Pre‐ and post‐expiry metal levels in canned dry milk

Levels of 12 metals (Ca, K, Na, Mg, Cu, Fe, Mn, Zn, Cd, Cr, Pb and Ni) were estimated in 19 different imported brands of unexpired and expired canned dry milk available from local markets. The HNO₃/HClO₄‐based wet digestion method was used for the analysis of the samples by the FAAS technique under optimum analytical conditions. Of the macronutrients, Ca showed highest at 1,144 μg/g in the dry milk from Holland. In the case of micronutrients, Fe showed the maximum level at 119.15 μg/kg in the milk from UK. Cr dominated at 23.19 μg/kg compared with other heavy toxic trace elements. The following order of decreasing concentration was observed for both unexpired and expired milk: Ca > Na > K > Mg > Fe > Zn > Cr > Pb > Cu > Ni > Cd. All the trace elements were found to have 100 per cent incidence of occurrence. The expired milk samples showed enhanced levels of Fe, Zn, Cr and Pb by a factor of 1.2‐1.6 on average. The results of the metal contents were compared with those for fresh cow milk. The data were statistically evaluated to find bivariate correlation between the metals in pre‐ and post‐expiry milks.