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Background: Particle-stabilised emulsions, so-called Pickering emulsions, are known to possess many beneficial properties, including being extremely stable. Starch granules isolated from quinoa have been used as emulsion stabilising particles. The granules were intact, 1-3 µm in diameter and modified with octenyl succinic anhydride to increase their hydrophobicity. Starch granules, as opposed to most other particles used to generate Pickering emulsions, are edible, abundant and derived from natural sources., Results: Emulsions produced by high shear homogenisation had droplet sizes of 9-70 µm depending on the starch-to-oil ratio. Droplet size decreased with increasing starch-to-oil ratio, but was unaffected by the oil phase volume over a range of 5-33% oil (v/v). Although the drops were large and subject to creaming, their size remained unchanged over a period of 7 days. By adjusting the starch-to-oil ratio drops could be made to be buoyancy neutral to prevent creaming. Rheological characterisation indicated a gel structure with an elastic modulus in the range 200-2000 Pa depending on droplet size., Conclusion: This work has demonstrated the successful use of starch granules to stabilise emulsions which may find applications beyond that of food, for example in cosmetics and pharmaceutical formulations., (Copyright © 2012 Society of Chemical Industry.)

The effect of barrier properties on in vitro intestinal lipolysis of three different types of emulsions based on oil-in-water starch granule Pickering stabilization has been investigated including non-heat treated, heat treated (gelatinized) and heat treated and stored (retrograded) emulsions. The stability of starch covered oil-water interfaces towards in vitro intestinal lipolysis was correlated to the rate of lipid hydrolysis using a pH-stat method. The results were compared with a sodium caseinate stabilized emulsion. The shape and size of the starch granules were characterized by scanning electron microscopy and light scattering. The physical properties of the emulsions were characterized by a light scattering particle size analyzer and light microscopy. In all cases, Pickering emulsions showed lower extents of lipolysis compared to the protein stabilized emulsion. In addition, heat treated starch Pickering emulsions were more susceptible to lipolysis compared to freshly prepared emulsions with no heat treatment. This was thought to be due to the gelatinized starch barrier being more susceptible to amylase present in the pancreatin. The results of this study demonstrate the interfacial layer properties can affect the rate and extent of lipolysis. Image 10264 • Pickering emulsions had lower degree of lipolysis than protein stabilized emulsions. • Heat treatment increased the degree of lipolysis in Pickering emulsions. • Higher digestibility of gelatinized starch barrier by amylase led to more lipolysis. • Bile salts or mixing did not destabilize the non-heated emulsions up to 1 h. [ABSTRACT FROM AUTHOR]

Pickering emulsions are emulsions that are stabilized by fine particles. They have been the focus of considerable research in the past decade due to their properties such as high stability with respect to coalescence and Ostwald ripening, as well as due to advances in nanotechnology that allows us to create and characterize nano-scale structures in new ways. This work reviews some of the recent work in the area of biomass-based particles for Pickering emulsions in the context of foods and topical creams, and discusses some of the theory and particularities of Pickering type emulsions. Formulation examples are given with a focus on two types of biomass-based particles isolated with their natural structure intact: starch granules from quinoa and egg yolk granules. In contrast to particles commonly used for Pickering emulsions such as latex, silica, and clay particles, starch (including hydrophobically modified starch) and egg-fractions are accepted food ingredients, as well as pharmaceutical and cosmetic excipients. The particle stabilization of emulsion drops is possible due to partial dual wettability of particles at the oil–water interface. Native starch is not intrinsically hydrophobic; however hydrophobicity can be increased by chemical modification with octenyl succinic anhydride. Egg-granules on the other hand are quite hydrophobic and at low ionic strength (<0.3 M NaCl) are insoluble with a compact structure. Quinoa starch granules and egg-granules can be used to generate Pickering type emulsions in the 10–100 μm range with high levels of stability. Size decreased with increasing concentration and could be controlled by the granule to oil ratio. In the case of starch granule stabilized oil drops, heat can be applied to induce a partial gelatinization of the starch granules forming a cohesive layer at the oil–water interface increasing barrier properties. Although the droplet size of granule stabilized emulsions was relatively large, their excellent stability, encapsulation properties, and freeze–thaw stability can prove suitable for applications such as encapsulation of sensitive, bioactive ingredients in food and topical formulations. [ABSTRACT FROM AUTHOR]

Highlights: [•] Oil powders with 80% oil were produced from starch granule stabilized emulsions by freeze-drying. [•] The oil powders could be reconstituted to stable emulsions. [•] Partial gelatinization of starch increased freeze-drying stability of emulsions. [•] Dispersed phase melting point affected freeze-drying stability of the emulsions. [•] Different freezing methods imposed different changes on stability of the droplets. [ABSTRACT FROM AUTHOR]

Abstract: Double emulsions have potential applications in the food, cosmetic and pharmaceutical industries as vehicles for encapsulation and delivery of nutrients during food digestion or for drug release. The major drawback of this type of emulsions is that they are often difficult to stabilize. Particle stabilized emulsions, known as Pickering emulsions, show special features, such as being extremely stable with respect to coalescence. Starch granules have proved to be a suitable stabiliser for food grade Pickering emulsions. In this work, starch double W1/O/W2 Pickering emulsions were prepared and their encapsulation stability was studied as well as the impact of varying the lipophilic emulsifier (PGPR90) content and the salt concentration in the W1 inner aqueous phase. Encapsulation properties were quantified by monitoring the release of a hydrophilic dye from the inner aqueous phase spectrophotometrically. Two double emulsion systems were studied, one with an inner aqueous phase with 0.1M NaCl and the other with 0.2M NaCl. The initial encapsulation efficiency was over 98.5% immediately after emulsification production. The encapsulation stability (ES) remained over 90% after 21 days for both systems studied, where 0.1M NaCl W1 emulsion had a ES of 95.2% and the 0.2M NaCl W1 emulsion had a ES of 91.1% respectively. [Copyright &y& Elsevier]