Changes in protein components and storage stability of Royal Jelly under various conditions

The changes in quality of Royal Jelly (RJ) stored at −20 °C, 4 °C, and room temperatures under dark and light conditions for up to 7 months were investigated. The results showed that colour, viscosity, fractions of water-soluble protein (WSP) and simple sugars of RJ changed significantly during storage at room temperature, but not at −20 °C. The viscosity and browning intensity increased with storage time, and were enhanced by the ambient temperature. Two major fractions in WSP of RJ were obtained by gel filtration, while four to five different protein components were found when subjected to SDS-PAGE. The relative amounts and molecular weight distributions of these WSP components varied during storage. The results indicated that the quality deterioration of RJ during storage was due to the Maillard browning reaction.