A method for a) controlling the timing of calcium-mediated cross-linking of polymers such as alginates and soy proteins to enable spray-dry encapsulation of biological moieties (e.g., proteins, cells, probiotics, nutraceuticals, etc.), and b) controlling the release of the encapsulated ingredients by controlling cross-linking and hydration properties of the encapsulation.
Alginates have been used for decades for the encapsulation of biological molecules, cells and chemicals. The traditional encapsulation process involved dissolving or dispersing the active agent in a sodium alginate solution, forcing the solution through an orifice to form a droplet which was then cross-linked by contact with a calcium chloride solution. This process was not easily scaled-up and was limited to particles larger than 500 μm. Spray-drying would be a commercially viable process to form a calcium alginate matrix particle in the size range of 10 – 20 μm; however, one would have to find a way of cross-linking the sodium alginate solution during atomization.
Researchers at the University of California Davis have developed a method that accomplishes this by spray-drying an aqueous formulation that contains sodium alginate, a calcium salt that is only soluble at reduced pH and an organic acid that has been neutralized to a pH just above the pKa with a volatile base. Under these conditions, the calcium salt is insoluble and calcium ions are not available for cross-linking. The solution in this fluid state is pumped through the nozzle of the spray dryer, where it is effectively atomized. Upon atomization, the volatile base is vaporized, which reduces the pH (hydrogen ions are released into solution) and in turn releases calcium ions from the calcium salt that cross-link the alginate. The incorporation of an additional polymer to the formulation allows for the control of hydration properties of the particles to control the release of the encapsulated compounds.
This same process can be used for encapsulation using soy protein.
|United States Of America||Issued Patent||9,700,519||07/11/2017||2010-695|
|United States Of America||Published Application||20170333360||11/23/2017||2010-695|
cells (including stem cells), probiotics, nutraceuticals, biochemicals, calcium-mediated cross-linking of polymers, spray-drying, cross-linking, alginates, soy proteins, encapsulation