Formation and stability of emulsions using a natural small molecule surfactant: Quillaja saponin (Q-Naturale®)

• Published in: Food hydrocolloids Vol. 30; no. 2; pp. 589 - 596
• Main Authors: Yang, Ying, Leser, Martin E., Sher, Alexander A., McClements, David Julian
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-03-2013
• Subjects: bark; droplets; electrostatic interactions; Emulsifier; emulsifiers; Emulsion; emulsions; flocculation; food industry; homogenization; imitation foods; ionic strength; Nanoemulsion; Natural; particle size; Q-Naturale; Quillaja saponaria; Quillaja saponin; salt concentration; sodium chloride; Stability; Surfactant; surfactants; Tween 80; Emulsion; Stability; Nanoemulsion; Emulsifier; Q-Naturale; Natural; Surfactant; Quillaja saponin; Tween 80
• ISSN: 0268-005X; 1873-7137
• DOI: 10.1016/j.foodhyd.2012.08.008

Q-Naturale® is a natural food-grade surfactant isolated from the bark of the Quillaja saponaria Molina tree. The major surface active components of Q-Naturale® are believed to be saponin-based amphiphilic molecules. In this study, we compared the effectiveness of this natural surfactant for forming and stabilizing emulsions with a synthetic surfactant (Tween 80) that is widely used in the food industry. We examined the influence of homogenization pressure, number of passes, and emulsifier concentration on the particle size produced. Q-Naturale® was capable of forming relatively small droplets (d < 200 nm) at low surfactant-to-oil ratios (SOR < 0.1) using high pressure homogenization (microfluidization), but the droplets were not as small as those produced using Tween 80 under similar conditions (d < 150 nm). Q-Naturale®-coated droplets were stable to droplet coalescence over a range of pH values (2–8), salt concentrations (0–500 mM NaCl) and temperatures (20–90 °C). However, some droplet flocculation was observed under highly acidic (pH 2) and high ionic strength (≥400 mM NaCl) conditions, which was attributed to screening of electrostatic repulsion. Indeed, Q-Naturale®-coated droplets had a relatively high negative charged at neutral pH that decreased in magnitude with decreasing pH. These results indicate that Q-Naturale® is an effective natural surfactant that may be able to replace synthetic surfactants in food and beverage products.
This paper describes the use of a new natural surfactant (saponin) to form and stabilize oil-in-water emulsions suitable for use in foods and beverages. This manuscript compares the performance of this natural surfactant with a synthetic surfactant for forming and stabilizing emulsions. [Display omitted]