The function of digestive enzymes on Cu, Zn, and Pb release from soil in in vitro digestion tests

Abstract

The bioaccessibility of soil heavy metals is the solubility of soil heavy metals in synthetic human digestive juice, which is usually determined using in vitro digestion test. To reveal the effects of digestive enzymes on soil heavy metals bioaccessibility, three representative in vitro digestion tests, Simple Bioaccessibility Extraction Test (SBET), Physiologically Based Extraction Test (PBET), and Simple Gastrointestinal Extraction Test (SGET), were chosen. The bioaccessibility of soil Cu, Zn, and Pb in each method were respectively evaluated with and without digestive enzymes, and the differences were compared. The results showed that the effects of digestive enzymes varied with different methods and elements. Because of digestive enzymes addition, the environmental change from acid gastric phase to neutral intestinal phase of PBET did not result in apparently decrease of the bioaccessibility of soil Cu. However, the solubility of soil Zn and Pb were pH-dependent. For SGET, when digestive enzymes were added, its results reflected more variations resulting from soil and element types. The impacts of digestive enzymes on heavy metal dissolution are mostly seen in the intestinal phase. Therefore, digestive enzyme addition is indispensable to the gastrointestinal digestion methods (PBET and SGET), while the pepsin addition is not important for the methods only comprised of gastric digestion (SBET).

Influence of Thermal Processing and in vitro Digestion on the Antioxidant Potential of Ginger and Ginger Containing Products

“…The process of digestion was proven to diminish the antioxidant activity of the samples in all studied types of digestion protocols. The obtained data is interesting and remains consistent with the previously published results for other plant species [12]. Based on these observations, the process of digestion seems to decompose phenolic constituents in the foods, leading to a marked decrease in its antioxidant potential.…”

Environmental and Health Risks of Heavy Metals in Farmland Soils of Drinking Water Protection Areas and a Contaminated Paddy Field in Taiwan

“…In contrast, the proportion of intestinal extraction (pH = 7.0) of PBET (range: 0.93-10.5%; average: 4.55%) was relatively smaller than those in the gastric phase extraction of SBET and PBET (pH = 1.5 and 2.5, respectively). These results suggest that Zn is more easily dissolved in an acidic condition, which is in consistence with the findings of a previous work [65].…”

Comparison of Gastric versus Gastrointestinal PBET Extractions for Estimating Oral Bioaccessibility of Metals in House Dust

“…As the pH rises, Cu appears to be stabilized in solution by complexation with available organic ligands from the dust matrix, and with other reagents used in the extraction procedure such as the malate ion and anions of bile acids [ 19 ]. An intermethod comparison study by Li et al [ 41 ] found that the digestive enzymes used in the PBET gastric phase kept soil Cu in solution during the intestinal phase, despite the increase in pH. Their study showed that the solubility of soil Cu in the intestinal phase of PBET remained constant or was even promoted as a result of the presence of the digestive enzymes, whereas the solubility of soil Zn and Pb was pH dependent [ 41 ].…”