Investigation of Processing Technology for Aged Black Jujube

We investigated how to use jujubes from Xinjiang to make black jujube by temperature-controlled wet high-temperature curing. Single-factor and orthogonal experimental designs L9(3)3 were used to optimize the color change process of the black jujube. The effect of blackening temperature, blackening time and added water amount on the content of cAMP, 5-HMF, polyphenols, total acids, reducing sugars and moisture content were investigated and optimized. The results showed that the optimum process conditions of red jujube aging and blackening black include blackening temperature of 75°C, blackening time of 55 h, and water addition amount of 150 mL per 600 g. Under the best technological conditions, the black jujube was fragrant, sweet, and delicious, and the content of all functional substances, including cAMP (0.0137 g/100g), 5-HMF (0.103 g/100g), polyphenols (2.71 g/100g), total acids (17.09 g/kg), reducing sugars (76.7 g/100g), reached high levels, at a moisture content of 26%.