Effect of gelatin properties in complex coacervation processes

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Abstract
The effects of Bloom grade and iso-electric-point of gelatin on the complex coacervation with acacia and micro-encapsulation of theobromine were investigated. The zetapotential of various gelatins and acacia was measured at different pH values and compared with the optimal pH range for complex coacervation. Values for electrical equivalence pH of gelatins and acacia were in the same range as the maximal coacervate volumes. For the high Bloom grade gelatins the pH range in which most complex coacervate was formed was smaller for Alkaline-processed gelatin than for Acid-processed gelatins. The same small pH range was observed for the low Bloom grade gelatin of the Acid-type compared to high Bloom grade gelatins of the same type. The total amount of complex coacervate increased and the relative contents of theobromine in microcapsules decreased for gelatins with high Bloom grade. Microcapsules prepared with a high Bloom grade gelatin were irregular shaped and showed poor flow characteristics. No differences in theobromine release profiles from the various microcapsules were observed