Accelerated Fermentation Process for the Manufacture of Fish Sauce Using Histidine

Addition of histidine accelerated hydrolysis of fish protein during fermentation in the manufacture of fish sauce and after 4 mo fermentation yielded a product typical of traditional fish sauce. The liquefaction rate of the histidine-treated sauce was faster than that of the control. The degree of hydrolysis was much greater in the histidine-added sauces than in the control. Most amino acids were higher in the histidine sauces compared to commercial patis sauce (as reference). Addition of histidine to the fish mixture during fermentation did not increase the histamine content of the sauces.     

A SPECIFIC QUALITATIVE DETECTION METHOD FOR PEANUT (ARACHIS HYPOGAEA) IN FOODS USING POLYMERASE CHAIN REACTION

A qualitative method for detection of peanuts in foods using polymerase chain reaction was developed. A universal primer pair CP 03‐5′/CP 03‐3′ was designed to confirm the validity of the DNAs for PCR. The plant‐specific amplified fragments were detected from 13 kinds of plants using the universal primer pair. In addition, for the specific detection of peanuts with high sensitivity, the primer pair agg 04‐5′/agg 05‐3′ was designed to detect the gene encoding the peanut agglutinin precursor. The primer pair specifically generates a 95‐bp amplified fragment from peanut genomic DNA. Five hundred femto grams of peanut genomic DNA can be detected using the established method. The same qualitative results were obtained from both model processed and nonprocessed food samples containing 0.001, 0.01 and 0.1% of peanut. Moreover, it was shown that the trace amount of peanut in the commercial food products could be qualitatively detected using this method. The reproducibility and applicability of the proposed methods were verified in a six‐laboratory collaborative study.     

Oxygen Effect on Volatile Acids Formation During Fermentation in Manufacture of Fish Sauce

Volatile acids of aerobically and anaerobically fermented fish sauces were investigated using GC and GC-MS. There was no significant difference in pH values of the two types of sauces. Volatile acids found in the aerobically fermented sauce had concentrations significantly higher than the anaerobically fermented one. Sensory evaluation revealed that the aroma of the anaerobically fermented sauce was a little sweet, less acidic and less rancid than the aerobically made sauce which was sharp, and cheesy. Thus, fermentation under anaerobic condition altered the aroma quality of the sauce during manufacturing, yielding an acceptable product.     

纤维增强树脂基复合材料拼接结构拉伸性能

为了解拼接结构的力学特性,更好地设计高强度的拼接结构,测试了三种含拼接结构的单向碳纤维增强环氧树脂基(CF/EP)层合板复合材料的拉伸性能,通过监测结构在拉伸过程中的形态分析其破坏特点,并利用有限元软件对不同拼接结构的拉伸过程进行模拟,分析拼接结构受拉过程中的受力特点。所有材料均采用真空辅助灌注工艺(VARTM)获得。结果表明,拼接结构的引入大大降低了CF/EP材料的拉伸强度;由于拼接位置产生明显的应力集中,结构破坏从拼接位置开始,最终破坏模式为层间破坏;拼接位置处的剪切应力和侧向拉伸应力是结构发生初始破坏的主要因素;为了尽可能避免产生拼接位置处的剪切应力和侧向拉伸应力以提高结构强度,应尽可能设计为对称结构。     

MOLECULAR PROPERTIES OF POST-MORTEM MUSCLE. 9. Effect of Temperature and pH on Tropomyosin-Troponin and Purified α-Actinin from Rabbit Muscle

SUMMARY– A study was done on the effects of in vitro storage of purified α-actinin, troponin, tropomyosin, and the tropomyosin-troponin complex on the activity of these protein fractions in the ATPase and superprecipitation assays. Storage was done at various combinations of temperatures between 0 and 40°C and pH values between 5.7 and 7.0. Even after 40 hr of storage, activities of purified tropomyosin and the tropomyosin-troponin complex were not affected by any combination of temperature and pH included in this study, but activities of purified α-actinin and troponin were almost completely lost after 16 hr at 40°C and pH 5.7. Storage for 40 hr at low pH (5.7) and low temperatures (0°C) did not affect the activity of either α-actinin or troponin, but 40 hr of storage at high temperatures (40°C) and neutral pH caused some loss in activity for both these proteins. This loss of activity caused by 40°C, pH 7.0 storage was much more noticeable in the case of troponin than in the case of α-actinin. Storage periods of 40 hr or longer were required before any loss of α-actinin activity could be detected at pH 7.0 and 40°C. Since most meat animal carcasses are chilled soon after exsanguination and attain muscle temperatures of 25°C or lower before the pH falls below 6.2, it is probable that α-actinin and tropomyosin-troponin activity remain almost unchanged in meat handled through normal market channels. However, myofibrillar tissue in those porcine animals whose musculature undergoes a very rapid post-mortem decline in pH so that values of 5.7 or less are reached while muscle temperatures are still 37°C or higher may lose much of its α-actinin and tropomyosin-troponin activity during the first 24 hr post-mortem.     

Improved Modified Switching Transient Pulse Width Modulation (MT‐PWM) Method Applied to H‐Bridge Type Step‐Down Converter

The authors have devised a new method to decrease high‐frequency harmonics in a specific frequency band by modifying the switching transient slope. In previous studies, there were several problems in applying modified transient pulse width modulation (MT‐PWM) to actual converters. In this paper, three problems are solved using an improved MT‐PWM method. First, the MT‐PWM signal was obtained using a trial‐and‐error approach that involved complex computation procedures in the previous studies. In this paper, a new calculation procedure for obtaining the MT‐PWM waveform using a simple calculation is proposed. Second, a new controller (drain‐source voltage controller) based on voltage feedback is proposed in order to realize a modified switching transient to increase the stability of the switching operation. Third, the dependency of MT‐PWM on source voltage variation is investigated in order to implement MT‐PWM in an actual step‐down converter. From this result, the concept of a new type of controller with the source voltage variation taken into consideration is proposed. Finally, the authors attempted to apply MT‐PWM to an H‐bridge converter to expand the application of MT‐PWM. An H‐bridge converter with MT‐PWM for a dc motor drive is successfully operated in an experiment.     

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).     

Dielectronic Recombination of Br-Like Tungsten Ions

Accurate data for dielectronic recombination of tungsten ions are essential in the modeling of tungsten impurity transport and radiative power loss in International Thermonuclear Experimental Reactor （ITER）. Theoretical calculations have been made for dielectronic recombi- nation （DR） rate coefficients of Br-like tungsten ions using a flexible relativistic atomic code （FAC） from i eV to 50 keV. Level-by-level calculations are carried out for evaluating the contributions to DR through all the relevant Kr-like tungsten ions autoionizing inner-shell excited configuration complexes： （3s23p63d10）-14s24p5nlntl＇ （n = 4-5, n＇ = 4-100,l＇ = 0-8）, （4s24pS）-lnln＇l＇ （n = 4-6, n＇ = 4-100, l＇ = 0-12）. Comparison of the rate coefficients for 3s, 3p, 3d, 4s and 4p subshell excitations shows that the 4p subshell excitation dominates over the whole temperature region, 4s subshell excitation at low temperature and 3p, 3d subshell excitations at high temperature can not be neglected. In order to facilitate simple applications, the total DR rate coefficient, △n = 0,1 and 2 core excitations DR rate coefficients are fitted to an empirical formula.