Detection of royal jelly adulteration using carbon and nitrogen stable isotope ratio analysis

Stable isotope ratios (13C/12C and 15N/14N) were measured in royal jelly (RJ) samples by isotope ratio mass spectrometry (IRMS) to evaluate authenticity and adulteration. Carbon and nitrogen isotope contents (given as delta values relative to a standard, δ13C, δ15N) of RJ samples from various European origins and samples from commercial sources were analyzed. Uniform δ13C values from −26.7 to −24.9‰ were observed for authentic RJ from European origins. Values of δ15N ranged from −1.1 to 5.8‰ depending on the plant sources of nectars and pollen. High δ13C values of several commercial RJ samples from −20.8 to −13.3‰ indicated adulteration with high fructose corn syrup (HFCS) as a sugar source. Use of biotechnologically produced yeast powder as protein source for the adulterated samples was assumed as δ15N values were lower, as described for C4 or CAM plant sources. RJ samples from authentic and from adulterated production were distinguished. The rapid and reliable method is suitable for urgent actual requirements in food monitoring. Copyright © 2005 John Wiley & Sons, Ltd.