The global diversity of distilled spirits
Posted: 14 October 2016 | | No comments yet
Paul Hughes, Assistant Professor of Distilling, Oregon State University gives us an excellent insight into the diffusion and diversity of spirits…
The inception of alcoholic drinks was invariably driven by the availability of local raw materials that could be effectively converted into fermentable substrate. In this way, wine therefore developed in regions where grapes were plentiful – particularly around the Mediterranean Sea – whilst beer made from barley was relatively widespread, being brewed both in Northern Europe and in sunnier climes, reflecting the broad range of climates in which barley can thrive. Fast-forward from the edges of prehistory and, with the increasing movement of agricultural commodities and final products globally, we can see examples of previously regional spirits (e.g. brandies, whiskies) being produced in non-traditional locations. Indeed to protect these various spirit categories, Scotch whisky, French brandies and tequila, in particular, are clearly defined in terms of their production, with regulations also clearly identifying restrictions as to the locations where such products can be made.
The production of distilled spirit-based drinks can be broken down into three broad operations: the preparation of a fermented extract; distillation; and downstream elaboration (Figure 1). Nevertheless, the diversity of raw materials used and the desired characteristics of the final products mean that there are many process variations across the distilled spirits sector. Here we review the global diversity of distilled spirits and compare and contrast methods of production.
Figure 1: Routes to the production of distilled spirit drinks. Pre-distillation stages are dictated by raw materials required and the micro-organisms used to perform the fermentation, whilst post-distillation, there is considerable diversity depending on the final drinks style and market positioning.
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In principle any raw material of agricultural origin that yields a source of fermentable sugars can be fermented and then distilled into a final spirit. This is broadly equivalent to the sugar/carbohydrate-bearing foods that have been consumed for millennia by populations across the globe (Figure 2, page 8). The raw materials used can be classified according to the complexity of the sugars contained. This is useful as most fermentation organisms work much more quickly on simple sugars. Indeed, most yeasts are unable to process complex carbohydrates and so need to be processed to break down complex carbohydrates into simpler, fer – mentable sugars.
The simple sugars are usually sucrose, glucose and fructose, all of which can be assimilated by a broad range of fermentation organisms to produce alcohol. The main complex carbohydrates used for alcohol fermentation are starch and inulin. Starch is made up of polymers of glucose whilst inulin – found principally in Agave for tequila production – is essentially a fructose polymer. So, for these to be effectively converted into alcohol they need to be hydrolysed. In the case of starch, amylase enzymes efficiently reduce starch to a range of simple sugars, including maltose, glucose and maltotriose.
For whiskies and brandies, in particular, strains of Saccharomyces cerevisiae are popular…