Fabrication and characterization of nanoemulsion-coated microgels: Electrostatic deposition of lipid droplets on alginate beads

A comparative study of the impacts of preparation techniques on the rheological and textural characteristics of emulsion gels (emulgels)

A subtype of soft solid-like substances are emulsion gels (emulgels; EGs). These composite material's structures either consist of a network of aggregated emulsion droplets or a polymeric gel matrix that contains emulsion droplets. The product's rheological signature can be used to determine how effective it is for a specific application. The interactions between these structured system's separate components and production process, however, have a substantial impact on their rheological imprint. Therefore, rational comprehension of interdependent elements, their structural configurations, and the resulting characteristics of a system are essential for accelerating our progress techniques as well as for fine-tuning the technological and functional characteristics of the finished product. This article presents a comprehensive overview of the mechanisms and procedures of producing EGs (i.e., cold-set and heat-set) in order to determine the ensuing rheological features for various commercial applications, such as food systems. It also describes the influence of these methods on the rheological and textural characteristics of the EGs. Diverse preparation methods are the cause of the rheological-property correlations between different EGs. In many ways, EGs can be produced using various matrix polymers, processing techniques, and purposes. This may lead to various EG matrix structures and interactions between them, which in turn may affect the composition of EGs and ultimately their textural and rheological characteristics.

Pickering emulsion stabilized by Haematococcus pluvialis protein particles and its application in dumpling stuffing

In this study, the oil-in-water Pickering emulsions were prepared using Haematococcus Pluvialis protein (HPP) particles as an emulsifier by a simple one-step emulsification method. The internal oil phase was as high as 70 % due to the excellent emulsifying properties of HPP, and the average size of oil droplets in the emulsion was around 20 μm. The emulsion prepared by 2.5 % HPP with the oil phase ratio of 70 % showed the best stability after 14 days of storage, and the emulsion could maintain stability at acidic condition, high ionic strength, low and high temperatures. However, all emulsion samples exhibited shear thinning phenomenon, and the higher HPP concentration and oil phase ratio led to greater G' and G″ modulus. NMR relaxation results showed that high concentration HPP could limit the mobility of free water in the emulsion and improve the emulsion stability. The HPP-stabilized emulsion could inhibit the oxidation of oil phase during storage due to the DPPH and ABTS radical scavenging activity of astaxanthin (AST) in HPP. Finally, the nutritional microspheres based on HPP-stabilized emulsion showed good stability in traditional dumplings and could reduce the loss of AST and DHA in algae oil during the boiling of dumplings.

Study on physical properties of four pH responsive Spodoptera exigua multiple nucleopolyhedrovirus (SeMNPV) microcapsules as controlled release carriers

This study provides a promising controlled release form of nuclear polyhedrosis virus (NPV) for targeted control of lepidopteran pests. However, the application of NPV is limited due to its sensitivity to UV inactivation. This study investigated the anti-UV properties of microcapsules of SeMNPV occlusion bodies (OBs) encapsulated by calcium alginate (CA), and also the influence of the modification of CA by chitosan (CS), whey protein (WP), and polydopamine (PDA). These capsules were used to deliver, in a controlled release manner virions under alkaline pH conditions. Characterization of the structure, morphology, particle size, encapsulation efficiency, contact angle, insecticidal activity, UV resistance and in vitro release of the microcapsules was conducted. The modified microcapsules had better sphericity, and were devoid of SeMNPV OBs on the surface. The encapsulation rate was 84.76 ± 0.59%. PDA@CA-NPV had the highest wettability and the contact angle was 74.51 ± 0.53°. The 50% lethal concentration values (LC₅₀) of CA-NPV, CS@CA-NPV, WP@CA-NPV and PDA@CA-NPV were 11.5, 10.7, 10.5 and 1.2 times that of SeMNPV OBs alone. The modified microcapsules all improved the anti-UV performance of the virus, and PDA@CA-NPV was the most UV-resistant. Using qPCR, it was observed that under alkaline conditions, a large number of virions were released from PDA@CA-NPV, CA-NPV and SeMNPV OBs. Microencapsulated virus under alkaline conditions did not change the release pattern of virions.

