Changes in composition of royal jelly harvested at different times: consequences for quality standards

Most of the studies on royal jelly (RJ) composition or properties as well as quality standards of commercially available royal jelly are based on RJ harvested three days (72 h) after grafting. In China, some beekeepers produce RJ harvested one (24 h) or two (48 h) days after grafting. There is a lack of knowledge about the quality of the royal jelly harvested earlier than 72 h. This study compared 32 colonies for their chemical compositions of RJ harvested at 24, 48 and 72 h after grafting, according to the proportion of moisture, protein, 10-HDA, total sugar and the value of acidity and superoxide dismutase activity. The analysis of RJ samples revealed that the composition varied significantly (for both fresh and dehydrated samples) and on some occasions above and below the range of present Chinese and Swiss standards. The results suggest that harvesting time should be considered when defining new quality standards of RJ.