Malted barley is also used by every Bourbon maker, but to a fairly small extent, sometimes making up less than 10 per cent of the total recipe, known as the mashbill. If less than that is used, it's possible that enzymes are added to spur the yeast along, but we've never met a distiller who admitted to this practice. The third grain used is either wheat or rye, and in choosing one or the other a few distilleries really start to produce flavours of their own. Wheated bourbons such as Maker's Mark (16 per cent wheat, 14 per cent malt), all of the Van Winkle bottlings (percentages undisclosed), Rebel Yell, W. L. Weller, and Old Fitzgerald (all 20 per cent wheat, five per cent malt), tend to be softer than those made with rye. But this is a rule proved only by exceptions such as the nicely spiced bottled-in-bond rendition of Old Fitzgerald. All other bourbons, and both Tennessee whiskeys, George Dickel and Jack Daniel's, are made with rye as a secondary small grain (the term 'small grain' applies to all grains other than corn used in American whiskeys). Although not every distillery will disclose its mashbill, rye content is usually between 10 and 15 per cent with malt varying between the five to 15 per cent mark. It would be wrong to conclude that all wheated bourbons are soft and mellow while their rye brethren are forthright and spicy. This does work as long as you remember that all generalisations, including this one, are incomplete. The malt aspect, however, is best seen in Maker's Mark and Wild Turkey. We have already stated that Maker's employs 14 per cent malt, and although the Wild Turkey makers are reticent to disclose exact percentages, we have been led to believe that they use a similar quantity. In our opinion both these whiskeys are full-flavoured and aromatic due, in part, to their high malt content.The grains
Most distilleries cook their grains at atmospheric pressure, though a couple cook under pressure to make the process a little faster. Using the more common method, though, the grains must be cooked using the three-step method, cooking the corn first at a temperature of over 60ºC (150ºF) for around 15 minutes. The rye or wheat is then added and the temperature is reduced to about 59ºC (148ºF) for five to 10 minutes. When the malted barley is added, the temperature is reduced again by about three degrees and the mash is allowed to cook for a further 10 minutes. The mash is then cooled to about 23ºC (76ºF) before being transferred to the fermenter where it will meet the yeast.The yeast
Many distilleries boast a strain that dates back, at the very least, to the repeal of Prohibition in December 1933. Some even claim that their strain was kept alive during Prohibition and was first used right after the Civil War. So fearful are Bourbon-makers of losing their yeast strain, that samples are often kept in at least three locations and sometimes in different counties. This means that they are on different power grids so that if one county loses electricity, the precious spores will survive in the other two places. The strain of yeast used by each distillery is its lifeblood, since different yeasts produce varying amounts of alcohol, and different amounts of congeners – aldehydes, esters, and higher alcohols known as fusel oils. Each of these components produces differing predominant flavours in the finished product referred to as jug yeast, simply because it's usually stored in a jug or similar receptacle under refrigeration. When it's time to propagate it in order to 'grow' enough to feed a fermenter full of cooked grains, on 'yeast day' it is added to a dona tub, usually filled with a cooked mixture of malted barley and rye. Dona tubs, presumed to be derived from the Latin wor d donna meaning mother, keep the mixture at the ideal temperature for the yeast to multiply, usually starting out at around six million spores per millilitre and growing to over 100 million. In Kentucky, there's something special about yeast day; a distiller who worked at the Heaven Hill distillery in Bardstown used to make himself a fry-up breakfast in the dona room while he worked with the yeast, feeding himself as he fed the spores.
