Influence of Interfacial Composition on Droplets Flocculation of Oil-in-Water Emulsions Stabilized By Garden Cress Seed Gum

Both keeping emulsion droplets away from instability and using natural components are important factors in making colloidal systems. Garden cress seed gum as a novel natural hydrocolloid source used in 0, 0.5 and 1% concentrations to determine the gum efficiency on droplets interface and its ability to avoid flocculation. For this purpose surface and interfacial tensions, creaming index and microscopic images studied. Hydrocolloid solutions kept for 24 h at 40C to attain maximum hydration. Surface and interfacial tensions measured at 250C after reaching to their equilibrium time. Storage time considered to be 28 days for all treatments. The result showed surface and interfacial tensions parameters decreased by increasing gum concentration. Surface tension was least for 1% concentration but it was not much less than 0.5% level. In the control sample (without gum), emulsions droplets flocculated immediately and consequently phase separation occurred at the first day. At the 0.5% concentration hydrocolloids associated at the interface and made a stable emulsion. Partial flocculation happened at this level but no gravitational separation observed. Emulsions made by 1% gum concentration were completely stable during storage. At this level, the interface was saturated of hydrocolloids and the extra amount stayed at media. Non-adsorbed hydrocolloids increased solution viscosity and also produced repulsion forces with adsorbed ones. It assumes that Garden cress seed gum can prevent dropletaggregation by thickening effect and electrostatic repulsion rather than interfacial activities.

کلیدواژه ها:

interfacial properties ، garden cress ، emulsion stability ، surface activity ، flocculation