Lighter Than Air: Low Carb and Gluten Free Beer

Low carb and gluten free beer are two different things that often get asked for in the same breath. This guide explains both, what you need for each, and how to brew them at home without giving up on beer that actually tastes like beer.

• DifficultyEasy, if you can brew a kit
• Hands-on timeAbout 30 minutes, the same as any kit
• Ready inAbout 4 weeks
• You'll needA normal brewing setup, plus Dry Enzyme or a gluten free kit

Two Different Questions #

It is easy to mix them up, so let us untangle them first:

	Low carb beer	Gluten free beer
What it is	Beer with less leftover sugar in it	Beer made without barley, wheat or rye
How you make it	Add an enzyme so the yeast can eat more of the sugar	Brew from grains that contain no gluten, such as sorghum
Still made from barley?	Yes, so it still contains gluten	No
Who it is for	People counting carbs, or who like a very dry, crisp beer	People avoiding gluten

A low carb beer is not gluten free, and a gluten free beer is not automatically low carb. If someone in your house avoids gluten, skip straight to the gluten free section.

Low Carb Beer #

Where the carbs in beer come from #

Malt contains two kinds of sugar. The simple ones the yeast eats happily and turns into alcohol and fizz. The others, called dextrins, are long chains the yeast cannot break down, so they stay in the finished beer. They give beer its body and a little sweetness, and they are where most of the carbs come from.

What Dry Enzyme does #

Dry Enzyme is a powdered enzyme that chops those long dextrins into small sugars the yeast can eat. The yeast then finishes the job, and the beer ends up drier, crisper and lower in carbs. It is the same idea behind the low carb lagers in the bottle shop.

What changes	What to expect
Carbs	Much lower, because far less sugar is left behind
Body and taste	Lighter, drier and crisper. Lovely in a lager, less so in a stout
Alcohol	A little higher, because the yeast has more to eat. Use slightly less sugar if you want the same strength
Final gravity	Lower than usual, often around 1.000 or just below. That is normal, not a problem
Fermentation time	Often a few days longer. The enzyme keeps working after the main ferment slows

All enzymes are not equal #

You will often see three enzymes on the shelf, and they are easy to mix up because they all promise to turn starch into sugar. They do, but each one cuts at a different stage, at a different temperature, for a different kind of brewer:

Enzyme	What it does	Who it is for
Morgan's Dry Enzyme	Breaks down the dextrins left in beer so the yeast can finish them. Works at normal fermenting temperatures, added with the yeast	Beer brewers wanting a drier, lower carb beer. This is the one for this guide
Still Spirits Distiller's Enzyme (alpha-amylase)	The rough chop. Cuts raw starch into shorter chains and turns a thick grain porridge runny ("liquefaction"). Works hot, while the grain is being cooked	Distillers making a wash from grain or potato. Step one of two
Pure Distilling Glucoamylase	The fine chop. Cuts those shorter chains right down to simple sugar. Used once the mash has cooled, and keeps working in the fermenter	Distillers, as step two after the alpha-amylase

A beer kit or a sugar wash needs no enzyme at all: the malt in the can has already been through this process at the factory, and sugar is already sugar. The distilling enzymes are for brewers starting from raw grain.

How to use it #

1. Brew your kit as normal (our first kit guide walks through it), ideally a lager or pale ale, with dextrose rather than a malty brew enhancer for the lightest result.
2. Add one sachet of Dry Enzyme (Morgan's or Mangrove Jacks) when you add the yeast. Check the packet for your batch size.
3. Ferment as normal, and expect it to take a few days longer.
4. Wait for the gravity to stay the same for 3 days in a row before bottling. With enzyme, a beer can look finished and still be slowly fermenting, and that is how bottles become fireworks.

Pop your first and last readings into our ABV calculator. The enzyme often adds a few tenths of a percent.

Low carb is not the same as low calorie. Alcohol has calories of its own, so a low carb beer that ends up stronger is not necessarily any lighter on the waistline.

Gluten Free Beer #

Ordinary beer is made from barley, which contains gluten. Gluten free beer is brewed from grains that do not, most often sorghum, which is a cereal widely grown in Australia and more often seen in stock feed than in a pint glass. Until now.

The kit #

Mangrove Jacks Craft Series Gluten Free Pale Ale is made with sorghum instead of malted barley. It makes 23 litres of pale ale at about 4.4%, comes with its own ale yeast, and needs 1kg of dextrose, which is also gluten free. Brew it exactly like any other kit.

Expect it to taste a little different from a barley beer: lighter, slightly tart and fruity. Many people come to prefer it, and it is very good cold on a hot afternoon.

Keeping it gluten free #

• Do not add anything malty. Malt extract, brew enhancers, body blends and most specialty grains are made from barley or wheat. Stick to dextrose and the kit itself.
• Check every extra, such as flavourings or a different yeast, if you are adding your own. Hops and dextrose are fine.
• Clean your equipment thoroughly. A fermenter, tap or bottles that have held barley beer can carry traces. If gluten is a serious issue for you, consider a fermenter and bottles used only for gluten free brewing.

If you have coeliac disease or a gluten intolerance, be careful. Home brewing equipment is shared and home brew is never tested, so we cannot promise any home brew is free of gluten. Follow your doctor's or dietitian's advice before relying on it.

Low Carb and Gluten Free? #

Yes, you can do both: add a sachet of Dry Enzyme to the gluten free kit when you add the yeast, and ferment it out fully. You get a drier, lighter, gluten free pale ale. Wait for 3 days of steady gravity readings before bottling, as above.

Very light beers show off any haze, so these two are the perfect excuse to try finings. Our clear beer guide explains how.

Happy brewing, and may your beer be light in carbs and heavy in compliments.