Sucrose and Ca2+ synergistically regulate the rheological properties of apple high-methoxyl pectin.

The thickening and gelling mechanism of high-methoxyl pectins (HMPs) with different degree of esterification (DE) values (60.6 %, 66.1 %, and 72.4 %) synergistically affected by calcium ion (Ca2+) and sucrose was investigated using several technical methods. Rheological measurements, including steady-shear flow, thixotropy and dynamic viscoelasticity tests, texture analysis, water-holding capacity (WHC), thermal analyses (TG), and microstructure observation (TEM), were all systemically conducted. The results showed that the main thickening and gelling mechanism of Ca2+ on different HMPs was complex and the presence of sucrose had a synergistic effect on structure formation in HMP systems. Ca2+ was not always conducive to structure formation, and excessive Ca2+ addition may hinder structure formation. HMP systems with lower DE values had higher gel strengths due to the presence of more binding domains. The results of the texture properties, WHC, and thermal characteristics coincided with those obtained from the rheological measurements, which reflect the variations in HMPs affected by Ca2+ and DE. All of these results showed that Ca2+ addition at an appropriate concentration in the presence of sucrose favors HMP gelation even in the absence of acid. The results obtained here are expected to broaden the application of HMPs in acid-free gel food products.

Mechanism underlying joint loading and controlled release of ß-carotene and curcumin by octenylsuccinated Gastrodia elata starch aggregates.

This study aimed to fabricate a novel codelivery system to simultaneously load ß-carotene and curcumin in a controlled and synergistic manner. We hypothesized that the aggregates of octenylsuccinated Gastrodia elata starch (OSGES) could efficiently load and control the release of ß-carotene and curcumin in combination. Mechanisms underlying the self-assembly of OSGES, coloading, and corelease of ß-carotene and curcumin by relevant aggregates were studied. The OSGES could form aggregates with a size of 120.2 nm containing hydrophobic domains surrounded by hydrophilic domains. For coloading, the increased solubilities were attributed to favorable interactions between ß-carotene and curcumin as well as interactions with octenyl and starch moieties via hydrophobic and hydrogen-bond interactions, respectively. The ß-carotene and curcumin molecules occupied the interior and periphery of hydrophobic domains of OSGES aggregates, respectively, and they did not exist in isolation but interacted with each other. The ß-carotene and curcumin combination-loaded OSGES aggregates with a size of 310.5 nm presented a more compact structure than ß-carotene-only and curcumin-only loaded OSGES aggregates with sizes of 463.5 and 202.9 nm respectively, suggesting that a transition from a loose cluster to a compact cluster was accompanied by coloading. During in vitro digestion, the joint effect of ß-carotene and curcumin prolonged their release and increased their bioaccessibility due to competition between favorable hydrophobic and hydrogen-bond interactions and the unfavorable structure erosion and relaxation of the loaded aggregates. Therefore, OSGES aggregates were designed for the codelivery of ß-carotene and curcumin, indicating their potential to be applied in functional foods and dietary supplements.

Hydrophobically modified polysaccharides and their self-assembled systems: A review on structures and food applications.

By reviewing the published literatures, especially from 2016 to 2021, preparative approaches of hydrophobically modified polysaccharides (HMP), mechanisms underlying their self-aggregation, and food applications of HMP and their self-aggregates, as well as perspectives and challenges, were discussed. Up to ten methods were reported for HMP preparations from various polysaccharides with different hydrophobic substituents. In contrast to their unmodified-counterparts, HMP displayed stronger assembling tendencies to form multimolecular self-aggregates. Different types of self-aggregates including micelles, polymersomes, hydrogels, and reverse-micelles, were analyzed and they were depended on structural parameters of HMP and their environmental conditions. Basically, their formation was mainly driven by intermolecular interactions of HMP such as hydrophobic, hydrogen-bonding, and electrostatic interactions. HMP and their self-aggregates could be used in food fields in different ways, such as carriers for targeted-delivery, controlled-release and stabilization of bioactive compounds, stabilizers for emulsions, and functional ingredients for antimicrobial films, improving nutrition and properties of foods.

Effect of temperature and pH on the encapsulation and release of ß-carotene from octenylsuccinated oat ß-glucan micelles.

Effect and working mechanism of temperature and pH on encapsulation and release of ß-carotene from octenylsuccinated-oat-ß-glucan-micelles (OSßG-Ms) were investigated. The stability and solubility of ß-carotene, and changes in surface hydrophilicity, core hydrophobicity, and size of ß-carotene-loaded-OSßG-Ms were determined. When exposed to temperature (25-45 °C) and pH (4.5-8.5), ß-carotene solubilization changed in parabolic manners. Size and absolute zeta-potential of ß-carotene-loaded-OSßG-Ms decreased with temperature, while they gave parabolic changing patterns with pH. Those results were ascribed to their hydrophilicity, hydrophobicity, and core/shell compactness via regulating molecule mobility, orientation, and interactions by temperature/pH. The higher temperature concluded with higher ß-carotene release, while a U-shaped release profile was observed with pH. Besides its diffusion, erosion-induced shrinking and collapsing of OSßG-Ms favored ß-carotene release at pH 1.2-4.5, which was replaced by swelling-induced structural-relaxation at pH 6.8-8.5. The results were favourable in controlling the behavior of ß-carotene-loaded-OSßG-Ms by selectively applying environmental parameters.