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Phase transitions of ascorbic acid and sodium ascorbate in a polymer matrix and effects on vitamin degradation
Author(s) -
Ismail Yahya,
Mauer Lisa J.
Publication year - 2020
Publication title -
journal of food process engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.507
H-Index - 45
eISSN - 1745-4530
pISSN - 0145-8876
DOI - 10.1111/jfpe.13073
Subject(s) - ascorbic acid , differential scanning calorimetry , chemistry , amorphous solid , relative humidity , vitamin c , sodium , crystallization , glass transition , food science , polymer , chromatography , nuclear chemistry , organic chemistry , physics , thermodynamics
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.