Corn whisky mash bills
Corn whiskey starts with a mash of at least 80% corn. It can be sold young, which makes it attractive to a new distillery. This guide covers the rules, the typical recipes and the cooking that makes or breaks yield.
What makes a corn whiskey
Under US rules, corn whiskey is made from a mash of at least 80% corn and distilled to no more than 80% ABV. If it is aged, it goes into used or uncharred new oak containers at no more than 62.5% ABV. Aging is not required. That separates it from bourbon, which needs at least 51% corn and new charred oak containers.
Those are American definitions. Spirit made in India from maize falls under Indian rules for whisky, which differ and can change. If you plan to sell into the US or use the term corn whiskey on a label anywhere, check the current regulations in that market.
Typical mash bills
A common corn whiskey mash bill is around 80 to 90% corn, with the balance made up of malted barley. The malt supplies enzymes to convert the maize starch. Some recipes include a little rye or wheat for flavour. A simple example for a 1,000 kg mash:
- 850 kg maize (85%)
- 150 kg malted barley (15%)
A recipe like that leans on the malt for its enzymes. Many distillers add commercial enzymes too, especially alpha-amylase during cooking, so they can cut the malt share and still convert fully. Our guide to bourbon mash bills covers the lower corn recipes.
Cooking maize properly
Maize starch is locked in hard, horny endosperm and gelatinises at higher temperatures than barley starch, commonly cited in the range of about 62 to 74 °C for the starch itself. In practice, distillers cook ground maize much hotter, near boiling or under pressure, to break open the grain fully.
A typical atmospheric cook brings a maize and water slurry up to around 90 to 100 °C, holds it for an hour or more with heat stable alpha-amylase to thin it, then cools it to the mid 60s °C before the malt goes in. Under cooked maize leaves starch locked away. You will see it as poor yield. Our guide to cooking maize and wheat covers the schedule in detail.
Grind matters
Maize for distilling is milled finer than barley malt for a malt whisky, since most corn whiskey is fermented and distilled on the grain without lautering. A fine grind exposes more starch to water and enzymes. Too fine and the mash can be harder to handle and more prone to scorching in a direct heated still.
Check the grind with a simple sieve test on each lot. A change in grind changes your yield more often than people expect.
What corn brings to flavour
Corn spirit is sweet, full and oily, with notes of cornbread, popcorn and sweetcorn when young. Unaged corn whiskey is clean and sweet. Aging in used or uncharred oak adds some colour and soft wood notes without the heavy vanilla and caramel of new charred oak.
Fermentation still shapes the result. A cleaner, cooler fermentation gives a sweeter spirit. A longer, warmer one adds more fruit and sometimes more harsh higher alcohols.
Indian maize for a craft distillery
India grows a lot of maize, much of it for animal feed and starch. That makes it widely available, though quality varies. Check each lot for moisture, foreign matter and signs of mould. Maize stored damp in humid weather can develop mycotoxins, so dry storage and moisture testing are basic quality steps, not extras.
Ask suppliers for the starch content and track litres of pure alcohol per tonne. That number, compared lot to lot, tells you whether your cook and fermentation are doing their job.
Distilling corn whiskey
Most corn whiskey is distilled on the grain, so the still must cope with solids. Steam jackets or steam coils with agitators reduce scorching. Direct fired pots can burn the grain onto the base, which gives a harsh, burnt note to the spirit and is hard to clean off.
American producers commonly use a column beer still followed by a pot still doubler. A craft distillery with only pot stills can double distil in the Scottish way, with a stripping run to low wines and a spirit run with cuts. Because the US rule caps distillation at 80% ABV, corn whiskey keeps plenty of grain character either way.
If you plan to sell it unaged, the cuts matter even more. There is no oak to soften heavy feints or sharp heads, so what you collect is what the drinker tastes.
Getting started
Run a small pilot cook with your intended mash bill. Do an iodine test on the mash after conversion: a blue black colour means starch is still present. Record cooking times, temperatures and the final gravity of the fermented wash, then work out your yield before scaling to production.
Common questions
How much corn must corn whiskey contain?
Under US rules corn whiskey must be made from a mash of at least 80% corn and distilled to no more than 80% ABV.
Does corn whiskey have to be aged?
No. If it is aged under US rules, it must go into used or uncharred new oak at no more than 62.5% ABV.
Why is maize cooked so hot?
Maize starch is held in hard endosperm. Cooking near boiling, often with heat stable alpha-amylase, breaks it open so the starch can be converted to sugar.
How do I check that starch conversion is complete?
Use an iodine test on a small mash sample. A blue black colour shows starch is still present.
