Physical properties and stability of filled hydrogel particles based on biopolymer phase separation: Influence of the ratio of protein to polysaccharide.

Filled hydrogel particles can be fabricated by incorporating an oil-in-water emulsion into portions of separated incompatible lower and upper phases together and remixing with later acidification to pH 5.0. The purpose of present study was to investigate the influence of different heat-denatured whey protein concentrates (HWPC)/high methoxy pectin (HMP) mass ratios (1:1, 2:1, 3:1, 4:1, and 5:1) of phase separated systems on the physical characteristics and stabilities of filled hydrogel particles. The results showed that the particle size of filled hydrogel particles significantly decreased with increasing HWPC/HMP mass ratios (P < 0.05), which was verified by reduced interfacial layer thickness. Moreover, decreased particle size also induced consistent reduction of the apparent viscosity and slightly increased the lightness. In particular, when the HWPC/HMP mass ratio was 3:1, the filled hydrogel particles exhibited the lowest amount of conjugated dienes and thiobarbituric acid-reactive substances after 10 days of storage (P < 0.05), which was mainly due to the highest amount of biopolymers distributed at the interfacial membrances (P < 0.05). Our results indicate that the phase separation system formed by HWPC/HMP mass ratio of 3:1 could be used to fabricate filled hydrogel particles with amplified stabilities at acidic pH for novel delivery systems.