Preparation of alginate/starch beads with hydroxyapatite for curcumin loading and application as a colorimetric pH...

Alginate is the most popular material used to produce beads for encapsulating bioactive substances. However, alginate beads tend to lose encapsulated compounds during preparation. Here, we incorporated hydroxyapatite (HAp) to improve the performance of alginate (Alg)/starch beads, particularly in terms of thermal and physical properties. To indicate food spoilage, we added curcumin to obtain in a single-step process reinforced Alg/starch beads with a pH-responsive dye. The addition of HAp increased the whiteness and degree of crystallinity of the obtained beads due to the good interaction between alginate, starch and HAp. Furthermore, in solutions of different pH, Alg/starch beads with 10%w/v HAp were the most stable and exhibited the least change in their swelling ratio. The Alg/starch beads with 10%w/v HAp were loaded with curcumin during the preparation of the bead mixture and the obtained beads were applied to monitor the freshness of packaged fish. After three days in the packaging, the color of the beads changed from bright yellow to dark brown. Therefore, an effective chromogenic pH-responsive material was prepared in only one step. Adding 10%w/v HAp increased the stability of the Alg/starch beads entrapping the curcumin indicator, and hence increased the potential of the beads for use in the food industry.