Ask Mr. Wizard

Steeping oats and flaked barley


Colin Henein • Ottawa, Ontario asks,

Serious brewing references say that grains like oats and flaked barley need to be mashed with base malts rather than just steeped. I have heard that steeping these grains leads to problems with haze, increased possibility of contamination and shorter shelf-life of finished beer. Despite this, I often see these ingredients in extract recipes with instructions to just steep at 160 °F (71 °C). Are the concerns about steeping these grains warranted, and these are just bad recipes? Alternatively, is there a time and place for steeping these grains and what differences can be expected from using them in this way?


I assume when you use the term “serious brewing references” you mean texts that are full of chemistry, biochemistry, microbiology and engineering principles. These serious references are totally devoid of recipes and none on my bookshelves have a picture of anyone actually drinking beer. Pictures of beer torture are the norm. Colloidal stability tests where beer is cycled hot and cold in incubators, foam stability tests where beer is sacrificed to assess its foaming potential and tests where beer is boiled to distill and assay its alcohol content are the photos in the serious texts. These texts are for commercial brewers.

Homebrew texts (presumably not so serious) do have recipes, photos of people drinking beer while brewing (a stunt that would get anyone’s can in serious trouble in the commercial world) and long chapters on the beer style. These books are targeted to homebrewers who are trying to brew the best beer they can using the sometimes limited tools and time that they are willing to buy, build and devote to their hobby.

I am a product of formal brewing education and like the science contained in these serious texts. When I put on my mortarboard I say that the only grains that belong in a steeping bag are crystal/caramel malts, roasted barley and roasted malts. Anything else must be mashed. This rule makes extract brewing fairly limited and would seem to suggest that all-grain is the way to go. While I am a big advocate of all-grain brewing, because it is the path to brewing freedom and also is not nearly as difficult as all-grain brewers claim when their chests are all puffed and inflated while critiquing the efforts of extract brewers, this method does add more time to the brew day. And if you are fastidious about your kitchen and don’t have a place that is as easily cleaned up with a hose as it is soiled by digging out a lauter tun, extract brewing has its benefits.

Extract brewers, in their pursuit of creativity, have tossed out much of the basics about mashing found in serious brewing texts. I typically turned a blind eye to many of the methods described in extract recipes because my brewing experience is different. The way I see it is that enough brewers are using materials in ways that fly in the face of commercial convention that their efforts are surely not the brewing equivalent of pounding sand.

But what does really happen when raw cereal grains and malted grains are steeped in a dilute solution at or above 160 °F (71 °C)? The starches and simple sugars contained in these grains will dissolve in the steeping liquor and any enzymes present will also be released into solution. The concentration of starches and enzymes in a brewery mash is considerably higher and, in accordance with Michaelis-Menten enzyme kinetics, the rate that these starches are converted to fermentable sugars is also considerably higher compared to what is seen in an extract brewer’s steep pot. Additionally, any enzymes present, for example if Munich malt is steeped, in this solution begin to denature because of the high temperature. In a nutshell, this means that not much starch degradation occurs.

Since brewing yeast does not secrete enzymes that degrade starch and do not ferment starch, any starch in wort will be found in the finished beer. And as you state, starch in beer can cause haze issues and can also cause problems with microbiological stability. Certain yeasts, such as Brettanomyces, and bacteria, such as Pediococcus, can cause super-attenuation. This means that these organisms can ferment compounds that brewing yeast do not. If starch remains in beer it is an invitation to these possible contaminants to grow and spread their funk into your beer. Usually this is unwanted, but if you wanted to brew something funky then these bugs may be just what are needed. As it happens lambics have starch in their worts before fermentation and the distinctive character in these beers arising during the long aging (after a somewhat normal yeast fermentation) requires residual carbohydrates for these bugs to chew on.

When I make suggestions about brewing I do stick to my formal training and I do not personally recommend steeping grains other than crystal/caramel and roasted types. Any other material used in the brewhouse needs to be enzymatically acted upon in a brewers mash.

With that being said, other brewers have different opinions and offer different advice. While it seems from the number of recipes suggesting unconventional advice that such advice may indeed work for those offering it, I do recommend taking this advice with some skepticism and caution. If one of the primary goals of homebrewing is to brew good beer a logical brewer will recognize that the practices used by commercial brewers share this goal. If a technique is not commonly used by commercial brewers there is probably a reason. Of course commercial brewers, with very few exceptions, employ a mashing method and techniques surrounding steeping that are totally irrelevant.

So if you are an extract brewer, I would heed the warnings of the texts while also listening to practical advice offered by fellow homebrewers who have developed good beers with unconventional methods.

Response by Ashton Lewis.