Abstract:

This paper reports the optimization of sample preparation conditions including reaction temperature, anthrone
concentration and amount, color development time and cooling time for the determination of soluble sugar in red jujube
fruits using a combination of single factor and orthogonal array designs. The results showed that 1 min reaction at room
temperature in the presence of 3 mL of 25 mg/mL anthrone reagent followed by 25 min of cooling was found to be optimal.
The established analytical method was characteristics of simple operation, rapidity and high sensitivity. Verification
experiments showed that the standard curve of sucrose standard solution in the range of 20–240 mg/mL had good linearity
(A = 0.004 5C - 0.013 4, R2 = 0.999 2), with a good reproducibility. The accuracy, expressed as RSD, was 0.20% (n = 3)
and the average recovery was 102.87% (n = 3) with a RSD of 0.84%. Dried red jujubes contained 68.43% soluble sugar as
determined by this method.

Key words: anthrone method, red jujube, soluble sugar, optimization