Physical and mechanical properties of alginate based composite gels

Alginate has become one of the most important natural ingredients widely used in encapsulation and controlled-release systems for food ingredients, bioactive compounds, and pharmaceutical materials due to its ability to form a gel matrix in the presence of divalent cations, primarily Ca2+ ions. However in certain cases, alginate gel is often inadequate as an encapsulation system due to its poor mechanical property and syneresis occurring during the formation of the gel. These factors reduce its effectiveness for encapsulating substances especially water-soluble ingredients such as proteins and bioactive compounds. Many studies have reported on alginate composite gels including alginate-hydrocolloids, alginate-proteins, and alginate-starches composite gels. This review compiled and critically discussed the effects of hydrocolloids, proteins, and starches on the physical and mechanical properties of alginate composite gels. Combining alginate gels with other natural polymers (hydrocolloids, proteins and starches) in correct proportions provides better protection, increasing substance entrapment yield and prolonging the release of the entrapped material since the added biopolymers can influence the density and strength of alginate gels.