Effect of milling, pasta making and cooking on minerals in durum wheat

The effect of technological processing on the contents of eight minerals - i.e., calcium, copper, iron, magnesium, phosphorous, potassium, selenium, and zinc - was investigated in pasta making. Milling of durum wheat as well as pasta making were carried out in a pilot plant by using three different grain samples. Pasta samples purchased on the market were also surveyed to gain information on the mineral content of commercial products. The effect of cooking was also investigated in order to determine the retention of the selected elements in the final 'ready-to-eat' product. Analyte concentrations in whole grains, semolina, pasta and cooked pasta were determined by inductively coupled plasma-mass spectrometry. Conventional roller milling significantly reduced the content of each mineral in durum wheat grains. However concentration losses as a consequence of milling widely differed among elements, from 16% for Se to 66% for Mg and Zn on a dry weight basis. Retention of elements after milling followed the order Se > Ca > Cu > P approximate to K > Fe > Mg approximate to Zn. Pasta making had little effect on element concentrations in semolina. Cooking caused an increase in the calcium content of pasta whereas the concentrations of the other elements were either unchanged or slightly reduced (0-18% on a dry weight basis) except potassium, which showed a decrease of 74%. Commercial pasta samples showed concentrations of minerals similar to those of the experimental samples, except selenium which was higher due to the use of imported wheat with higher levels of selenium in industrial semolina production. Overall, pasta appears to be a valuable source of several minerals, especially selenium, copper, magnesium, and zinc. (C) 2008 Elsevier Ltd. All rights reserved.