Quick and Dirty Science – Steel Cut Oats

TLDR – Lord You Talk Too Much Drew – Executive Summary

It looks like no, Steel cut oats don’t necessarily need to be pre-cooked to use in a mash, but judging by the results I saw – it still helps.

For Those Who Like To Read

I am a huge fan of oats in beer as listeners of the podcast will discover shortly. I tend to use them in a lot of places, because why not. It’s probably because I’m part Scottish or something. (honestly family lineages are so screwy who can tell)

Anywho.. digressions aside. The second episode of the Brew Files – The Crushable Cream Ale, led to me getting tagged on a Facebook homebrewing post about steel cut oats. (Homebrewers Roundtable is a closed group, so you’ll need to ask to be a member of the group.)

Namely, can they just be mashed like normal or should you cook them first? I got tagged because listener Paul Galardy suggested – “maybe they should be cereal mashed and you can hear Drew drone on about it here” (Paul was nicer than my editorializing!)

The question comes – well, the tables that are out there say oats gelatinize at temps lower than mash temps (~125-144F) Basically for oats, that’s the range in which the starches bust out of their cages and go racing free into the soaking liquid. Different cereal grains gelatinize at different temps. You can see from the photo I borrowed from Adam, oats, rye, wheat all happily gooify below saccharification temps. Corn and rice, on the other hand, do not. So that’s why when we talk about Cream Ale (or American Light Lager), you have to talk about pre-cooking the grain.

But not all grain types are equal. I would bet good money that the majority of people think of oats as looking like this.

Those are flaked oats and they’re versitile and wonderful to use. Big thing about flaked grains in general – they’re already gelatinized – hit them with hot water and the starches are free to disperse. That’s why so many brewers will use flaked corn or flaked rice. Less work!

But steel cut oats are a little different, they’re little pieces, but they haven’t been pre-cooked and when made for breakfast, they take a good long while to cook. Is a regular mash hot enough and long enough to hydrate the cereal and get the starch into solution to be enzymatically transformed to sugary good times? See what they look like? (For more information about oat forms – check out this kitchn article)

Steel Cut Oats – Plus Look 20+ years later and sexy knife scar still on the pinky!

The “Experiment”To answer the question at hand, I set up a quick and dirty experiment – two mason jars, 1 sous vide circulator, 1 quart water per jar and ~0.8lbs of domestic 2-row and oats split 50/50. This would put us close to the traditional 1.25 quarts/lb mash ratio many homebrewers use.


Seems so ridiculously tiny, but there you are one pound of Great Western 2-Row
Grind The Barley.

I ground a pound of barley through my lovely MM3 mill to produce a nice even crush.

Crush Your Barley!

Weigh In:

I weighed out 6.4 oz of two row and oats for each jar. This 50/50 ratio is well above what all but the most fool hardy brewers would use, but what the heck. Let’s push this

Weighing in at 6.4oz – The Main Show – US 2-Row

And in this corner – 6.4 oz of Steel Cut Oats
Pre-Heating Jars

When the dumb idea occurred to me, I grabbed my half gallon mason jars, added one quart of water and threw them into a Cambro with my Anova circulator (newer model in link, my old one is discontinued). I set the circulator to 152F and walked away for an hour to let the jars and water heat through.

The Soak

With the water at temp, I mixed the grist into the water and let it soak in the warm bath. Now this is arguably the tactical error I made with the setup. The grains dropped the temps into the high 130’s. To compensate, I let the jars run for 2 hours in the water bath. The first hour was all a slow ramp to 152F and the last hour was the “mash rest” for conversion. Turns out this is about as ideal a scenario as you could get for hydrating the steel cut oats. (Next time, I’ll heat the strike water separately and then dose into the pre-heated jars.)

Time and Temperature Doing It’s Thing

Play with the Hugo While Waiting for the Sciencing to Resume
The Lauter

Take one fine mesh strainer, one giant Rubbermaid pitcher and strain. Each set of grain was allowed to drain. I let the wort drain for about 10 minutes after which we’d collected at least a pint of wort. (In theory we should have collected about 1.2 pints per sample, but I wasn’t being finicky here.)

