Test meal analyses
Meal analyses were performed in freeze-dried, ground potato meal samples. The analysis (except for ascorbic acid) was performed on test meals prepared using a subset of the tubers used for the preparation of the test meals, 2 wk before the preparation of all the test meals. To test for variation during processing and storage, ascorbic acid was analyzed in cooked and mashed tubers immediately after preparation, and also in cooked and mashed tuber samples after storing at −20°C for 5 mo and thawing at room temperature overnight.Grinding of samples was done in a stainless-steel mill only used for potato samples to avoid sample contamination. Iron concentration was measured using a method based on Mwesigye et al. [