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Gin quality management

Ross Aylott

Aylott Scientific is a technical consultancy providing specialist expertise and training to the beverage industry. It offers businesses and organisations unique scientific and technical insights that add value to in-house capabilities and provides a complete service to senior management that delivers projects in the following key areas:

  • Brand protection, counterfeit investigation, authenticity analysis
  • Product regulatory compliance of liquids, their packaging and labelling
  • Science and technology that support product quality, innovation, process enhancement, risk management, due diligence, documentation review and competitor product analysis
  • Scientific and technical insights

Aylott Scientific
Tillyrie, Ramoyle, Dunblane, Perthshire FK15 0BB
Tel: +44 (0) 1786 824090

Gin distillers are closely involved in the quality of their brands. Quality management starts with the 3 key ingredients in gin, namely juniper berries and other botanical materials, neutral alcohol and water.

1 Botanical materials
The essential botanical ingredient in gin is the juniper berry (Juniperus communis), commonly harvested in Italy and the former Yugoslavia. The second commonly used ingredient is coriander seed (Coriandrum sativum) typically from Morocco and Russia, followed by angelica (Archangelica officinalis) from central Europe and orange and lemon peels. Precise recipes are closely guarded commercial secrets. Some manufacturers choose to be less secretive. For example, Bombay Sapphire Gin has juniper, coriander, angelica, cassia bark, cubeb berries, orris, liquorice, almonds, lemon peel and grains of paradise listed on its bottle label.

Distillers require botanical materials of both a high and consistent quality. The distiller will be aware of differences in the properties of botanical materials from different geographical and climatic regions and potentially, differences from year to year. Their laboratories often assess the moisture and oil contents of parcels of botanical materials, as well as sensory properties.

Botanical materials will be purchased in bulk and may be stored for 2 years before being selected for distillation. As the moisture content of juniper berries diminishes during storage, slight changes in their sensory character also occur and this is taken into account when blending botanicals prior to distillation.

2 Neutral alcohol
Alcohol for gin distillation is commonly known as neutral alcohol, neutral spirits and “ethyl alcohol of agricultural origin” in the European Union regulations. Essentially it is pure high alcoholic strength ethanol that is neutral, having no distinctive character, aroma or taste so that all the resulting gin flavour comes from the botanical ingredients. Individual distillers have their own specifications, both in terms of sensory character and chemical purity that go beyond the standard for set in EU Regulation No. 110/2008 Annex I.

Neutral alcohol may be fermented from various carbohydrate sources including cereal grain (maize or wheat), molasses, grapes, potatoes and lactose (from whey) and distilled at >96% alcoholic strength. Gin distilled from grain alcohol is often presented as the premium quality, but it is possible to obtain excellent alcohol from other substrates, providing there is appropriate rectification during the neutral alcohol distillation process.

The choice of carbohydrate source depends upon quality, availability, branding, price and any local tariff restrictions in the country of manufacture.

3 Water
Water makes up approximately 60% of a bottled gin at 40% vol. alcoholic strength. It is required to dilute the neutral alcohol prior to distillation and then to dilute the resulting distilled gin down to bottling strength ready for the consumer. This water must be clear, pure and without any odour or taste and is subjected to both sensory and chemical quality checks. Historically, gin distilleries were located near good sources of water (such as Clerkenwell and Goswell near the City of London).

Nowadays good quality water is obtained from most local supplies and treated by an appropriate demineralisation process at the distillery/bottling plant, followed by carbon filtration and UV irradiation to eliminate any microbiological activity in the water.

Gin distillation
So what actually happens during gin distillation? The gin still is charged with botanical materials, alcohol and water. As heat is applied the temperature of the mixture increases until the alcohol and volatile components in the botanicals start to evaporate. These vapours are carried through the top of the still into the condenser where the gin distillate is collected.

Distillers normally discard the initial distillate (known as heads), collect the middle gin fraction and discard the final liquid (tails). The gin fraction is subjected to rigorous sensory cheeks before being transferred from the distilling to the bottling operation.

Gin bottling and distribution
Gin may be bottled in any suitable plant, providing certain criteria are met, such as the availability of stainless steel reducing vats and good quality reducing water. This enables product distilled at one location to be transported to another for bottling. For example, London Gin distilled in the UK is often exported at high alcoholic strengths in large stainless steel tanks, ready for reduction and bottling at the destination. Such operations have the advantage of reduced costs relative to cased goods and also potentially reduced tariffs (through the addition of locally added value).

In common with other distilled spirits, most gins are packaged in glass bottles, the standard size being 700/750ml, although miniature (50ml), 500ml and 1 Litre sizes are particularly common in duty-free markets.

Bottle closures are made from aluminium or plastic and in certain markets special fitments incorporating oneway valves are used on bottles in order to reduce the risk of illegal refilling.

Science in the gin laboratory
Sensory tests and alcoholic strength measurement are the two most important quality management techniques to the gin distiller. Sensory assessment is normally conducted by nose against an approved reference sample. It is common practice to place a sample of the gin in a tulip-shaped glass and cover with a watch glass for a few minutes before nosing by a trained sensory panel. Some panellists prefer to dilute the sample with water down to approximately 20% v/v
alcoholic strength before nosing.

Alcoholic strength must be precisely controlled, particularly for bottled product as strength must be declared on the product’s label and excise duty paid. This measurement is usually based on the density of the liquid. Water and alcohol have different densities and by knowing the density of the gin, it is possible to calculate its alcoholic strength. Alcoholic strength measurements, traditionally conducted by hydrometry or pycnometry, are now commonly undertaken on a precision electronic density meter.

Gas chromatography (GC) is the technique used to analyse the trace components (known as congeners) in alcohol and gin. First GC is used to check that the neutral alcohol meets its quality standard by having very low concentrations of  fermentation by-products such as acetaldehyde, methanol, ethyl acetate, npropanol, isobutanol and fusel oils. These by-products are removed during the neutral alcohol distillation process.

Secondly, GC is used to analyse the natural flavour congeners in gin distillate that come from juniper and other botanical materials. These are known as the botanical congeners and mainly comprise of a series of compounds known as terpenes, terpineols and sesquiterpenes.

The output from the gas chromatograph instrument is known as the botanical chromatogram and shows the presence of specific congeners, many of which relate to juniper, coriander, angelica, cassia bark and so on. These analyses are of particular value when investigating quality issues, competitor products and brand authenticity.

Gin authenticity
Lastly, the more popular gin brands are subject to generic and brand authenticity issues. Generic authenticity concerns whether the product in question is entitled to use gin as its category name while brand authenticity concerns whether the liquid corresponds to the brand name on the label. If a particular product holds a protected designation of origin / geographical indication, then this may be infringed when it is subject to either generic or brand counterfeiting.

The most common type of brand counterfeiting is ontrade substitution where the liquid of a popular gin brand is substituted by another, usually cheaper brand. The consumer is deceived and the producer of the genuine gin loses business. In order for enforcement agencies to apply appropriate consumer protection laws, analytical evidence is required to check the authenticity of suspect samples. The two important tools deployed here are botanical congener analyses (as described above) and authenticity indicators, where brand owners are able to detect a unique flavouring or a trace added component that is unique to their brand.

Further reading
Vodka, Gin and Other Flavored Spirits. R I Aylott, in Fermented Beverage Production, Second Edition, Eds: A G H
Lea and J R Piggott, Kluwer Academic / Plenum Publishers, New York, 2003, 289 – 307.