Development of a Freshness Assay for Royal Jelly Based on the Temperature- and Time-Dependent Changes of Antimicrobial Effectiveness and Proteome Dynamics of Royal Jelly Proteins

Although the antimicrobial,
nutritional, and health-promoting properties
of royal jelly (RJ) have been widely confirmed, the effects of storage
temperature and time on RJ quality remain to be further explored.
Herein, the antimicrobial and proteomic dynamics of RJ stored under
different conditions were comprehensively investigated to identify
consistent and sensitive markers of RJ degradation. We confirmed the
negative correlation between antimicrobial properties and increased
the storage temperature and duration in RJ. Using surface plasmon
resonance, we showed the protein degradation-induced conformation
changes in RJ, which reflected the overall variation in RJ proteins
caused by the storage conditions. Further proteomic and western blotting
analyses demonstrated the sensitivity and reliability of major RJ
protein 4 (MRJP4) as a measure of temperature- and time-dependent
RJ changes. Based on these results, we developed a colloidal gold
immunoassay strip for MRJP4 detection, providing a reliable, simple,
and rapid method for the evaluation of RJ freshness.