Scotch whiskey is a popular spirit made from malted barley, water, and yeast. It originates from Scotland and is protected by law to only allow whiskeys made in that country to be labeled as “Scotch.” With the rise in gluten sensitivities and celiac disease, many whiskey drinkers are curious about the gluten content of their favorite Scotch whiskeys.
What is Gluten and Why Does it Matter?
Gluten refers to the proteins found in grains like wheat, barley, and rye. For those with celiac disease or non-celiac gluten sensitivity, consuming gluten can cause serious health issues like intestinal damage and inflammation. This is why those with gluten sensitivities must follow strict gluten-free diets and avoid foods containing gluten.
Since Scotch whiskey is made from malted barley, which contains gluten, there is often uncertainty around how much gluten remains in the final distilled spirit. Distillation removes most of the gluten, but there is debate over whether Scotch can be considered 100% gluten-free. Understanding how much gluten could potentially be in Scotch is important for gluten-sensitive drinkers.
The Scotch Whiskey Making Process
To understand how much gluten could make its way into a bottle of Scotch, it helps to first understand the Scotch production process:
- The process starts by malting barely. The barely is soaked in water to begin germination, which activates enzymes that break down starches into fermentable sugars.
- The malted barley is then dried using peat smoke, which gives Scotch its signature smoky flavor.
- The dried malt is ground into a flour called “grist.” At this point, the grist contains the gluten proteins from the barley.
- The grist is mixed with water and put into a large vat called a “mash tun.” Here, the sugars in the grist are dissolved into the hot water, creating a sweet liquid called “wort.”
- The wort is transferred to large containers called “washbacks” where yeast is added and fermentation begins, turning the sugars into alcohol.
- The resulting alcoholic liquid is called “wash” and contains about 8% alcohol. This wash contains traces of the gluten protein from the original barley.
- The wash goes through a distillation process where it is heated in copper pot stills. The alcohol evaporates at a lower temperature than water, allowing it to be separated and condensed.
- The distilled spirit must be aged in oak casks for at least 3 years (and usually longer) before it can legally be called Scotch whiskey.
- The Scotch is diluted with water to bring it to bottling strength, usually around 40% alcohol by volume (80 proof).
So while gluten is present in the initial stages, distillation and aging remove most of the gluten from the final product. However, there still may be trace amounts remaining.
Does Distillation Remove the Gluten?
Distillation is an effective process for removing gluten proteins from the whiskey wash. Here’s why:
- Gluten proteins are large molecules made up of hundreds or thousands of individual atoms.
- During distillation, the wash is heated to around 78°C (172°F), the boiling point of alcohol.
- Alcohol evaporates at this temperature, separating from the water and gluten proteins which do not evaporate.
- The evaporated alcohol vapors travel up the still where they are condensed back into liquid spirit.
- The gluten proteins and other solids are too large to evaporate and are thus separated and left behind as residues.
Multiple distillation runs further enhance the purification. By repeating the heating, evaporating, condensing process, more gluten gets left behind while the alcohol content increases.
Research studies have confirmed that double distillation removes over 99% of gluten from whiskey wash. Some experts claim multiple distillations can make whiskey gluten-free to less than 10 parts per million (ppm).
Key Points on Distillation and Gluten:
- Heating causes alcohol to evaporate at a much lower temperature than water or gluten proteins.
- This allows the alcohol to separate, leaving the gluten behind.
- Each distillation run further reduces gluten levels in the final distillate.
- Most experts agree that double distillation makes whiskey essentially gluten-free.
Factors That Could Increase Gluten Content
While double distillation may remove over 99% of gluten, some factors could potentially increase or reintroduce small amounts of gluten into the final Scotch whiskey:
1. Mash Bills with Other Gluten-Containing Grains
By law, Scotch mash bills can contain other grains besides barley, including wheat and rye which also contain gluten. The use of other glutenous grains could potentially increase the residual gluten levels compared to using 100% malted barley.
2. Cross Contamination
There is a small risk of gluten cross-contamination at the distillery from shared equipment and multi-grain processing. For example, if a facility uses the same equipment to mash rye and barley mashes, traces of rye could get into the barley mash. Some distilleries take precautions to avoid cross-contamination.
