Heavy and light beer: a carbon isotope approach to detect C4 carbon in beers of different origins, styles, and prices
2002
Brooks, J.R. | Buchmann, N. | Phillips, S. | Ehleringer, B. | Evans, R.D. | Lott, M. | Martinelli, L.A. | Pockman, W.T. | Sandquist, D. | Sparks, J.P.
The carbon isotope ratios (delta13C) of 160 beers from around the world ranged from -27.3 to -14.9 per thousand, primarily due to variation in the percentage of C3 or C4 plant carbon in the final product. Thirty-one percent of beers had a carbon signature of C3 plants (barley, rice, etc.), whereas the remaining 69% contained some C3-C4 mixture (mean of mixtures, 39 +/- 11% C4 carbon). Use of C4 carbon (corn, cane sugar, etc.) was not confined to beers from any particular region (Pacific Rim, Mexico, Brazil, Europe, Canada, and the United States). However, the delta13C of European beers indicated mostly C3 plant carbon. In contrast, U.S. and Canadian beers contained either only C3 or C3-C4 mixtures; Brazilian, Mexican, and Pacific Rim beers were mostly C3-C4 mixtures. Among different lagers, U.S.-style lagers generally contained more C4 carbon than did imported pilsners. Among different ales, those brewed by large high-production breweries contained significant proportions of C4 carbon, while C4 carbon was not detected in microbrewery or home-brew ales. Furthermore, inexpensive beers generally contained more C4 carbon than expensive beers.
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