Analysis of nine kinds of sweeteners in foods by LC/MS

A simple and rapid method for the simultaneous determination of nine kinds of sweeteners (acesulfame potassium, AK; sucralose, SUC; saccharin, SA; cyclamate, CYC; aspartame, APM; dulcin, DU; glycyrrhizic acid, GA; stevioside, STV; rebaudioside A, REB) in various foods by high-performance liquid chromatography-electrospray mass spectrometry (LC/ESI-MS) was developed. The LC separation was performed on a ZORBAX Eclipse XDB-C18 (2.1 mm x 150 mm) with a mobile phase of 5 mmol/L dibutylammonium acetate (DBAA) and acetonitrile-water (8: 2). Mass spectral acquisition was done in the negative ion mode by applying selected ion monitoring (SIM). The sweeteners were extracted from foods with 0.08 mol/L phosphate buffer (pH 7.0)- ethanol (1:1), and the extract was cleaned up on a Sep-pak Vac C18 cartridge after the addition of tetrabutylammonium bromide and phosphate buffer (pH 3.0). The recovery of the nine kinds of sweeteners from five kinds of foods fortified at the level 0.01 g/kg, 0.05 g/kg and 0.20 g/kg was 75.7-109.2%, and the between-day SD values were 0.5-10.9%. The quantification limits of AK, SA, CYC, APM and STV were 0.001 g/kg, and those of SUC, DU, GA and REB were 0.005 g/kg. A recovery test from each cleaned-up sample solution was necessary to detect ionization suppression.     

Enhancing the antioxidant effect of α-tocopherol with rosemary in inhibiting catalyzed oxidation caused by Fe and hemoprotein

A mixture of α-tocopherol and rosemary extract (0·035% + 0·035%) was used to inhibit fish lipid oxidation catalyzed by Fe²⁺ or hemoprotein. In a sardine oil model system, a mixture of α-tocopherol and rosemary extract showed a significantly stronger antioxidant effect, as it prolonged the induction period for 10 and 16 days longer than α-tocopherol alone and rosemary extract alone, respectively. In addition, the effective lifetime of α-tocopherol in samples treated with the α-tocopherol and rosemary extract mixture was 10 days longer than in samples with only α-tocopherol added even though the amount of added α-tocopherol in the latter case was twice that for the mixture. In fish dark muscle, the mixture of α-tocopherol and rosemary extract also showed a stronger anti-oxidant effect than either tocopherol or rosemary extract alone. Treatment of samples with this mixture also led to a lower rate of decomposition of highly unsaturated fatty acids, myoglobin and hemoglobin, and triglyceride compared to samples treated with tocopherol or rosemary extract alone.     

Effect of soy peptide on brewing beer

Here, we examined the effect of soy peptides (SPs) on the fermentation and growth of Yeast Bank Weihenstephan 34/70 (W34/70), a bottom-fermenting yeast. We compared fermentation for SP with that for a free amino acid (FAA) mixture having the same amino acid composition as SP, as a nitrogen source. Maltose syrup was used as a carbon source, and the medium contained excess amounts of essential minerals and vitamins. We observed that SP was better than FAA mixture at promoting fermentation and growth and that much more beta-phenylethyl alcohol was produced during fermentation with SP than with FAA mixture. Subsequently, we compared fermentations with the FAA mixture and selected mixtures containing various dipeptides of Phe as a nitrogen source. We found that the rates of Phe metabolism and beta-phenylethyl alcohol generation were much higher when Phe was presented as a dipeptide (Phe-Asp, Phe-Leu, or Phe-Phe) than when presented as FAA. These results show that amino acids such as Phe are absorbed more rapidly when presented as a peptide than as FAA, resulting in a more rapid production of beta-phenylethyl alcohol.     

Chemical composition,functional properties,and bioactivities of rapeseed protein isolates

In order to utilize rapeseed protein from oil industry waste for food applications, rapeseeds were pretreated to remove the oil using hexane. Two protein isolates were prepared, one by precipitation at controlled pH and the other by ultrafiltration. The precipitated and ultrafiltered protein isolates, respectively, contained 70.8% and 98.7% protein. The ultrafiltered protein isolate had a better emulsification capacity than had whole egg. The ultrafiltered protein isolate had a protein solubility of 52.5–97.2% in the range pH 3–9, whilst the maximum protein solubility of the precipitated protein isolate was 26.4% in the pH range 7–9. There were no significant differences between the precipitated and ultrafiltered protein isolates regarding their angiotensin converting enzyme inhibition are their bile acid-binding capacity. Their bile acid-binding capacity and angiotensin converting enzyme inhibition capacities were lower than of those de-oiled soybean. They showed stronger DPPH radical-scavenging activity than did de-oiled soybean.     

