Structural Behaviour of Lipid Droplets in Protein-stabilized Nano-emulsions and Stability of α-Tocopherol

Over 100 years of vitamin E: An overview from synthesis and formulation to application in animal nutrition

The groundbreaking discovery of vitamin E by Evans and Bishop in 1922 was an important milestone in vitamin research, inspiring further investigation into its crucial role in both human and animal nutrition. Supplementing vitamin E has been proved to enhance multiple key physiological systems such as the reproductive, circulatory, nervous and muscular systems. As the main antioxidant in the blood and on a cellular level, vitamin E maintains the integrity of both cellular and vascular membranes and thus modulates the immune system. This overview showcases important and innovative routes for synthesizing vitamin E on a commercial scale, provides cutting-edge insights into formulation concepts for successful product form development and emphasizes the importance and future of vitamin E in healthy and sustainable animal nutrition.

Food grade nanoemulsions: promising delivery systems for functional ingredients

Nano-emulsions are receiving great attention in various industries, especially in the food sector. Peculiar properties of nano-sized droplets and high surface area are most suited for the development and delivery of functional ingredients. Nano-emulsions systems are suitable for encapsulation, protection, improving bioavailability, and target release of sensitive functional compounds. Nano-emulsions have promising potential for the delivery of nutraceuticals, probiotics, flavors, and colors. Nano-emulsions with active ingredients (antimicrobials) have a key part in ensuring food safety, nutrition, and quality of food. Nanoemulsions can also be used for biodegradable coating, packaging, antimicrobial coating, and quality and shelf life enhancement of different foods. The current review includes an overview of nanotechnology nano-emulsions, materials, techniques for formulation & production of nano-emulsions for food and nutrition. Furthermore, the analytical approaches used for the characterization of nano-emulsions and finally, the applications and limitations of nano-emulsions in the food industry are discussed in detail.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-022-05387-3.

Influence of the Mixtures of Vegetable Oil and Vitamin E over the Microstructure and Rheology of Organogels

Candelilla wax (CW) and 12-hydroxystearic acid (12HSA) are classic solid-fiber-matrix organogelators. Despite the high number of studies using those ingredients in oily systems, there is scarce literature using a mixture of oil and antioxidants. Vitamin E (VE) is an important candidate for its lipophilicity and several applications on pharmaceutical, cosmetics, and food industries. In this work, we investigated the influences of mixtures between vegetable oil (VO) and VE on the microstructures and rheological properties of CW and 12HSA organogels. A weak gel (G′′/G′ > 0.1) with a shear-thinning behavior was observed for all samples. The presence of VE impacted the gel strength and the phase transition temperatures in a dose-dependent pattern. Larger and denser packed crystals were seen for 12HSA samples, while smaller and more dispersed structures were obtained for CW organogels. The results obtained in this work allowed the correlation of the structural and mechanical properties of the organogels, which plays an important role in the physical-chemical characteristics of these materials.

Vitamin E-loaded bigels and emulsions: Physicochemical characterization and potential biological application

Bigels have been studied as topical formulations for its benefits over sensory and drug delivery parameters. However, there is still few evidences about the properties of the combination of organogelators, oily phases and bioactive molecules into rheological and stability behavior. We investigated the use of classical organogelators (candelilla wax and 12-hydroxystearic acid) and oily phases (sunflower and mineral oil) in 5/95 organogel/polymeric hydrogel ratio to compare vitamin E bigels with its corresponding emulsions. The rheological measurements, microstructure, physical and oxidative stability properties and biological behavior were evaluated. The obtained oil-in-water bigels and emulsions showed crystallization pattern at the interface with high thermal and centrifuge-stress stability. Viscoelastic weak gels were obtained with higher thixotropy and consistency of 12-hydroxystearic bigels. The diameter of the inner phase was increased by vitamin E, despite its little influence over physical and oxidative stability of bigels and emulsions. Those findings indicated that sensory attributes may be regulated by the organogel composition.

Nanoemulsions for health, food, and cosmetics: a review

Nanoemulsions are gaining importance in healthcare and cosmetics sectors as a result of the unique properties of nanosized droplets, such as high surface area. Here we review nanotechnology and nanoemulsions with focus on emulsifiers and nanoemulsifiers, and applications for drugs and vaccines delivery, cancer therapy, inflammation treatment, cosmetics, perfumes, polymers, and food. We discuss nanoemulsion safety and properties, e.g., stability, emulsification, solubility, molecular number and arrangements, ionic strength, pH and temperature.

