Product Development-90
Rice found superior to corn in brewing study



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Project Leader and Principal UC Investigators

Michael J. Lewis, Dept. of Food Science and Technology, UC Davis


Almost one quarter of the rice produced in the United Sates is used to make beer. However scholarly journals and anecdotal reports from brewers have indicated a certain "intractable behavior" of rice in the brewing process-a perceived technological barrier that has inhibited its more widespread use in the industry.

To understand more clearly the problems rice posed in the brewing process, the researchers explored three primary objectives:

  • Determine the qualities of rice that make it a desirable or undesirable adjunct for brewing and compare those attributes to corn.
  • Develop or select tests that can be used to screen rice products and other extract sources for their brewing quality
  • Evaluate rice and corn for their brewing quality.

Yield of extract-a measure of soluble solids-is the primary standard for brewer adjuncts. Small differences in extract yield are economically important to brewers. The researchers confirmed earlier observations that rice significantly outperformed corn in small-scale brewing tests.

In previous work, the researchers examined how well rice breaks down in the presence of different commercially available enzymes. They found that rice slightly but consistently outperformed corn by giving higher soluble solids, more extensive starch breakdown, slightly superior fermentability and lower viscosity and filterability. More recent small-scale brewing tests confirmed those results with observations of a satisfactory mash mixing, high extract yield, pale color, normal aroma and flavor, and other factors.

Researchers also developed an iodine test to show how starches from rice behave differently from those of corn. Their work showed that "wort" (the fermenting substance that eventually becomes beer) made from rice has superior fermentable sugar than worts made from corn. This partly results from the way enzymes are used, suggesting that this may form the basis for a useful predictor of brewing quality.

To conclude the research, commercial rices were examined in a "pilot-scale" brewing program. Brews were monitored for a variety of beer-making criteria: wort quality, processing parameters, fermentation qualities and flavor, Aroma and other beer qualities. Only small and statistically insignificant differences were found between beers made from corn and those made from rice.

The research project was undertaken to determine the veracity of the reputed "intractable behavior" of rice in the brewing process. Although the analyses revealed some differences among rice varieties and corn, the differences are small ones, and are generally in favor of rice, not corn. The results led researchers to conclude that rice is in some ways superior to corn as an adjunct for brewing. Put another way, rice has been given "a bum rap." Further research into altered field practices, storage and processing is suggested to make rice more economically attractive to brewers.


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