Dérick Rousseau

Fat crystals and emulsion stability - a review.

The effects of fat crystals in food emulsion formation and stability are reviewed. Topics discussed in detail include fat crystal wettability, interfacial rheology, crystal microstructure, and particle location. Specifics on the potential future direction of the field are discussed.

The ratio of serum 24,25-dihydroxyvitamin D3 to 25-hydroxyvitamin D3 is predictive of 25-hydroxyvitamin D3 response to vitamin D3 supplementation

24,25-Dihydroxyvitamin D (24,25VD) is a major catabolite of 25-hydroxyvitamin D (25VD) metabolism, and may be physiologically active. Our objectives were to: (1) characterize the response of serum 24,25VD(3) to vitamin D(3) (VD(3)) supplementation; (2) test the hypothesis that a higher 24,25VD(3) to 25VD(3) ratio (24,25:25VD(3)) predicts 25VD(3) response. Serum samples (n=160) from wk 2 and wk 6 of a placebo-controlled, randomized clinical trial of VD(3) (28,000IU/wk) were analyzed for serum 24,25VD(3) and 25VD(3) by mass spectrometry. Serum 24,25VD(3) was highly correlated with 25VD(3) in placebo- and VD(3)-treated subjects at each time point (p<0.0001). At wk 2, the 24,25:25VD(3) ratio was lower with VD(3) than with placebo (p=0.035). From wk 2 to wk 6, the 24,25:25VD(3) ratio increased with the VD(3) supplement (p<0.001) but not with placebo, such that at wk 6 this ratio did not significantly differ between groups. After correcting for potential confounders, we found that 24,25:25VD(3) at wk 2 was inversely correlated to the 25VD(3) increment by wk 6 in the supplemented group (r=-0.32, p=0.02) but not the controls. There is a strong correlation between 24,25VD(3) and 25VD(3) that is only modestly affected by VD(3) supplementation. This indicates that the catabolism of 25VD(3) to 24,25VD(3) rises with increasing 25VD(3). Furthermore, the initial ratio of serum 24,25VD(3) to 25VD(3) predicted the increase in 25VD(3). The 24,25:25VD(3) ratio may therefore have clinical utility as a marker for VD(3) catabolism and a predictor of serum 25VD(3) response to VD(3) supplementation.

Effect of flaxseed gum on reduction of blood glucose and cholesterol in type 2 diabetic patients

The effects of ingestion of flaxseed gum on blood glucose and cholesterol, particularly low-density lipoprotein cholesterol, in type 2 diabetes were evaluated. Flaxseed gum was incorporated in wheat flour chapattis. Sixty patients of type 2 diabetes were fed a daily diet for 3 months, along with six wheat flour chapattis containing flaxseed gum (5 g), as per the recommendations of the American Diabetic Association. The control group (60 individuals) consumed an identical diet but the chapattis were without gum. The blood biochemistry profiles monitored before starting the study and at monthly intervals showed fasting blood sugar in the experimental group decreased from 154±8 mg/dl to 136±7 mg/dl (P=0.03) while the total cholesterol reduced from 182±11 mg/dl to 163±9 mg/dl (P=0.03). Results showed a decrease in low-density lipoprotein cholesterol from 110±8 mg/dl to 92±9 mg/dl (P=0.02). The study demonstrated the efficacy of flax gum in the blood biochemistry profiles of type 2 diabetes.

Organogels as Matrices for Controlled Drug Delivery: A Review on the Current State

Over the last two decades, organogels have found tremendous use in the pharmaceutical, food, and cosmetics industries with notable developments as drug delivery matrices and trans and saturated fat replacers in processed foods. The functionality of organogels benefits from their ease of preparation, cost effectiveness, and ability to contain both hydrophilic and lipophilic constituents. This review provides thorough insight into different organogelators, their mechanisms of organogel formation, various characterization techniques and their biocompatibility when administered in vivo. Finally, a special treatise is given on the applications of organogels as controlled drug delivery vehicles for topical, dermal/transdermal, parenteral, oral, and nasal routes. In situ forming organogels and their potential for tailored release of incorporated active ingredients are also discussed.

Intermolecular Interactions during Complex Coacervation of Pea Protein Isolate and Gum Arabic

The nature of intermolecular interactions during complexation between pea protein isolate (PPI) and gum arabic (GA) was investigated as a function of pH (4.30-2.40) by turbidimetric analysis and confocal scanning microscopy in the presence of destabilizing agents (100 mM NaCl or 100 mM urea) and at different temperatures (6-60 degrees C). Complex formation followed two pH-dependent structure-forming events associated with the formation of soluble and insoluble complexes and involved interactions between GA and PPI aggregates. Complex formation was driven by electrostatic attractive forces between complementary charged biopolymers, with secondary stabilization by hydrogen bonding. Hydrophobic interactions were found to enhance complex stability at lower pH (pH 3.10), but not with its formation.

Flocculation and coalescence in water-in-oil emulsions stabilized by paraffin wax crystals

Abstract Water-in-mineral oil emulsions were prepared with small amounts of paraffin wax (0–2% w/w) added to the continuous phase, either by addition of pre-crystallized wax to the emulsion prior to emulsification or via subsequent quench-cooling of wax crystals in situ. Stability of the emulsions was examined using pulsed NMR droplet-size analysis, sedimentation and microscopy. Both pre and post-crystallized wax decreased the degree of droplet coalescence, however, emulsions made with post-crystallized wax were more stable over a 10-day period. Microscopy showed that visible crystals were strictly associated with droplets and droplet clusters indicating an affinity of the crystals to the interface. The incorporation of as little as 0.125% wax resulted in a notable decrease in emulsion sedimentation. After 24 days of storage, samples prepared with post-crystallized wax showed no sedimentation or flocculation, unlike pre-crystallized samples which were still somewhat destabilized despite the presence of as much as 2% wax. From these findings, rapid crystallization of wax in the continuous phase of a water-in-oil emulsion following emulsification is an effective means of enhancing long-term stability.