Whatever the strain, though, when it comes to propagating the yeast, distilleries use different methods. The two main ways of growing it in Kentucky are the sour-yeast-mash-method and the hopped-yeast-mash-method. The first adds lactic bacteria to the cooked grain soup used to propagate the yeast, but hops – yes, hops – are substituted in the latter. “Why do you add hops?” we asked when we first heard of this custom. We were answered by a puzzled look and a mumbled, "Well, that's the way my Daddy did it."The addition of either lactic bacteria or hops to the yeast mash, actually alters the pH balance in the mash and provides a friendlier environment for the yeast to multiply. What difference does the chosen method make to the finished product? We can't find a common thread, but we do know that one distiller who usually uses lactic bacteria once experimented with a hopped yeast mash and swears that the resultant whiskey just didn't taste like his usual tipple.The backset
Before the cooked mash and yeast is put into the fermenter a liquid known as backset must first be added. Backset is also known as sour mash which is is simply the liquid drawn from the mash of grains after distillation. It is added to the mash in order to control the pH balance, providing a suitable environment for the yeast to do its work. The backset usually makes up over 20 per cent of the total mash. Every brand of straight American whiskey on the market today is made by the sour mash method.The fermenters
Many fermenters in Kentucky are made of cypress wood, and although some distillers claim that this makes a difference to their final product, we know of one distillery that experimented with just one stainless-steel vessel for over eight years before deciding that the whiskey produced from it was no different than that made in cypress fermenters. Depending on the temperature, total fermentation, resulting in a mash with an alcoholic content of around 10 per cent, will take three to four days. Some distilleries control the heat of the fermenters with water-filled coils fitted to the interior, and are able to decide how long the fermentation will take (perfect for two batches during a seven-day week). The mash is now known as beer, or distiller's beer, and it's ready for its primary distillation.The stills
With just one exception – the Labrot and Graham Distillery – American whiskey-makers use continuous stills for their primary distillation. Although the resultant liquid is sometimes referred to as 'low wines' since it runs off the still at between 55 and 62 per cent abv (alcohol by volume), technically this is already a distilled spirit. The low wines are then run through one of two types of secondary stills: a doubler or a thumper. Doublers are basically pot stills, and although most are nowhere near as elegant as the ones in Scotland, they do the job. Many doublers look like giant cans of baked beans with an upturned funnel sitting on top, and although a few are made of copper, some merely have sheets of copper sitting inside. The purpose of the copper is to strip the spirit of sulphur compounds that would produce off-notes in the whiskey.Thumpers look just like doublers But their purpose isn't technically to perform a secondary distillation since the vapours from the continuous still are merely piped into the bottom where they bubble through water and make, well, a thumping noise, as they travel. So here's yet another way that American whiskey-makers can differentiate their whiskeys, though we challenge anyone to be able to tell us which bourbons emanate from either type of still merely by tasting them.The real craft of the stillmaster in America comes down to the proof at which the new spirit runs off the secondary still. By law, all straight whiskeys made in the United States must run off the final distillation at less than 80 per cent abv. But to our knowledge, no bourbon or Tennessee whiskey runs off at above 70 per cent abv, and most are distilled at even lower proofs. We have seen many a Scottish eyebrow raise upon hearing this fact, simply because this is an expensive
proposition. A gallon of whiskey at 80 per cent abv will fill far more bottles when brought down to, say, 43 per cent, than a gallon of whiskey that runs out at around 65 per cent, as is the case with many American whiskeys. Why do American distillers do this? They want flavour. When whiskey ages, the congeners develop into the 'flavour particles' in the spirit and whiskeys that come off the still at lower proofs contain more congeners. The resultant whiskey has more flavour.The boilermaker
Americans reading this piece know only too well that a boilermaker is a wonderful liquid duet comprising of a shot of whiskey with a short beer alongside. Others might despair, but don't worry, they don't get mixed together. Usually the shot is downed in one and the beer sipped or gulped afterwards. In fact it feels time for a boilermaker now since we are wrapping up our whisky saga for this issue. You may have noticed that we haven't yet looked at the ageing process, the barrels, the filtration, nor the difference between Bourbon and Tennessee whiskey. Well that’s all for next time. The history American whiskey-making started back in the 1700s when farmers on the East Coast used their surplus grains to make a little hooch for their own use. Usually, they used rye as their grain of choice; most were familiar with it and as new immigrants from Europe, they weren't yet familiar with American corn. But although they made whiskey, we probably wouldn't recognise it as such – they rarely aged it so it probably tasted like cheap white rum (all spirits taste somewhat similar when they run off the still). Later in that century, when pioneers started heading westward where corn was cultivated in massive quantities, farmers used what was plentiful and close at hand to keep them warm at night. And typically, some made better whiskey than others and became full-time distillers who bartered their whiskey with neighbours who had other talents. By the end of the 1700s, whiskey was being shipped down river to places such as New Orleans from a little place in Kentucky called Limestone Springs. And Limestone Springs just happens to have been in Bourbon County.