摘要:

SUMMARYThree pectin methyl esterase fractions were obtained from banana pulp by successive extraction with water (Fraction I), a solution of 0.15MNaCl (Fraction II), and a solution of 0.15MNaCl after adjusting the pH of the mixture to 7.5 (Fraction III). The changes in the activities of these fractions during post‐harvest ripening were investigated. The activities of all three fractions increased as the banana skin began to change from green to yellow. Thereafter Fractions I and II remained relatively constant while Fraction III continued to increase in activity throughout the period of ripening studie

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1965.tb01865.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SUMMARYSlices of potato tubers were subjected to cyclic elongation, stress relaxation, and breaking in an Instron materials‐testing instrument. Cubes of such tissues and of ripe, fruits of pears and apples were subjected to cyclic compression and stress relaxation. The time required for 20% relaxation of the stress was progressively longer with each of 3 cycles. Cycling increased the apparent values of Young's modulus,E, for slices treated in acetone, treated in acetone and rehydrated, and frozen and then thawed, but decreased values for slices soaked overnight in H2O at 6°C. With potato slices and cubes, treatments which wilted them resulted in shorter times for a 20% relaxation of stress. Cubes of pear and apple soaked 3 hr in H2O tended to disintegrate and also showed much shorter times for relaxation of stress than cubes treated in 0.5Msucrose. The general features of all curves were qualitatively similar, except that compressing cubes of potato tubers beyond a stress of about 0.9 Kg/cm2resulted in a sharp, reversible increase in apparent values o

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1965.tb01866.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SUMMARYEggplant polyphenolase oxidized chlorogenic acid much faster than it did any other substrate. In contrast, the substrate oxidized most rapidly by the avocado preparation was nordi‐hydroguaiaretic acid (NDGA), followed by catechin and catechin. Resorcinol was a moderately effective competitive inhibitor (Kt= 0.02M), whereas hydroquinone (Kt= 0.005M) was a slightly less potent noncompetitive inhibitor. All the chlorides tested depressed eggplant polyphenolase activity to a similar but limited extent. The copper‐chelating agents 1‐phenyl‐2‐thiourea and sodium diethyldithio‐carbamate were powerful inhibitors; the former (Kt= 0.01mM) was shown to act non‐

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1965.tb01867.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SUMMARYTo elucidate the changes of “myosin B” during storage of rabbit muscle, investigation was made of the dissociation of “myosin B” into myosin A and actin, their content of “myosin B,” and the interaction of “myosin B” with ATP. The approximate contents of myosin A and actin in “myosin B” were variable, showing a maximum content of actin in “myosin B” extracted from the muscle at 2 days after slaughter. This can also be inferred from changes of viscosity and the salting‐out curve of “myosin B,” as recently shown. Moreover, the interaction between actin and myosin A in “myosin B” became less

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1965.tb01868.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SUMMARYThe activity of 17 or 18 specific enzymes in the longissimus dorsi muscle of five beef and 18 pork carcasses was followed by histochemical procedures. Beef samples were removed from carcasses within 10 min up to 20 days port‐mortem, and pork samples within 16 min up to 24 and/or 48 hr post‐mortem. The beef carcasses were submitted to so‐called normal cooling procedures. However, one side of each of 13 pork carcasses was placed at –29°C, while the other side was subjected to 37°C for the first 41/2–5 hr post‐mortem.In beef muscle, the histochemical activity of lactate dehydrogenase, alpha‐glycerophosphate dehydrogenase, succinate dehydrogenase, isocitrate dehydrogenase, TPN diaphorase, and DPN diaphorase showed a steady decrease with increasing time post‐mortem. Reactions for both alcohol dehydrogenase and glutamate dehydrogenase were very weak or entirely absent at 48 hr post‐mortem and all subsequent sampling periods. Positive reactions for glucose‐6‐phosphate dehydrogenase and beta‐hydroxybutyrate dehydrogenase were observed in the initial samples only. No acid phosphatase, leucine amino peptidase, or 6‐phosphogluconate dehydrogenase activity was detected in any of the samples.In pork muscle, the activity of lactate dehydrogenase, alpha‐glycerophosphate dehydrogenase, succinate dehydrogenase, isocitrate dehydrogenase, and DPN diaphorase was slightly weaker at both 0 and 24 hr post‐mortem than similar activity in beef muscle. Alcohol dehydrogenase activity was weaker than that observed for the above enzymes, while the activity of glutamate dehydrogenase was of intermediate intensity. Traces of glucose‐6‐phosphate dehydrogenase and 6‐phosphogluconate dehydrogenase activity were observed in only a portion of the initial samples. Similarly, weak reactions for beta‐hydroxybutyrate dehydrogenase were observed only at 0 hr post‐mortem. None or only weak activity was observed for malic dehydrogenase, and TPN diaphorase activity was unexplainably absent from all samples. Moderate levels of cytochrome oxidase activity were observed at both 0 and 24 hr post‐mortem. LTDPG‐glycogen transferase was completely inactivated by the 37°C treatment post‐mortem, but the treatment had a less marked effect upon phosphorylase and branching enzyme. The presence of acid and alkaline phosphatase activity in muscles of 7 carcasses suggested that a

