Fish muscle analysis

In contrast to milk, where samples are primarily derived from cows, meat analysis has to be performed in samples of a widely different animal origin including cattle, lamb, swine, poultry, and fish. Muscle is a complex matrix with a pH of 5.7, composed of muscle fibers, various types of connective tissue, adipose tissue, cartilage, and bones. Sarcoplasmic proteins such as myoglobin, and glycolytic enzymes are soluble in water while the myofibrillar proteins such as myosin and actin are soluble in concentrated salt solutions (14). The connective tissue proteins, collagen and elastin, are insoluble in both solvents. 

Zooplankton population samples for isotope analysis were composites of 50-200 individuals. Population samples are less variable in isotope composition than are samples of individuals. Replicate isotope analyses of composite samples of zooplankton or POM collected at different locations within the lake varied by no more than 0.5%. Larger organisms such as molluscs, insects, and fish were analyzed individually. Molluscs were soaked in dilute HCl to remove carbonates and then rinsed copiously with distilled water. Fish muscle was analyzed. Sediment trap material was collected in replicate cylinders (11.4-cm diameter, 76.2-cm length) suspended at 4.5-m depth. All isotope samples were dried at 60 °C before analysis. 

When the structure in Fig. 29A is put into the fish muscle A-band unit cell (Fig. 29B note that the analysis of Hudson et al. [1997] defined the absolute orientation of the filament within the A-band lattice), it can be seen that the actin-binding sites on the myosi n heads are already close to... 

Al-Khayat, H. A., Morris, E. P., Powell, A. S., Kensler, R. W., and Squire,J. M. (2005a). 3D structure of vertebrate (fish) muscle myosin filaments by single particle analysis. 

Enormous efforts have been devoted to the analysis of the extractive components of fish muscles and much information has been accumulated. In recent years, the distribution of nitrogenous components in the muscle extracts of several species of fish has been elucidated almost completely (JJ, 10, 11, 12, 13). However, few studies have correlated these analytical data directly with taste. 

In recent years several applications of the HC1 proteolysis have been published in the field of Se speciation, for example, as regards Se-enriched lactic acid bacteria [66], mullet and cockles [8], and algae [67], where the technique provided extraction efficiencies of greater than 90 percent and preserved the integrity of the selenoamino acids. The general usefulness of this method of Se speciation is, however, questionable. Sometimes the authors do not state clearly whether phenol - an essential compound for the prevention of oxidation of SeCys - was used or not. In practice, neither phenol nor the short-duration MW-assisted irradiation can prevent the alteration of selenoamino acids [68-71], At the moment, no final conclusion on the applicability of HC1 proteolysis can be drawn, as CRMs certified for SeCys are still unavailable. On the other hand, an Se extraction efficiency of 80-90 percent can be achieved with this method only if either proteins are at least partly separated from the other components of the matrix, for example, separate analysis of fish muscles is carried out [8], or a considerable portion of Se is originally contained in inorganic forms in the sample, as observed by B Hymer and Caruso [1] in the case of Se-enriched food supplements. 

Most of the studies indicate that denaturation of muscle proteins plays the dominant role in the quality changes of the frozen stored meats. The muscle proteins of fish and other aquatic animals have been found to be much less stable than those of beef animals, pigs and poultry (1 ). The present paper will be limited primarily to fish muscle as one representative of vertebrate muscle and it will also deal primarily with the behavior of fish proteins at sub-zero temperatures. In order to do a thorough analysis within the space limit permitted, focus will be on the changes of the proteins per se leaving peripheral problems to other reviews (2-18). 

The analyses carried out up to now on such extracts have been based upon differences of solubility (see p. 235). The discussion of the results obtained has made clear that a reinvestigation of these mixtures is necessary in order to define more accurately the structure proteins of fish muscle. Electrophoresis, which permits the analysis of such mixtures with a minimum of alteration, appears a particularly suitable method. It has been applied as yet only to carp muscle extracts of high ionic strength (Hamoir, 1951b, 1954, 1955). In view of the very constant electrochemical behavior of the muscle structure proteins (see Hamoir, 1953a), it seems safe to assume that similar results will be obtained with other fishes. The results already obtained will therefore be more extensively described. The slight difference in extractibility previously mentioned between white and red rabbit muscles (Crepax, 1952) suggests that a separate study of both fish muscles would also be desirable in this case, but it has not yet been undertaken. 

Actomyosin. Solubility. Studies have dealt with changes in the solubility of proteins during frozen storage of fish muscle or solutions of isolated actomyosin (33,51,52). Analysis by gel filtration of the salt extracts has shown that the actomyosin fraction decreases in solubility during frozen storage whereas the sarcoplasmic proteins remain essentially unchanged (53). 

Wei, Q.-K., Chen, T.-R., and Fang, C.-W. (1995). Analysis of biogenic amines in fish muscles by high performance liquid chromatography. J. Food Drug Anal. 3(4), 313. 

ICES (1989) Statistical analysis of the ICES cooperative monitoring programme. Data on contaminants in fish muscle tissue (1978-1985) for determination of temporal trend. Cooperative Research Rep No 162. International Council for the Exploration of the Sea, Copenhagen... 

Various veterinary residues can be found in food, particularly antibacterial agents used as curative or prophylactic treatments in livestock. A concern with the presence of residual levels of these antibacterial drugs in foods is the increase in antimicrobial resistance. CE methods have been applied to the determination of drug residues in fish and chicken muscle. The quantitative analysis of oxolinic acid fish muscle can be achieved using CZE with a basic phosphate buffer (pH 9) after solid-phase extraction. Enroflox-acin and its metabolite ciproflaxin are detectable in chicken muscle using LIE detection after separation by CZE in an acidic phosphate buffer (pH 2.2). Oxolinic acid and flumequine can be simultaneously determined in chicken by using a basic phosphate buffer (pH 8.02) and UV-visible diode array detection. 

Determining the main chemical constituents, namely, fat, moisture, and protein, in meat and fish muscle is often the most important point of analysis in a production process. Knowing the chemical composition of the raw materials to be used in a process makes it possible to optimize the composition of the final product. However, quality characteristics other than chemical composition may also be important for some products, such as sensory attributes, texture, added NaCl, and added starch. 

Direct injection into the FIA system has also been assayed in the case of TMA and TVB-N determination in liquid samples, for example, fish sauce however, the results were disappointing, and it was apparent that prior extraction in acid would be required, as for the procedure used for muscle (Ruiz-Capillas et al., 2000). The outcome was similar when an attempt was made to analyze TMA and TVB-N by FIA directly in fish exudate (from applying pressure to the fish muscle) to obviate the need for prior extraction and be able to do the analysis directly in the FIGD system (QUALPOISS 2 project) so as to render FIA determination suitable for online or line-to-line use. The reason for this unsatisfactory result was that the exudate also contained other components, such as lipids and proteins, which significantly interfered with the analysis. 

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