Physical characterisation of high amylose maize starch and acylated high amylose maize starches.

The particle size, water sorption properties and molecular mobility of high amylose maize starch (HAMS) and high amylose maize starch acylated with acetate (HAMSA), propionate (HAMSP) and butyrate (HAMSB) were investigated. Acylation increased the mean particle size (D(4,3)) and lowered the specific gravity (G) of the starch granules with an inverse relationship between the length of the fatty acid chain and particle size. Acylation of HAMS with fatty acids lowered the monolayer moisture content with the trend being HAMSB View Article and Find Full Text PDF

Water sorption properties, molecular mobility and probiotic survival in freeze dried protein-carbohydrate matrices.

The moisture uptake and molecular mobility of freeze-dried powders containing whey protein isolate-carbohydrate matrices (1WPI:2maltodextrin; 1WPI:1maltodextrin:1d-glucose; and 1WPI:1maltodextrin:1l-glucose) and encapsulated Lactobacillus rhamnosus GG (LGG) in these matrices were investigated at 25 °C and 33% and 70% relative humidity (RH). The inactivation rate constant for probiotics in freeze-dried matrices were positively correlated (R(2) = 0.98) to moisture uptake and molecular mobility measured by NMR relaxometry.

Extraction of silver(I) from aqueous solutions in the absence and presence of copper(II) with a methimazole-based ionic liquid.

The ionic liquid (IL) 2-butylthiolonium bis(trifluoromethanesulfonyl)amide, [mimSBu][NTf(2)], facilitates the efficient extraction of silver(I) from aqueous media via interaction with both the cation and anion components of the IL. Studies with a conventional aqueous-IL two phase system as well as microextraction of silver(I) by a thick IL film adhered to an electrode monitored in situ by cyclic voltammetry, established that [mimSBu][NTf(2)] can extract electroactive silver(I) ions from an aqueous solution. The pH of the aqueous phase decreases upon addition of [mimSBu](+), which is attributed to partial release of the hydrogen attached to the N(3) nitrogen atom of the imidazolium ring.

Comparison of diffusivity data derived from electrochemical and NMR investigations of the SeCN¯/(SeCN)2/(SeCN)3¯ system in ionic liquids.

Electrochemical studies in room temperature ionic liquids are often hampered by their relatively high viscosity. However, in some circumstances, fast exchange between participating electroactive species has provided beneficial enhancement of charge transport. The iodide (I¯)/iodine (I(2))/triiodide (I(3)¯) redox system that introduces exchange via the I¯ + I(2) ⇌ I(3)¯ process is a well documented example because it is used as a redox mediator in dye-sensitized solar cells.

Microencapsulated Lactobacillus rhamnosus GG powders: relationship of powder physical properties to probiotic survival during storage.

Freeze-dried commercial Lactobacillus rhamnosus GG (LGG) were encapsulated in an emulsion-based formulation stabilized by whey protein and resistant starch and either spray-dried or freeze-dried to produce probiotic microcapsules. There was no difference in loss of probiotics viability after spray drying or freeze drying. Particle size, morphology, moisture sorption, and water mobility of the powder microcapsules were examined.

Nitrile functionalized methimazole-based ionic liquids.

The alkylation reaction of 2-mercapto-1-methylimidazole 1b with 2-chloroacetonitrile and 2-chloropropionitrile produced S-alkyl methimazole chlorides 2a and 2b which were subjected to anion metathesis with lithium bis(trifluoromethanesulfonyl)amide, LiNTf(2), to afford nitrile functionalized methimazole-based room temperature ionic liquids 3a and 3b in 94% and 89% yields, respectively. Ionic liquids 3a and 3b have reasonably wide electrochemical windows. The efficient extraction of Ag(+) from aqueous media into 3a and 3b is also reported.

Extraction of copper(II) ions from aqueous solutions with a methimazole-based ionic liquid.

The recently synthesized ionic liquid (IL) 2-butylthiolonium bis(trifluoromethanesulfonyl)amide, [mimSBu][NTf(2)], has been used for the extraction of copper(II) from aqueous solution. The pH of the aqueous phase decreases upon addition of [mimSBu](+), which is attributed to partial release of the hydrogen attached to the N(3) nitrogen atom of the imidazolium ring. The presence of sparingly soluble water in [mimSBu][NTf(2)] also is required in solvent extraction studies to promote the incorporation of Cu(II) into the [mimSBu][NTf(2)] ionic liquid phase.

Synthesis, X-ray structure and electrochemical oxidation of palladium(II) complexes of ferrocenyldiphenylphosphine.

Four new complexes, [PdX(κ(2)-2-C(6)R(4)PPh(2))(PPh(2)Fc)] [X = Br, R = H (1), R = F (2); X = I, R = H (3), R = F (4)], containing ferrocenyldiphenylphosphine (PPh(2)Fc) have been prepared and fully characterised. The X-ray structures of complexes trans-1, cis-2 and cis-4, and that of a decomposition product of 4, [Pd(κ(2)-2-C(6)F(4)PPh(2))(μ-I)(μ-2-C(6)F(4)PPh(2))PdI(PPh(2)Fc)] (5), have been determined. These complexes show a distorted square planar geometry about the metal atom, the bite angles of the chelate ligands being about 69°, as expected.

