Asparagus Tuber
Asparagi Tuber
Asparagus Tuber is the tuber of
Asparagus cochinchinensis Merrill
(Liliaceae), from which most of the cork layer is removed, usually, after being
steamed.
Description:
Asparagus Tuber is a fusiform
to cylindrical tuber, 5 - 15 cm in length, 5 - 20 mm in diameter; externally light
yellow-brown to light brown, translucent and often with longitudinal wrinkles;
flexible, or hard and easily broken in texture; fractured surface, grayish
yellow, glossy and horny.
Odor, characteristic; taste,
sweet at first, followed by a slightly bitter aftertaste.
Under a microscope, a
transverse section of Asparagus Tuber reveals stone cells and bundles of them
on outer layer of cortex; mucilaginous cells containing raphides of calcium
oxalate in the parenchyma cells of cortex and stele; no starch grains.
Identification:
To 1 g of coarsely cut
Asparagus Tuber add 5 mL of a mixture of 1-butanol and water (40:7), shake for 30
minutes, filter, and use the filtrate as the sample solution.
Perform the test with the
sample solution as directed under
Thin-layer Chromatography. Spot
10 μL of the sample solution on a plate of silica gel for thin-layer chromatography,
develop the plate with a mixture of 1-butanol, water and acetic acid (100)
(10:6:3) to a distance of about 10 cm, and air-dry the plate. Spray evenly
dilute sulfuric acid on the plate, and heat at 105oC for 2 minutes:
the spot of a red-brown at first then changes to brown color appears at an Rf
value of about 0.4.
Purity:
(1) Heavy metals. Proceed with 3.0 g of pulverized Asparagus Tuber
according to Method 3, and perform the test. Prepare the control solution with
3.0 mL of
Standard Lead Solution (not
more than 10 ppm).
(2) Arsenic. Prepare the test solution with 0.40 g of pulverized
Asparagus Tuber according to Method 4, and perform the test (not more than 5
ppm).
Loss on drying:
Not more than 18.0z (6 hours).
Total ash:
Not more than 3.0z.
Containers and storage:
Containers.Well-closed containers.
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