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 selec-tively 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 & delta;13C values of the RJs varied from -24.0%0 to -17.2%0 (average-19.3%0). 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 < 0.01). The & delta;13C values and sucrose contents showed a weak positive correlation with harvest time when artificial feed was selectively supplied to bees according to seasonal changes (p < 0.01). This study highlights the characteristics and composition ranges of Korean RJ and compares the differences between the tested samples and RJ samples produced outside Korea. The results provide information necessary for determining the authenticity and quality grade of RJ by investigating the effect of bee colonies selectively provided with artificial feed according to seasonal changes on the compositional changes of RJ.