Total and soluble contents of calcium, magnesium, phosphorus and zinc in yoghurts

Abstract

This paper examines the content of major minerals (calcium, magnesium, phosphorus and zinc) and its distribution between soluble (non-sedimentable) and micellar fractions of 16 commercial yoghurts from five different branches. These elements were determined by atomic absorption spectrometry after mineralisation by dry ashing. Total mineral contents showed wide intervals of variation (calcium 1090–2050 mg l−1, magnesium 101–177 mg l−1, phosphorus 878–1560 mg l−1 and zinc 4.0–7.3 mg l−1) due to the addition during manufacturing of different dairy products or fractions. Most of the minerals were found in the non-sedimentable fraction. Practically all calcium was measured in the supernatants of ultracentrifugation. Lower proportions of magnesium and zinc were determined in the non-sedimentable fraction (between 87 and 96%) whereas the lowest ones (63–77%) were found for phosphorus.