市販ホウレンソウ中のシュウ酸、硝酸含量の酵素法による測定 [in Japanese] Measurement of the Contents of Oxalate and Nitrate in Commercially Available Spinach by Enzymatic Analysis [in Japanese]
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I measured the contents of oxalate and nitrate by enzymatic analysis in spinach sold in the' Kitakyushu area from spring in 1997 to spring in 2001. Although it was previously reported that about 600 to 1OOOmg of oxalate was included in 1OOg of raw spinach, the results in the present study indicated that the content (200 to 6OOmg in 1OOg spinach) was lower than those reported previously. As for nitrate, about 80 to 800mg of nitrate was included in 1OOg of raw spinach. Thus, there was ten times the difference between the samples having the lowest and the highest contents. When measuring spinach by separating it into the blade and stalk portions, in most samples, I found that the blade portion included more oxalate, while the stalk portion included more nitrate. When spinach was boiled for 2.5 minutes with five times as much water as the spinach weight, the residual contents of oxalate was decreased by 40-80%, and that of nitrate was decreased by 30-80%. The residual amounts of nitrate tended to be larger than oxalate. In the differences of contents of oxalate and nitrate in spinach, no particular patterns specific to the period of cultivation and the area of production were observed.
- Bulletin of Seinan Jo Gakuin University
Bulletin of Seinan Jo Gakuin University 9, 104-111, 2005
Seinan Jo Gakuin University