Tailor it up! How we are rolling towards designing the functionality of emulsions in the mouth and gastrointestinal tract

Demulsification of Pickering emulsions: advances in understanding mechanisms to applications

Pickering emulsions are ultra-stable dispersions of two immiscible fluids stabilized by solid or microgel particles rather than molecular surfactants. Although their ultra-stability is a signature performance indicator, often such high stability hinders their demulsification, i.e., prevents the droplet coalescence that is needed for phase separation on demand, or release of the active ingredients encapsulated within droplets and/or to recover the particles themselves, which may be catalysts, for example. This review aims to provide theoretical and experimental insights on demulsification of Pickering emulsions, in particular identifying the mechanisms of particle dislodgment from the interface in biological and non-biological applications. Even though the adhesion of particles to the interface can appear irreversible, it is possible to detach particles via (1) alteration of particle wettability, and/or (2) particle dissolution, affecting the particle radius by introducing a range of physical conditions: pH, temperature, heat, shear, or magnetic fields; or via treatment with chemical/biochemical additives, including surfactants, enzymes, salts, or bacteria. Many of these changes ultimately influence the interfacial rheology of the particle-laden interface, which is sometimes underestimated. There is increasing momentum to create responsive Pickering particles such that they offer switchable wettability (demulsification and re-emulsification) when these conditions are changed. Demulsification via wettability alteration seems like the modus operandi whilst particle dissolution remains only partially explored, largely dominated by food digestion-related studies where Pickering particles are digested using gastrointestinal enzymes. Overall, this review aims to stimulate new thinking about the control of demulsification of Pickering emulsions for release of active ingredients associated with these ultra-stable emulsions.

High-purity 1,2-dimyristoyl-sn-glycero-3-phosphocholine: synthesis and emulsifying performance evaluation

Introduction

1,2-Dimyristoyl-sn-glycero-3-phosphocholine (DMPC) is a promising emulsifier for bioactive delivery systems, but its industrial applications are limited by the lack of cost-effective and scalable synthetic routes. The purpose of this study was to economically produce high-purity DMPC by replacing commonly used column chromatography methods and to evaluate the emulsifying performance.

Methods

DMPC was synthesized from sn-glycero-3-phosphocholine using Steglich esterification followed by sequential recrystallization from ethyl acetate and acetone. The structure of DMPC was identified and its purity was confirmed using various spectroscopy and chromatography techniques. The emulsifying performance was evaluated by examining the effects of storage on the properties of o/w emulsions prepared using soybean oil with (i) soy PC, (ii) soy PC + DMPC (1:1, w/w), and (iii) DMPC as emulsifiers.

Results

The chemical impurities formed during the synthesis of DMPC was removed, and its final purity was 96%, and the melt transition temperature was 37.6°C. No visible difference between the three emulsions (soy PC, soy PC+DMPC, and DMPC) was observed during two-week storage, and the DMPC-based emulsion was more stable than soy PC emulsion, showing smaller particle size distribution during 6 months.

Discussion

The highly pure DMPC was synthesized by an economical method, and DMPC-based emulsions demonstrated physicochemical stable, highlighting its potential for food and pharmaceutical industry-related applications. Our findings suggest that DMPC holds promise as an emulsifier with broad applications in the food industry.

Starch-based particles as stabilizers for Pickering emulsions: modification, characteristics, stabilization, and applications

The potential utilization of starch as a particle-based emulsifier in the preparation of Pickering emulsions is gaining interest within the food industry. Starch is an affordable and abundant functional ingredient, which makes it an excellent candidate for the stabilization of Pickering emulsions. This review article focuses on the formation, stabilization, and properties of Pickering emulsions formulated using starch-based particles and their derivatives. First, methods of isolating and modifying starch-based particles are highlighted. The key parameters governing the properties of starch-stabilized Pickering emulsions are then discussed, including the concentration, size, morphology, charge, and wettability of the starch-based particles, as well as the type and size of the oil droplets. The physicochemical mechanisms underlying the ability of starch-based particles to form and stabilize Pickering emulsions are also discussed. Starch-based Pickering emulsions tend to be more resistant to coalescence than conventional emulsions, which is useful for some food applications. Potential applications of starch-stabilized Pickering emulsions are reviewed, as well as recent studies on their gastrointestinal fate. The information provided may stimulate the utilization of starch-based Pickering emulsions in food and other industries.

Current trends in flavor encapsulation: A comprehensive review of emerging encapsulation techniques, flavour release, and mathematical modelling

Food flavors are volatile compounds that impact the human sensory perception profoundly and find extensive applications in various food products. Because of their volatility and high sensitivity to pH, temperature, oxidation, and external conditions, they require adequate protection to last for a longer duration. Encapsulation plays a critical role in preserving food flavors by enhancing their thermal and oxidative stability, overcoming volatility limitations, and regulating their rapid release with improved bioavailability in food products. The current review focuses on the recent developments in food flavor encapsulation techniques, such as electrospinning/spraying, cyclodextrin inclusion complexes, coacervation, and yeast cell micro-carriers. The review also comprehensively discusses the role of encapsulants in achieving controlled flavor release, the mechanisms involved, and the mathematical modelling for flavor release. Specific well-established nanoencapsulation techniques render better encapsulation efficiency and controlled release of flavor compounds. The review examined specific emerging methods for flavor encapsulation, such as yeast cell encapsulation, which require further exploration and development. This article provides readers with up-to-date information on different encapsulation processes and coating methods used for flavor encapsulation.

Biophysical insights into modulating lipid digestion in food emulsions

During the last decade, major scientific advances on understanding the mechanisms of lipid digestion and metabolism have been made, with a view to addressing health issues (such as obesity) associated with overconsumption of lipid-rich and sucrose-rich foods. As lipids in common foods exist in the form of emulsions, the structuring of emulsions has been one the main strategies for controlling the rate of lipid digestion and absorption, at least from a colloid science viewpoint. Modulating the kinetics of lipid digestion and absorption offers interesting possibilities for developing foods that can provide control of postprandial lipaemia and control the release of lipophilic compounds. Food emulsions can be designed to achieve considerable differences in the kinetics of lipid digestion but most research has been applied to relatively simple model systems and in in vitro digestion models. Further research to translate this knowledge into more complex food systems and to validate the results in human studies is required. One promising approach to delay/control lipid digestion is to alter the stomach emptying rate of lipids, which is largely affected by interactions of emulsion droplets with the food matrices. Food matrices with different responses to the gastric environment and with different interactions between oil droplets and the food matrix can be designed to influence lipid digestion. This review focuses on key scientific advances made during the last decade on understanding the physicochemical and structural modifications of emulsified lipids, mainly from a biophysical science perspective. The review specifically explores different approaches by which the structure and stability of emulsions may be altered to achieve specific lipid digestion kinetics.