Hydrocolloid sponges are in essence dry-gel products. They were produced by preparing cold-set 1% alginate gels containing vitamin A. All gels were freeze-dried and kept over silica gel to avoid rehydration prior to testing, or were packaged in a laminate before clinical testing. Eighty children from a rural area in Northern Ethiopia were fed edible, fortified hydrocolloid sponges carrying 4000 IU of vitamin A. The edible sponges were being tested as a means of supplementing preschool children in an area with endemic vitamin A deficiency. Levels of vitamin A increased significantly following ingestion of the edible cellular solid, suggesting its usefulness as a carrier of vitamin A for children. The sponge consisted of hydrocolloid matrices to which oil had been added by homogenization. After gelation and freeze-drying, a crunchy, chewable, cellular solid designed as 'packaging' for the vitamin A was produced. Because it is devoid of flavor, odor and color, these characteristics can be controlled and incorporated during processing, to ensure broad acceptance by the targeted subjects. The product was studied for its mechanical (textural) properties to enable customized, affordable, stable packaging. The sponges were compressed to ~80% deformation between parallel lubricated plates and the stress-strain relationships were fitted to a compressibility model previously developed for the sigmoid stress-strain relationships of cellular solids: σ = C1ε/[(1 + C2ε)(C3 - ε)], where σ and ε are the stress and strain, respectively, and C1, C2 and C3 are constants. The sponge's inner structure was studied by scanning electron microscopy.
Bibliographical noteFunding Information:
This work was supported in part by GiFAiD and IAEA grants.