BREWING
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.
BREWER AND DISTILLER INTERNATIONAL ● 6
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