Oats

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General

Oats (Avena sativa)

Oats are a member of the Avena genus in the grass family (Poaceae). The common oat (Avena Sativa) is the cultivated variety grown most widely worldwide for human and animal consumption. Other cultivated varieties include the Naked oat (Avena nuda), the Ethiopian oat (Avena abyssinica), and the Bristle or Black oat (Avena strigosa) grown for livestock. Annual global oat production is approximately 25 million metric tonnes, making it seventh in the list of global cereal production (see graph).[1] Oats originated in the Fertile Crescent of Egypt and Mesopotamia and eventually were domesticated throughout the Middle East and Europe around 4000 BCE where they frequently grew alongside other cereal crops (as "weeds").[2] Oats grow well in cooler, wetter conditions.

Source: Food and Agriculture Organization of the United Nations


Are oats gluten free?

Oats can be a controversial topic in the gluten free world. For one, they contain avenin, a protein similar to the celiac-reactive gluten prolamins found in wheat (gliadin), barley (hordein), and rye (secalin). Oats have a much higher ratio of globulin (75-80%) to prolamin (10-15%) proteins in comparison to wheat (where prolamins, inversely, represent about 80-90% of the protein content). Several studies have looked at oat tolerance among celiac patients (examining damage to villi) with the conclusion that many, but not all individuals with celiac disease can consume oats without negative impact.[3][4]

Because they are often grown or processed alongside gluten containing grains, oats are also a high risk cereal (from a cross contact/contamination perspective) unless they have been grown and processed to mitigate this risk. While some countries (Canada and United States for example) designate "gluten free oats" that meet those standards, government and celiac agencies in other countries (e.g. Argentina, Australia and New Zealand) do not consider any oats to be gluten free.[5] Noting uncertainty of testing, a 2015 Coeliac Australia position statement recommends that people with CD do not consume oats and Food Standards Australia and New Zealand (FSANZ) guidelines stipulate that beers labeled gluten free cannot contain oats.[6] However, recent genomic analysis[7] with involvement from Australian researchers[8] suggests oats are a high value food with low risk for individuals with celiac disease.[9] In Canada the Canadian Celiac Association recommends that individuals with celiac disease wait to (re)introduce oats until they've stabilized on a gluten free diet (6 - 18 months) and advise that the high fibre content of oats can cause some initial gut discomfort that may be confused with "being glutened".[4] (The CCA also acknowledges that a small percentage of individuals may also have a relapse of celiac-related symptoms due to oats).[10]

In our 2021 survey of Zero Tolerance members worldwide, 20% of respondents strongly or somewhat disagreed with the statement "Certified GF oats are safe for GF brewing". A broader 61% agreed that certified GF oats were safe.[11]

Given that many individuals with celiac avoid eating oats altogether, several dedicated gluten free breweries have opted to exclude oats entirely from their ingredient list. If you are brewing for a celiac audience:

  • It's important to clearly communicate what the ingredients are, including oats
  • Any oat product (flaked, malted, oatmilk, or otherwise) should be certified gluten free (if that designation exists in your country)

Oats in Brewing

History

Though they rarely play a starring role, oats have been used alongside other grains in brewing dating back to the second millennium BCE.[12] Koyt, brewed in the Netherlands in the 15th century, was made from a grain bill of oats, barley and wheat. Horner bier (from what is now Austria) was an all oat malt beer with a slightly tart palate (from the use of potassium bitartrate aka cream of tartar) enjoyed by Amadeus Mozart.[13] And in the north of England and Scotland -- where oat production was significant -- oat ales may have survived to the beginning of the 19th century.[14]

Prior to the 21st century, the most likely modern beer association with oats was oatmeal stout. The Free Mash-Tun Act (aka the Inland Revenue Act) in 1880 expanded the arsenal of grains that UK brewers would consider, especially when barley yields or quality were poor.[15] In the 1890s oatmeal stouts began to appear in the UK (particularly Scotland and northern England). According to Ron Pattinson, the relatively small, Scottish Maclay brewery was the first to innovate on the oatmeal stout style by using malted (vs flaked) oats, going so far as to patent the oat malt stout style.[16] Whether due to the patent, lack of oat malt access, or challenges brewing with the grain, London stout brewers apparently used only token amounts of oats in their oatmeal stouts (under 1%). Maclay and other northern brewers on the other hand were more liberal in their usage (13% in 1905 and up to 33% in the mid-1960s).

