Detection of Free Radicals in Beer Oxidation

Short-lived radicals produced during the incubation of beer at 60°C were detected by electron spin resonance (ESR) spectroscopic analysis using N-tert-butyl-α-phenylnitrone (PBN) as a spin trapping reagent. The hyperfine splitting (hfs) constants were 15.7 ± 0.2 G and 3.2 ± 0.2 G for α_N and a^β_H, respectively. The hfs constants of PBN adducts produced by Co⁶⁰γ irradiation were 15.6 ± 0.3 G and 3.1 ± 0.2 G for α_N and α^β_H in beer and 15.7 ± 0.3 G and 3.3 ± 0.3 G for α_N and α^β_H in double distilled water. It is proposed, therefore, that short-lived radicals produced during the incubation of beer at 60°C may be hydroxyl radicals.     

RELATIONSHIPS BETWEEN BINDING QUALITY OF MEAT AND MYOFIBRILLAR PROTEINS

The binding quality of the heat set gel increased when F-actin was present in an appropriate ratio to myosin A. It increased further when tropomyosin was added to the myosin A/F-actin model system. The water holding capacity was increased by tropomyosin only. Thus, the contribution of not only myosin A but also of native tropomyosin and actin should be controlled in sausage manufacture. The presence of 0.6 M NaCl or KCl in the sol was necessary to produce high binding quality and high water holding capacity of heated myosin B gels. NaCl is preferred because of the taste effect on the meat product. Heating temperature (65, 80, or 90°CC) affected the physical properties of heated myosin B gels. The water holding capacity and the maximum relaxation time decreased with increasing temperature. In the manufacture of meat products, the heating temperature should be selected in accordance with the desired properties in the finished product.     

Crack Stability in the Work-of-Fracture Test: Refractory Applications

The conditions necessary to achieve valid work-of-fracture tests were examined for several aluminosilicate refractories. On the basis of an energy balance, construction of a test stability diagram permitted evaluation of the effects of refractory properties, specimen dimensions, and the testing machine characteristics to determine the optimum test conditions. The results illustrate the important experimental features necessary to achieve stable work-of-fracture measurements.     

RELATIONSHIPS BETWEEN BINDING QUALITY OF MEAT AND MYOFIBRILLAR PROTEINS: III: Contribution of Myosin A and Actin to Rheological Properties of Heated Minced-Meat Gel

Myosin A and myosin B gels formed by heating exhibited similar binding abilities as measured by the breaking energy, but different physical properties. At equivalent concentrations, myosin A gels exhibited smaller values for the Young's modulus of elasticity and larger values for strain at the breaking point. It was inferred from the results of a simple model experiment that in sausage manufacture the physical properties of the heat set minced meat gel are of the myosin B type when no pyrophosphate is present, and similar to the myosin A type when pyrophosphate is added. In the latter case, the contribution of actin may be significant. The binding quality of the heat set myosin B gel increased with myosin concentration. Hence, the binding quality of sausage should be influenced by the myosin B content of meat.     

Characteristics of Acid Hydrolysate from Defatted Peanut Flour

We hypothesized that aflatoxin-contaminated defatted peanut flour could be acid hydrolyzed to produce an aflatoxin-free seasoning sauce. Physical and chemical properties and amino acid composition of the flour hydrolyzed at 120°C for 4 hr with 5N HCI and destruction of aflatoxin B, during hydrolysis were investigated. The pH (5.72), specific gravity (1.20), total solids (402 mg mL-¹), and reducing sugar (2.9 mg mL^-1) and total nitrogen (17.5 mg mL-¹) contents of the peanut hydrolysate were similar to those of commercial soy sauces or seasoning sauces made by chemical processes. Glutamic acid, aspartic acid, arginine and glycine were the major amino acids in the hydrolysate and should contribute substantially to enhancing flavor. Aflatoxin B, was totally destroyed during acid hydrolysis at 100 or 120°C.     

The Effects of Geometric Uncertainties on Micro-Channel Heat Transfer—A CFD Study on the Tilted-Cover Problem

The present paper attempts to shed light on issues that so far have been unaddressed in research on micro-channel heat transfer. The first part of the paper summarizes the uncertainty sources likely to be present in micro-channel cooling devices incorporated in the electronic package. The effects of uncertainties on the heat transfer performance of the cooling device are difficult to assess due to the coupling of diverse factors in a narrow physical space. The CFD simulation offers a means to sort out the effects from multiple factors by assuming uncertainties from one of the sources or a set of selected sources into an analytical model.

A model channel is defined to illustrate the application of the CFD-based methodology to situations involving geometric uncertainties. The model has a 20 mm × 20 mm heater plate set in a channel having an adiabatic cover and side-walls and cooled by a dielectric coolant. The tilt of the cover plate is chosen as an uncertainty factor from among all possible factors. CFD simulations were performed for the cases where the nominal channel height was changed from 1 mm to 0.1 mm with a proportionate reduction of the cover tilt from 1° to 0.1°. The results indicate a measure of required stringency in assembling the micro-channel cooling device. Also, a hypothetical experiment is considered where the performance of a channel having an optimum height is compared with that of a non-optimum channel under a given pumping power. Examination of the simulation results revealed that the cover tilts in both channels could blur or amplify the optimality of the channel height to an appreciable extent.     

Two-Phase Heat Spreaders Utilizing Microfabricated Boiling Enhancement Structures

Results from various enhancement techniques to improve the performance of a recently developed two-phase heat spreader are reported. The spreader has a central evaporator section, with an integrated condenser along the edges. A micro-fabricated three-dimensional enhancement structure is employed to improve the heat transfer performance of the spreader. This study considers the performance of several liquid coolants to be used with the device and evaluates the effect of initial pressures on the thermal performance of the spreader plate. Liquids with lower boiling points were found to result in lower wall temperatures of the spreader plate due to earlier onset of boiling. Studies also showed an improvement in heat transfer performance with increase in stack height of the enhancement structures used in the evaporator section.     

PASSION FRUIT STARCH AND EFFECT ON JUICE VISCOSITY

Starches in the juices of yellow passion fruit, Passiflora edulis f. flavicarpa , and purple passion fruit, P. edulis f. edulis , were isolated and characterized. Starch granule sizes for the yellow variety (7.8 μm) and purple variety (6.4 μm) were similar. Gelation temperature ranges for the yellow variety (58.5–67.0 ° c) and purple variety (58.5–66.5 ° C) were also similar. The amylose content was slightly higher in the yellow variety (8.7%) than in the purple variety (5.8%). Viscosity differences between juices of the two varieties after treatment with heat and α-amylase were attributed to differences in pH and starch content between the yellow variety (pH 2.8, 0.06% starch) and the purple variety (pH 4.2, 0.74% starch). α-amylase was effective in reducing the viscosity of passion fruit juice in which the starches are gelatinized.