Preparation and properties of OSA-modified taro starches and their application for stabilizing Pickering emulsions.

In this study, the octenylsuccinylated taro starches (OSTS) with different degree of substitution (DS, from 0.009 to 0.032) were prepared and their structural properties such as granule size, wettability and morphology were studied. The purpose of this work was to elucidate the OSTS with different DS using as particle stabilizers for Pickering emulsions, and the effect of DS on the stability, droplet size, microstructure and rheological properties of OSTS-stabilized emulsions were investigated. Octenylsuccinic anhydride (OSA) modification had slight effects on the morphology or granule size of taro starch, but markedly increased the contact angle from 25.4° to 70.1°. Octenylsuccinylation significantly improved the emulsifying capacity of taro starch granules, and thus OSTS-stabilized emulsions formed at higher DS exhibited better stability. Droplet size distribution results and microscopic observations revealed that OSTS-emulsion prepared at DS of 0.032 had the smallest droplet size and most uniform distribution compared with the other emulsions. The rheological results indicated that both OSTS-emulsions (DS, from 0.009 to 0.032) showed shear-thinning behavior as a non-Newtonian fluid, and the viscosities of emulsions were progressively improved with the increase of DS. Moreover, the G' and G″ values of OSTS-emulsions increased with increasing DS, reflecting the enhanced viscoelastic properties and exhibiting an improved rigidity of the emulsions. The above results suggested that higher-DS favored the formation of superior OSTS-emulsions, and thus OSTS with a high DS (DS ≥ 0.018) can be used for preparing stable Pickering emulsions.

Preparation of camellia oil-based W/O emulsions stabilized by tea polyphenol palmitate: Structuring camellia oil as a potential solid fat replacer.

Water-in-oil (W/O) emulsions with a discontinuous aqueous phase dispersed in a continuous camellia oil phase were prepared by using tea polyphenol palmitate (Tp-palmitate) particle as effective stabilizers and their properties were characterized by droplet size, slip melting point (SMP), stability, microstructure and rheology. The d(4,3) and d(3,2) decreased from 7.96 µm to 4.67 µm and from 5.98 µm to 3.07 µm, respectively, and the SMP rose from 33.73 °C to 38.60 °C when the Tp-palmitate concentration increased from 1.0% to 2.5% (m/v). The storage stability, freeze/thaw stability and thermal stability significantly enhanced and the droplets aggregation progressively increased with the increasing of Tp-palmitate concentration. The liquid camellia oil was transformed into solid-like viscoelastic emulsion gels with a SMP of 38.6 °C when using 2.5% Tp-palmitate as particle stabilizers. This study provides a promising method for production of edible gel-like W/O emulsions using polyphenol-lipid complexes to potentially replace solid fats.