High Tech!
The Settle

I decided it was best to let some of the massive protein charge in these worts settle first before taking a sample. Oats sure do throw some gunk don’t they. Interestingly that even after an hour, the flaked oats were still messy as all get out. For the record, yes, the fine mesh strainer is a coarser separation mechanism than our usual gear.

After lautering both. The Steel Cut on the left has a 10 minute head start, but it’s clarity was always leaps and bounds. See next pic

One Hour Later – Steel Cut on Left is still much, much clearer
The Tests

I decided to subject the samples to four tests.

  • Mash Taste Test: How did the mash taste? Sweet? Dry?
  • Iodine Starch Conversion: Was there free floating starch in the wort. (The iodine test isn’t exact, but it’s a good rough measure)
  • Original Gravity: How much sugar did we get?
  • Wort Taste Test: How did the wort taste?

The Results:

Steel Cut Oats:

  • Mash Taste: Oats themselves are soft, but still with a bit of tooth. Some noticeable sweetness left in the mash. Remove the barley husk from this and I could totally see this being a Scotsman’s breakfast. (I would seriously eat it)
  • Iodine: The test showed complete conversion and with the wort being clearer, there was no confusion to the readings – iodine went in iodine colored and stayed iodine color
  • OG: ~15.2B (aka 15.2P), compared to the theoretical max of 27.5P means we gathered to the wort ~55.3% of the sugar. This is less than the Flaked (see next section) Makes me a little worried about the overall extract.
  • Wort: Wort tastes very oaty with a hearty mouthfeel and clean nutty component. Definite impact from the oats on the overall character. Would definitely enjoy this in the morning. Might be the ultimate Hot Scotchy.

Contact! Iodine Stays Iodiney (Even after swirling and mixing)

Some days my refractometer photo game is on point. This was not one of those days Steel Cut – reading about 15.2B
Flaked Oats:

  • Mash Taste: This mash was total mush. The oats had no residual presence having just dissolved away. The mash itself was mostly bland, lacking sweetness, indicating it had moved into the wort.
  • Iodine: The test showed complete conversion, though the extra material carried into the wort was causing some color change that eventually settled back to dirty iodine color
  • OG: ~18B (aka 18P), compared to the theoretical max of 27.5P means we gathered to the wort ~65.5% of the sugar. Not too shabby.
  • Wort: Much, much sweeter than the steel cut. The body is much thicker, more viscous. Feels like an old English nursemaid’s recovery drink “Beechum’s Barley Oat Tonic Revitalizes Your Sapped Spirits. Now With Radium for Extra Pep!”

Muddier, but still iodine color (the blotch of purple in the upper corner did fade back)

That’s no horizon, but it’s a lot higher than the steel cut!
Conclusions (aka Finally you get to the point you rambling so and so.)

Ok, so it’s fairly clear that we get extract when using steel cut oats raw in a mash. Even in this dirty test we see the grain softened and starches released. Now, this was also the best case scenario – the oats had a nice long (120 minute) mash, but a good portion of that was the ramp up to saccharification, so the soak would have been slower.

Does this mean I feel comfortable saying “eh, just go and throw your steel cut oats in the mash”? I’m going to say “maybe”. I think there was a fair amount of extract left in the steel cut  compared to the flaked. This leads me to say that if you want a better guarantee of full extract from your steel cut oats, you should probably still cook them first just to give everything a head start.

The steel cut wort was clearer, but I’m not certain that’s going to matter with a proper mash with proper lautering, boiling, chilling and then a whole cycle of fermentation and racking. Besides isn’t oat haze part of all the rage these days?

What was also nice to see was just how much impact the oats had on the worts. If you’ve ever doubted oats were doing anything at the usual brewer’s addition rate of 5-10%, 50% will definitely convince you that there’s an impact.

