Assessment of royal jelly freshness by HILIC LC-MS determination of furosine

- Development of a new method based on LC-MS to quantify furosine in royal jelly.
- First study dealing with furosine content in French royal jellies.
- 85 RJs from different origins are studied (French and imported).
- Comparison of 2 storage temperature really observed for RJ, −18 °C and +2/+5 °C.

Royal jelly (RJ) is a high added value product, which can be spoiled and may lose its health-promoting properties according to the storage temperature and duration. Furosine, a compound generated at the early stages of the Maillard reaction, is a good marker of the freshness of RJ which can be used to detect heat treatments or prolonged storage of RJ samples. The determination of furosine content of RJ has been developed and validated by LC-MS. This new analytical method has the advantages of being sensitive and rapid. Moreover it avoids the time-consuming and cost-intensive SPE purification step of the usual HPLC-UV method.The influence of the storage temperature was studied on 55 French RJs. Ten of them were additionally analyzed just after harvest which exhibited furosine contents around 20.1 mg/100 g of protein. The furosine content remained stable when stored 9 months at −18 °C, whereas a slight increase was observed for a storage temperature of +2/+5 °C, with values increasing up to 61.3 mg/100 g of protein. The analysis of 27 commercial RJs, after 9 months of storage at +2/+5 °C, displayed higher furosine contents up to 219.9 mg/100 g of protein with a mean at 97.1 mg/100 g of protein. These results underline that furosine is a suitable marker for assessing the quality of storage conditions and freshness of RJ.