BREWING
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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