Abstract Mixtures of fully hydrogenated canola oil and high‐oleic sunflower oil were interesterified chemically and enzymatically with sodium methoxide and Candida antarctica lipase, respectively. Polymorphic behavior and crystal morphology of the10–100% blends before and after interesterification were studied using powder X‐ray diffraction spectroscopy and polarized light microscopy. X‐ray analysis revealed a predominance of the β' form in the IE‐blends (interesterified, both chemical and enzymatic) and the β form crystals in the NI‐blends (non‐interesterified). Dilution and crystallization at 20, 30, 40 and 50 °C did not change the polymorphism of the NI‐blends, but did in the IE‐blends. Small changes in the long spacings of the blends after interesterification were observed. Small‐angle reflections centered at 45 Å suggested the presence of a 2L lamellar crystalline structure. Needle‐like crystals were predominant in the IE‐blends while large symmetrical spherulites were observed in the NI‐blends crystallized at 30 °C for 24 h. Over 75% of the structural elements had areas between 1 and 20 µm 2 in the NI‐ and IE‐blends, and the NI‐blends showed a higher percentage of crystals in this range compared to the IE‐samples. The box counting dimension ( D b ) increased as a function of crystalline area fraction in polarized light micrographs of the samples. Moreover, a higher D b in the chemically interesterified sample relative to the enzymatically interesterified sample at an equivalent area fraction, was attributed to the homogeneity in the distribution of crystalline mass.
The in vitro lipolysis and β-carotene (BC) transfer from oil to aqueous phase of canola oil ethylcellulose (EC) oleogels were measured using a static monocompartmental model simulating oral, gastric, and duodenal digestive stages. The effects of EC oleogelation on gel in vitro digestibility were examined, using un-structured canola oil as a control. The physicochemical properties of oleogels containing BC were also measured. It was found that oleogels made with 10% 10 cP and 10% 20 cP did not differ significantly in their extent of lipolysis or BC transfer compared to canola oil; however 10% 45 cP and 15.5% 20 cP had a significantly lower extent of lipolysis and BC transfer compared to other formulations. The structure and mechanical strength of the oleogels were both determined to be factors affecting lipolysis and transfer. The presence of BC did not significantly affect the mechanical strength of the gels and EC oleogelation delayed BC degradation under accelerated storage conditions compared to a heated canola oil control. These findings could contribute to the development of new applications for EC oleogels, specifically for the effective delivery of lipophilic molecules.
Abstract The effect of surface quality on fat crystallization was examined for glass and gelatin surfaces using three‐dimensional polarized light microscopy in an attempt to develop a model system for how fat may crystallize in arteries. A mixture of the high‐melting fraction of milk fat and triolein was crystallized from 60 °C to 30 °C at a rate of 0.5 °C/min on both glass and gelatin surfaces. Crystallization of fat on the gelatin surface led to an increase in the amount of nucleation and resulted in a more even distribution of crystal mass than crystallization on the glass surface. No evidence of crystal precipitation or glass surface crystallization was evident. We postulate that the gelatin acted as a template for nucleation. Similar trends were identified using fractal analysis. Fat crystallized on gelatin had a higher fractal dimension than fat crystallized on glass.
Abstract Biomechanical cues from the extracellular matrix (ECM) are essential for directing many cellular processes, from normal development and repair, to disease progression. To better understand cell-matrix interactions, we have developed a new instrument named ‘OptoRheo’ that combines light sheet fluorescence microscopy with particle tracking microrheology. OptoRheo lets us image cells in 3D as they proliferate over several days while simultaneously sensing the mechanical properties of the surrounding extracellular and pericellular matrix at a sub-cellular length scale. OptoRheo can be used in two operational modalities (with and without an optical trap) to extend the dynamic range of microrheology measurements. We corroborated this by characterising the ECM surrounding live breast cancer cells in two distinct culture systems, cell clusters in 3D hydrogels and spheroids in suspension culture. This cutting-edge instrument will transform the exploration of drug transport through complex cell culture matrices and optimise the design of the next-generation of disease models.
