In case of potatoes surveyed same as in other food stuffs right after cooking especially when fizzled or fried in oil comparatively substantial amount of Dehydro ascorbic acid was found. This is assumed because Diketo-gulonic acid (DKG) is produced while the material is being cooked. Hitherto, it has been known that while Potatoes are stored or damaged, DKG is produced and though DKG does not increase while in store, it has been reported that it does when boiled. So, in case of potatoes tests were made taking these in consideration. Again, assuming the effect of measured value of oxidized enzyme contained in them took caution to boil them previously. On potatoes, made separate test on Diketo-gulonic acid specially, However in order to avoid the effect of enzyme oxide as the preliminary experiment, we first made some potatoes steamed to make them immune to enzyme and then found out the differences of weight and the volume of C content in comparison with those of raw potatoes.
The enrichment of “amanatto” (sweet string bean) with dicetyl thiamine sulfate (heat stable thiamine derivative) was studied. It was found that the double incubations of the original boiled beans in a concentrated treacle mixed with the thiamine derivative is the best method for the enrichment.