What do you think? Any ideas for other “quick and dirty” science things we can perform? I did this in a single afternoon because it bugged me I didn’t know the answer.

Experiment – Comparing pellet hops to whole hops

A couple months ago, my friend Mitch Scheele, who writes for the Northwest Brewing News, contacted me about an experiment he wanted to do. He had invented a piece of equipment he calls the “Hop Screw”. It’s a stainless tell cylinder with holes in it, a bar across the top to attach it to your boil kettle, and a plate and screw handle on top. A bit like a stainless cider press. The idea is that you attach it to your kettle before you start collecting wort. The hops go into the cylinder in the kettle and when the boil is finished you screw the plate down to press the hops, recovering trapped wort and hopefully hoppy goodness. His idea was to compare a beer made with whole hops and the Hop Screw to the same beer made with pellet hops. In the format of the book, the question was “How do whole and pellet hops compare in the same beer?” and the hypothesis was “Whole hops pressed with the Hop Screw will give up more oils, leading to a beer with better hop character”.

We settled on a toned down version of the Hop Stoopid recipe from the book “Craft Beer for the Homebrewer” (Voygeur Press, 2014). Toned down meaning we cut the OG back to about 1.065 from 1.080 and the IBU from 321 to “only” about 270. We figured that since it’s such a hoppy beer that it would give us a chance to really evaluate what was going on with the hops. I mashed enough grain to produce 11 gal. of finished beer and we split it between our kettles. As the boil progressed, I tossed my pellet hops in loose and Mitch put loose whole hops into the Hop screw inside his kettle. The Hop Screw seemed to reduce the vigor of the boil a bit, so he compensated by adjusting his burner. Once the boil was over, I began chilling while Mitch screwed his hops (yes, I’ve been waiting to say that!). Each batch was put into a 7.5 gal. bucket to ferment, and the buckets were transferred to tubs of water to maintain fermentation temperatures as closely as possible. Fermentation went on for 2 weeks, then the beers were transferred to different buckets and dry hops added to each for a week at room temperature. The beers were then kegged and allowed to settle.

For the tasting, 2 2L bottles were pulled from each keg, fitted with carbonater caps, and allowed to settle in the fridge for a few days. For the tasting, Mitch brought along his brother and a friend and participated in the tasting himself. Obviously, he knew what the experiment was about, but he hadn’t tasted the beers yet and had no idea which was which. Aaron Brussat, the beer steward at the hottest beer bar around, and Norm Vidoni, who owns an organic hop farm and brewery, also participated. We did a classic blind triangle tasting. Each taster was given 3 samples of the beer in opaque cups labelled A, B, and C and asked to pick out the beer that was different. Beer A was made with pekllet hops and B & C were the beer made with whole hops. Although I had tasted the beers myself and had a clear preference, it was a little bit of a surprise that all 5 tasters correctly identified the different beer. But only a little bit! They were then given a sample of each beer along with a form with questions about the beers. Below are the questions, along with some of the responses. Q

1. Which beer tasted more bitter? Results: 3 A 2 B

Comments A – Apparent immediately on the back of the tongue. Clean crisp finish. Bitter not better. Coats the whole inside of my mouth, lingers quite a bit. Not too harsh or unpleasant

Comments B – Bright but firm. Fairly piquant. Lingers as much as the sweet malt flavors. Bitterness apparent a bit later, stronger later on. More end bitterness

Q2. Which beer had more hop flavor? (3A, 1B, 1 no preference)

Comments A – Citrus, concentrated fruitiness. Grapefruit peel and a bit of pith. Spicy and citrusy

Comments B – Bright and sweet fruit, orange strawberry, guava. Earthier than A, less pithy up front. Citrus, stronger fruitiness.

Q3. Which beer had more hop aroma? (3A, 1B, 1 no preference)

Comments A – Fruity, bold, very apparent citrus. Tropical, mango, guava, some pineapple, red apple. Lower pine/fir notes.

