Effects of iron-alginate ratios and pHs of gelation on characteristics of iron bead encapsulation

Encapsulation is one of the methods to protect iron from oxidation. Among the encapsulation methods, gelation could be the simplest one. This method requires the matrix which could form a gel. Alginate fulfills the requirements as an encapsulant by creating beads. However, performances of the encapsulation are determined by the conditions of the gelation process. The aim of this study was to study the effect of the iron -alginate ratios (0.05-0.5, w/w) and pHs of gelation (5-10) on the properties of alginate beads for iron encapsulation. CaCl2 solution was used as a cross-linked agent to form beads. Solution of iron-alginate was dropped into CaCl2 solution (150 mL, 1 M) using 5- mL unneedled syringe from about 5 cm above the cross-linked solution surfaces. The results showed that the ratio of iron-alginate and pH have a negative correlation with moisture content, diameter beads, and encapsulation efficiency but iron loading. Neutral pH-gelation produced softer bead texture. The highest efficiency encapsulation was found in pH 5 of gelation. Release of iron was higher in pH 6.8 than that in pH 1.2. Increase in iron-alginate ratio led to have more syneresis effect. However, higher pH-gelation tended to have lower syneresis.