Pure Corn whiskey is made from the simple and natural ingredients: corn; malt; water; and yeast. The mash should be composed of 80 to 90% corn with a 10 to 20% adjunct of malt to supply enzymes. Malt enzymes will be explained below and in the chapter on Mashing.
Corn in most of its forms (e.g. cornmeal, corn flour, flaked maize) can be used to make whiskey. The corn must be top quality food-grade corn. Any attempts to use cow corn or chicken feed will only produce inferior results, possibly with noxious off-flavours due to additives that may be present in the feed.
The starches in hard grains such as cornmeal or corn flour require dispersing in the mash water by performing a full boil for about 20 or 30 minutes. This is described in Appendix A - Other Mashing Methods. However, with flaked maize, which is already-dispersed corn that has been hot-rolled the way rolled oats are made, the grain starches readily disperse into the 65.5oC (150oF) mash water without the need of boiling.
Not having to boil the grain makes for a considerably more convenient mashing process, and for that reason flaked maize has been chosen as the primary form of corn in this text. How to mash other forms of corn as well as other types of grain is described in Appendix A.
Flaked maize can be purchased at most health food or bulk food stores. Some such stores don't stock it because the demand for it for home use is fairly low, but most will gladly order it for you since it comes from the same distributors that supply all their other grain products. You may have to ask them to order it anyway even if they do carry it since you will generally want a 22.7K (50 lb) bag of it, which is often more than they will have on hand. Ordering it typically takes about a week. It can also be purchased at home brewers' supply shops.
At full retail price, flaked maize usually costs a little more than cornmeal, but if you buy a 22.7K (50 lb) bag it will be cheaper than the retail price of cornmeal.
The word "malt" describes a process, as much as it is the name of certain grain products.
Any type of grain can be malted. That is, sprouted then kiln dried to kill the sprouts. When grain is just beginning to sprout it produces many different enzymes to break down the endosperm (i.e. the large starchy mass in each kernel of grain) to provide food to nourish the rapidly growing grain plant. The sprouts are heated in a kiln at this early stage to kill them and preserve both the enzymes and the endosperm before the young plants consume them. The malt can then be used as a source of enzymes to convert grain starches, including its own, to fermentable sugars in a beer or whiskey mash.
Of the many different enzymes produced during malting, the diastatic enzymes (i.e. enzymes that convert starch to sugar) are the most important to mashing. Also of importance to mashing are the protein degrading enzymes. These produce nutrients that improve yeast performance in the subsequent fermentation step.
Most of the common grains (e.g. corn, rye, barley, wheat) are available in malted form, but barley malt is by far the most widely used for making whiskey, and is therefore the choice in this text.
The best place to buy barley malt is from home brewers' supply shops. These shops sell many varieties of barley malt, but only certain ones are suitable for making whiskey.
First of all, malt extract (available as syrup or powder) has no diastatic enzymes and cannot be used for mashing. Only certain varieties of all-grain barley malts have the diastatic enzymes needed to convert the comparatively large quantities of starches in a whiskey mash to sugar.
All-grain barley malts come in different varieties from pale malts to caramelized malts to a full spectrum of roasted malts. Only the pale ale or light lager malts stated to be of high diastatic power are suited to making whiskey. The caramelized and roasted malts have, for all practical purposes, no diastatic power. Fortunately, the above-mentioned pale ale and light lager malts are the main staples of all-grain brewing and are the most abundant varieties stocked by the home brewers' shops. They are usually the least expensive varieties as well.
There are two types of high diastatic pale malts, two-row and six-row, and most home brewers' shops carry both. Six-row barley malt is well known to have the highest diastatic power. Six-row barley kernels are smaller than two-row because their endosperms are smaller. Even though the kernels are smaller, each kernel produces the same amount of enzymes as larger kernels. With smaller kernels there are more kernels per kilogram of malt, and therefore more enzymes per kilogram. However, this is no longer of concern. The well-modified high diastatic two-row pale malts made nowadays have very nearly the same diastatic power as the six-row malts and work just as well for making whiskey.
A lot of home brewers' shops also carry wheat malt and rye malt among their malt selection. These malts tend to be of high diastatic power and are well suited to whiskey making. Their use will not be covered in this book, but they can be substituted unit for unit for barley malt in any of the procedures described in the following chapters. After you are comfortable with the processes of whiskey making, it is worthwhile experimenting with different grain malts.
One last word about malt is the crush. In order to mash with malted grains they have to be crushed with a grain grinder. Nearly all home brewers' shops will crush the grain for you, or avail you of an on-premise grinder you can use to crush the malt you are buying.
Beer mash requires sparging (i.e. a process of rinsing the sweet liquid from the spent grains after the starch conversion is complete). In order to sparge, the grain must form a filter bed that is loose enough to allow the liquid to pass through it. This requires a fairly coarse crush.
Whiskey mash doesn't require sparging so the crush can be much finer. A finer crush exposes slightly more of the enzymes and starch to the mash and is therefore beneficial. If the grain grinder is adjustable, adjust it for a fairly fine crush. If it's not adjustable, as a lot of roller mills aren't, the regular brewers' grind will work just fine.
