Stable Carbon Isotopic Composition of the Wine and CO 2 Bubbles of Sparkling Wines: Detecting C 4 Sugar Additions LUIZ A. MARTINELLI,* ,² MARCELO Z. MOREIRA, ² JEAN P. H. B. OMETTO, ² ANDRE Ä R. ALCARDE, ‡ LUIZ A. RIZZON, § ERIK STANGE, # AND JAMES R. EHLERINGER # Cena, Av. Centena ´rio 303, 13416-000 Piracicaba, SP, Brazil; Departamento de Agroindu ´stria, Alimentos e Nutric ¸ a ˜o. Escola Superior de Agricultura “Luiz de Queiroz”. Av. Pa ´dua Dias 11, 13418-900 Piracicaba, SP, Brazil; Embrapa Uva e Vinho, Rua Livramento 515, 95700-000 Bento Golc ¸ alvez, RS, Brazil; and Department of Biology, University of Utah, Salt Lake City, Utah 84112 Sparkling wines have become a popular beverage in recent years, and the production of these wines is subject to adulteration during fermentation. This study investigated the stable carbon isotopic composition (expressed as δ 13 C) of the wine and of the CO 2 bubbles produced during the second fermentation for a number of sparkling wines produced in different countries around the world. Carbon isotope ratio analyses were used to estimate the addition of sugar obtained from C 4 plants (sugar cane or corn). The average δ 13 C values of the Brazilian brut, demi-sec, and doux sparkling wines were -20.5 ( 1.2‰ (n ) 18), -18.1 ( 1.3‰ (n ) 9), and -15.8‰ (n ) 1), respectively. These values were statistically heavier (more positive carbon isotope ratio values) than the average δ 13 C of sparkling wines produced in other parts of South America (Argentina and Chile, -26.1 ( 1.6‰, n ) 5) and Europe (France, Germany, Italy, Portugal, and Spain, -25.5 ( 1.2‰, n ) 12), but not statistically different from sparkling wines produced in the United States or Australia. The most likely explanation for differences in the carbon isotope ratios of wines from these different regions is the addition of C 4 sugar during the production of some sparkling wines from Australia, Brazil, and the United States. The isotopic composition of the CO 2 bubbles (δ 13 C-CO 2 ) followed similar trends. The average δ 13 C-CO 2 of most of the Brazilian and Argentine sparkling wines was -10.8 ( 1.2‰ (n ) 23), indicating that the likely source of carbon for the second fermentation was sugar cane. Conversely, the average δ 13 C-CO 2 of most of the sparkling wines produced in Chile and Europe was -22.0 ( 1.2‰ (n ) 13), suggesting that a different sugar (most likely sugar beet) was most used in the second fermentation. It was concluded that in many cases, the carbon isotope ratios of sparkling wine and CO 2 bubbles can provide valuable information about the sugar sources. KEYWORDS: Sparkling wine; isotopic composition; C4 sugar; CO2; bubbles INTRODUCTION Sparkling wine is a beverage that originated in the Cham- pagne region of France and that has now become a popular beverage globally, so that it is now produced in other regions of the world. The production of sparkling wines typically consists of two fermentation steps: a first fermentation that results in ethanol synthesis and a second short fermentation to produce CO 2 . Normally the second fermentation is achieved by the addition of small amounts of sugar. In efforts to control the quality of sparkling wines, many countries have developed specific legislation to describe the final composition and fermentation steps that are allowable in order to maintain the original characteristics of the product. For instance, Brazilian legislation allows the addition of sugar to the grape must during the initial fermentation in order to increase an ethanol content of up to 3 °GL [Gay-Lussac (GL) is the volumetric percentage of alcohol in a beverage]. Therefore, the addition of sugar in making a Brazilian sparkling wine could occur during either or both of the two fermentation steps. In Brazil, sugar can also be added following the second fermentation in order to adequately sweeten the wine in accordance with its sweetness type. However, in California (United States), where a large number of sparkling wines are produced, legislation allows only the addition of sugar for the second fermentation step. In Europe, where restrictions are often tighter, the addition of sugar will depend on both the region and method of production of the sparkling wine. There are two main methods * Author to whom correspondence should be addressed (fax 55 19 34 34 92 10; e-mail zebu@cena.usp.br). ² Cena. ‡ Escola Superior de Agricultura “Luiz de Queiroz”. § Embrapa Uva e Vinho. # University of Utah. J. Agric. Food Chem. 2003, 51, 2625-2631 2625 10.1021/jf026088c CCC: $25.00 © 2003 American Chemical Society Published on Web 03/28/2003