Enlarging calcium alginate liquid-core capsules: Manufacturing, microstructure, and beverage packaging applications

Area of Science:

• Food Science
• Materials Science
• Chemical Engineering

Background:

• Calcium alginate liquid-core capsules (LCCs) are typically micrometer-scale, limiting their use in larger applications like beverage packaging.
• Scaling up LCC production presents challenges in maintaining structural integrity and preventing leakage.

Purpose of the Study:

• To develop a scalable method for producing centimeter-scale LCCs.
• To investigate the relationship between alginate chain architecture and the microstructure, mechanical properties, and leakage of the LCC shells.
• To evaluate the potential of these LCCs for sustainable beverage packaging.

Main Methods:

• A freeze-reversed spherification technique using frozen calcium chloride hemispheres as templates.
• Incubation of templates with sodium alginate solution.
• Optimization of secondary immersion parameters.
• Characterization of shell microstructure, mechanical properties (bursting force), and leakage using spectroscopy and molecular descriptors.

Main Results:

• Successfully fabricated centimeter-scale LCCs using the freeze-reversed spherification method.
• Optimized secondary immersion increased bursting force by 19.5%.
• Resulting LCCs exhibited denser outer layers, reduced interlayer spacing, favorable pore dimensions, improved water retention, stronger Ca2+-carboxylate binding, higher dimer packing density, and shorter interchain distance.
• Encapsulated kiwi and corn juices, maintaining sensory quality during storage.

Conclusions:

• The freeze-reversed spherification route enables the production of centimeter-scale LCCs with enhanced mechanical integrity and reduced leakage.
• Alginate chain architecture significantly influences shell properties.
• These LCCs demonstrate significant potential for application in sustainable beverage packaging.