Nano- and Micro-Technologies Applied to Food Nutritional Ingredients

New technologies are currently investigated to improve the quality of foods by enhancing their nutritional value, freshness, safety, and shelf-life, as well as by improving their tastes, flavors and textures. Moreover, new technological approaches are being explored, in this field, to address nutritional and metabolism-related diseases (i.e., obesity, diabetes, cardiovascular diseases), to improve targeted nutrition, in particular for specific lifestyles and elderly population, and to maintain the sustainability of food production. A number of new processes and materials, derived from micro- and nano-technology, have been used to provide answers to many of these needs and offer the possibility to control and manipulate properties of foods and their ingredients at the molecular level. The present review focuses on the importance of micro- and nano-technology in the food and nutritional sector and, in particular, provides an overview of the micro- and nano-materials used for the administration of nutritional constituents essential to maintain and improve health, as well as to prevent the development and complications of diseases.

Milk fat nanoemulsions stabilized by dairy proteins

Droplet size, polydispersity, physical and polymorphic stability of milk fat nanoemulsions produced by hot high-pressure homogenization and stabilized by whey protein isolate (WPI pH 4.0 or 7.0) or sodium caseinate (NaCas pH 7.0) were evaluated for 60 days of storage at 25 °C. Smaller droplets were observed for the NaCas pH 7.0 nanoemulsion, which also showed a lower polydispersity index, resulting in a stable emulsified system for 60 days. On the other hand, the nanoemulsion with bigger droplet size (WPI pH 4.0) showed reduced stability, probably due to the pH near the isoelectric point of the whey proteins. The nanostructured milk fat exhibited the same melting behavior as the bulk milk fat, with a balance between liquid and crystallized fat, and crystals in polymorphic form β'. This could be an advantage concerning the application of the system for delivery of bioactive compounds and improvement of the sensory properties of fat-based food. In summary, nanoemulsions stabilized by NaCas (pH 7.0) showed higher kinetic stability over the storage time, which from a technological application point of view is a very important factor in the food industry.

Potential of Milk Fat to Structure Semisolid Lipidic Systems: A Review

Food production and consumption patterns have changed dramatically in recent decades. The universe of oils and fats, in particular, has been changed due to the negative impacts of trans fatty acids produced industrially through the partial hydrogenation of vegetable oils. Regulations prohibiting its use have led the industry to produce semisolid lipid systems using chemical methods for modification of oils and fats, with limitations from a technological point of view and a lack of knowledge about the metabolization of the modified fats in the body. Milk fat is obtained from the complex biosynthesis in the mammary gland and can be a technological alternative for the modulation of the crystallization processes of semi-solids lipid systems, once it is naturally plastic at the usual processing, storage, and consumption temperatures. The natural plasticity of milk fat is due to its heterogeneous chemical composition, which contains more than 400 different fatty acids that structure approximately 64 million triacylglycerols, with a preferred polymorphic habit in β', besides other physical properties. Therefore, milk fat differs from any lipid raw material found in nature. This review will address the relationship between the chemical behavior and physical properties of semisolid lipids, demonstrating the potential of milk fat as an alternative to the commonly used modification processes.

Solid lipid nanoparticles as carriers for lipophilic compounds for applications in foods

Nanotechnology is a new subject of interest in the field of food industry. Therefore, scientific and technological studies have been intensified in the last 10 years because of the promising results associated with the potential application of functional properties in food products, such as physical and chemical stability, protection and controlled release of bioactive compounds, and facilitated solubility of lipophilic compounds. Lipids have been used as raw material for the preparation of nanostructures, mainly owing to the solubilization capacity of lipophilic bioactive compounds, as well as because of the advantage of potentially using natural ingredients for production on an industrial scale. Thus, in this review, we describe the information reported in scientific literature on the chemical, physical, and structural properties of lipids used in the preparation of solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs). We reviewed the production methods; structural lipid components; emulsifying systems; bioactive lipophilic compounds; and the physical, thermal, and oxidative properties of SLN and NLC. In addition, important methods for characterizing these systems with regard to particle size, polydispersity index, zeta potential, morphology, crystallization behavior, and polymorphism are discussed with examples, in order to support studies that consider physical stability during processing and storage. Furthermore, studies on the applications of SLNs and NLCs in foods are only found for model systems, justifying the compilation of a series of studies on the potential applications to encourage future works. In addition, we have described the aspects still under discussion, related to the possible risks and regulatory aspects of nanotechnology in food.

