Oxalate content in the different taro cultivars in Central Viet Nam and the effect of simple processing methods on oxalate concentrations

Du Thanh Hang, T R Preston and G P Savage

HUAF, Hue, Vietnam
hangduthanh@yahoo.com.vn

Abstract

Eight varieties of forage taro grown in Central Viet Nam were analyzed for oxalate content of the leaves and stems. The total oxalate content of the stems ranged from 2404 to 4416 while the levels in the leaves ranged from 2021 to 6342 mg/100 g DM. The soluble oxalate content of the stems ranged from 142 to 2794 and the leaves ranged from 83 to 1475 mg/100 g DM. The insoluble content of the leaves ranged from 961 to 6259 while the levels in the stems ranged from 811 to 3613 mg/100 g DM. The mean value of total and insoluble oxalate in leaves was higher than in stems but soluble oxalate content in stem was higher than in the leaves. There was no significant difference in the total, soluble and insoluble oxalate concentration between taro forages grown in lowland or sandy soils.  The total oxalate content of taro stems and leave can be reduced using simple processing methods; soaking reduced the concentration by 23.5%, cooking 56.7% and ensiling for14 days 36.8%.  However, washing and wilting only reduced the concentration by 9.2 and 14.2% respectively.

Key words:  cooking, ensiling, insoluble, leaves, oxalate,  soaking, soluble, stems, washing, wilting