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1965.tb01869.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SUMMARYAn experiment was conducted to establish the fiber arrangement and micro‐structure at three sites in the longissimus dorsi of horizontally placed and vertically suspended bovine carcass sides. Fiber angles, from transverse processes, increased markedly from anterior to posterior positions. Conversely, the fiber angles, from the spinous processes, decreased from anterior to posterior positions. In comparison with horizontal placement, vertical suspension released some of the tension on the longissimus dorsi and allowed rearrangement of its internal construction. This rearrange. ment was noted by larger angles, from both the transverse and spinous processes, and shorter sarcomeres in the vertically suspended than in the horizontally placed sides. Differences were also observed in muscle shape and marbling coarsenes

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1965.tb01870.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SUMMARYA study was made of the effects of length of cold storage and of heating on histological appearance of muscles from 4–5‐month‐old rabbits. The rabbit muscles appeared to contain little if any elastin except in and around blood vessels. The changes in histological appearance with increasing cold storage and with heating resembled in general those found in beef, although there were several exceptions. The rabbit muscle fibers showed less tendency to granulate, but the contraction nodes tended to disappear with longer storage, especially in the heated tissue. Also, at the longer storage times, heating tended to destroy even the granulated structure of collagen, reducing it to an amorphous state. Within the muscle bundles, rabbit muscles appeared to have more fine strands of collagen in the endomysium than did beef. Also, within the bundles, heating appeared to produce some granulation from the muscle fibers themselves, from the fine collagen strands, and from the endomysial reticulum, rather than primarily from the muscle fibers as in

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1965.tb01871.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SUMMARYThe red fiber content of several porcine muscles was estimated by a histochemical method (affinity for Sudan Black B due to high intracellular lipid content) and a biochemical method (high succinic dehydrogenase activity). Even though the muscles varied widely in total lipid content, the histochemical method was comparable to the biochemical method in categorizing porcine muscles as red or white. Red muscles (>40% red fibers) contained greater myoglobin concentrations and generally had longer post‐rigor sarcomeres than white (<30% red fibers) muscles. Interrelationships of percent red fibers, succinic dehydrogenase activity, fat content, glycolytic rate, and post‐rigor contraction state were discus

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1965.tb01872.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SUMMARYThree protein components with peroxidase activity were separated fromFicus glabratalatex by chromatography on diethylaminoethyl cellulose at pH 7.0. Purification was aided by carboxymethyl cellulose adsorption and ammonium sulfate precipitation. These three components were identical to horse‐radish peroxidase II with respect to molecular weights, absorption spectra, and activity‐pH relationships. They differed markedly from horseradish peroxidase II with respect to isoelectric points [at pH 4.25–4.45 (acetate buffer), vs. pH 7.2]. They were more heat‐stable than horse‐radish peroxidase II. While one of the F. glabrata peroxidases hadVmaxvalues similar to those of horse‐radish peroxidase II on hydrogen peroxide and guaiacol, the other twoF. glabrataperoxidases had quite different kinetic parameters. The threeF. glabrataperoxidases differed in chromatographic, electrophoretic, heat stability, and kinetic properties (componentsBandC, vs.A), but all other properties measured were identical or similar for the three

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1965.tb01873.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SUMMARYA mild method for the isolation of mucoprotein from bovine skeletal muscle is described. Minced skeletal muscle was extracted twice with neutral 0.6MKCl. The washed stromal residue was extracted twice with acetone, air‐dried, and pulverized. The stromal residue powder was extracted twice with 10% CaCl2. The pooled CaCl2extracts were added to 1.5 volumes ice‐cold ethanol and refrigerated. The crude mucoprotein precipitate was obtained by centrifugation, and suspended in 5% sodium acetate. After extraction for 24 hr at 4°C, the mucoprotein suspension was filtered through Celite and purified. The final dried product was pulverized to a light tan powder. Dissolved in phosphate buffer, it gave a viscous milky‐white solution. Quantitative hexosamine and nitrogen values obtained at each major step of the isolation procedure are given, and their significance is discussed. Less than 10% of the total stromal residue hexosamine is ex‐tractable by CaCl2. The CaCl2‐extractable fraction was isolated and purified and designated the “soluble mucoprotein fraction.” Hydrolysates of this fraction were analyzed by paper chromatography. The consistent observation of galactosamine and glucuronic acid indicated that chondroitin sulfate was present. Glucosamine was also noted consistently, along with galactose, but their presence was not ea

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1965.tb01874.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY