A series of alkenylated inulin samples were synthesized in aqueous solution using alkenyl succinic anhydrides with varying alkenyl chain lengths (C8-C18). The inulin derivatives (ASA-inulins) were characterized using NMR and FTIR and their degree of substitution determined. The solution properties of ASA-inulins were investigated using dye solubilization, surface tension, and dynamic light scattering, and all three techniques confirmed that the molecules aggregated in solution above a critical concentration (critical aggregation concentration, CAC). The value of the CAC was found to be reasonably consistent between the different techniques and was shown to decrease with increasing alkenyl chain length, from 0.08% for the octenyl succinylated sample to 0.005% for the octadecenyl succinylated sample. The hydrodynamic diameter of ASA-inulins above the CAC was determined from dynamic light scattering studies and was shown to increase with alkenyl chain length, from 4 nm for the octenyl derivative to 55 nm for the hexadecenyl derivative. All ASA-inulins were shown to be able to produce oil-in-water emulsions with a droplet size similar to that of emulsions prepared using Tween 20 on storing for 21 days. The fact that the derivatives are able to form micellarlike aggregates and stabilize emulsions makes them suitable candidates for the encapsulation and delivery of water-insoluble active compounds, with potential application in food, cosmetic, personal care, and pharmaceutical formulations.

Hydrophilic−hydrophobic core−shell microparticles are highly appealing for a variety of industrial applications (foods, pharmaceutics, cosmetics, biomedicines, etc.) owing to their unique properties of moisture resistance and controlled release. However, the fabrication of such structured microparticles proves to be nontrivial due to the difficulty in assembling two materials of distinctly different hydrophilicities and hydrophobicities. This paper reports a facile method to fabricate hydrophilic−hydrophobic core− shell microparticles using all-natural food-grade polysaccharides and proteins, based on a novel principle of gel-networkrestricted antisolvent precipitation. Immersion of microgel beads prepared from hydrophilic polysaccharides (i.e., alginates, κ-carrageenan, agarose) into a hydrophobic protein solution (i.e., zein in 70% aqueous ethanol) enables slow and controllable antisolvent precipitation of a protein layer around the microbead surface, leading to the formation of a hydrophilic−hydrophobic core−shell structure. The method applies to various gelling systems and can easily tailor the particle size and shell thickness. The resulting freeze-dried microparticles demonstrate restricted swelling in water, improved moisture resistance, and sustained release of encapsulants, with great potential in applications such as protection of unstable and/or hygroscopic compounds and delivery and controlled release of drugs, bioactives, flavors, etc. The method is rather universal and can be extended to prepare more versatile core−shell structures using a large variety of hydrophilic and hydrophobic materials.

Octenyl-succinylated inulins (OSA-inulin) were synthesized in aqueous solutions using inulin with varying degrees of polymerization (DP). They were characterized using 1 H NMR and FTIR and their degrees of substitution were determined. All the samples formed micellar aggregates in aqueous solution above a critical aggregation concentration (CAC) and solubilized beta-carotene. The amount of beta carotene solubilized within the micelles ranged from 12 -25mg/g of OSA-inulin and depended on the inulin molar mass. Dynamic light scattering showed that the aggregates, with and without dissolved beta-carotene, were ~10-15 nm in size and this was confirmed by Transmission Electron Microscopy which also indicated that the micelles had a globular shape. OSA-inulin particles containing encapsulated beta-carotene were produced by freeze-drying. The encapsulated beta-carotene was not released from the freeze-dried particles when introduced into simulated gastric fluid at pH 2.5 but was readily released in simulated small intestinal fluid at pH 7. The results demonstrate the potential application of OSA-inulin in the encapsulation, dissolution and targeted delivery of hydrophobic drug molecules for nutraceutical, pharmaceutical and medical applications.

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A B S T R A C TA series of inulin derivatives were synthesized in aqueous solution using acyl chlorides with varying alkyl chain length (C10-C16). They were characterised using a number of techniques including MALDI TOF-MS, 1 H NMR and FTIR and their degree of substitution determined. The solution properties of the hydrophobically modified inulins were investigated using dye solubilisation and surface tension and it was confirmed that the molecules aggregated in solution above a critical concentration (critical aggregation concentration, CAC). The value of the CAC was found to be reasonably consistent between the different techniques and was shown to decrease with increasing hydrophobe chain length. It was found that the C10, C12 and C14 derivatives formed stable oil-inwater emulsions and the emulsion droplet size decreased with increasing alkyl chain length. The C16 derivative was not able to produce stable oil-in-water emulsions; however, it was able to form stable water-in-oil emulsions. The fact that the derivatives are able to form micellar-like aggregates and stabilise emulsions makes them suitable candidates for the encapsulation and delivery of active compounds with potential application in food, cosmetic, personal care and pharmaceutical formulations.