Phytases Improve Inositol Bioaccessibility in Rye Bread: A Study Using an Method of Digestion and a Caco-2 Cell Culture Model.

Preparations of 6-phytase A (EC 3.1.3.26) and phytase B (acid phosphatase, EC 3.1.3.2) were applied alone and combined in the preparation of dough to estimate their catalytic potential for inositol liberation from rye flour in the breadmaking technology. The experimental bread samples were ground after baking and subjected to determination of inositol bioavailability by an method that simulated digestion in a human alimentary tract, followed by measurements of inositol transport through enterocyte- -like differentiated Caco-2 cells to determine its bioaccessibility. inositol content was measured by a high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD) technique. The concentration of inositol in the dialysates of control bread was 25.3 µg/mL, whereas in the dialysates of bread sample baked with 6-phytase A, the concentration increased to 35.4 µg/mL, and in the bread baked with phytase B to 64.98 µg/mL. Simultaneous application of both enzymes resulted in inositol release of 64.04 µg/mL. The highest bioaccessibility of inositol, assessed by the measurement of the passage through the Caco-2 monolayer was determined in the bread baked with the addition of 6-phytase A. Enzymatically modified rye bread, particularly by the addition of 6-phytase A, may be therefore a rich source of a highly bioaccessible - -inositol.