Stability and partitioning of β-carotene in whey protein emulsions during storage

Raman spectra of β-carotene in a droplet O/W emulsion, with bands originating from vibrations of the isoprene units of β-carotene molecules.

Enhancement of physical stability and bioaccessibility of tangeretin by soy protein isolate addition

Soy protein isolate (SPI) was selected to fabricate supersaturated self-emulsifying nanoemulsions, aiming to enhance physical stability and bioaccessibility of hydrophobic tangeretin. Dissolution studies demonstrated that tangeretin had the highest solubility in Tween 80, followed by oil phase solutions, and polymer solutions. Supersaturated tangeretin in oil phases easily formed crystals. That metastable zone was found to vary with its initial concentrations. After encapsulation by nanoemulsions, the addition of glycerol compressed the retention amount of tangeretin from 76% to 53%, but benefited the transparency. Whereas, the combination of glycerol and SPI could not only maintain high-loading tangeretin (>85%), but also provide high transparency for nanoemulsions. When tangeretin concentration was 4.83mM, combination of 50% glycerol and 1% SPI could maintain around 88% tangeretin in the nanoemulsion within one month. Its bioaccessibility of different systems were at 60-65%. These findings can provide useful information for protein to be a potential precipitation inhibitor.

Vitamin A degradation in triglycerides varying by their saturation levels

Vitamin A deficiency has a widespread occurrence globally and is considered as one of the world's most serious health risk factors. Potential solutions to address this deficiency include dietary diversification or supplementation, but food fortification is generally accepted as the most cost-effective solution. The main issue with food fortification of this vitamin is related to its high instability in food matrices. Dilution of vitamin A in triglycerides is a natural and appropriate way to stabilize this compound. We show here that vitamin A palmitate stability increases with increasing concentration of triglycerides. Moreover, we found that vitamin A palmitate displays improved stability in more saturated oils. Using various temperatures, and Arrhenius plots of experiments performed at storage temperatures between 30°C and 60°C for oils varying by their saturation and crystallinity, we demonstrate that crystallization is not responsible for this phenomenon. Additionally, we show by centrifugation that vitamin A is preferably solubilized in the liquid phase compared to the crystalline phase, explaining that triglyceride crystallization does not stabilize vitamin A palmitate. It is proposed that unsaturated fats generate more oxidation products such as radicals and peroxides, leading to a quicker degradation of vitamin A.

Stability of the Metastable α-Polymorph in Solid Triglyceride Drug-Carrier Nanoparticles

Colloidal dispersions of crystalline nonpolar lipids are under intensive investigation as carrier systems in pharmaceutics and nutrition. In this context, the controlled preparation of particles in a metastable polymorphic state is of some interest for the delivery of active substances. In the present study, tristearin particles stabilized with three α-polymorph-preserving emulsifier regimes ((I) sodium glycocholate/saturated long-chain phospholipids, (II) sodium glycocholate, and (III) poly(vinyl alcohol) (PVA)) were investigated concerning the stability of the metastable α-polymorph after controlled crystallization of the particles from the melt. Upon long-term storage, the α-polymorph was preserved best in PVA-stabilized dispersions, followed by those stabilized with the glycocholate/phospholipid mixture and finally those stabilized solely with the bile salt. In particular for rapidly crystallized nanoparticles, the formation of an α-polymorph with highly reduced lamellarity was observed. According to time-/temperature-resolved synchrotron X-ray diffraction analysis with simultaneous DSC (differential scanning calorimetry) studies, this less-ordered α-polymorph transformed into the common, lamellar α-form upon heating. Although the presence of the less-ordered form is probably related to the extraordinarily high stability of the metastable α-polymorph observed in some of the dispersions, it could not completely prevent the transition into the stable β-polymorph. The higher the transition temperature of the less-ordered α-form to the ordered one, the slower was the polymorphic transition to the stable β-polymorph. To estimate the polymorphic stability of the differently stabilized particles upon isothermal long-term storage, standard DSC measurements on samples stored at 23 °C for 4 weeks seem to be of predictive value.

