Changes in the chemical composition of royal jelly produced through artificial bee-feeding in response to seasonal variations during non-migratory beekeeping

A reliable database was established from the analysis of 60 royal jellies (RJs) produced by bee colonies selectively provided with artificial feed according to seasonal changes at an apiary in Gyeongsangnam-do, Korea. The moisture content of RJs ranged from 60.1 % to 67.1 % (average 65.2 %), and the trans-10-hydroxy‐2–decenoic acid (10-HDA) content ranged from 1.4% to 2.5% (average 1.9 %), indicating a wide range during the harvest period. The δ13C values of the RJs varied from − 24.0‰ to − 17.2‰ (average −19.3‰). Sugar contents were 1.9–6.1 % for fructose, 2.8–5.5 % for glucose, and 0.7–7.7 % for sucrose. Pearson correlations were determined between harvest time and RJ components. The 10-HDA content showed a weak negative correlation with harvest time (p