Effect of Enzyme Amounts Used in Gastrointestinal Digestion Upon Solubility and Caco-2 Cell Uptake Assays of Minerals from Infant Formulas

Abstract

The effect of enzyme amounts used in gastrointestinal in vitro digestion upon the solubility and Caco-2 cell uptake of calcium, iron and zinc from infant formulas (IFs) was studied. Different amounts of enzymes (g enzyme/g IF), pepsin (0.002 and 0.048), pancreatin (0.0005, 0.002 and 0.01) and bile extract (0.003, 0.125 and 0.0625) were assayed. Mineral soluble contents and mineral uptakes by Caco-2 cells were affected by the enzyme amounts used in digestion. Although the highest mineral solubility (Ca 98.6 vs 46.2%; Fe 98.1 vs 83.9%; Zn 98.4 vs 83%) was obtained when the lowest enzyme (pepsin 0.002 vs 0.048; pancreatin 0.0005 vs 0.01g/g IF) and bile extract (0.003 vs 0.0625g/g IF) amounts were used, under these conditions uptake decreased with respect to that obtained when the highest amounts were used (Ca 0.4 vs 1.8%; Fe 0.3 vs 4.8%; Zn 1.7 vs 37%), that indicated a lack of relationship between solubility and absorption. Interactions among different products resulting from the proteolytic activity of digestive enzymes and minerals can modify the physicochemical forms in which minerals are available for absorption after gastrointestinal digestion.