Degradation of Vitamin E in Nanoemulsions during Storage as Affected by Temperature, Light and Darkness

Vitamin E (VE) nanoemulsions confront physical instabilities and chemical degradation during processing and/or storage. Therefore, thermal stability and degradation kinetics of VE in nanoemulsions fabricated using low-energy emulsification method as a function of temperature under light and in the dark were studied. Nanoemulsions had small droplet diameter (≈110 nm). The thermal degradation of VE followed the first-order kinetics with samples heated at 75°C and above presenting the highest degradation rate and short half-life (5.22 min). The degradation of VE in long-term storage fitted the Weibull model with highest degradation in nanoemulsions stored under light at 40°C. However, VE retained in nanoemulsions after certain period of time might be boosted up when nanoemulsions are stored in the dark. Results showed that the physical stability tests alone are not enough to judge the stability of VE delivery systems, as the encapsulated VE might be lost during processing and storage.

Fat crystallisation at oil-water interfaces

This review focuses on recent advances in the understanding of lipid crystallisation at or in the vicinity of an interface in emulsified systems and the consequences regarding stability, structure and thermal behaviour. Amphiphilic molecules such as emulsifiers are preferably adsorbed at the interface. Such molecules are known for their ability to interact with triglycerides under certain conditions. In the same manner that inorganic crystals grown on an organic matrix see their nucleation, morphology and structure controlled by the underlying matrix, recent studies report a templating effect linked to the presence of emulsifiers at the oil/water interface. Emulsifiers affect fat crystallisation and fat crystal behaviour in numerous ways, acting as impurities seeding nucleation and, in some cases, retarding or enhancing polymorphic transitions towards more stable forms. This understanding is of crucial importance for the design of stable structures within emulsions, regardless of whether the system is oil or water continuous. In this paper, crystallisation mechanisms are briefly described, as well as recent technical advances that allow the study of crystallisation and crystal forms. Indeed, the study of the interface and of its effect on lipid crystallisation in emulsions has been limited for a long time by the lack of in-situ investigative techniques. This review also highlights reported interfacial effects in food and pharmaceutical emulsion systems. These effects are strongly linked to the presence of emulsifiers at the interface and their effects on crystallisation kinetics, and crystal morphology and stability.

Effects of green tea extract and α-tocopherol on the lipid oxidation rate of omega-3 oils, incorporated into table spreads, prepared using multiple emulsion technology

This study examined the effectiveness of fat and water soluble antioxidants on the oxidative stability of omega (ω)-3 rich table spreads, produced using novel multiple emulsion technology. Table spreads were produced by dispersing an oil-in-water (O/W) emulsion (500 g/kg 85 camelina/15 fish oil blend) in a hardstock/rapeseed oil blend, using sodium caseinate and polyglycerol polyricinoleate as emulsifiers. The O/W and oil-in-water-in-oil (O/W/O) emulsions contained either a water soluble antioxidant (green tea extract [GTE]), an oil soluble antioxidant (α-Tocopherol), or both. Spreads containing α-Tocopherol had the highest lipid hydroperoxide values, whereas spreads containing GTE had the lowest (P < 0.05), during storage at 5°C, while p-Anisidine values did not differ significantly. Particle size was generally unaffected by antioxidant type (P < 0.05). Double emulsion (O/W/O) structures were clearly seen in confocal images of the spreads. By the end of storage, none of the spreads had significantly different G' values. Firmness (Newtons) of all spreads generally increased during storage (P < 0.05).

Fabrication of vitamin E-enriched nanoemulsions: factors affecting particle size using spontaneous emulsification

