Abstract: The effects of four kinds of microwave drying equipment on total flavonoids, total organic acids, vitamin C and color of hawthorn were studied, and the suitable drying methods of hawthorn were studied. Using hyperoside as standard, the content of total flavonoids in four kinds of drying methods was determined by colorimetric method. The total organic acid content in four kinds of drying methods was determined by acid-base titration with phenolphthalein as indicator. The content of vitamin C in hawthorn was determined by 2,6-dichlorophenol titration method. The color data of four kinds of dry hawthorn powder were determined by colorimeter.
The results showed that the contents of total organic acids, total flavonoids and vitamin C in the four drying methods were significant. The total organic acid and vitamin C content of the freeze-dried samples were the highest, respectively 133. 25 mg / g and 0. 322 4 mg / g; the lowest in natural drying, 94. 55 mg / g and 0. 163 1 mg / g. The content of total flavonoids in microwave drying samples was the highest, and the content of naturally dried samples was the lowest, respectively. 26 mg / g and 32. 25 mg / g. In terms of color, vacuum freeze-dried hawthorn has the best color. Vacuum freeze-drying, on the basis of maximally retaining vitamin C, reduced the loss of total flavonoids to a certain extent and exhibited the most desirable color.
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