NMR relaxation and self-diffusion study at high and low magnetic fields of ionic association in protic ionic liquids.

NMR relaxation and diffusion characterization of several protic ionic liquids at high and low magnetic fields are reported. The dynamics of cations and anions were similar at both frequencies, with similar trends and magnitudes for a fixed component paired with oppositely charged species. An Arrhenius relationship was displayed between the molecular motion and the glass transition temperature.

Preparation of protic ionic liquids with minimal water content and (15)N NMR study of proton transfer.

Low-molecular-weight Brønsted acids and amine bases were used to reproducibly prepare very dry, high-purity room-temperature protic ionic liquids (PILs). A series of eight amine bases and six Brønsted acids were combined to produce 48 mixtures, of which 18 were liquid at room temperature. The phase transitions and thermal decomposition temperatures were determined for each mixture; whereas viscosity, density and conductivity were determined for the room-temperature liquids.

Physical and electrochemical properties of thioether-functionalized ionic liquids.

The preparation and characterization of a series of ionic liquids based on S-alkyl thiolonium, S-alkyl thiotetrazolium, or S-alkyl thiobenzolium cations coupled with bis(trifluoromethanesulfonyl)amide, trifluoromethanesulfonate, alkyl phosphate, chloride, and hexafluorophosphate anions are reported. All are liquid at room temperature, except the chloride salt, which has a melting point of 92 degrees C. The electrochemical characteristics of this class of ionic liquid have been determined by cyclic voltammetry.

Nonadditivity of Faradaic currents and modification of capacitance currents in the voltammetry of mixtures of ferrocene and the cobaltocenium cation in protic and aprotic ionic liquids.

Unexpected nonadditivity of currents encountered in the electrochemistry of mixtures of ferrocene (Fc) and cobaltocenium cation (Cc(+)) as the PF(6)(-) salt has been investigated by direct current (dc) and Fourier-transformed alternating current (ac) cyclic voltammetry in two aprotic (1-butyl-3-methylimidazolium tetrafluoroborate and 1-butyl-3-methylimidazolium hexafluorophosphate) and three protic (triethylammonium formate, bis(2-hydroxyethyl)ammonium acetate, and triethylammonium acetate) ionic liquids (ILs). The voltammetry of the individual Fc(0/+) and Cc(+/0) couples always exhibits near-Nernstian behavior at glassy carbon and gold electrodes. As expected for an ideal process, the reversible formal potentials and diffusion coefficients at 23 +/- 1 degrees C in each IL determined from measurement on individual Fc and Cc(+) solutions were found to be independent of electrode material, concentration, and technique used for the measurement.

Methimazole-based ionic liquids.

The alkylation reaction of 2-mercapto-1-methylimidazole 1a with iodoethane and chlorobutane produced S-alkylmethimazole halides 2a and 2b which were subjected to anion metathesis with two different metal salts (MA) to afford methimazole-based room-temperature ionic liquids 3a, 3b, and 3c in 82%, 85%, and 87% yields, respectively. S-Alkylation giving 2a and 2b suggests that methimazole reacts through the thione tautomer.

Wheat-gluten-based natural polymer nanoparticle composites.

A series of wheat-gluten-based nanocomposites were produced by dispersing Cloisite-30B nanoclay particles into plasticized wheat gluten systems under thermal processing conditions. The exfoliation of the nanoparticles as confirmed by wide-angle X-ray diffraction and transmission electron microscopy has resulted in significant enhancement of the mechanical properties for both deamidated proteins and vital gluten systems under 50% relative humidity (RH). Such strength improvement was also pronounced for wheat gluten (WG) systems under a high humidity condition (RH = 85%).

Chemical modification of wheat protein-based natural polymers: cross-linking effect on mechanical properties and phase structures.

Chemical modification of wheat protein-based natural polymer materials was conducted using glyoxal as cross-linker, and the cross-linking effect was studied on mechanical properties under different humidity conditions, the molecular motions of each component, and the phase structures/components of the whole materials. The cross-linking significantly enhanced the mechanical strength of wheat gluten (WG) materials under RH = 50%. The elongation of materials was also increased, which was in contrast to many cross-linked protein systems.

pH effect on the mechanical performance and phase mobility of thermally processed wheat gluten-based natural polymer materials.

The mechanical properties, phase composition, and molecular motions of thermally processed wheat gluten- (WG-) based natural polymer materials were studied by mechanical testing, dynamic mechanical analysis (DMA), and solid-state NMR spectroscopy. The performance of the materials was mainly determined by the denaturization and cross-linking occurring in the thermal processing and the nature or amount of plasticizers used. The pH effect also played an important role in the materials when water was used as the only plasticizer (WG-w).

Intermolecular interactions and phase structures of plasticized wheat proteins materials.

The intermolecular interactions and phase structures of thermally processed wheat proteins with glycerol and water as plasticizers were studied by dynamic mechanical analysis and solid-state high-resolution NMR spectroscopy. The results of phase structures at scales of molecular level to tens of nanometers were correlated with the mechanical properties of the materials. The strong hydrogen bonding intermolecular interactions between the components in wheat proteins and the plasticizers resulted in a significant change in molecular motions of wheat protein materials.