STABLE CARBON-ISOTOPE RATIO ANALYSIS OF HONEY - VALIDATION OF INTERNAL STANDARD PROCEDURE FOR WORLDWIDE APPLICATION

Stable carbon isotope ratio analysis (SCIRA) of honey for undeclared p resence of cane or corn sugars has been available for 20 years. its us e with domestic and imported honeys is reviewed. Six years of data fro m the internal standard isotope ratio analysis (ISCIRA) method support its worldwide validity for honey analysis. The ISCIRA database of pur e honeys has been increased from 64 U.S. samples to 224 by addition of data from Germany, United Kingdom, Mexico, Italy, and Spain. ISCIRA a nalyses of 131 commercial honeys from the United States, Mexico, and S pain found that 17 are adulterated, Analyses of 303 Chinese honeys pro ves that they should have carbon isotope values similar to honeys from other areas, contrary to claims that the observed differences are int rinsic because of the variability of environmental conditions and of p lants used in honey production in China. Addition of corn or cane (C-4 ) sugars to honeys in amounts that do not produce a delta(13)C value g reater than -23.5 parts per thousand for the mixture cannot be detecte d by the original 1978 SCIRA procedure. Such adulteration however is d etected by ISCIRA procedure from the delta(13)C value of the protein c ontained in the honey, which shows the isotopic composition of the hon ey before addition of C-4 sugars. Forty-three percent of 98 honeys rec eived in the United States in 1994-1997 with delta(13)C < -23.5 parts per thousand were suspected and found to be adulterated.