Effects of different water activities on the stability of carotenoids in puff-dried yellow peach powder during storage

The stability of carotenoids in puff-dried yellow peach powder during commercial storage under different water activity conditions was studied. The results showed that when the corresponding water activity was above 0.576, the loss of adsorbed water in yellow peach powder was closely related to the crystallinity of the amorphous sugar matrix. However, the adsorption isotherms confirmed by water absorption behavior, X-ray diffraction (XRD) pat-terns, and scanning electron microscopy did not clearly indicate this loss of adsorbed water. The content changes of individual carotenoids (lutein, zeaxanthin, β-cryptoxanthin, α-carotene, and β-carotene) during storage followed pseudo first-order kinetics, and the degradation of lutein and zeaxanthin occurred quickly over time. The stability of total carotenoids gradually increased when the water activity was less than 0.576, but the carotenoids degraded sharply when the water activity was between 0.753 and 0.843. The loss of carotenoids was related to the water absorption and crystallization of the sugar matrix in the powder.