Physicochemical properties, antioxidant activity, antimicrobial potential and 10-hydroxy-2-decanoic acid (10-HDA) content of Bulgarian royal jelly

Royal jelly is a precious and valuable product secreted by the mandibular and hypopharyngeal glands of worker honeybees ( Apis mellifera L.) and used as an essential food for the bee larvae and the queen bee. In recent years, royal jelly has gained a reputation as a “superfood” due to its rich chemical composition, exceptional nutritional value and health benefits. The aim of this study was to investigate the physicochemical properties, antioxidant potential, antimicrobial activity and 10-hydroxy-2-decanoic acid content of 16 Bulgarian royal jelly samples. The moisture content varied between 45.88 and 68.49 %, while pH was between 3.92 and 4.15. The total phenolic content took values from 22.84 to 32.62 mg GAE/g. The values of antioxidant activity determined by the DPPH method were between 8.37 and 68.09 mM TE/g, while those obtained by the FRAP method varied from 12.69 mM TE/g to 34.83 mM TE/g. The 16 royal jelly samples showed moderate to high antibacterial activity, but low antifungal activity. The content of 10- hydroxy-2-decanoic acid (one of the major bioactive components in royal jelly) was from 1.19 to 2.52 mg/g. The obtained results revealed the great potential of royal jelly for application in various functional food products, including dairy products.