Displacement of interfacially-bound monoglyceride crystals in water-in-oil emulsions by a non-ionic surfactant

Recent advances in studying crystallisation of mono- and di-glycerides at oil-water interfaces

This review focuses on the current understanding regarding lipid crystallisation at oil-water interfaces. The main aspects of crystallisation in bulk lipids will be introduced, allowing for a more comprehensive overview of the crystallisation processes within emulsions. Additionally, the properties of an emulsion and the impact of lipid crystallisation on emulsion stability will be discussed. The effect of different emulsifiers on lipid crystallisation at oil-water interfaces will also be reviewed, however, this will be limited to their impact on the interfacial crystallisation of monoglycerides and diglycerides. The final part of the review highlights the recent methodologies used to study crystallisation at oil-water interfaces.

Extrusion as pretreatment for complexation of high-amylose starch with glycerin monostearin: Dependence on the guest molecule

Low-moisture extrusion (LME) can modify starch structures and enrich their functionality. These LME-made starches may efficiently form inclusion complexes (ICs) with hydrophobic guest molecules, which is profoundly impacted by the guest molecule concentration. In this work, the influence of glycerin monostearin (GMS) concentration on the structure and in vitro digestibility of pre-extruded starch-GMS complexes was investigated. The results showed that LME pretreatment increased the complex index of high-amylose starch with GMS by 13 %. The appropriate GMS concentrations produced ICs with high crystallinity and excellent thermostability. The presence of IC retarded amylose retrogradation and dominated bound water in starches. In addition, highly crystallized ICs were resistant to enzymolysis and had a higher proportion of resistant starch. The acquired knowledge would provide a better understanding of the LME-modified starch and GMS concentration-regulated IC formation.

Demulsification of water-in-oil emulsions stabilized with glycerol monostearate crystals

HYPOTHESIS

Colloidal particles can be used to generate water-in-oil (W/O) emulsions resistant against coalescence. Demulsification is possible with addition of low molecular weight surfactants to the emulsion continuous oil phase. Whether surfactants demulsify particle-stabilized W/O emulsions depends on their ability to modify the wettability of interfacially-bound particles.

EXPERIMENTAL

Crystals of glycerol monostearate (GMS) were prepared followed by water addition to generate GMS-stabilized W/O emulsions. The surfactants sorbitan monooleate (SMO), sorbitan monolaurate (SML), citric acid esters of monoglycerides (CITREM), sorbitan trioleate (STO), propylene glycol monolaurate (PgML), and polyglycerol polyricinoleate (PGPR) were added to the emulsion oil phase. Emulsion microstructure was characterized by light microscopy and cryo-scanning electron microscopy. Surfactant activity and crystal wetting were characterized by interfacial tension and three-phase contact angle measurements. Salt release from within the emulsions was used to assess demulsifier efficacy.

FINDINGS

Emulsions stabilized by platelet-like GMS crystals were generated. Of the six surfactants, SMO, SML, and CITREM were effective demulsifiers whereas STO, PgML, and PGPR were ineffective. The former three sufficiently modified the wettability of GMS crystals on the droplet surface, as they adsorbed to both the oil-water interface and GMS crystal surface. Emulsion destabilization was associated with faster NaCl release from the emulsion internal phase.

Crystallization of lipids and lipid emulsions treated by power ultrasound: A review

The actual food system with fat is always complex and fat crystal and fat crystal networks have important effects on the physical properties of food. Recently, power ultrasound (PU) had been widely recognized as an auxiliary technology of fat crystallization to modify food properties. This review expounded on the mechanism of ultrasonic crystallization, and summarized effects of various factors in the process of ultrasonic treatment on fat crystallization. Based on the above, combined with the application of ultrasound in emulsions, the ultrasonic fat crystallization effect in the emulsion system was judged and described. Research results indicated that PU could shorten the induction time of crystallization, accelerate the formation of crystal nuclei, and change the polymorphism of fat crystals. The product treated by PU formed smaller and more uniform crystals to produce a more viscoelastic fat crystal network. In emulsion systems, ultrasonic treatments showed the same effect, but the effect of ultrasonic crystallization on the emulsion stability was different due to fat crystals in different emulsion systems. Meanwhile, the importance of ultrasonic crystallization in lipid emulsions was emphasized, thus ultrasonic crystallization had great potential in emulsion systems.