Thermal Stability and in Vitro Digestion of Alginate–starch–iron Beads for Oral Delivery of Iron

Ferrous bisglycinate can be used as an oral therapy for iron deficiency. However, the low thermal stability of ferrous bisglycinate powder to oxidation of ferrous ions hinders its application to fortification of foods that are heated before consumption. In this study, ferrous bisglycinate powder and beads prepared from alginate, starch, ferrous bisglycinate powder, and water in a ratio of 2:1:2:100 (w:w:w:v) were subjected to thermal treatment at 90 degrees C and 180 degrees C for 90 min. Heating changed the geometry of the beads. Large fractures appeared on the surface of the heated beads, while multiple pores formed in their cores. The beads increased the oxidative stability of Fe (II) at 180 degrees C, with 83.53% Fe(II) and 16.47% Fe(III) after heating, compared with 65.08% and 34.92% for ferrous bisglycinate powder alone. In a temperature-dependent manner, the amounts of bioaccessible Fe(II) and Fe(III) released from bisglycinate powder under in vitro gastric conditions ranged from 153.31 to 118.42 mg and 10.81-74.75 mg, respectively, compared to 32.90-42.49 mg and 7.94-14.51 mg released from the beads. At the end of the simulated oral-gastric-intestinal digestion, the beads heated to 180 degrees C released 1.22-fold more bioaccessible ferrous ions (147.85 mg) than were released from the corresponding bisglycinate powder (121.57 mg). These experimental results indicate that alginate-starch-ferrous bisglycinate beads thermally treated at 180 degrees C are promising carriers for oral delivery of iron.