Comments B – Fruity, more mild, mild yeast notes come through. Tropical, but sweeter. Gravitates more toward tangerine. Some sweetness may come from malt/fermentation byproducts. Lemon/grape aroma after drinking

Q4. Which beer did you prefer? (4A, 1B – the B guy doesn’t like bitter beers)

Comments – I preferred A, though it was less balanced than B. The myriad tropical notes in A were pronounced and distinct. I’m not a fan f harsh bitterness so B wins on that count. Tough decision overall. B finishes cleaner, but A has the definition. A aroma much more aggressive. B bitterness more strong, felt sweeter. A with less bitterness at the end. So, there ya go…what was the takeaway from all this? Before we get to that, it’s important to look at some areas where this experiment fell short. For hops with known IBU we matched the IBU between pellets and whole as closely as possible. But 2 of the 4 hops varieties Mitch used were homegrown, so we simply matched weights with those. We did not attempt to account for the reported 10% increase in utilization due to using pellet hops. In retrospect, we might have been better off to use all commercial hops of known IBU.

You also have to take into consideration the age and packaging of the hops. Pellet hops respond to storage better than whole, and despite the fact that all the whole hops were vacuum sealed and kept in a freezer, taking a whiff of the whole hops before use seemed to indicate a bit of oxidation of some of them. The hop aromas were more muted than the pellets, with some very slight off notes. Finally, there’s the terroir aspect to consider. To make this a completely balanced test, we would have had to have pellets made from the same hops as the whole. Chances of that happening are slight, so we simply had to make assumptions and move on.

Where does this get us? Hell, I’m not quite sure. I know that the beer made with pellets had more of the clean bitterness, fruity hop flavor, and fragrant hop aroma that I look for in an IPA. But looking at the comments, it’s apparent that the beer made with whole hops didn’t suck! A lot of it comes down to the personal preference of the tasters. I wonder if possibly some the hop character was affected by the use of the Hop Screw.

Could it have pressed out polyphenols that affected the bitterness and flavor perception? I think that the next experiment is to split a batch and use whole hops for both, but use the Hop Screw on one of them. That would likely be a better test of its usefulness. Simply testing whole hops against pellets will always be problematic unless you’re able to get both types from the same source.

A couple years ago I began using Martin Brungard’s excellent Bru’nwater spreadsheet to calculate additions to my water for various types of beers. I immediately began noticing improvements so I decided to dig a little deeper. I decided I’d concentrate on improving my IPAs with water adjustments. The main area I concentrated on was increasing my sulfate levels a step at a time and see what kind of effect it had. I decided to experiment on my Rye IPA recipe since I’ve brewed it dozens of times and know it well. Since the time I developed the recipe years ago, I’d just thrown a teaspoon of gypsum into the kettle and called it good. With my base of about 57 ppm of sulfate, that (I think) was getting me into the (maybe) 150 ppm range. Over the course of the last several batches, I’ve gone to 200, 250, 300, and finally 350 ppm of sulfate. I’ve also been concentrating on keeping the chloride level under 100 ppm, since advice from Martin was that high chloride levels along with high sulfate levels can create harshness. Another advantage of increasing the gypsum has been that my calcium levels have also been increasing. This equates to healthier fermentations and clearer beer, both of which I’ve found in these recent batches. The most recent batch of Rye IPA may be the best one I’ve ever made. Crisp, clean, clear, with a very direct, in your face hop presence and a beautiful dry finish. Again according to Martin, the increased gypsum is responsible for that dry finish.

This is an example of the way I started experimenting years ago. Read as many ideas as you can find. See if past experience backs up what the person is saying. Maybe you’ve read other things by that person that may or may not lend credence to what you read. Think about how your own past experience plays into what the person said. Then, take ideas that make sense based on those criteria and start experimenting with them. Decide for yourself how those ideas affect your brewing. That’s the best way to discover what could be a way for you to improve your beers.