Comparison of Pickering and Network Stabilization in Water-in-Oil Emulsions

We compared the efficacy of Pickering crystals, a continuous phase crystal network, and a combination thereof against sedimentation and dispersed phase coalescence in water-in-oil (W/O) emulsions. Using 20 wt % water-in-canola oil emulsions as our model, glycerol monostearate (GMS) permitted Pickering-type stabilization, whereas simultaneous usage of hydrogenated canola oil (HCO) and glycerol monooleate (GMO) primarily led to network-stabilized emulsions. A minimum of 4 wt % GMS or 10 wt % HCO was required for long-term sedimentation stability. Although there were no significant differences between the two in mean droplet size with time, the free water content of the network-stabilized emulsions was higher than Pickering-stabilized emulsions, suggesting higher instability. Microscopy revealed the presence of crystal shells around the dispersed phase in the GMS-stabilized emulsions, whereas in the HCO-stabilized emulsion, spherulitic growth in the continuous phase and on the droplet surface occurred. The displacement energy (E(disp)) to detach crystals from the oil-water interface was ∼10(4) kT, and was highest for GMS crystals. Thermal cycling to induce dispersed phase coalescence of the emulsions resulted in desorption of both GMS and GMO from the interface, which we ascribed to solute-solvent hydrogen bonding between the emulsifier molecules and the solvent oil, based on IR spectra. Overall, Pickering crystals were more effective than network crystals for emulsion stabilization. However, the thermal stability of all emulsions was hampered by the diffusion of the molten emulsifiers from the interface.

Freeze-thaw stability of water-in-oil emulsions

Factors influencing water-in-oil emulsion stability during freeze/thaw-cycling, namely interfacial crystallization vs. network crystallization and the sequence of crystallization events (i.e., dispersed vs. continuous phase or vice versa), are assessed. We show that destabilization is most apparent with a liquid-state emulsifier and a continuous oil phase that solidifies prior to the dispersed phase. Emulsions stable to F/T-cycling are obtained when the emulsifier crystallizes at the oil-water interface or in emulsions where the continuous phase crystallizes after the dispersed aqueous phase. The materials used are two food-grade oil-soluble emulsifiers - polyglycerol polyricinoleate (PGPR) and glycerol monostearin (GMS) and two continuous oil phases with differing crystallization temperatures - canola oil and coconut oil. Emulsion stability is assessed with pulsed field gradient NMR droplet size analysis, sedimentation, microscopy and differential scanning calorimetry. This study demonstrates the sequence of crystallization events and the physical state of the surfactant at the oil-water interface strongly impact the freeze-thaw stability of water-in-oil emulsions.

Microstructure of fat bloom development in plain and filled chocolate confections

Temperature-controlled environmental scanning electron microscopy was used to examine the microstructural changes in plain solid chocolate and its counterpart stored against a tricaprylin-based filling cream. Sample storage at 26 °C for 40 days led to significant changes in microstructure as a function of time. Surface imperfections (pores, pits, etc.) initially present on the filled confection disappeared within two days whereas those on the control did not throughout the storage period. Morphological changes on the surface of the control were dominated by the growth of needle-like crystals whereas spherulites appeared on the filled chocolate, with large crystals (upwards of 100 microns in length, in some cases) observed in both cases. From a microstructural perspective, both diffusion and capillarity appear to have a part in fat bloom initiation and propagation, though temperature and the presence of a filling fat strongly dictate which mechanism will dominate.

Genetic Variation in Putative Salt Taste Receptors and Salt Taste Perception in Humans

The objective of this study was to determine whether single nucleotide polymorphisms (SNPs) in the SCNN1A (3), SCNN1B (12), SCNN1G (6), and TRPV1 (10) genes affect salt taste perception. Participants were men (n = 28) and women (n = 67) from the Toronto Nutrigenomics and Health study aged 21-31 years. Taste thresholds were determined using a 3-alternative forced-choice staircase model with solutions ranging from 9×10(-6) to 0.5 mol/L. Suprathreshold taste sensitivity to 0.01-1.0 mol/L salt solutions was assessed using general labeled magnitude scales. None of the SNPs in the SCNN1A and SCNN1G genes were significantly associated with either outcome. In the SCNN1B gene, 2 SNPs in intronic regions of the gene modified suprathreshold taste sensitivity (mean iAUC ± SE). Those homozygous for the A allele of the rs239345 (A>T) polymorphism and the T allele of the rs3785368 (C>T) polymorphism perceived salt solutions less intensely than carriers of the T or C alleles, respectively (rs239345: 70.82±12.16 vs. 96.95±3.75, P = 0.02; rs3785368: 57.43±19.85 vs. 95.57±3.66, P = 0.03) In the TRPV1 gene, the rs8065080 (C>T, Val585Ile) polymorphism modified suprathreshold taste sensitivity where carriers of the T allele were significantly more sensitive to salt solutions than the CC genotype (98.3±3.8 vs. 74.1±8.3, P = 0.008). Our findings show that variation in the TRPV1 and the SCNN1B genes may modify salt taste perception in humans.