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.