Effect of Cooking on the Oxalate Content of Selected Thai Vegetables

Onladda Juajun, Leo Vanhanen, Chancherdchai Sangketkit, Geoffrey Savage

Agro-Industry Department, Faculty of Agriculture and Technology, Rajamangala University of Technology Isan, Surin Campus, Na- khon Ratchasima, Thailand.
Agro-Industry Department, Faculty of Agriculture and Technology, Rajamangala University of Technology Isan, Surin Campus, Na- khon Ratchasima, Thailand;.
Food Group, Agriculture and Life Sciences, Lincoln University, Canterbury, New Zealand..

DOI: 10.4236/fns.2012.312213                

Abstract

Total and soluble oxalate content levels were measured in thirteen selected vegetables purchased from a local market in Surin Province in the northeast of Thailand. Total oxalate contents of the leaves, shoots and roots of the fresh vegetables ranged from 249.5 ± 12.1 to 7597.9 ± 77.6 mg oxalate/100g dry matter (DM) while soluble oxalate content ranged from 205.0 ± 2.3 to 2677.6 ± 19.0 mg oxalate/100 g DM. Very high levels of total oxalates were found in three of the selected Thai vegetables, Polygonum odoratum (7597.9 ± 77.6 mg/100g DM), Piper aurantaucum (7026.6 ± 76.9 mg/100g DM) and Limnophila aromatic (6179.0 ± 23.6 mg/100g DM). However, the soluble oxalate content of L. aromatic was low and the highest soluble oxalate contents of fresh vegetables were found in P. odoratum, P. aurantuacum and Neptunia oleracea at 2677.6 ± 19.0, 2152.2 ± 65.3 and 1640.8 ± 3.4 mg/100g DM, respectively. Boiling the vegetables reduced the soluble oxalate content between 30.4 and 65.0%. The insoluble oxalate levels increased in eleven of the cooked vegetables while small decreases were observed in L. aromatic and N. oleracea.

Keywords

Total Oxalate; Soluble Oxalate; Insoluble Oxalate; Thai Vegetables

Conflicts of Interest

The authors declare no conflicts of interest.

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