The Scots and the Irish have maintained for centuries that the secret to making good whiskey lies in the mash water used. Modern science has revealed that the characteristics of the mash water are not only important to the quality of the whiskey, but some (e.g. iron content, and pH) are pivotal to the function of the malt enzymes.
The water used must be very nearly devoid of iron. A high iron content will denature (i.e. destroy) the enzymes. On the other hand, a fairly high calcium content (50-250 Parts Per Million (ppm)) is beneficial to the subsequent fermentation and the resulting flavour of the finished whiskey.
Sulphates are preferable to carbonates or bicarbonates, but all are acceptable in the process. If you are adding calcium (explained in the chapter on Mashing) choose calcium sulphate (gypsum) over calcium carbonate (precipitated chalk)
pH: pH is a measure of the acidity or alkalinity of an aqueous solution (i.e. a solution in water). A pH of 7 is exactly neutral, neither acid nor alkaline (e.g. pure water). A pH below 7 is acidic, the lower the pH the stronger the acidity. A pH above 7 is alkaline, the higher the pH the stronger the alkalinity. The full range of the pH scale is from 1 through 14.
Malt enzymes will function in a pH from as low as 4.6 to as high as 8.0. However, at the extremes the starch conversion will be very slow and incomplete. The optimum range is from 5.2 to 5.5, but conversion does work very well at 6.0 and even as high as 7.0.
Most source waters, even some of the best, will require some pH adjustment. This will be discussed in detail in the chapter on Mashing. Very few source waters are too acidic for mashing. Almost all are either close to neutral or are alkaline. Virtually all municipal tap waters are alkaline. Most have a pH between 8 and 9, but some are carefully adjusted to around pH 7.4. If a municipal tap water were even slightly acidic (e.g. pH 6.9), over a period of years the water would corrode the metallic parts in the water distribution system. Because of this, municipal water treatment plants ensure the water is not acidic by passing the water over crushed limestone, which is a crude unrefined form of calcium oxide (CaO). CaO turns to calcium hydroxide (Ca(OH)2) when mixed with water. This process is very cursory and does not offer very precise control over the resulting pH, so the resulting pH typically varies between 8 and 9. Some municipal water treatment plants use purified calcium hydroxide (Ca(OH)2) instead of crushed limestone and adjust the pH to an exact value such as 7.4. Either way, the pH needs adjustment downward for mashing.
Most municipal water treatment plants will happily send you a copy of their current water analysis. All you really need to look at is: the overall hardness level; iron content; calcium content; and pH. Although hardness, in of itself, is not bad for mashing, it's generally preferable to have fairly soft water (i.e. overall hardness level of 8 or less). Iron content should be very low, if not zero (i.e. less than 25 ppm). A preferred calcium content is between 50 and 250 ppm, but if it's higher this is not a significant concern, and if it's lower gypsum can be added. The pH will invariably be too high, but this can be adjusted as discussed in the chapter on Mashing.
If suitable source water is not available, you can use deionized or distilled water as sold in pharmacies and supermarkets. It's advisable to add 10 ml (2 tsp) of gypsum (calcium sulphate, CaSO4) per 20L of pure water. This will establish a calcium content of about 150 ppm.
In the end, what we are doing here is emulating some variation of the mountain spring waters used to make the world's finest whiskies. Some of the more well-known regions are: the Scottish Highlands; Ireland; Kentucky; Tennessee; and many other areas in the Appalachian Mountains.
Yeast is a living organism and is in the mould family of plant cells. The yeast used for fermenting grain mash can be any brewers' yeast. Bakers' yeast is simply a form of brewers' yeast, and works just as well. However, commercial whiskey distilleries use specific strains of brewers' yeast, and these strains are closely guarded proprietary secrets. And, each whiskey distillery seems to have its own strain.
A home brewer can go to a commercial brewery and most breweries will gladly give them a sample of their particular strain of brewers' yeast. But, a home distiller cannot seem to get a commercial whiskey distillery to share their proprietary yeast strain.
Anyway, baker's yeast works excellently, and each different strain of pure brewers' yeast (e.g. as produced by Wyeast®, Brewers' Choice®, or YeastLabs®) (available at home brewers' supply shops) gives a slightly different nuance or character to the finished whiskey. With one strain of pure yeast the whiskey will have a distinct nutty character, with another the whiskey will have a creamy flavour, and so on. It's certainly worthwhile experimenting with different strains of brewers' yeast, but until you are thoroughly comfortable with the process, it's highly recommended that you stay with bakers' yeast.
Turbo Yeasts: Over the past ten years, a series of yeast preparations for home distillers has been introduced called Turbo Yeasts. Most of these Turbo Yeasts are produced in Sweden, and they are absolutely excellent for producing pure alcohol for vodka, gin, and essence-based spirits. Turbo Yeasts come in packages of 90 to 200g and are typically formulated to ferment a 25L batch of straight sugar and water. They usually ferment 5 to 8K of sugar per batch and they produce from 13 to 20% alcohol depending on how much sugar they are designed to ferment. For the 13 to 14% formulations, they ferment in two to four days. For the higher alcohol contents like 17, 18, and 20%, they take up to two weeks.
