Investigation of the Incorporation and Authenticity of C₄ Sugars in Natural Sugar Products Distributed in Jeju Using Carbon Isotope Ratio

Abstract

This study examined whether C4 sugars were incorporated into natural sugars and discriminated their authenticity by carbon isotope ratio analysis. The δ 13 C values were analyzed in 141 samples of commercially available honey (n=48), sugar-fed honey (n=10), maple syrup (n=23), agave syrup (n=17), sugar (n=13), corn syrup (n=20), and rice syrup (n=10). The δ 13 C values of 45 natural honey products were −26.9‰ to −22.9‰, showing that they were suitable, while three products showed −12.9‰, −13.1‰, and −14.5‰, which were over −22.5‰ and did not meet the quality standards. The δ 13 C values of sugar-fed honey were suitable at −15.1‰ to −12.6‰. One out of 23 cases of maple syrup had a carbon isotope ratio of −11.0‰ and was confirmed to contain C4 sugar. The δ 13 C values of cane sugar and corn syrup were −13.3‰ to −12.0‰ and −12.6‰ to −11.4‰, respectively. One of the 23 maple syrup samples did not meet the AOAC maple syrup standards. Therefore, it is necessary to set maple syrup under the sugar syrup category in the Food Code and add carbon isotope ratio standards.