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 content. C3 plants have an average delta(13)C value of -27 parts per thousand, against an average value of -12 parts per thousand for C4 plants. This difference is large enough to permit determination of the origin of the ethanol fermented from plants. There are two types of brandy in Brazil: one called "conhaque-de-gengibre", where ethanol from any plant can be used, and another called "brandy", where only ethanol from grapes can be used. The less expensive brandies, classified as "conhaque de gengibre", have their ethanol content derived exclusively from sugar-cane (average delta(13)C equal to -12.9 parts per thousand), while in the Brazilian brandies it was a mixture of sugar-cane and grapes (average delta(13)C equal to -18.0 parts per thousand). In Brazilian "brandies" there was an inverse relationship between its price and the carbon isotopic composition, indicating that higher prices is associated to larger proportions of ethanol from grapes. (C) 2000 Canadian Institute of Food Science and Technology. Published by Elsevier Science Ltd. All rights reserved.