The Layered Encapsulation of Vitamin B2 and β-Carotene in Multilayer Alginate/Chitosan Gel Microspheres: Improving the Bioaccessibility of Vitamin B2 and β-Carotene

This research underlines the potential of alginate multilayered gel microspheres for the layered encapsulation and the simultaneous delivery of vitamin B₂ (VB) and β-carotene (BC). Chitosan was used to improve the stability and controlled release ability of alginate-based gel microspheres. It was shown that a clear multilayered structure possessed the characteristics of pH response, and excellent thermal stability. The sodium alginate concentration and the number of layers had notable effects on mechanical properties and particle size of gel microspheres. Fourier-transform infrared spectroscopy and X-ray diffraction analyses further proved that VB and BC were encapsulated within the gel microspheres. Compared with the three-layer VB-loaded gel microspheres, the total release of VB from the three-layer VB and BC-loaded gel decreased from 93.23% to 85.58%. The total release of BC from the three-layer VB and BC-loaded gel increased from 66.11% to 69.24% compared with three-layer BC-loaded gel. The simultaneous encapsulation of VB and BC in multilayered gel microspheres can markedly improve their bioaccessibility and bioavailability. These results showed the multilayer gel microspheres synthesized herein have potential for applications in the layered encapsulation and simultaneous delivery of various bioactive substances to the intestinal tract.

Advances in edible nanoemulsions: Digestion, bioavailability, and potential toxicity

The design, fabrication, and application of edible nanoemulsions for the encapsulation and delivery of bioactive agents has been a highly active research field over the past decade or so. In particular, they have been widely used for the encapsulation and delivery of hydrophobic bioactive substances, such as hydrophobic drugs, lipids, vitamins, and phytochemicals. A great deal of progress has been made in creating stable edible nanoemulsions that can increase the stability and efficacy of these bioactive agents. This article highlights some of the most important recent advances within this area, including increasing the water-dispersibility of bioactives, protecting bioactives from chemical degradation during storage, increasing the bioavailability of bioactives after ingestion, and targeting the release of bioactives within the gastrointestinal tract. Moreover, it highlights progress that is being made in creating plant-based edible nanoemulsions. Finally, the potential toxicity of edible nanoemulsions is considered.

Encapsulation of emulsions by a novel delivery system of fluid core–hard shell biopolymer particles to retard lipid oxidation

Colloidal delivery systems could be designed to retard lipid oxidation in foods, thereby extending their shelf-lives and improving their nutritional quality.

Microgels at fluid-fluid interfaces for food and drinks

Various aspects of microgel adsorption at fluid-fluid interfaces of relevance to emulsion and foam stabilization have been reviewed. The emphasis is on the wider non-food literature, with a view to highlighting how this understanding can be applied to food-based systems. The various different types of microgel, their methods of formation and their fundamental behavioral traits at interfaces are covered. The latter includes aspects of microgel deformation and packing at interfaces, their deformability, size, swelling and de-swelling and how this affects their surface activity and stabilizing properties. Experimental and theoretical methods for measuring and modelling their behaviour are surveyed, including interactions between microgels themselves at interfaces but also other surface active species. It is concluded that challenges still remain in translating all the possibilities synthetic microgels offer to microgels based on food-grade materials only, but Nature's rich tool box of biopolymers and biosurfactants suggests that this field will still open up important new avenues of food microstructure development and control.

Microgel-in-Microgel Biopolymer Delivery Systems: Controlled Digestion of Encapsulated Lipid Droplets under Simulated Gastrointestinal Conditions

Structural design principles are increasingly being used to develop colloidal delivery systems for bioactive agents. In this study, oil droplets were encapsulated within microgel-in-microgel systems. Initially, a nanoemulsion was formed that contained small whey protein-coated oil droplets ( d₄₃ = 211 nm). These oil droplets were then loaded into either carrageenan-in-alginate (O/M_C/M_A) or alginate-in-carrageenan (O/M_A/M_C) microgels. A vibrating nozzle encapsulation unit was used to form the smaller inner microgels ( d₄₃ = 170-324 μm), while a hand-held syringe was used to form the larger outer microgels ( d₄₃ = 2200-3400 μm). Calcium alginate microgels (O/M_A) were more stable to simulated gastrointestinal tract (GIT) conditions than potassium carrageenan microgels (O/M_C), which was attributed to the stronger cross-links formed by divalent calcium ions than the monovalent potassium ions. As a result, the microgel-in-microgel systems had different gastrointestinal fates depending upon the nature of the external microgel phase; i.e., the O/M_C/M_A system was more resistant to rupture than the O/M_A/M_C system. The rate of lipid digestion under simulated small intestine conditions decreased in the following order: free oil droplets > O/M_C > O/M_A > O/M_A/M_C > O/M_C/M_A. This effect was attributed to differences in the integrity and dimensions of the microgels in the small intestine, because a hydrogel network surrounding the oil droplets inhibits lipid hydrolysis by lipase. The structured microgels developed in this study may have interesting applications for the protection or controlled release of bioactive agents.