Effect of trace elements,molybdenum, and intercritical heat treatment on temper embrittlement of 2-1/4Cr-1 Mo steel

To minimize the temper-embrittlement susceptibility of 2 l/4Cr-lMo steel, minor changes in trace-element content and/or heat treatment will provide an improvement. Specimens containing two trace-element and six molybdenum levels were quenched and tempered to 100 ksi (690 N/mm²) tensile strength and embrittled by either isothermal aging at 900?F (480°C) for 1000 h or step cooling. When 33 ppm of P, Sn, As, and Sb are present, fracture appearance transition temperature (FATT) remains at about -130°F (-90°C) between 0.5 and 1.4 pct Mo. When 405 ppm of the trace elements are present, embrittled FATT reaches a minimum -50?F (-45°C). Thus, temper embrittlement can be suppressed by maintaining low trace-element concentrations. Intercritical heat treatment at 1575°F (855°C) also reduces temper embrittlement in air-cooled l/2 in. (13 mm) thick plates which simulate water-quenched heavy plates.     

Control of lattice spacing in a triangular lattice of feeble magnetic particles formed by induced magnetic dipole interactions

We studied methods of controlling the spacing between particles in the triangular lattice formed by feeble magnetic particles through induced magnetic dipole interaction. Formation of a triangular lattice is described by the balance between the magnetic force and the interaction of induced magnetic dipoles. The intensity of the magnetic force is proportional to the volume of particles V and the difference in the magnetic susceptibilities between the particles and the surrounding medium Δχ. On the other hand, the intensity of the induced magnetic dipole interaction depends on the square of V and Δχ. Therefore, altering the magnetic susceptibility difference by changing the susceptibility of the surrounding medium, volume of the particles, and intensity and spatial distribution of the applied magnetic field effectively controls the distance between the particles. In this study, these three methods were evaluated through experiment and molecular dynamics simulations. The distance between the particles, i.e. the lattice constant of the triangular lattice, was varied from 1.7 to 4.0 in units of the particle diameter. Formation of self-organized triangular lattice through the induced magnetic dipole interaction is based on magnetism, a physical property that all materials have. Therefore, this phenomenon is applicable to any materials of any size. Consequently, structure formation through induced magnetic dipole interaction is a potential way of fabricating materials with ordered structures.     

Catalytic activities of niobium oxide for the liquid-phase hydrogenation of maleic anhydride and hydration of succinonitrile

Co and Pd supported on Nb₂O₅ catalyst was active for the hydrogenation of maleic anhydride to γ-butyrolactone and tetrahydrofuran in the liquid-phase. The catalyst was more active than Co and Pd supported on diatomaceous earth, SiO₂ and Al₂O₃. Co and Pd seem to be stable on Nb₂O₅.

Nb₂O₅ · nH₂O was active for the hydration of succinonitrile to β-cyanopropionamide, that is an intermediate for -pyrrolidone, in the liquid-phase. Niobium oxide showed unique catalytic activities, especially, in the presence of water.     

Effect of addition of alkali metal salts in hydrothermal synthesis and post heat-treatment on porosity of SBA-15

SBA-15 was hydrothermally synthesized at 80 °C for 48 h, and then the surfactant template for mesopore formation was removed by extraction with ethanol, washing with nitric acid, and heating at 200 °C. Addition of alkali metal chlorides to a synthesis gel of SBA-15 increased its mesopore diameter in the following order: no added salt < LiCl < KCl < CsCl. The micropore volume did not change with the addition of any alkali metal and was around 0.17 mL g^–1. These results suggest that alkali metal salt is inside the mesopore with a micelle template. When a small amount of potassium chloride was impregnated in SBA-15 after extraction and washing, micropore volume reduced almost to zero with heating at 400 °C in dry air, and the mesopore diameter and pore wall thickness were reduced by a larger amount than for non-impregnated SBA-15. It is likely that the micropores in the mesopore wall vanish due to condensation of silanols and/or reconstruction of siloxane bonds on the micropore wall, which are catalyzed by alkali metal halides.     

A novel quasi-dimeric oxidation product of (+)-catechin from lipid peroxidation

A novel quasi-dimeric oxidation product of (+)-catechin, formed during the radical-scavenging reaction that prevents lipid peroxidation, was isolated by chromatography, and its structure was elucidated by infrared, ultraviolet and¹H and¹³C nuclear magnetic resonance spectra and mass spectrometry. It was 5′-[3-[3,4-(3′,5′-dihydroxy) benzo-8-oxo-2,7-dioxabicyclo [4.4.0] deca-3,9-dien-10-yl]acryloyl]-(+)-catechin. It is an unusual type of dimer of flavan-3-ol derivatives, which is different from the naturally formed dimer, procyanidin.     

Effects of Grain Size of Hot-Pressed Silicon Nitride on Contact Damage Morphology and Residual Strength

Effects of the grain size of hot-pressed Si₃N₄ on contact damage morphology and residual strength were studied using the elastic/plastic indentation method with a spherical indenter. The contact damage, initially formed with increasing indentation load, was Hertzian cracks in the Si₃N₄ consisting of fine grains (mean grain size: 0.2 μm). In the coarser-grained Si₃N₄ (mean grain size: 0.8 μm), there was a damage texture, consisting of grain-sized microcracks. The residual strength was degraded at a load slightly higher than the critical load for contact damage formation. The strength degradation was not caused by contact damage but the residual stress formed around the impressions.