The aim of this randomized crossover study was to investigate the influences of TAG droplet physical state at 37°C and emulsion gastric colloidal stability on gastric emptying (GE), postprandial lipemia and satiety in healthy men. It was hypothesized that emulsions susceptible to flocculation in the stomach would augment GE compared to acid stable emulsions, and that the acute lipemic and satiety responses would be attenuated for emulsions containing crystalline TAG and/or an acid unstable emulsifier. Twenty % palm stearin or palm olein emulsions with similar particle size distributions where formulated using either Tween80 (acid stable emulsifier) or Span60 (acid unstable emulsifier). The four emulsions contained partially crystalline droplets that remained stable (SS) or destabilized (SU) or contained liquid droplets that remained stable (LS) or destabilized (LU) when exposed to simulated in vitro gastric conditions. Fifteen healthy adult male non-restrained eaters (mean ± SD age: 24.9 ± 4.5; BMI: 26.0 ± 2.0 kg/m2; fasting TAG: 0.9 ± 0.3 mmol/L) consumed 250 mL of one of the emulsions on four occasions separated by at least 6 days. Baseline fasting and 6-hr postprandial ultrasound gastric antrum measurements, satiety visual analogue scales (VAS), and blood samples for analysis of plasma TAG and hunger and satiety hormones were collected. Gastric antrum area decreased faster (P ≤ 0.01) for the acid unstable emulsions (SU and LU) indicating faster GE. Postprandial TAG response did not differ significantly between any of the emulsions, but there were differences in postprandial satiety responses. 3-hr incremental area under the curve (iAUC) was significantly lower for hunger (P = 0.021) and desire to eat (P = 0.031) ratings and 6-hr iAUC was significantly higher for ghrelin (P = 0.028) with LS compared to SU. Plasma PYY and GLP-1 change from baseline values were also higher following consumption of LS compared to LU (P = 0.028) (for PYY), and compared to SU (P = 0.008) and LU (P = 0.001) (for GLP-1). Emulsion phase separation in the stomach was associated with delayed GE, which corresponded to enhanced satiety with the acid stable emulsion containing TAG in the liquid state. Canada's Natural Sciences and Engineering Research Council.
Abstract Gels were prepared by cooling dilute solutions (2% wt/wt) of 12‐hydroxystearic acid (12‐HSA) in canola oil and storing them at 30 °C for 24 h. The gel's in‐situ supramolecular network structure was imaged using four techniques: polarized light microscopy (PLM), 3‐dimensional deconvolution polarized light microscopy (3DPLM), and cryo‐scanning electron microscopy (cryo‐SEM) of the xerogel and of an osmium tetroxide vapor fixed gel washed with isobutanol. Most of the canola oil was immobilized in the gel by fixation with osmium tetroxide therefore very little of the canola oil was removed during washing unlike the xerogel where all of the canola oil has been displaced. The in‐situ supramolecular network structure as observed by PLM, was comparable to that seen through the new cryo‐SEM method for fixed organogel. Cryo‐SEM images of the xerogel did not show similar length scales or strand thickness as compared to the PLM images. The lengths of the network strands were much shorter for the xerogel as compared to the osmium tetroxide treated sample and the structures visualized by PLM. Furthermore, the thickness of the strands observed using PLM or cryo‐SEM were in the size range of 3–10 μm while the xerogels had strands in the range of 0.01–0.1 μm thick. Therefore, the removal of canola oil from the gel using 80/20% v/v hexane/acetone with no fixation disrupted the supramolecular network.
Adipose tissue (AT) expansion induces local hypoxia, a key contributor to the chronic low-grade inflammation that drives obesity-associated disease. Apple flavonols phloretin (PT) and phlorizin (PZ) are suggested anti-inflammatory molecules but their effectiveness in obese AT is inadequately understood. Using in vitro models designed to reproduce the obese AT microenvironment, 3T3-L1 adipocytes were cultured for 24 h with PT or PZ (100 μM) concurrent with the inflammatory stimulus lipopolysaccharide (LPS; 10 ng/mL) and/or the hypoxia mimetic cobalt chloride (CoCl2; 100 μM). Within each condition, PT was more potent than PZ and its effects were partially mediated by peroxisome proliferator-activated receptor (PPAR)-γ (p < 0.05), as tested using the PPAR-γ antagonist bisphenol A diglycidyl ether (BADGE). In LPS-, CoCl2-, or LPS + CoCl2-stimulated adipocytes, PT reduced mRNA expression and/or secreted protein levels of inflammatory and macrophage chemotactic adipokines, and increased that of anti-inflammatory and angiogenic adipokines, which was consistent with reduced mRNA expression of M1 polarization markers and increased M2 markers in RAW 264.7 macrophages cultured in media collected from LPS + CoCl2-simulated adipocytes (p < 0.05). Further, within LPS + CoCl2-stimulated adipocytes, PT reduced reactive oxygen species accumulation, nuclear factor-κB activation, and apoptotic protein expression (p < 0.05). Overall, apple flavonols attenuate critical aspects of the obese AT phenotype.
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