TITLE:
Effect of Processing on the Oxalate and Calcium Concentrations of Two Local Dishes, Cơm Hến and Canh Chua Bạc Hà, Prepared from Taro Stems
AUTHORS:
Du Thanh Hang, Than Thi Thanh Tra, Le Minh Tuan, Geoffrey Peter Savage
KEYWORDS:
Washing, Slicing, Wilting, Boiling, Taro, Petioles, Total, Soluble, Insoluble Oxalates
JOURNAL NAME:
Food and Nutrition Sciences,
Vol.8 No.6,
June
26,
2017
ABSTRACT: Stems
of sweet taro (Colocasia
esculenta) grown
in Thua Thien Huế Province in Vietnam and were used as an ingredient
to prepare two local dishes, Cơm Hến and Canh Chua Bạc
Hà. This study investigated the effect of simple processing treatments used to
prepare these popular dishes on the total, soluble and insoluble oxalate and
calcium contents of the taro stems. Raw stems were used to prepare Cơm
Hến. Three treatments, removing the skin then washing and slicing,
slicing and washing, or slicing and then allowing the stems to wilt overnight
were compared to the whole raw stems with the skin retained. Overall, processing
the stems reduced the soluble oxalate contents by a mean of 8% when compared
with the original raw stems. The mean total calcium bound in the insoluble
oxalate fraction of the three processing treatments was 43.3% ± 2.0%. Canh Chua Bạc
Hà was prepared by boiling peeled taro stems. In this experiment the peeled
stems were boiled for 10, 15 and 20 min and this resulted in 63.4%, 74.5% and 76.6% reductions in
soluble oxalate content, respectively, when compared to the original peeled
stems. Boiling for 20 min was the most effective way to reduce both the total
and soluble oxalate contents of the stems. 39% of
the total calcium in the raw taro stems was bound
to the insoluble oxalate fraction and this was reduced to a mean of 17.2% ± 2.6% by the three cooking
treatments.