so still expensive and require replacement more frequently than components in a non-mechanical thermal system. Although membrane systems do not subject the beer to thermal load there is still a signi cant impact on the avour of the beer processed. Molecules other than water and ethanol are rejected through the membrane. Changes in avour compounds caused by the membrane dealcoholisation are shown bin Table 2. As with thermal dealcoholisation there is a signi cant loss of aroma compounds and while this is slightly lower with mem-
The Alfa Laval De-alcoholisation Module enables breweries to produce non-alcohol or very low alcohol beer without facing the heavy capital investments typically required for such applications. The cost- and energy-ef cient de-alcoholisation concept provides chilled low-alcohol beer below 0.05% alcohol by volume. This is achieved by an innovative combination of diverse technologies, from beer degassing and culinary steam generation to vacuum stripping and alcohol condensing, which work in tandem as an integrated system. The system also produces a condensate stream composed of water, stripped alcohol and other volatiles that can be reused for ethanol production and concentration of aroma volatiles. © Alfa Laval.
than that of the osmotic pressure (in practice vastly greater). In the case of beer dealcoholisation, this is in essence applying pressure to a stream of beer to push the ethanol (and water) through a membrane which is selectively permea- ble for these molecules. Unlike standard dead-end mem- brane ltration the liquid bring pro- cessed runs parallel to the RO mem- brane which reduces fouling. The AFB is retained within the equipment and called the retentate while the ethanol, water and some vola- tiles are rejected across the membrane and termed the permeate. Selection of membranes for membrane dealcoholi- sation plants is critical. As well as the appropriate pore size for the molecules to be rejected the hydrophobicity/hydrophilicity of the membrane is also important to avoid fouling and rejection of molecules you want in the retentate. GEA and Alfa Laval sell similar mem- brane dealcoholisation plants. The Alfa Laval unit uses nano ltration whereas the GEA plant uses RO. These are skid
water and alcohol
Water and alcohol crossing the membrane
mounted, fully automated and almost plug and play units, carrying cleaning in place equipment. Additional plant required is, as a minimum, a receiving and recirculation vessel and facility to produce demineralised deaerated water. The bene t over thermal dealco- holisation is that they operate at a low temperature and hence contribute no thermal load. They are also designed to t into existing cellars so are smaller in size and certainly in height than thermal units. The GEA AromaPlus RO plants are used commercially at Adnams Brewery in Southwold UK and Kloster Andechs Brauerei in Germany. The unit at Adnams is operated at 0 ° C. Membrane dealcoholisation plants operate in a loop from and to the beer process tank. Pumps on the skid maintain a pressure of 30-40 bar in the
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brane dealcoholisation there is a loss of avour-active fatty acids at the same time. Adnams found there to be an increase in pH due to the loss of acidic compounds through the membrane. Despite this, sensorially, membrane dealcoholised AFBs rated better in terms of body and sweetness than their thermally dealcoholised counterparts. Improving overall avour With both physical methods for dealco- holisation the brewer can use his/her skill to reduce the impact of the dealcoholisa- tion on the avour of the beer. Producing a beer which is higher in the attributes diminished by the process through changes to the recipe – like adding more hops or special malts – or manipulating the conditions of fermentation to encour- age ester formation is one approach. At Adnams the rst trial batches of an AFB were too bitter and insuf ciently sweet, so the process was adjusted to compensate. Blending the AFB with a beer which has been subject to arrested fermen- tation (see later) or a 6% addition of krausen from a standard beer are established techniques for improving overall avour as is cold conditioning the beer with yeast. As thermally dealcoholised beer is generally lower in ABV it offers a better prospect for these approaches as they will all increase ethanol concentration to a degree. Other post-processing ad- ditions include hop derived avours or dry hopping and glycerol which is used to ameliorate the loss of palate fullness due the removal of ethanol. Both physical methods of AFB pro- duction remove almost all the CO 2 so the nal beer needs to be recarbonated. As ethanol plays a part in the stabilisation of foam the use of head positive additives such as reduced iso extracts has also been found to be necessary for both physically and biologically produced AFBs. In researching this article, I had the pleasure of dealing with a great number of key players in the supply of dealco- holisation technologies. Interestingly, all bar one said their technology had the lowest impact on avour of any on the market today. Data to enable an effective comparison of the technologies are not available so when deciding which system to adopt it is therefore essential to: • Ask pertinent questions of the refer- ence sites for the technology • Sample the reference sites’ AFBs and conventional beers • Conduct a total cost of ownership
Parameter
Unit
Pre RO Beer
Post RO AFB
OG
% Weight
10.86
2.46
Ethanol
% v/v
4.92
0.4
Bitterness
EBU
24.6
12.3
1-propanol
mg/l
12
2
2-methyl propanol
mg/l
17
5.1
2-methyl 1-butanol
mg/l
4.3
2.8
3-methyl 1-butanol
mg/l
3
10
Iso amyl alcohol
mg/l
79
17
Phenyl ethyl alcohol
mg/l
40
3.7
Total higher alcohols
mg/l
148
27.9
Ethyl acetate
mg/l
15
1.8
Iso amyl acetate
mg/l
1.5
0.16
2-phenyl ethyl acetate
mg/l
0.63
0.04
Total esters
mg/l
17.6
2
Iso valeric acid
mg/l
0.76
0.18
Caproic acid
mg/l
2
0.22
Caprylic acid
mg/l
3.6
0.35
Total fatty acids
mg/l
7.9
0.9
Table 2: Beer attributes before and after membrane dealcoholisation (adapted from Branyik et al. 2012)
