Go Green: Brewing with Unkilned Malt

Stephen Mastroianni of Nova Scotia's unusual Horton Ridge Malt and Grain—a craft maltster and brewery—explains how green malt yields none of the typical malt flavors, opening up a whole new canvas on which to brew.

Stephen Mastroianni Mar 31, 2020 - 7 min read

Go Green: Brewing with Unkilned Malt Primary Image

Malt flavors in beer are traditionally described as toasty, roasty, sweet, nutty, caramel, coffee, or chocolate. These flavors come from the kilning and roasting of the grain. But what happens if you brew a beer with malt that hasn’t been kilned or roasted? Green-barley malt has a flavor profile that centers on cucumber, melon, and cut grass, with a slight astringency. The aromatics are similar to a summer’s day after a rain shower.

Horton Ridge Malt and Grain Company is a small craft (floor) malt house and nano brewery in Nova Scotia, and we make a beer from unkilned (green) malt. Our first green-malt beer came as a result of the St. Patrick’s Day green-beer idea. The thought process was that bars around the world add food coloring to make their beer green, but we’re a malt house, and we have green malt. Why couldn’t we make a real green-malt beer? A quick Internet search revealed a 1963 scholarly article from S. R. Duff entitled Use of Green Malt in Brewing, which reached the conclusion that “acceptable potable beer can be produced” from green malt. Fueled by enthusiasm from knowing it was possible, we set out to make a green-malt beer. The first step was easy—picking a style. A pale ale seemed like a good idea; it would limit the number of variables and keep it simple.


The first challenge made itself quickly known: milling. Green malt has a moisture content ranging from 38 to 45 percent, which leads to two main problems. First, the green malt clumps together and bridges in the hopper. Second, the high moisture content causes the rollers to turn the green malt into a sticky, doughy mess. After disassembling the mill, cleaning it, and further trial and error, we developed a system that solved both problems. Using a feed scoop to slowly but constantly hand feed the green malt directly onto the mill rollers resulted in an acceptable squash. For any sort of large-scale production, a high-moisture grain mill would be ideal, but for small batches, a roller miller and some (actually, considerable) patience will get the job done.


Mashing with green malt is easier than with dried malt. The high moisture content negates any worries of a stuck mash. However, due to the retained water in green malt, the volume of strike water needs to be reduced. In addition, the cooler temperature of the malt means the temperature of the strike water needs to be increased. We increase our strike-water temperature by 12°F (7°C) to adjust for these factors to achieve a mash temperature of 155°F (68°C). We use green malt at a rate of 120 pounds (54 kg) per barrel (19 lb/8.6 kg per 5 gallons/19 liters) to achieve a starting gravity of 1.050.


The other big difference is mash length. We’ve experimented with 60-, 90-, and 120-minute mash times, and we’ve found that the optimal mash time is 120 minutes. We mash out and sparge as normal.

Protein Haze

Part of the kilning process involves removing the rootlets from the sprouted grain. These rootlets are very high in protein, and as a result, the green malt is very high in protein. During the boil—specifically before, during, and right after the hot break—skimming the top of the boil kettle is necessary to collect the coagulated protein if you want to achieve a clear-ish beer. Not removing the protein will produce a New England–style IPA haze in the finished beer. The only issue that we have encountered by not removing the protein is that the resulting protein clumps lead to clogging.


As a malt house, our focus is malt-forward beers. In developing our “green” beer, we wanted to find a hops profile that allowed the green malt to shine but also featured complementary flavors that rounded out the beer into something unique and enjoyable. For a fresh and light flavor profile, we use hops with citrus and fruity profiles. Our favorites are Mosaic, Azacca, Citra, Huell Melon, Cascade, and Mandarina Bavaria. Not wanting to lose the flavors that make the green malt distinctive, we settled on a small bittering addition with a focus on flame-out and dry hopping. Our green-malt beer checks in at 15 IBUs, but because of the astringency from the green malt, the perceived bitterness is in the 30–40 IBUs range.


The trickiest aspect of brewing with green malt is fermentation. Of the first five batches, only two came out of the fermentor a success. We struggled with over- and under-attenuation and an abundance of ester and phenol production. In keeping with limiting the number of variables, we elected to use Safale US-05 American Ale yeast. After each failure, we made a fermentation-side adjustment until we continually hit our targets. The system that works for us with US-05 is a pitch rate of 125g/hl and a dose of WLN1000 White Labs Yeast Nutrient at the recommended rate of 0.2 grams per barrel or ½ teaspoon per 5 gallons (19 liters). Post fermentation, we’ve had no issues with spoilage; however, we have found that the hops profile tends to fade quicker than normal.

Our customers’ appreciation for the final product has inspired more experimentation! We’ve dabbled with a green-wheat malt beer. Unfortunately, the results were uninspiring, as the resulting beer didn’t have any of the interesting flavors present in the green-barley malt. (The main flavor was similar to a soggy piece of white bread.)

Now that we have our base green-malt beer dialed in, we’re excited to explore other styles with green malt. By next summer, we hope to have a green-malt sour (or possibly gose), and we believe that the flavors in the green malt are very favorable to a Brettanomyces fermentation.

Photo: Matt Graves/