Oil-in-water nanoemulsions are finding increasing use as delivery systems to encapsulate lipophilic bioactive components in functional food, personal care, and pharmaceutical products. We have investigated the influence of system composition and preparation conditions on the particle size of vitamin E acetate (VE)-loaded nanoemulsions prepared by spontaneous emulsification. This method relies on the formation of very fine oil droplets when an oil/surfactant mixture is added to water. The oil-to-emulsion ratio content was kept constant (10 wt.%) while the surfactant-to-emulsion ratio (%SER) was varied (from 2.5 to 10 wt.%). Oil phase composition (vitamin E to medium chain triglyceride ratio) had a major effect on particle size, with the smallest droplets being formed at 8 wt.% VE and 2 wt.% MCT. Surfactant type also had an appreciable impact on particle size, with TWEEN® 80 giving the smallest droplets from a group of food-grade non-ionic surfactants (TWEEN® 20, 40, 60, 80, and 85). Surfactant-to-emulsion ratio also had to be optimized to produce fine droplets, with the smallest droplets being formed at SER=10 wt.%. Particle size could also be reduced by increasing the temperature and stirring speed used when the oil/surfactant mixture was added to water. By optimizing system composition and homogenization conditions we were able to form VE-loaded nanoemulsions with small mean droplet diameters (d<50 nm) and low polydispersity indexes (PDI<0.13). The spontaneous emulsification method therefore has great potential for forming nanoemulsion-based delivery systems for food, personal care, and pharmaceutical applications.

Food protein aggregates as vitamin-matrix carriers: impact of processing conditions

We studied the ability of protein aggregates for loading and protection of α-tocopherol, a model of heat- and light-sensitive bioactive compounds. Aqueous dispersions of whey proteins (4.5 wt.%, pH 6.7) in the absence and presence of α-tocopherol (4 wt.%) were prepared using an ultradisperser (10,000 rpm for 10 min and 65 °C), and then submitted to further high-pressure homogenisation (HPH) at 300 or 1200 bar for 12 cycles. Relative to free-vitamin dispersions, increasing HPH conditions in the presence of vitamin led to higher protein denaturation, more tryptophan quenching and wavelength blue-shift (by 10nm), in parallel with increased zeta potential values (by -10 mV), particle sizes (by 50%), and newly formed protein dimers, trimers and high molecular weight aggregates. As a result, the degree of vitamin degradation under increasing HPH and long-term storage was shown to decrease from 66% (ultradisper) to 50%, or to 30% (subject to further treatments at 300 or 1200 bar, respectively).

Stability of β-carotene in protein-stabilized oil-in-water delivery systems

Inclusion of liposoluble bioactive compounds in fortified foods represents a complex challenge due to the labile nature of such compounds and the instability of oil-in-water emulsion-based delivery systems. In the present study, dispersions prepared with 10% (w/w) sunflower oil (SO) or hydrogenated palm kernel oil (HPKO) containing 0.05% (w/w) β-carotene were stabilized by various concentrations of whey protein isolate (WPI) or sodium caseinate (NaCas) (0.1 to 2.0% w/w) in 30% (w/w) sucrose aqueous solutions. Physicochemical characterization of emulsions was done considering the particle size, the particle surface protein coverage, and the physical state of continuous and dispersed phases. Physical stability of the systems and their protection properties on β-carotene were compared. The lipid carrier type and interfacial structure were investigated as the two key factors which regulate the stability of labile lipophilic bioactive molecules in food model systems. Our results showed high β-carotene stability when O/W systems were stable (protein concentration ≥0.8% w/w.) A (partially) solid lipid carrier (HPKO) enhanced protection compared to the liquid carrier (SO) as the bioactive molecules were entrapped in isolated domains within the solid lattice and kept apart from reactive species in the surroundings. NaCas provided a better barrier than WPI due to the different amino acid composition and interface structure which significantly reduced β-carotene degradation rate.

Lipid nanoparticles as vitamin matrix carriers in liquid food systems: On the role of high-pressure homogenisation, droplet size and adsorbed materials