During the Second World War Britain was forced to become more self-sufficient in brewing ingredients (where significant amounts of barley had previously been imported to the country). This extended to the use of oats, particularly after a bumper crop in 1942 and a short-lived (i.e. 1943) government directive to brewers to replace 10% of the barley in each grain bill with oats -- in all beers, not just stouts. With lower extract yields from oats, this meant that milds, IPAs and strong ales had grain bills with oats in the 10 - 17% range during this exceptional period.[17][18]

New England IPAs (NEIPA or sometimes North East or just hazy) began appearing in the 2010s. Unlike the usually clear and more IBU-driven American West Coast IPA variety, NEIPAs have focused on a more creamy mouthfeel, relatively low bitterness and "juicy" hop aroma and flavor. The haze that essentially serves as the vehicle for those hop characteristics is typically due to a combination of proteins from the grains, the polyphenols from the hops, and low yeast flocculation. Though the protein contribution can come from a variety of different grains, conventional (non GF) brewers have frequently harnessed the proteins in wheat and/or oats to more reliably achieve the haze. Credited with providing a creamy mouthfeel, flaked oats have proven a popular choice for this style of beer.

Brewing Properties

Property Estimate / Range Sources
Protein 9 - 11% dry matter Klose[19]
Beta Glucan 1.9 - 5.0 % dry matter Schnitzenbaumer[20]
Extract Potential
Malted		 25 - 30 PPG Grouse[21] Rahr[22]
Starch Amylose: 28%, Amylopectin: 72% Tester[23]
Gelatinization:
Range		 135 - 162 F, 57 - 72 C Hertrich[24] / Janish[25]
125 - 147 F, 52 - 64 C Briggs[26]
113 - 163 F, 45 - 73 C Tester[27]
Gelatinization:
Onset		 111 - 116 F, 44 - 47 C Tester[27]
Gelatinization:
Peak		 133 - 138 F, 56 - 59 C Tester[27]
Diastatic Power
Malted		 13 - 25? Litner Crisp Malting[28]
Diastatic Power
Unmalted (flaked, raw)		 Nil
FAN / Amino Acids 246 mg/L (pale oat malt) Grouse[21]
161 - 172 mg/L Klose[19]
151 mg/L (100% malted oats) Kordialik[29]
89 - 110 mg/L (malted and unmalted oats) Kordialik[29]

Diastatic power

Like other gluten free grains, oats have limited enzymatic capability (diastatic power). There is limited information specifying the diastatic power of malted oats (Crisp Malting cites 17 Litner for their malted naked oats), but the consensus is that it is significantly lower than in malted barley.

Brewing Benefits and Impacts

Mouthfeel

Mouthfeel is one of the prime reasons for using oats in brewing. Beta-glucans are polysaccharides which form from the cell walls of cereal grains. With relatively high levels of this gummy beta-glucan material, oats will generally increase the viscosity (essentially the perceived "thickness") of the wort and final beer. Whether in oatmeal stouts or NEIPAs, oats have the potential to contribute a "creamy" body, though not necessarily creamy foam (see foam impacts below). While starches and proteins can also contribute mouthfeel, brewer and beer writer Scott Janish suggests that a grain bill would need to contain upwards of 18% oats to achieve the 900 mg/L beta-glucan threshold corresponding to viscous mouthfeel.[30]

Haze contribution

The relatively higher beta glucan, protein and nitrogen levels in oats can all contribute to haze.[29] In some beer styles (e.g. NEIPAs) this may be desirable and the intended effect. Glucanase and proteinase enzyme activity during the mash may potentially reduce that impact somewhat.

Stuck mash

The relatively high beta glucan and protein content of oats, combined with lower endogenous glucanase and proteinase activity[29] that would help to break down cell walls and gels, has the potential to reduce wort filtration in grain bills that are high in oats and create a "stuck mash" (consider a bowl of oatmeal's usually gelatinous texture).[25] Techniques for counteracting this problem include:

Foam impacts

There are mostly negative factors associated with oats and head formation and retention. The higher lipid and fat content of oats may be a significant foam-negative influence, (though at least one research paper suggests that the high lipid content of oats does not necessarily lead to a higher fatty acid content of the finished beer, due to uptake by yeast during fermentation).[31] Lower Total Soluble Nitrogen (TSN) and high-molecular-weight proteins in oats may be another foam-negative factor.[20] On a foam-positive note, Schnitzenbaumer indicates that higher viscosity in beer (associated with oats) benefits foam stability by reducing the liquid drainage rate. As Janish summarizes in A Case for Brewing with Oats, the Schnitzenbaumer study found that using up to 10% (unmalted) oats in the grain bill had limited impact on head retention. Above the 10% mark (at 20 - 40%), beers made with unmalted oats did substantially reduce foam retention.[20] See Beer foam and head retention for additional information on influencing foam and head retention.

