Effect of cooking loss on mineral intake in diabetic diets.

摘要

The foodstuffs were 31 samples of vegetables, 2 samples of potatoes, 4 samples of dried noodles and 7 samples of fish. The iron, zinc, copper, magnesium and potassium contents of each sample were analysed by atomic absorption spectrometry before andafter cooking. The percentage decrease in each of these elements was calculated from the difference in the values before and after cooking. The decreases in the mineral contents of the vegetables were greater when boiled in water than when dipped at room temperature. The percentage decrease with dipping rose as the contact surface with the water increased. Losses in the grating process used with such vegetables as radish and carrot were around 14-20% and when a squeezing process was added after boiling, the losses increased to 26-46%. This was the largest cooking loss with the vegetables. Potassium was decreased most by the boiling or dipping process, but iron was not affected much. This decrease may have depended on the characteristics of each element. It is concluded that cooking loss is one important reason why the chemically analysed mineral values for diabetic diets are often lower than the calculated values. It is necessary to take care in the preparation of food to minimize the cooking loss ofthose minerals which are likely to be insufficient, especially with low-energy diabetic diets.