Changes in Quality of Royal Jelly during Storage

Abstract

Fresh royal jelly (abbreviated as RJ) was stored at various temperatures, -40°C, 5°C and room temperature, and the changes in physical properties and chemical compositions of RJ were investigated. The results were as follows: (1) Color and viscosity of RJ stored at -40°C did not change but those of RJ stored at 5°C and room temperature changed considerably. A remarkable change was observed when the RJ was stored in bright place at room temperature. (2) The ratio of waterinsoluble nitrogen to total nitrogen in RJ stored at 5°C and room temperature increased and the increasing pattern of this ratio was just the same as that of viscosity. (3) When fresh RJ was stored at 5°C and room temperature, there was an increase in its acidity, but the amounts of 10-hydroxyΔΔ²-decenoic acid, 10-hydroxydecanoic acid and gluconic acid in carboxylic acids of RJ were constant regardless of the storage conditions. (4) The total amount of free amio acid of RJ stored at room temperature and 5°C decreased with time and its amino acid composition changed. (5) Glucose oxidase activity significantly decreased at higher temperature. The lowering of glucose oxidase activity was found to be similar to that of the amount of water-soluble nitrogen. (6) The increase of viable count of RJ stored under various conditions was not found, and the viable counts were 1010²-10³. The quality of RJ was stable in view of microbiology.