Variation in chemical composition of fresh and commercial Royal Jelly associated with international standards

Abstract

The chemical composition of fresh (local) and commercial (imported) Royal Jelly (RJ) from Saudi Arabia was investigated. 10-hydroxydec-2-enoic acid (10-HDA), protein content, sugar profile, moisture content, pH, free acidity, electric conductivity (EC), and macro and micro-minerals were analyzed in both RJ groups. Most samples and about 50 % of fresh RJ samples showed 10-HDA and protein content percentages lower or higher than the international standard limits. Differences were significant (p < 0.0001) between fresh and commercial RJ samples in all tested parameters except moisture content. Furthermore, 29 percent of the commercial samples did not pass the 10-HDA standard limits. On the other hand, lactose, a non-RJ sugar, was detected in two commercial samples indicating some contamination or adulteration of these samples. The minerals Zinc (Zn), Iron (Fe), Copper (Cu), Aluminum (Al), Manganese (Mn), Phosphorous (P), Potassium (K), Magnesium (Mg), Sodium (Na), and Calcium (Ca) were detected in all samples. Zinc (Zn), Iron (Fe), Potassium (K), Magnesium (Mg), and Sodium (Na) were significantly higher in fresh RJ samples (P < 0.05). Sodium, potassium, and phosphorus demonstrated significantly higher occurrence in fresh RJ samples from Saudi Arabia and might be good candidates for its characterization. Although 10-HDA and protein ratios are important parameters of RJ authenticity, the current standards of both parameters (ISO,12824:2016) should be updated to cover occurrence limits worldwide. Moreover, mineral analyses might be useful to characterize RJ's originality and explore RJ's adulteration.