Study Shows Rice Malt Has a Prominent Role in Beer Brewing

A new study titled “Investigating the Malting Suitability and Brewing Quality of Different Rice Cultivars” published in February by the Beverages journal suggests the potential for malted rice to yield robust fermentations in gluten-free, all-malt beer.

It is nothing new that rice and corn have been used as an adjunct grain by American brewers since the 1860s. However, the rice has been milled white rice, and not melted. One goal of the study was to identify rice cultivars with high malting potential as the malting qualities of U.S. rice cultivars had not yet been evaluated for brewing qualities.

Bernardo P. Guimaraes, a University of Arkansas Food Science graduate, was the lead author of the malted rice study, providing the first publicly available data on 19 rice varieties important to the U.S. rice industry that were malted and analyzed for brewing qualities. Flavor chemist and assistant professor in the Food Science Department Scott Lafontaine served as Guimaraes’ adviser on the research.

Lafontaine said, “Does rice have what it takes? Scientifically, yes, it is possible.” They found rice malts with enough enzymatic capacity to fully convert their starch source into fermentable sugar, also known as self-saccharifying malts, that produce a sugary liquid called “wort” in brewing. According to Lafontaine, the wort from rice malt “seems to yield healthy fermentations with a standard yeast, without adding enzymes or nitrogen supplementation.” 

Malting is the process of germinating a grain through hydration and then drying and heating it to halt germination. The process produces enzymes required to turn the starch into sugar when soaked in hot water for the phase of brewing called “mashing.” Brewers have typically used milled white rice and not rice malled as milled white rice calls for an additional brewing vessel because it needs to be boiled to gelatinize the starch to convert it into the sugary liquid called wort.

Malted rice may not require a second vessel as Guimaraes and Lafontaine showed the malted rice to be self-saccharifying with the appropriate mashing conditions. It means that with the right temperature and time, the starch could be broken down into fermentable sugars that yeast can assimilate and turn into alcohol.

As wheat flour is to bread, malted barley is to beer, with recipes calling for varying levels of a barley as a base malt along with other grains like wheat, rye, and oats for different styles of beer. Additional ingredients like roasted barley, and roasted malted barley, develop different flavors and aromas.

The study showed that long-grain rice when malted, had the most promise as a competitor to malted barley for sugar content and other brewing qualities. Short, medium, and long-grain varieties of “paddy rice’ were also looked at in the study. Wild varieties of rice that had purple-pigmented brans yielded interesting results as they produced naturally colored gluten-free beers with hues close to wine.

Lafontaine said that rice varieties had different gelatinization temperatures and mashing parameters seemed to have an impact on the onset of gelatinization. He added, “While we are not sure exactly what is occurring yet, this is likely due to the unique enzymatic profile of the rice malts and shows that brewers just have to alter their mashing conditions to effectively leverage this material in the brewery.”

Another unexpected finding of the study was that malted rice showed higher protein levels, offering potential applications as an alternative protein source in foods. The protein content ranged from 7% to 10.5%, and some rice cultivars had protein content comparable to malted barley.

While the chemical analysis of malted rice is promising, Lafontaine is working with the Agricultural Economics and Agribusiness Department to conduct a feasibility study considering many economic factors that compare malted rice and malted barley.

One of the most pressing factors is the cost of barley, which has increased in the past four years. Lafontaine said, “The increase has made long-grain rice “cost equivalent” to barley. Barley is grown in areas with cooler climates, while rice is grown in warmer climates. So, climate change and global warming are other factors for long-term economic impacts of barley and rice as beer ingredients.”

The study also mentioned, “By offering a more locally sourced grain for Southern and U.S. brewers, despite paddy rice being proportionally more carbon dioxide intensive to grow than malted barley, the lack of international shipping may potentially make up the difference in carbon dioxide. Additionally, rice is a gluten-free source of starch for brewers and beverage/food producers.”

Lafontaine and Guimaraes have noticed, for example, that some aromatic varieties of rice produced elevated levels of diacetyl, which has a buttery popcorn aroma often considered an off-flavor in beer. Lafontaine also intends to conduct a sensory panel with the various beers produced from rice malt.