Static in vitro digestion methods for assessing essential minerals in processed meat products

The consumption of processed meat products has increased due to its convenient preparation and characteristics related to taste and consumer acceptance. In this study, we evaluated the content and bioaccessibility of iron (Fe), zinc (Zn), calcium (Ca) and magnesium (Mg) in processed pork and beef products by dialysis assay. In addition, different assays of static in vitro digestion (traditional solubility and INFOGEST) were applied to verify the results on the bioaccessibility of these essential elements. The average content of essential elements (expressed in mg/100 g) were 0.78 +/- 0.24 and 1.51 +/- 0.51 for Fe; 1.79 +/- 0.55 and 3.57 +/- 1.42 for Zn; 13.24 +/- 9.99 and 20.29 +/- 10.45 for Ca and 19.43 +/- 2.78 and 26.15 +/- 7.33 for Mg, in pork and beef products, respectively. However, we observed high variation between brands and batches. The dialysis assay presented variations in bioaccessibility for all essential elements evaluated in the samples. The results for dialyzable Fe were lower than expected (in vivo assays), probably due to the mechanism simulated in dialysis. This assay was considered inadequate for the simulation of in vitro digestion for meat samples that contain heme-Fe. When comparing the different static in vitro digestion assays employed, the dialysis test showed the lowest bioaccessibility percentages for all essential elements evaluated, when compared with the other in vitro digestion methods. The highest bioaccessible fractions were obtained by applying the INFOGEST protocol. We found that according to the in vitro digestion simulation assay used, the results for bioaccessible percentage displayed high variation. These observations highlight the importance of the assay type used for this purpose. These results did not indicate which is the better assay, but demonstrated the differences of each and their relevance for estimating bioaccessibility of essential elements in meat products.