Twelve oil-in-water nano-emulsions were prepared using a melt high-pressure homogenisation process (HPH) at 300, 800 or 1200 bar. The resulting emulsions containing 20 wt% palm oil in the absence or presence of α-tocopherol were stabilised by whey proteins alone or in mixture with lecithin. Lipid nanoparticles in these emulsions were characterized for their particle size, surface charge and protein surface concentration (PSC) in relation to their stability against aggregation and coalescence, and to their ability for encapsulation and protection of α-tocopherol against chemical degradation. Increasing HPH values were accompanied by the formation of lipid nanoparticles with decreasing size and PSC, but increasing long-term stability against aggregation and coalescence in parallel with an increase in α-tocopherol degradation (up to 15 wt% for 1200 bar). Presence of α-tocopherol, led to increasing (or decreasing) PSC values with increasing (or decreasing) HPH values for lipid nanoparticles stabilised by proteins alone (or in mixture with lecithins). In addition to these structural properties, the ability for α-tocopherol long-term stability of nanoparticles in emulsions was shown to differ more depending on their adsorbed materials (protein alone, or in mixture with lecithin) than on their particle size values. After 2 months storage, α-tocopherol in emulsions prepared at 300, 800 or 1200 bar was protected against chemical degradation at 79, 77, 67 wt%, respectively, when whey proteins were used alone, instead of 66, 63, 48 wt% when proteins were used in mixture with lecithins. These results indicated the dominant role of adsorbed proteins on the protection of vitamin models by nanoemulsions. They are of a great technological importance for production of lipid nanoparticles presenting a high volume-to-diameter ratio values and consequently high exchange surfaces between the matrix carrier and water and oxygen environmental factors.

Scanning microbeam small-angle X-ray diffraction study of interfacial heterogeneous crystallization of fat crystals in oil-in-water emulsion droplets

We performed scanning microbeam small-angle X-ray diffraction (micro-SAXD) experiments, differential scanning calorimetry (DSC) analysis, and optical microscopic observation of palm mid fraction (PMF) crystals in oil-in-water emulsion droplets. The scanning micro-SAXD experiment was performed by irradiating a synchrotron radiation X-ray microbeam having an area of 5 x 5 microm(2) onto different positions on a 50 microm diameter emulsion droplet after the crystallization of PMF by chilling the emulsion at 5 degrees C. The micro-SAXD patterns were recorded with a two-dimensional (2D) detector, which enabled spatial analysis of polymorphic structures and the orientation of lamella planes of PMF crystals at different positions inside the emulsion droplet. Particular attention was paid to compare the crystallization of PMF in two types of emulsion droplets, hydrophilic polyoxyethylene sorbitan mono-oleate (Tween 80) alone (Tween 80 emulsion) and Tween 80 and hydrophobic sucrose palmitic acid oligoester (P-170) (Tween 80+P-170 emulsion). The DSC study revealed that the PMF crystallization temperature in the Tween 80+P-170 emulsion droplets increased by 3 degrees C compared to that of the Tween 80 emulsion because of the effects of the P-170 additive in promoting PMF crystallization. The micro-SAXD studies revealed the following results. (1) The lamella planes of PMF crystals near the outer edges of the droplet in the Tween 80+P-170 emulsion were mostly parallel to an oil-water interface, whereas the lamella planes of PMF crystals were not always aligned with the oil-water interface in the Tween 80 emulsion droplet. (2) The degree of orientation of the lamellar planes of PMF crystals, which was evaluated from the values of full width at half-maximum of 2D micro-SAXD patterns with respect to azimuthal angle extension, was remarkably higher in the Tween 80+P-170 emulsion than in the Tween 80 emulsion. (3) Polymorphic transformation of PMF from alpha to beta' in the Tween 80+P-170 emulsion was retarded compared to that in the Tween 80 emulsion. These results confirmed that the P-170 additive caused interfacial heterogeneous nucleation through hydrophobic interactions at the oil-water interfaces in the emulsion, which subsequently influenced the arrangements of fat crystals so that the lamellar planes of fat crystals were parallel to the oil-water interface.

Temperature scanning ultrasonic velocity study of complex thermal transformations in solid lipid nanoparticles

The purpose of this study was to determine whether temperature scanning ultrasonic velocity measurements could be used to monitor the complex thermal transitions that occur during the crystallization and melting of triglyceride solid lipid nanoparticles (SLNs). Ultrasonic velocity ( u) measurements were compared with differential scanning calorimetry (DSC) measurements on tripalmitin emulsions that were cooled (from 75 to 5 degrees C) and then heated (from 5 to 75 degrees C) at 0.3 degrees C min (-1). There was an excellent correspondence between the thermal transitions observed in deltaDelta u/delta T versus temperature curves determined by ultrasound and heat flow versus temperature curves determined by DSC. In particular, both techniques were sensitive to the complex melting behavior of the solidified tripalmitin, which was attributed to the dependence of the melting point of the SLNs on particle size. These studies suggest that temperature scanning ultrasonic velocity measurements may prove to be a useful alternative to conventional DSC techniques for monitoring phase transitions in colloidal systems.