Stable carbon isotopic analysis and the botanical origin of ethanol in Brazilian brandies

Carbon isotopic composition (delta(13)C) of Brazilian brandies was used to determine the contribution of sugar from C3 or C4 plants to their ethanol c ontent. C3 plants have an average delta(13)C value of -27 parts per thousan d, against an average value of -12 parts per thousand for C4 plants. This d ifference is large enough to permit determination of the origin of the etha nol fermented from plants. There are two types of brandy in Brazil: one cal led "conhaque-de-gengibre", where ethanol from any plant can be used, and a nother called "brandy", where only ethanol from grapes can be used. The les s expensive brandies, classified as "conhaque de gengibre", have their etha nol content derived exclusively from sugar-cane (average delta(13)C equal t o -12.9 parts per thousand), while in the Brazilian brandies it was a mixtu re of sugar-cane and grapes (average delta(13)C equal to -18.0 parts per th ousand). In Brazilian "brandies" there was an inverse relationship between its price and the carbon isotopic composition, indicating that higher price s is associated to larger proportions of ethanol from grapes. (C) 2000 Cana dian Institute of Food Science and Technology. Published by Elsevier Scienc e Ltd. All rights reserved.