analysis for the system and AFB pro- duction operation • Conduct pilot scale trials on the sup- plier’s pilot plant using your beer • Undertake sensory analysis on the beer produced including hedonic tests with a panel of your target market Biological methods These are the lowest CapEx option for producing AFBs. In some cases, no in- vestment is required. Biological methods seek to produce a wort which is dif cult to ferment and/or prevent fermentation proceeding past a desired point. This is the prevalent approach to AFB production, certainly in Europe. In a recent survey of Czech AFBs only 4 out of 30 brands on the market were not produced by biological methods. Wort production The bulk of the ethanol in a conven- tionally-brewed beer is fermented from maltose. Mashing techniques which limit the activity of β -amylase and hence con- version of starch to maltose can therefore be used to reduce ethanol concentrations in the fermented wort and the make cows local to the brewery extremely happy. So-called jump mashing (the won- derfully named Springmaischverfahren in German) is temperature programmed mashing where the sacchari cation step
is skipped. This is useful for under mod- i ed malt which may be low in FAN and also helps downstream processing by still enabling proteases and β -glucanas- es to go to work. When a single temperature stand is used, mash temperatures of 75-80 ° C are used to rapidly denature the more heat labile β -amylase and limit dextri- nase leaving α -amylase to undertake liquefaction. Other exotic methods of mashing, like cold water extract and spent grain mashing have been pro- posed and trialled but are not undertak- en commercially. Barley mutants lacking the ability to synthesise β -amylase or those produc- ing a more heat labile β -amylase have been identi ed but they have also not made it into the commercial realm. Special malts produced by stew- ing or kilning at high-moisture levels such as crystal and cara malts can be used as their extracts are compara- tively low in maltose. In addition, their non-enzymatic browning-derived avour compounds contribute to body and sweetness and have been reported to reduce the perception of worty avours in the nished beer. And of course, with modern craft styles there is the option to load the wort with hops both on the hot and cold side to mask unwanted avour elements.
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undertaking these steps in the brewhouse on their own will be insuf cient to produce an AFB worth marketing. They need to be combined with the following adjustments in fermentation and beyond. Arrested fermentation In arrested fermentation, the wort is pitched with yeast and allowed to pro- ceed until the required level of attenuation is achieved. It has been found that the lower the OG at the start of fermentation the lower the perceived level of worty notes of the beer produced. Fermentation can be stopped by applying rapid cooling, removal of the yeast through a centrifugal separator or by applying a high pressure to the fermentation vessel. Where pressure is applied, CO 2 is added through the bottom of the FV af- fording a degree of cold stripping at the same time. The temperature of fermen- tation has been found to be relatively unimportant with regard to reduction of worty avour compounds – so arrested fermentations tend to be lower than standard fermentations due to the potential for fermentation to overrun if a higher temperature is used.
Of the three methods to arrest fermentation applying crash cooling is most practical and hence common. A cold maturation (0-1 o C) of at least seven days is used for beers produced using arrested fermentation to reduce the level of sulphur containing off notes. Restricted fermentation The cold contact process (CCP) – not to be confused with a critical control point – is fermentation carried out at 0-4 ° C often at a high pitching rate (circa 30x10 6 cells per ml) with a wort which has not been oxygenated. The high pitching rate means that compounds important to beer which originate from yeast cells are added to the wort without signi cant yeast growth or fermentation taking place. Yeast slurries can contain around 6% ABV so are often washed before pitching to ensure no alcohol pick up. The lower temperature of CCP means that ethanol production is slow so the contact time with the yeast can be extended. Yeast contact time is thought to be important not only for the production of aroma compounds typical of fermenta-
One of the most signi cant avour defects in biologically produced AFBs is a worty avour. Strecker aldehydes (3-Methylbutanal, 2-methylbutanal and 3-methylthiopropionaldehyde) formed in kilning and heating processes in the brewhouse are implicated as the culprits, or at least as an index to them. In the kettle, hot stripping can be per- formed where either nitrogen or CO 2 is blown through the wort to help remove these aldehydes. The same approach in fermenta- tion is called cold stripping (a lot less comfortable) which in some breweries is undertaken using the exhaust from a standard fermentation. Cold strip- ping using this method has the added bene t of increasing the level of typical fermentation volatiles in the AFB, al- though some brewers feel the risk of the entrainment of unwanted volatiles like sulphur-containing off notes and vicinal diketones is too great. Another obvious adjustment to stand- ard brewhouse practice is to produce a wort with a lower OG and hence potential alcohol level, 1020-1030 SG (5.0-7.6 Plato) is typical. It should be noted that
“Over the past few years we looked at lots of differ- ent ways of making low alcohol beers, the reverse osmosis method gave by far the best tasting beer. It allows us to brew and ferment as normal and then at cold temperatures remove the alcohol whilst leaving the other avours of the fermentation in the beer. It’s all very high-tech magic allowing our Ghost Ship to sail away free from alcohol but remaining full of its original avours and aromas.” Fergus Fitzgerald, Head Brewer at Adnams.