Oxidation

There may be a greater tendency for beers made with flaked oats to become oxidized, with perceptible (darkening) color changes and development of off-flavors.[32] One potential culprit that has been identified is manganese -- a mineral that occurs in higher levels in unmalted, flaked oats, and that seems to promote more rapid staling in beer through the production of "reactive oxygen species".[33]

Formats

Flaked (aka rolled) oats

This is probably the most readily available format, especially when looking for a "gluten free" designation. Flaked oats are unmalted. Hulled (dehusked) oat groats are steamed (thus undergoing some gelatinization) and then pressed between rollers. This process makes starches more readily available and eliminates the need for a cereal mash step. Flaked oats were originally developed to improve livestock nutrition (gelatinization and rolling making the starches much more readily available and digestible).[34][35]

Malted oats

Per the history section above, oats have been malted in Europe for at least a couple of centuries and more recently in North America, though they remain fairly uncommon. A subset of maltsters in the UK and North America (e.g. Thomas Fawcett, Simpsons, Canada Malting, Haus Malts) offer malted oats, but nearly all of them coming from malt houses that also deal with gluten containing grains (see key considerations for utilizing malts from non dedicated sources). In 2022, dedicated gluten free maltster Grouse introduced an oat malt available for both commercial and (limited) retail sales (via GlutenFreeHomeBrewing.com). Grouse uses certified gluten free oats for malting. The extract potential listed for Grouse oat malt is 25 - 30 PPG.[21] Gluten Free Brew Supply sells oat malt from Haus Malts (a malt house that also malts gluten containing grains) with a listed PPG of 25.

Malted oats have low endogenous enzyme content (low diastatic power), but can be treated like any other gluten free grain in that regard -- either mashing with exogenous enzymes, or leveraging endogenous enzymes from other malted grains. Malted oats -- unlike flaked and whole/steel cut formats -- do have husks, improving lautering (separation of liquid extract from the grain) during the mash. (Malted naked oats would be an exception to this of course, however there are currently no suppliers of gluten free malted naked oats). There is theoretically no ceiling on the percentage of oat malt that would be used in a grain bill, though 10-15% is probably a typical amount in most conventional brewery settings. A 2011 Irish/German study found that brewing with 100% oat malt produced a beer in many ways comparable to a 100% barley malt beer, with some notable findings: oat malt has a lower extract yield, attenuation was lower, unadjusted pH was higher, and foam stability was relatively poor. The oat malt beer had lower acetaldehyde and ethyl acetate levels (two key esters that can create fruity aromas). Butanediol, a product of diacetyl reabsorption by yeast, appeared to be above the taste threshold (which should elicit butterscotch-like aromas). The sensory panel identified raspberry, blueberry, and yoghurt as the primary aroma and flavor characteristics.[19]

Raw and steel cut oats

Oats in less processed form include steel cut and raw (de-husked whole oats usually referred to as groats). Without the additional processing associated with malting or steaming/rolling, starch molecules remain less exposed and available. Grain kernels will be hard and resistant to starch extraction so a cereal mash is recommended to gelatinize the whole grain ahead of the main mash.

Oatmilk

This dairy alternative beverage is showing up occasionally as a novel ingredient in conventional (non-gluten free) beer.[36][37] If you're experimenting with oatmilk in a gluten free beer, ensure that the oatmilk itself comes from a gluten free source. A 2017 Brulosophy experiment comparing a NEIPA made with flaked oats and one made with oatmilk indicated that most blind testers were able to accurately distinguish between the two beers, with the majority (13 out of 18) preferring the flaked oat version. While the two versions initially had a similar level of haze, the oatmilk version became relatively clear soon after keg carbonation.[38]

Alternatives to oats

Unlike oats, there is no controversy around the gluten protein content of the following gluten free grains. Brewing properties of these alternatives may provide similar benefits to oats.

