Characterization and Food Application of an Amperometric Needle-Type L-Lactate Sensor

There have been increasing needs for biosensing in the food industry because it is accurate, rapid and efficient. A needle-type L-lactate sensor with a three-layer membrane system which uses lactate oxidase as the biological component was prepared. The sensor had an optimum pH around 9–10 and an optimum temperature at 45 C. The current response was stable over 40 days and specifically responded to L-lactic acid. The sensor gave accurate L-lactate measurements in kimchi and yogurt of 187.4 ± 4.1 and 734.1 ± 34.5 mg/dL, similar to those of a spectrophotometric L-lactate kit.     

Selective O–H Bond Cleavage in the Radiolysis of Quartz

Cleavage of the O–H bond in quartz was studied by Fourier transform infrared spectroscopy and ESR spectroscopy. When quartz single crystals and fused silica glass are γ-irradiated at 77 K, hydrogen atoms are produced by rupture of O–H bonds. The initial efficiency of O–H bond cleavage in quartz single crystals, i.e. the initial yield of H atoms, was three times as great as that in fused silica glass, although the concentration of O–H bonds in quartz single crystals (70 ppm) is much lower than that in fused silica glass (4000 ppm). The efficiency of O–H bond cleavage in quartz single crystals indicates that energy transfer from the irradiated single crystal to the O–H bonds takes place effectively at 77 K. The efficiency of O–H bond cleavage decreases with increasing γ-ray dose, i.e. with increasing amounts of radiation-induced defects in quartz single crystals. When the radiation-induced defects are removed by annealing the irradiated quartz single crystal at 773 K, the O–H bonds are ruptured again as effectively as for a fresh quartz single crystal. The distance of the energy transfer, estimated by a target model, is ∼15 nm.     

Novel Measurement of Hypoxanthine in Fish Using Direct Measurement Probe and Chemiluminescence Flow Injection Analysis

Direct measurements of hypoxanthine (Hx) in fish flesh were carried out using a sardine and a grunt twice with the same fish, and the average of 10 successive measurements (from 120 sec to 480 sec after pressing the probe against fish tissue) was taken as the Hx concentration by direct measurement. Results with two nearby tissues of one sample were 42.9 ± 4.9 μM and 42.6 ± 2.6 μM for the sardine, and 639 ± 33 μM and 598 ± 29 μM for the grunt. For sardine, Hx results from this direct method did not agree well with perchloric acid extraction measurements, but they were much better for grunt.     

DEATH KINETICS OF ESCHERICHIA COLI IN A COMBINED TREATMENT WITH HEAT AND MONOLAURIN

A kinetic study was performed on the combined effect of monolaurin and heat on the death of Escherichia coli. The following results were obtained: (1) Monolaurin was about eleven times more active than that of sodium laurate; (2) Temperature enhanced the effect of monolaurin. True enthalpyentropy compensation effect was shown in this death reaction. The value of 341.9°K was obtained from the formula of ΔH*= T_c·ΔS*+ b and 331.5°K from Arrhenius plots as a compensation temperature; (3) The apparent minimum enhancing concentration of monolaurin ranged from 0.0056 mM to 0.013 mM, varying with the heating temperature. It may be concluded from the results of this study that the enhancing effect of monolaurin on the thermal death of E. coli corresponds to that of the amphoteric surfactant type (S type) agent defined in our previous report.     

Hydration of heat-treated soy protein isolate and its effect on the molten flow properties at an elevated temperature

The relationship between the flow properties of soy protein isolate (SPI) at 140°C, measured using an extrusion viscometer, and changes in the hydration state were investigated. The state of the water in SPI was analysed by measurement of the freezable water content using differential scanning calorimetry (DSC) and by spin-spin relaxation rate (R₂) measurements using pulsed nuclear magnetic resonance (NMR). The dependence of the flow properties on the state of water was indicated by the correspondence between the water content at which the flow characteristics of molten SPI changed, and the critical water content indicated by DSC measurement of the minimum freezable water content, and by the inflection point in NMR measurement of the spin-spin relaxation rate (R₂).     

Microparticulation by Jet Mill Grinding of Protein Powders and Effects on Hydrophobicity

A method was studied for microparticulation of protein for use as fat substitutes by superfine grinding. A jet mill produced particles <3 μm from egg white, casein and soybean hull. Microparticulation by grinding of egg white was easier than with casein or soybean hull. Hydrophobicity of casein increased by grinding to super fine particles but little or no effect was observed on soybean hull and egg white.     

Mechanism of inactivation of heat-tolerant spores of Bacillus stearothermophilus IFO 12550 by Rapid Decompression

The effect of three rapid decompression methods to clear the mechanism of inactivation of heat tolerant spores of Bacillus stearothermophilus IFO 12550 was investigated. Pressurization of the spores at 200 MPa and 75°C for 60 min caused a kill of 10⁴ CFU/mL by the link-motion system but the nonrotational rod valve and E.G. seal methods gave a kill of about 10³ CFU/mL. Sterilization was due to the physical breakdown of spore coat, and was induced by its physical permeability of water at high pressure and temperature. Rapid decompression by the link-motion system at 200 MPa decreased the D-value of the spores from 3000 min (100°C, one atmosphere) to 6 min, 11 min, and 17 min at 95, 85, and 75°C, respectively.     

Switched-capacitor DFT and IDFT circuit

The switched-capacitor realization of the discrete Fourier transform (DFT) is treated in this paper as well as the inverse discrete Fourier transform (1DFT). The output of the DFT has a sinusoidal waveform including the amplitude and phase information of the required spectra. These spectra are given simultaneously and almost in real time. The output of the 1DFT is given merely by adding DFT outputs. Furthermore, the circuit configuration of this system-from input to DFT, from DFT to 1DFT, and from 1DFT to output-is a very simple configuration constructed by a non-recursive filter circuit.     

新型Gemini阳离子表面活性剂的合成和性能（1）：从长链烷基二甲基胺及其盐酸盐和环氧氯丙烷合成双烷基双季铵盐阳离子

概述了从长链烷基二甲基叔胺及其盐酸盐和环氧氯丙烷或其他连接剂在温和条件下合成新型双烷基双季铵盐型阳离子表面活性剂的方法,产品的表面活性以及烷基链长、连接基团结构对产物表面活性的影响。