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tions (esters, higher alcohols etc.) and reduction of Strecker aldehydes but also for the clari cation of the beer through adsorption on the yeast cell surface. In addition, undesirable intracellular aldehydes, formed as intermediates in cellular metabolism are reduced to higher alcohols, e.g. 1-propanol, iso- butanol, and iso-amyl alcohol as time progresses. Although CCP optimises all of the above, reduction of the worty aldehydes does not proceed beyond the point where more than 20% are removed, meaning they remain above their avour threshold in the beer. As with arrested fermentation a long cold conditioning period (1-3 weeks) is recommended to improve colloidal stability and reduce the risk of gushing. In both restricted and arrested fermentation, the sum consumption of buffering compounds and secretion of organic acids by yeast is a great deal lower than in standard fermenta- tions therefore the typical pH drop is not encountered. Acidi cation of the wort before fermentation is therefore required. Aiming for 4pH has been found bene cial experimentally although commercially it tends to be in the range of 4.0-4.5pH typically with lactic acid.
Brewdog’s Nanny State: “If you think low alcohol equals low taste, think again. We made a hardcore beer and left the alcohol out. Nanny State breaks the curfew and slips under the radar. A brigade of speciality malts and North American hops sends bitterness to the brink and back. Squeezing this many hops in, and the alcohol out, is a testament to our craft.”
Non-standard yeast Saccharomycodes ludwgii which
to be highly drinkable (at least without tooth loss) or biologically stable. The production of a strain of saccharomyces which has the per- fect attributes to make an excellent AFB through genetic engineering is a real prospect although not one worth pursuing while restrictions on the use of genetically-modi ed organisms in food production exist.
All the brewers making AFBs that I have spoken to have stated that trialling as many techniques and technologies as possible before investing is essential. They all have strengths and weakness- es and the right approach for one beer will be different to another. As with conventional brewing, our equipment and ingredient suppliers, researchers and network can provide the means to make an AFB, it is the brewer’s job to use this knowledge and these technologies to make it a brilliant one.
cannot ferment maltose or maltotriose has been trialled for the production of AFBs. In one study its fermentation of wort was slow and lead to a higher level of esters and higher alcohols and lactic acid than is produced by Saccha- romyces so was considered unsuitable. In two more recent studies the beer produced was found to be similar to a low-alcohol beer fermented by Saccha- romyces apart from slightly lower level of esters. It is reported in some papers that the commercial use of Saccharomyco- des ludwgii to produce AFBs is wide- spread, although I have not been able to nd anyone owning up to doing so. There is much ongoing work to nd a suitable yeast species and strain to enable effective AFB production with Hanseniaspora, Torulaspora, Zygosac- charomyces all in the frame. Fermentis is on the cusp of bringing a dried malt- ose non-fermenting strain of Saccharo- myces to the market. Any beer ferment- ed without the attenuation of maltose will have a high level of sugar in the nal beer unless the wort is produced to signi cantly restrict the maltose level. While maltose is only half as sweet as sucrose the resultant AFB is not likely
Things to consider
By producing AFBs, you are removing at least one of beer’s hurdles to spoilage and indeed the potential to cause harm to consumers. Issues with microbiologi- cal stability on a standard beer have the potential to upset someone, whereas micro on alcohol-free beer could cause serious illness and even death. For this reason, the majority of small pack AFBs are tunnel pasteurised. There are some brave souls who do not pasteurise and for these GMP, aseptic lling and modern rapid micro detection are essential requirements. For the purposes of regulation, the lack of ethanol in an AFB makes it a food stuff in some jurisdictions and hence AFBs require full ingredients listing, nutritional information and full compliance with allergen labelling rules.
Bibliography
Ambrosi A, Sérgio N, Cardozo M & Tessaro I. Membrane Separation Processes for the Beer Industry: a Review and State of the Art, Food Bioprocess Technology (2014), vol.7 pp921–936 Falkenberg A. Removal of Alcohol from Beer Using Membrane Processes, Master’s Thesis
(2014) University of Copenhagen Branyik, T., D. P. Silva, R. L. Martin
Baszczynski, and J. B. A. e Silva (2012). A review of methods of low alcohol and alcohol-free beer production. Journal of Food Engineering , vol.108 pp493-506 Alcohol-free Beer: Methods of Production, Sensorial Defects, and Healthful Effects (2010) Sohrabvandi, S, Mousavi, S.M., Raza- vi S.H., Mortazavian A.M., & Rezaei, K, Food Reviews International , vol.4 pp335-352
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