Turbo Yeasts are comprised of a high-alcohol-tolerant yeast strain mixed with yeast nutrients to supplement the nutrient-lacking sugar-and-water substrate they are designed to ferment.
These Turbo Yeasts have improved significantly every year since they were introduced about ten years ago, and it is anticipated that the advancements in genetically engineered yeast strains will open the door to other dimensions of improvements.
However, grain-mash fermentation has little to gain from Turbo Yeasts. As mentioned above, Turbo Yeasts are formulated to ferment very high percentages of alcohol in very nutrient-deficient substrates. Grain mash fermentations are neither high-alcohol nor nutrient deficient, and therefore do not need a Turbo Yeast. It's much like adding chemical fertilizer to watermelons growing in a manure heap. It's great stuff, but they just don't need it.
Where to buy yeast: Most people are familiar with buying bakers' yeast in supermarkets in small envelopes or jars intended for home baking. But, for the quantities required for making whiskey this would be a prohibitively expensive way to buy bakers' yeast. Bakers' yeast can be purchased very cheaply in bulk from: a supermarket baking section; delicatessen; health-food store; or bulk-food store. Most bakers' yeast nowadays comes in dried granules called "active dried yeast", however, some bakeries still sell it in "yeast cakes" which is a wet creamy form that resembles a pound of butter in its packaging. This form doesn't keep nearly as long as active dried yeast, and you have to use 2^ times as much to get the same number of yeast cells. For example, if a recipe called for 60g of active dried bakers' yeast, you would have to use 150g of bakers' yeast cake.
For pure brewers' yeasts, you can buy them at home brewers' supply shops. These yeasts usually come in liquid form in vials or foil envelopes. They are quite expensive and the quantity is usually quite low. In order to use these yeasts you will have to make a yeast starter to build up the yeast population as is done for home brewing. This is usually explained on the yeast packaging.
For any yeast you are buying you should always check the "use by" date. Expired yeast will not work for fermentation.
Calcium Sulphate (CaSO4)
Calcium sulphate, aka gypsum, is used to increase the calcium content of the mash water. This helps to prepare a mash water that emulates the properties of the mountain spring waters used to make the finest whiskies in the world.
Calcium sulphate can be purchased at home winemaking and brewers' supply shops or at chemical suppliers.
Gluco-amylase is a laboratory-prepared enzyme that is used in mashing to reduce, if not eliminate, the proportion of unfermentable sugars in the mash. Mashing using malt enzymes produces a small proportion of unfermentable sugars (dextrins, and polysaccharides). In brewing, these unfermentable sugars are essential to the body and malt character of the beer, but in distilling they only represent lost alcohol yield. By employing gluco-amylase, these unfermentable sugars are converted to fermentable sugars and thereby increase the overall yield.
Gluco-amylase as used in the distilling industry is produced by pharmaceutical companies and is not easily accessible in small quantities by the home distiller. Another form of it is packaged for homebrewers to be used in making dry beer, and can be purchased at home brewers' supply shops. It's often just called "amylase" in these shops.
Some home distillers have observed that the use of homebrewers gluco-amylase has very little affect on the reduction of unfermentable sugars, and have decided to stop using it altogether. It's suggested that you prepare a batch or two without using gluco-amylase and compare the Terminating Gravity (TG), explained in the Chapter on Fermentation, to the TG of batches prepared with gluco-amylase. If the gluco-amylase is working well you will observe a noticeably lower TG when it is used.
95% Sulphuric Acid (H7SO4)
95% sulphuric acid is used to adjust the pH of the mash water downward. This is covered in the chapter on Mashing. Very small amounts, in the order of 10 to 15 drops per 20L, are ever used.
Sulphuric acid is an extremely dangerous and corrosive strong acid and should not, under any circumstances, come into contact with any part of the body or clothing. It should always be stored in a tightly closed container, out of the reach of children. Furthermore, it should only be handled by persons suitably schooled in laboratory procedures for handling strong acids.
If you are not comfortable with the idea of handling strong acids; citric or tartaric acid (available at home winemaking supply shops) is perfectly harmless and not poisonous, and can be used with acceptable results. However, since they are weak acids, more will be required to achieve the same pH-lowering results.
If using sulphuric acid, it should be the common commercial grade available from chemical suppliers as 95% H2SO4, NOT battery acid used in the automotive industry. Automotive battery acid contains depolarizing agents and other toxic compounds. Also, it's typically only about 5% H2SO4.
Calcium Carbonate (CaCOQ
Calcium carbonate, aka precipitated chalk, is used to adjust the pH of the mash water upward. This is covered in the chapter on Mashing.
Calcium carbonate can be purchased at home brewers' supply shops or at chemical suppliers.
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