In Vitro Bioavailability of Mineral Nutrients in Breakfast Cereals

The bioavailability of both micro- and macroelements was investigated under conditions simulating the digestion processes in the human alimentary system. A one-step enzymatic extraction was applied using buffered solutions containing pepsin, trypsin, alpha-amylase or pancreatin, which are enzymes that hydrolyse different nutritional food components such as peptides, carbohydrates and lipids, as the extractant. Corn flakes and multigrain breakfast cereals containing taste additives from a local market in the Wroclaw agglomeration were selected for study as an important kind of ready-to-eat meal. The most popular brands (corn flakes from Nestlé, Mlekolaki and Hanne as well as wheat-based breakfast cereals from Chocapic, Nesquik and Fitness) were analysed. Microwave digestion was employed for sample preparation, and the total concentrations of both micronutrients (Al, Ca, Cu, Fe, Mg, Mn, P, Sr and Zn) and metals released during enzymatic in vitro digestion were measured by inductively coupled plasma-optical emission spectrometry (ICP-OES). Analysis of a Standard Reference Material was performed to validate the applied analytical procedure. Fractionation of the metals bound to the peptides, lipids and carbohydrates was evaluated and discussed.