Dietary fiber in raw and cooked potatoes
1991
Mullin, W.J. | Smith, J.M.
Soluble and insoluble dietary fiber were determined in potatoes, total dietary fiber was expressed as the sum of the soluble and insoluble fiber. New and stored potatoes were purchased locally in lots of 100 lb each. The new potatoes were analyzed raw and boiled; the stored potatoes were analyzed raw, microwaved, and baked. In each treatment, the dietary fiber in the flesh, flesh plus skin, and skin was determined separately. The moisture content of the new potatoes was higher than that in the old potatoes with very little lost on boiling. The raw skin component of the stored potatoes was higher in moisture than all other samples, cooked or raw. In microwave cooking the moisture in both skin and flesh was mostly retained in contrast to skin in baked potatoes which retained only 49% moisture. In all the cooking treatments the apparent total dietary fiber increased. In the new potatoes the increase was mainly due to insoluble fiber but in the stored potatoes both soluble and insoluble dietary fiber increased. The skin contained considerably more total dietary fiber than the flesh, for example, 22.6% dry basis for the microwaved skin compared to 7.5% dry basis in the microwaved flesh. The ratio of the soluble to the insoluble fiber was highest in the flesh and lowest in the skin. There was no consistent change in the soluble/insoluble ratio due to cooking.
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