Sapid Components in Carrot

SUMMARY: The relationship between various substances present in carrot to its taste was studied. Nucleic acid derivatives found in hot water extracts of carrot were adenine, adenosine, inosine, hypoxanthine, 5'-AMP, 5'-UMP, UDP, but 5'-IMP and 5'-GMP were absent. The contents of these derivatives were extremely small. Silica gel chromatography showed the presence of small quantities of succinic acid, α-ketoglutaric acid, lactic acid, pyroglutamic acid, citric acid and glycolic acid.
Amino acids in hot water extracts of carrot were detected by two-dimensional thinlayer chromatography and automatic amino acid analyzer. Identified were glutamic acid, valine, leucine, aspartic acid, lysine, and serine etc. Glutamic acid content was relatively large. Sucrose, maltose and glucose were detected in carrot and these carbohydrates were responsible for the sweetness of carrot. The taste of carrot was due mainly to the presence of glutamic acid and the buffer action of various amino acids.     

Oxygen-Sensor-Based Simple Assay of Histamine in Fish Using Purified Amine Oxidase

Oxygen consumption was measured by an oxygen sensor after addition of purified fungal amine oxidase to fish extracts. The oxidation of histamine to imidazoleacetaldehyde proceeded stoichiometrically. Based on the equimolar relationship between histamine and oxygen consumption, histamine was determined selectively by the oxygen sensor. Neither sample pretreatment removing interfering materials nor daily calibration by histamine standard was required. Histamine contents in scombroid fish were determined rapidly with good accuracy. AOAC and oxygen sensor methods showed a very high correlation (r=0.999, n=6).     

A new testing method to obtain mode II fatigue crack growth characteristics of hard materials

Flaking type failure in rolling‐contact processes is usually attributed to fatigue‐induced subsurface shearing stress caused by the contact loading. Assuming such crack growth is due to mode II loading and that mode I growth is suppressed due to the compressive stress field arising from the contact stress, we developed a new testing apparatus for mode II fatigue crack growth. Although the apparatus is, as a former apparatus was, based on the principle that the static K_I mode and the compressive stress parallel to the pre‐crack are superimposed on the mode II loading system, we employ direct loading in the new apparatus. Instead of the simple four‐point‐shear‐loading system used in the former apparatus, a new device for the application of a compressive stress parallel to the pre‐crack has been developed. Due to these alterations, mode II cyclic loading tests for hard steels have become possible for arbitrary stress ratios, including fully reversed loading (R=?1); which is the case of rolling‐contact fatigue. The test results obtained using the newly developed apparatus on specimens made from bearing steel SUJ2 and also a 0.75% carbon steel, are shown.     

Determination of Polycyclic Aromatic Hydrocarbons in F-15J,C-130H,and F-4EJ Aircraft Exhaust

There are occupational health concerns at Japan Air Self-Defense Force bases in regard to the exposure of military flightline personnel to carcinogens in aircraft emissions, such as polycyclic aromatic hydrocarbons (PAHs). To characterize the PAHs in military aircraft emissions from different types of engines, aerosol and gas samples were separately collected downwind from aircraft with a turboprop engine (C-130H), turbojet (F-4EJ), and turbofan (F-15J). The gas-phase PAHs were determined by gas chromatography coupled to mass spectrometry and the aerosol-phase PAHs were determined by high-performance liquid chromatography with fluorescence detection. The F-4EJ engine was a source of naphthalene vapor and aerosol PAHs, including carcinogens such as chrysene, benzo (b) fluoranthene, benzo (k) fluoranthene, benzo (a) pyrene, dibenzo (a,h) anthracene, benzo (ghi) perylene, and indeno (1,2,3-cd) pyrene. These heavier (five and six-ring) PAHs were also included in the emissions from the F-15J with its newer, high-temperature F-100 turbofan engine, but the concentrations were approximately one-tenth of those in the F-4EJ. In contrast to these fighter aircraft, the C-130H was found to be a significant aerosol source of the lighter, three-ring (phenanthrene and anthracene) and four-ring (fluoranthene and pyrene) PAHs, but not the heavier ones. These results demonstrate that various aircraft are sources of PAHs in the military flightline environment.     

Hexagonal β-SiC Particles

Among small β-SiC particles (0.2 ∼ 0.4 μm in size) produced by chemical vapor reaction, hexagonal particles having diameters around 0.2 μm are sometimes found. When observed by TEM, they have image contrasts reminiscent of "multiply twinned particles". Analysis of diffraction patterns and image contrasts observed indicates that these particles consist of multiple twins with twin planes parallel to the basal plane. The characteristics of growth processes of such particles are discussed.     

ROLE OF MUSCLE PROTEINASES IN MAINTENANCE OF MUSCLE INTEGRITY AND MASS

Current evidence indicates that, of the thirteen known lysosomal peptide hydrolases, only seven, cathepsins A, B, C, D, H, L, and lysosomal carboxypeptidase B are located inside skeletal muscle cells. Only one of the reported neutral and alkaline proteases is located inside skeletal muscle cells', this neutral protease is the Ca²⁺-dependent proteinase, CAF. With the possible exception of cathepsin N, which can degrade collagen, it seems probable that any protease that contributes to postmortem tenderization needs to be located inside muscle cells. Because very little degradation of myosin or actin occurs in postmortem muscle, most of the small amount of proteolytic degradation of the myofibrillar proteins that occurs during postmortem storage must be due to CAF, which is unique in being unable to degrade myosin and actin. It is not certain that postmortem proteolysis by CAF causes increased tenderness; some recently discovered actin-fragmenting proteins could be involved.     

Survey of Rabbit Skeletal Muscle Peptidases Active at Neutral pH Regions

A survey of oligopeptide hydrolases active at neutral pH regions responsible for increased free ammo acids on aging of high ultimate pH muscles were performed examining chromatographic behavior and substrate specificity of rabbit skeletal muscle extract. The DEAE-cellulose chromatography of muscle extract revealed five major activity peaks respectively ascribable to a dipeptidase, an aminotripeptidase, an ammopeptidase, leucine aminopeptidase and the 160,000 dalton-aminopeptidase purified previously by us. Since the 160,000 dahon-ammopeptidase showed a broader substrate specificity than the two other aminopeptidases, it is most likely that this enzyme shares the largest part in the tetrapeptide hydrolysis in rabbit skeletal muscle at neutral pH regions.