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

Abstract

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.