LAUSR

The phase transformations and stability of the two most common forms of vitamin C (ascorbic acid [AA] and sodium ascorbate) were explored in colyophilized polyvinylpyrrolidone polymer matrices. Solutions containing controlled vitamin:polymer ratios (0:100 to 100:0) were lyophilized and stored in controlled temperature (20–60°C) and relative humidity (0–85%RH) environments. Samples were analyzed over time using X‐ray diffraction to document physical state and high performance liquid chromatography to document vitamin degradation. Moisture sorption profiling, microscopy, infrared spectroscopy, and differential scanning calorimetry were also used to characterize the samples. Vitamins were more labile when amorphous than when crystalline, and sodium ascorbate was more labile than AA. Significant vitamin degradation occurred in the glassy state. All vitamins degraded significantly more when present at lower proportions in the amorphous solid dispersions, thus most degradation was found in the dispersions with the highest glass transition temperatures. PRACTICAL APPLICATIONS: The most common ingredient forms of vitamin C (ascorbic acid [AA] and sodium ascorbate) are likely to be amorphous in low moisture food products that were produced by first dissolving ingredients and then rapidly dehydrating the products. Challenges for product quality and shelf‐life are that: (a) both vitamin C forms were found to degrade in storage environments that maintained the products in the glassy amorphous state (which is desirable for the texture of many low moisture products), and (b) both vitamin forms degraded faster when present at lower proportions in the polymer matrices. In such conditions, AA was more stable than sodium ascorbate.