Whole, unmalted and unmodified heirloom purple corn is an excellent addition to the mashbill for bourbon or corn whiskey; brewers can use it for color and flavor adjustment in pale lager, traditional cream ale, and other beer styles.
In brewing trials, purple corn brought sensory notes of corn chip, honey, and fruit, as well as a red-to-purple hue depending on inclusion rate and recipe. Distilled spirit produced from a base of pale barley malt and purple corn displayed strong fruity, sweet, and almond attributes with undertones of caramel.
The main difference between our flaked corn and this product is that the purple corn is not gelatinized. When brewing with purple corn, it’s recommended to follow a cereal mash procedure to gelatinize and liquefy the starches in the unmalted grain.
Cereal Mash Procedure
In a cereal mash, a small proportion of malt from the grain bill is added to a separate boiling vessel called the adjunct cooker, along with the entire charge of unmalted grain. The malt and grain mixture in the adjunct cooker undergoes a short mash rest followed by boiling, after which it is added to the main mash with the remainder of the malt. Boiling gelatinizes the starch in the unmalted grain, while the malt enzymes help liquefy the gelatinized starch before and during the main mash.
As a reference, the following schedule was used to brew a 3 hL batch of purple corn lager at the Rahr Technical Center pilot brewery:
Mash Tun Profile and Ingredients
- Grain bill- 80.00% Rahr Premium Pils, 20.00% Purple Corn
- Enzyme Additions – Hitempase 2XL – 12 g, Bioglucanase – 15 mL
- Adjunct Cooker Mash –
- Mash In 105°F
- 1st Rest – 105°F for 20 min
- 2nd Rest – 212°F for 15 min
- Three Step Mash
- Mash In 122°F
- 1st Rest – 122°F for 20 min
- 2nd Rest – 156°F for 45 min
- Mash-Off – 171°F for 1 min
Purple Corn: Pilot Brewing Trial Overview, Rahr Technical Center, July 2020
MBAA Practical Handbook for the Specialty Brewer Vol. 1: Raw Materials & Brewhouse Operations, 2016