Abstract:

In this study, the contents of folic acid in main grain crops, fruits and vegetables were determined and evaluated
to provide a theoretical basis for reasonable supplementation of folic acid for people’s daily consumption. A total of 38
samples, including 11 kinds of main grain crops, 17 kinds of common vegetables and 8 kinds of common fruits, were
collected from some households and local markets in Shanxi Province. Grain samples were prepared by grinding and sieving
through 100 mm sieve, and fresh fruits and vegetables samples were randomly prepared by collecting the edible parts
and were chopped into small pieces. The contents of folic acid in all samples were extracted with potassium dihydrogen
phosphate in water bath. The optimum extraction was achieved by addition of the active carbon adsorbent treated by
aniline to the extraction solvent, the extracts were eluted continuously with a mixture containing 3% ammonia and 70%
ethanol, and indirect fluorescent method was used to determine the fluorescent intensity of folic acid oxidized by potassium
permanganate. Data showed that there was a significant difference in the contents of folic acid between the main grain
crops, which were all over 1.56 μg/g md, and the grain crops containing higher folic acids included soybean, peanut, mung
bean, foxtail millet, oat, corn and buckwheat. The vegetables with higher folic acid content surpassing 1.53 μg/g mf were
in decreasing order: spinach, rapeseed, shiitake, leaf lettuce, lettuce, cabbage, green pepper, celery, Chinese cabbage
and pumpkin. The folic acid content in the fruits for daily consumption was over 1.74 μg/g mf. These data may provide a
scientific basis for reasonable dietary supplementation of folic acid as well as reasonable adjustment in dietary structure
based on intake of fruits and vegetables.

Key words: grain crop, fruit, vegetable, folic acid content