Because of its low alcohol content, ginger ‘beer’ is a popular drink with British children. Dean Madden from the National Centre for Biotechnology Education, University of Reading, UK, gives his recipe for introducing younger students to the principles of fermentation, food hygiene and the biochemistry of respiration.
The predecessors of modern carbonated soft drinks were often brewed at home. In late 19th century Britain, ‘small beers’ were fermented drinks with a very low alcohol content. These were usually safer to drink than water, which was often contaminated.
Ginger beer originated in England in the mid-1700s and was exported worldwide. This was made possible by the use of strong earthenware bottles that were sealed by a liquid- and gas-tight glaze (called ‘Bristol glaze’). The British Excise Regulations of 1855 required that the drink contained no more than 2% alcohol, and usually it was far less potent: hence ginger beer became popular with children. By the start of the 20th century it was produced commercially in almost every town in the United Kingdom. The ‘beer’ was often sold by street hawkers, and it was sometimes dispensed from a ‘beer engine’ – an elaborate device like an upright piano with beer pump handles that was pulled through the streets by a pony.
In 1935 there were more than 3000 producers of ginger beer in the United Kingdom: today, however, only one British firm makes a traditional brewed product – modern ‘ginger beer’ is usually made with flavourings and carbonated with pressurised carbon dioxide.
There are many recipes for ginger beer; the basic ingredients are ginger, lemon, sugar and yeast. Real ginger beer is made from fresh root ginger (Zingiber officinale), often with other flavourings such as juniper (Juniperus communis), liquorice (Glycyrrhiza glabra) or chilli (Capsicum annuum) – which gives the product extra ‘bite’. Yarrow (Achillea millefolium) is sometimes used to inhibit bacterial growth (as it was in normal beer before the introduction of hops). Jamaican ginger beer is sometimes made with lime instead of lemon juice.
The following recipe is for one litre and can be scaled up and changed as required – some suggest that the ginger should be grated rather than sliced and crushed. Others recommend boiling the mixture before adding the yeast, to extract more flavour from the ingredients.
* There is no need to use boiled water to rinse the bottles after sterilisation. The sterilising step is to get rid of major contaminants left in reused bottles. The tap water used for rinsing should not introduce contaminants, and should it do so, they will be quickly out-competed by the relatively large inoculum of yeast. The low pH of the liquid (from the lemons) will also prevent bacteria (although not yeast) from growing.
Glass bottles must NEVER be used, as the gas produced will cause them to explode. This drink should always be made in plastic bottles, and it should always be refrigerated and consumed within six days. The short fermentation period and refrigeration ensure that the alcohol content of the drink remains low.
Please remember that some religious groups object even to the consumption of products that contain little or no alcohol but have been produced by brewing. The students may, however, be happy to take part in the practical without drinking the resulting ginger beer. Teachers should be sensitive to such concerns.
It takes approximately 90 minutes to prepare the drink, including a cooling period of 60 minutes. The initial fermentation takes 24 hours, followed by up to 48 hours fermentation in bottles. The bottles can be sterilised in advance if desired.
This practical activity can be used as the starting point for other practical investigations, some of a technological nature. These include:
All of the materials required to make ginger beer can be bought from a supermarket, market or a supplier of wine-making equipment.
Note, however, that ginger beer was traditionally made not with pure yeast, but with a mixed culture of lactobacilli and yeasts that is sometimes called a ‘Ginger beer plant’ or a ‘Beeswine’ culture. This is similar to a kefir culture and can be maintained and passed on to others who wish to make ginger beer.
The ‘ginger beer plant’ was described in:
Ward HM (1892) The ginger beer plant and the organisms composing it. Philosophical Transactions of the Royal Society of London. B 183: 125–197
According to the UK National Collection of Yeast Cultures (www.ncyc.co.uk/beeswine.php), the only safe commercial source of this culture in Europe is now the German culture collection, DSMZ. They have a special education price for this culture, DSMZ No. 2484 (www.dsmz.de/microorganisms/html/strains/strain.dsm002484.html).