  • Quinoa: Flaked or torrefied quinoa are both high in protein and relatively low in foam negative lipids and fats.
  • Buckwheat: Source of beta glucan (viscosity, mouthfeel).

Zero Tolerance Facebook Discussion Threads

References

  1. ↑ Food and Agriculture Organization of the United Nations data for 2020
  2. ↑ Oxford University: Oxford Plants 400: Avena Sativa L.
  3. ↑ To Be Oats or Not to Be? An Update on the Ongoing Debate on Oats for Patients With Celiac Disease, Cohen et al. (2019)
  4. ↑ 4.0 4.1 Nutrition and Celiac Disease, Catassi and Fasano (eds) (2013)
  5. ↑ Coeliac Australia FAQ on oats
  6. ↑ Coeliac Australia Position Statement on Oats
  7. ↑ Nature: The mosaic oat genome gives insights into a uniquely healthy cereal crop (Kamal et al)
  8. ↑ Coeliac cereal – Research shows oats could be the answer
  9. ↑ Why Oats Are Safe and Healthy for Celiac Disease Patients, Gillisen et al (2016)
  10. ↑ Canadian Celiac Association - Statement on Oats
  11. ↑ 2021 Zero Tolerance Gluten Free Brewing Survey
  12. ↑ Nelson, Max. Beer in Greco-Roman Antiquity. University of British Columbia, 2001.
  13. ↑ On Balling, Mozart, and Oat Beers Where the Sun Don’t Shine
  14. ↑ Ron Pattinson, Shut Up About Barclay Perkins (2008)
  15. ↑ Ian Hornsey, The Oxford Companion to Beer via Craft Beer & Brewing Magazine
  16. ↑ A Brief History of Oatmeal Stout, Ron Pattinson, Craft Beer & Brewing Magazine (2016)
  17. ↑ Ron Pattinson, Scotland! Volume II (Mini book series), 2017
  18. ↑ Ron Pattinson, Shut Up About Barclay Perkins (2020)]
  19. ↑ 19.0 19.1 19.2 Klose, Christina, et al. "Brewing with 100% oat malt." Journal of the Institute of Brewing 117.3 (2011): 411-421.
  20. ↑ 20.0 20.1 20.2 Fundamental studies on the application of enzymes when brewing with unmalted oats and sorghum
  21. ↑ 21.0 21.1 21.2 Personal correspondence with Grouse Malt House, August 25, 2022.
  22. ↑ Rahr Malting Co, oat malt specifications (60 fine grind minimum ÷ 100) × 0.04621 = 27 PPG
  23. ↑ Swelling and Gelatinization of Oat Starches, Tester and Karkalas (1996)
  24. ↑ Hertrich, Topics in brewing: brewing adjuncts, MBAA Tech Quart 50 (2013): 72-81.
  25. ↑ 25.0 25.1 A Case for Brewing with Oats, Scott Janish blog, Janish (2016)
  26. ↑ Brewing Science and Practice, Briggs et al (2004)
  27. ↑ 27.0 27.1 27.2 Swelling and Gelatinization of Oat Starches, Tester and Karkalas (1996)
  28. ↑ Crisp Malting Naked Oat Malt COA
  29. ↑ 29.0 29.1 29.2 29.3 Malted and unmalted oats in brewing, Kordialik-Bogacka et al (2014)
  30. ↑ A Case for Brewing with Oats, Scott Janish blog, Janish (2016)
  31. ↑ Brewing of English-style ales with malted cereals, other than barley, Taylor et al (1998) quoted in Janish, A Case for Brewing with Oats
  32. ↑ How to Reduce Oxidation of NEIPAs, Beer Maverick blog (2021)
  33. ↑ [https://doi.org/10.1094/ASBCJ-2016-2638-01 Manganese in Brewing Raw Materials, Disposition during the Brewing Process, and Impact on the Flavor Instability of Beer, Porter and Bamforth (2018)
  34. ↑ History of Feed Processing, John Matsushima (2006)
  35. ↑ Master Brewers Podcast, Episode 243, Terrified of Being Torrified (2022), Master Brewers Association of the Americas
  36. ↑ https://collectiveartsbrewing.com/beers/stranger-than-coffee-and-oat-milk/
  37. ↑ https://www.marketwatch.com/story/americans-cant-get-enough-oat-milk-now-its-in-their-beer-11614359421
  38. ↑ exBEERiment, Flaked Oats Vs. Oat Milk in Hazy IPA, Brülosophy (2017)
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