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The physical stability of oil-in-water emulsions containing β-carotene was investigated to assess the emulsification of three hydroxypropyl methylcellulose (HPMC) of varying substitution and viscosity and gum acacia (GA) control dispersions. Initially, emulsions stabilized with GA had particle sizes of 0.79 μm, whereas the HPMC stabilized emulsions possessed particle sizes of about 1.38–1.96 μm. Following storage at 25 °C or 37 °C for up to 12 days, no significant differences between the initial and final particle sizes for two of the three HPMC stabilized emulsions (P < 0.05) were observed and remained <2.0 μm. However, the particle size distributions changed with time of storage at 25 °C or 37 °C in all emulsions, but were minimal in the emulsion containing the highest initial viscosity HPMC (0.401 Pa s). Images from light microscopy demonstrated that variability in droplet sizes was more prominent in low viscosity, low M:HP HPMC stabilized emulsions. Small amplitude oscillatory shear measurements revealed that the HPMC that possessed a viscosity of 0.401 Pa s and high M:HP (4.45) displayed characteristics of a weak gel network, which likely provided additional resistance against particle size increase. The analysis of the data demonstrates that HPMC with high viscosity, high M:HP produce emulsions with greater physical stability. [ABSTRACT FROM AUTHOR]

Abstract: The interaction of non-fat dry milk, caseinate and casein (CSN) fractions with charge modified pectins (B-Pec and U-Pec) and unmodified pectin (O-Pec) in acidified dispersion systems was investigated. U-Pec led to more precipitation of proteins than O-Pec or B-Pec. Casein dispersions with pectin had larger particle size, especially U-Pec and B-Pec, than dispersions without pectin. Dispersions with charge modified pectins showed more negative ζ-potential than dispersions with unmodified pectin or dispersions without pectin. U-Pec enhanced negative ζ-potential of β-CSN more than B-Pec. There was no significant difference in flow behavior among non-fat milk samples regardless of pectins added. In contrast, non-Newtonian behavior, shear thinning behavior was observed in modified pectin added κ-CSN. Analysis by light microscopy of non-fat milk and κ-CSN showed that sizes and shapes were changed by addition of O-Pec and U-Pec. The results suggest a specific affinity between pectin and κ-CSN, which is related to the charge distribution of pectin. [ABSTRACT FROM AUTHOR]