Vitamins C and B1: Amorphization, Crystallization, New Salt Forms, and Stability

L.J. Mauer
Purdue University,
United States

Keywords: vitamin C, vitamin B1, crystallization


The water soluble essential vitamins C and B1 are commonly distributed in their crystalline forms. These crystals may dissolve or melt during food production, and then, depending on formulation or processing conditions, have the potential to re-solidify in crystalline or amorphous forms. The objectives of this study were to compare the phase transformations, amorphization, and chemical degradation of vitamins C and B1 in different formulations. In one set of studies, two forms of each vitamin (ascorbic acid, sodium ascorbate, thiamine chloride hydrochloride, thiamine mononitrate) were used in solid dispersion formulations with select polymers (polyvinylpyrrolidone, pectins, polyacrylic acid, gelatin, guar gum, etc.). Solutions containing controlled vitamin:polymer ratios (0:100 to 100:0) were lyophilized and stored in controlled temperature (25-80°C) and relative humidity (0-75%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. Increasing storage RH often resulted in vitamin crystallization, while increasing storage temperature at a constant low RH resulted in enhanced vitamin degradation. While different polymers resulted in different Tgs, moisture sorption profiles, and vitamin degradation rates, the key findings from this study were: 1) vitamins were more labile when amorphous than when crystalline; 2) vitamin amorphization was found in the presence of a variety of polymers, with both vitamin form and polymer type influencing the minimum amount of polymer needed; 3) all vitamins degraded significantly more when present at lower amounts in the amorphous solid dispersions, thus most degradation was found in the dispersions with the highest Tgs; and 5) intermolecular interactions influenced vitamin physical and chemical stability. Vitamin degradation was found in storage environments that maintained T