Dependence of Vacuum Electrical Breakdown Field and Field Enhancement Factor on the Number of Apertures Drilled in Small Electrodes

Dark current based on field emission current is considered to be a factor causing the vacuum electrical breakdown between multiaperture acceleration grids in the JT‐60 negative ion source. In this paper, we focus on field enhancement factor, which is a key parameter of field emission from the electrode. Vacuum breakdown testing for small‐sized electrodes simulating the multiaperture acceleration grids of the negative ion source was performed. We found the field enhancement factor and breakdown field for multiaperture electrodes, and we investigated the dependence of each parameter on the number of apertures. The results revealed that an increase in the average field enhancement factor after the end of conditioning resulting from an increase in the number of apertures led to a decrease in the dielectric strength of the multiaperture electrodes.     

Effect of Maillard Reaction on Some Physical Properties of Ovalbumin

Ovalbumin freeze-dried with or without the addition of glucose was stored at 50°C and 65% relative humidity to study the effect of the Maillard reaction on some physical properties of ovalbumin. In the early stage of the reaction in which ovalbumin-glucose complexes were formed, there were soluble types of monomer and aggregates of which α-helix and available lysine contents were gradually decreased with length of storage and degree of aggregation. These compounds were characterized by properties possessing a marked resistance towards destruction of conformation and coagulation. With progress of the reaction, ovalbumin-glucose complexes changed to insoluble forms having higher particle weight and breakdown products.     

DNA ANALYSIS FOR IDENTIFICATION OF FOOD-ASSOCIATED FOREIGN SUBSTANCES

To identify food‐associated foreign substances, a DNA analysis consisting of 18S rDNA sequencing and homology search analysis has been developed. In this method, we designed universal primer pairs for specific amplification of animal and plant 18S rDNA and constructed an original DNA database storing partial 18S rDNA sequences of 222 organisms commonly used for culinary purposes. In the model experiments, food materials were successfully identified, indicating that our DNA analysis method can be practically applied to the identification of food‐associated foreign substances. It is also expected that this method complements conventional morphological and compositional analysis, leading to more accurate and reliable identification of food‐associated foreign substances.     

DIFFERENT ARRANGEMENT OF ɛ-(γ-GLUTAMYL)LYSINE CROSS-LINKING IN ALASKA POLLOCK (THERAGRA CHALCOGRAMMA) SURIMI PROTEINS BY STREPTOVERTICILLIUM AND ENDOGENOUS TRANSGLUTAMINASES DURING SUWARI PROCESS

The objective of the present study is to compare the protein cross‐linking reaction in Alaska pollock surimi that is catalyzed by a commercially available microbial transglutaminase and by endogenous Alaska pollock transglutaminase. The endogenous transglutaminase was inhibited by EGTA and activated by CaCl₂ The microbial transglutaminase was added to the salted surimi with and without EGTA and CaCl₂. These surimi pastes were incubated at 25C up to 24 h followed by cooking at 90C. The resultant gels were fractionated into soluble and insoluble (aggregate) fractions by SDS‐urea extraction. Compositional analysis revealed that the aggregate consisted predominantly of cross‐linked myosin heavy chain. The distribution of ?‐(γ‐glutamyl)lysine isopeptide in the soluble and aggregate fractions andpeptide mapping analyses of the aggregate fraction demonstrate that the formation of isopeptide cross‐links in Alaska pollock surimi proteins during suwari process differs when catalyzed by the microbial transglutaminase and endogenous transglutaminase.     

HYDROLYSIS OF PHYTATE IN BROWN RICE-ADDED BREAD BY ADDITION OF CRUDE AND PURIFIED ASPERGILLUS NIGER PHYTASE PREPARATIONS DURING BREAD MAKING

Brown rice-added breads were prepared with and without crude and purified Aspergillus niger phytase preparations. By adding 30% (w/w) brown rice flour and no phytase preparation, the phytate (myo-inositol hexaphosphate; IP₆) content of the bread was increased and the loaf volume was reduced. The direct addition of a food-additive grade phytase preparation (3,000 U) resulted in a significant decrease in the IP₆ content. However, it collapsed the bread crust. The crude phytase preparation had significant protease and amylase activities. A simple chromatographic method for the separation of phytase activity from the protease and amylase activities was developed. By using purified phytase, the IP₆ content was reduced without any adverse effects on the rising of the bread, which indicates that protease and amylase may be responsible for the collapse of the crust by the commercial phytase preparation.

PRACTICAL APPLICATIONS

Phytate in unrefined cereals and beans lowers bioavailability of minerals. On the other hand, these materials are rich in health-promoting components. To reduce the phytate in them during processing, some commercially available phytase preparations are now used. However, we found that such preparation contains significant amylase and protease activities, which may cause adverse effect on the appearance and textural properties of final products. To solve these problems, a simple and inexpensive procedure for separation of phyatase from amylase and protease was developed in the present study. The purified phytase can reduce phytate in brown rice-added bread without adverse effect on rising of bread. These results would encourage prepare the phytase preparation in high purity in an industrial scale to improve nutritional value of unrefined cereal- and bean-based functional foods.     

Heat-Induced Aggregation of Egg White Proteins as Studied by Vertical Flat-Sheet Polyacrylamide Gel Electrophoresis

Heat-induced aggregation of proteins in egg white was investigated by a vertical flat-sheet polyacrylamide gel electrophoretic method. The fractional and step-wise aggregation of egg white proteins was caused by heating. Even with a heating time of 120 min, ovalbumin and globulins Al and A2 failed to aggregate in egg white (pH 7 and 9) at 70°C, and ovotransferrin and ovomucoid also did not aggregate in egg white at 60°C (pH 9) and 76°C (pH 7 and 9), respectively. The ovoinhibitor was much more unstable than ovomucoid under heat-treatment, and the time dependency of heat-induced aggregation of flavoprotein was greater than those of the other proteins in egg white.     

Chemical Characterization of Sardine Meat Powder Produced by Dehydration with High Osmotic Pressure Resin and Defatting with High Pressure Carbon Dioxide

Oils and fishy odor were extracted from the minced sardine meat with liquid carbon dioxide after dehydration with high osmotic pressure resin. This treatment resulted in higher quality minced sardine meat usable as “Surimi.” The lipids of the minced sardine meat defatted with liquid carbon dioxide was half that of undefatted meats; residual lipids were mainly composed of polar lipids such as phospholipids. Although soluble nitrogen and ATPase activity in sardine meat were decreased by dehydration and defatting, the Kamaboko-forming ability was present, and its flavor was improved after defatting. Moreover, sardine meat defatted with liquid carbon dioxide had good stability against protein deterioration and lipid peroxidation.     

GIBBS DERIVATIVES IN LINEAR SYSTEM THEORY

In this paper we first give a general characterization of Gibbs derivatives on groups and then discuss their use in linear systems theory considering systems with both deterministic and stochastic input/output signals. We introduce the concept of p-adic linear stochastic systems, offering in that way another field for the application of Gibbs derivatives in a manner corresponding to that used in the theory of dyadic systems and stochastic dyadic systems.