科研之友
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摘要
The ionotropic gelation of double-layered emulsions composed of sodium caseinate and kappa-carrageenan at pH values of 7 and 3.5 was evaluated, in order to obtain potential encapsulation matrices for hydrophobic compounds. The influence of some of the extrusion process variables (nozzle diameter at fluid exit and collecting distance) on the microbead production was studied, as well as the stability of the microbeads. The fluid nozzle diameter showed little influence on the shape of the microbeads, with a slight tendency for a decrease in microbead diameter with increase in fluid nozzle diameter. On the other hand, the collecting distance strongly influenced the microbead shape and they became more spherical (aspect ratio was reduced from similar to 2.0 to similar to 1.4) as the collecting distance was increased from 10 cm to 50 cm. The emulsion pH did not affect the aspect ratio of the microbeads, but the diameter was greater for microbeads produced at pH 3.5. This difference was attributed to the kind of interactions occurring between the kappa-carrageenan and sodium caseinate at these distinct pH values. The microbeads were highly unstable when dispersed in deionized water, sugar solutions and low salt concentrations, releasing the encapsulated oil. However, no release of oil from the microbeads was observed when they were dispersed in ethanol or potassium chloride solutions with concentrations above 0.75 %, although their shape was modified when dispersed in ethanol. In general, the results obtained demonstrated the viability of the extrusion process to produce biopolymer-based microbeads and the potential application of these systems.
- 出版日期2012-9