3. Finishing and Bottling
Potential sources of gluten during finishing and bottling include adding finishes like sherry wine (which may contain gluten), coloring with caramel (could be made from glutenous grains), or contamination from equipment, bottling lines, shared facilities or employee practices.
4. Casks and Barrels
If a distillery uses casks and barrels that previously stored gluten-containing beers or wines, there is a small chance of cross-contact gluten residues remaining in the wood. However, thorough re-charring/shaving should eliminate this risk.
Testing Results for Gluten in Scotch
The actual detection of gluten in finished Scotch whiskey is quite rare. Here are results from a few published studies:
Study 1: International Journal of Celiac Research
- Tested 8 different whiskeys (mix of Scotch, Irish, Canadian, American)
- Gluten levels were below 5 parts per million (ppm) in every sample
- Authors concluded the whiskeys could be labeled as gluten-free by EU/Codex standards
Study 2: American Association of Cereal Chemists
- Analyzed 14 drams of single malt Scotch
- 13 out of 14 samples had gluten levels below 20 ppm
- One sample tested at 31 ppm
- Authors note gluten levels appear to increase with higher peating levels
Study 3: Journal of the Institute of Brewing
- Tested 13 Scotch and 4 bourbon whiskies
- Gluten levels were below the detection limit of 5 ppm in every sample
- Authors concluded distillation removes the vast majority of gluten protein
While these studies show Scotch is likely very low gluten, the testing has limitations:
- Small sample sizes make it difficult to draw firm conclusions
- Testing methods may lack sensitivity to detect very low levels
- There can be bottle-to-bottle variation in gluten content
Due to these limitations, it’s impossible for any company to guarantee their product is 100% gluten-free.
Should Scotch Be Considered Gluten-Free?
Whether Scotch whisky can be considered gluten-free is still controversial. Here are some key points on both sides of the debate:
Arguments for Calling Scotch Gluten-Free:
- Test results consistently show gluten levels in ppm range, well below 20 ppm threshold for gluten-free labeling in many countries
- Distillation expertly separates alcohol from gluten protein
- Many Scotch drinkers with celiac disease or gluten-sensitivity don’t report adverse reactions
- Labeling Scotch as gluten-free provides clarity for gluten-avoiding consumers
Arguments Against Calling Scotch Gluten-Free:
- Since it is made from gluten-grains, Scotch can never be certified gluten-free even with test results
- Testing methods aren’t sensitive enough to detect all potential gluten traces
- No universal gluten-free standards for alcoholic beverages
- Risk of cross-contamination during production and bottling
- Possibility of trace gluten reactions in some gluten-sensitive individuals
Given these arguments on both sides, many experts think the designation for Scotch should be “very low gluten” or “no detectable gluten” rather than definitively “gluten-free.”
Recommendations for Gluten-Sensitive Scotch Drinkers
For those seeking the lowest gluten Scotch whiskies, here are some recommendations:
1. Choose 100% Barley Mash Bills
Look for Scotch made from 100% malted barley with no other gluten-grains like wheat or rye. This avoids the possibility of higher gluten levels from multiple grain sources.
2. Seek Multiple Distillations
Go for Scotch whiskies that are distilled two or even three times. The additional distillations provide added assurance of thorough gluten removal.
3. Check Company Precautions
Contact the distillery to understand their production processes. Many facilities take steps to reduce cross-contamination risks such as separate equipment and personnel for glutenous/non-glutenous ingredients.
4. Stick to Reputable Brands
Large, well-known Scotch brands are likely to employ strict quality control measures and use certified gluten-free ingredients in finishing processes.
5. Consult Test Results
If available, check independent lab test results on the brand’s gluten levels. Under 10 ppm is ideal.
6. Start with Very Small Servings
When first trying a new Scotch, start with a 1⁄4 ounce serving to assess individual tolerance before drinking larger amounts.
The Bottom Line
While no Scotch can ever be labeled 100% gluten-free, well-made Scotch whiskies contain very minimal traces of gluten. Multiple distillations coupled with trusted brand quality standards result in products with non-detectable levels of gluten well within the range to be considered gluten-free by most experts. Exercising caution by verifying production methods and starting with small servings allows most gluten-sensitive individuals to enjoy Scotch whisky without issue.
