Removal of potassium from tuberous root vegetables by leaching.
OBJECTIVE
To determine analytically the amount of potassium in raw tuberous root vegetables (TRV); to estimate the amount of potassium that can be leached from raw TRV by soaking in water; and to determine whether the duration of soaking and the cooking method selected affect potassium extraction.


METHODS
Fresh TRV (ie, fresh and sweet batata, cocomalanga, dasheen, eddo, black yam, white yam, yellow yam, yampi, malanga, red yautia, white yautia, and yuca) were obtained from an ethnic market. Five experimental conditions with variations in soak time and cooking method were applied. Potassium was extracted from the ash of dried samples. The potassium content of aqueous extractions was determined through atomic absorption spectrophotometry.


RESULTS
Mean potassium content was highest in raw cocomalanga and lowest in raw dasheen. All of the raw TRV, except for dasheen, had a potassium content >200 mg (5.1 mEq)/100 g sample. Soaking was not effective in the leaching of significant amounts of potassium from most TRV. The double cooking (DC) method (ie, boil, rinse, boil again) leached more potassium from most TRV than did the normal cooking (NC) method (ie, boil), except with dasheen and yellow yam. More vegetables retained a potassium content >200 mg (5.1 mEq)/100 g following NC versus DC (92% versus 54%).


CONCLUSIONS
The potassium content of raw TRV varied considerably, with most tubers retaining a moderate or high potassium content following the leaching procedures. However, this study showed that DC appears to be more effective than NC for leaching potassium from TRV.
Burrowes
Jerrilynn D
JD
Department of Nutrition, School of Health Professions and Nursing, C.W. Post Campus of Long Island University, Brookville, New York 11548, USA. jerrilynn.burrowes@liu.edu
Ramer
Nicholas J
NJ
D002908:Chronic Disease; D003296:Cooking / Q000379:methods; D003469:Culture; D027742:Dioscorea; D005006:Ethnicity; D005504:Food Analysis / Q000379:methods; D006358:Hot Temperature; D006801:Humans; D007674:Kidney Diseases / Q000178:diet therapy; D002365:Manihot; D035281:Plant Tubers / Q000737:chemistry*; D011188:Potassium / Q000032:analysis / Q000302:isolation & purification*; D017419:Potassium, Dietary / Q000008:administration & dosage / Q000009:adverse effects / Q000032:analysis; D014675:Vegetables / Q000737:chemistry*; D014867:Water
D017419:Potassium, Dietary; D014867:Water; D011188:Potassium