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Properties of Z-Disc Actin from Chicken Pectoral Muscle
INVESTIGATIONS ON AUTOLYSIS RESISTANT SEDIMENT IN ACID FISH SILAGE. Magadi R. Raghunath** and Alan R. McCurdy, Department of Applied Microbiology and Food Science, University of Saskatchewan, Saskatoon, Saskatchewan. The autolysis resistant sediment in acid fish silage could be solubilized in SDS and alkali, but not in KCI, urea or mercaptoethanol. Over one half of the sediment was water soluble and most of the remaining was soluble in alkali. At pH 4.0 alkali solubilized sediment (AKSS) precipitated and the precipitate behaved similarly to a high mol. wt. fraction of AKSS during gel filtration. SDS-PAGE of the precipitate and AKSS showed the existence of macromolecular aggregates of low mol. wt. products. Formation of such aggregates seemed to be due to hydrophobic and electrostatic associations.
EFFECT OF METHOD OF CATCHING AND TIME OF YEAR ON COMPOSITION OF ATLANTIC COD (GADUS MORHUA). J .R. Botta*, K.M. Kennedy, B.E. Squires, Inspection Division, Canada Department of Fisheries and Oceans, St. John's, Newfoundland. During the normal commercial fishing season in Newfoundland, June-October, in 1983 and 1984, the effects of method of catching and time of year on the composition of Atlantic cod (Gadus morhua) were investigated. Relationships between gear type (gillnet, longline, handline, trap, ottertrawl) time of catching, pH, physical characteristics and composition were examined. While similar trends in protein, fat, ash, and moisture values were observed with each gear type over time, actual protein and moisture values significantly differed (Pr ~ 0.05) with gear type. Fat and ash content showed significant interaction with gear type.
OPTIMISATION DE LA TENDRETE DE LA CHAIR DE BUCCIN. Lucien Adambounou*, CRESALA, Universite du Quebec a Rimouski, Quebec; Jean Lavallee et Francois Castaigne, Universite Laval,Sainte-Foy, Quebec. Dans ce travailles auteurs ont etudie les effets de la taille des buccins, du temps de cuisson et de la concentration de papalne sur la tendrete de la chair de buccin (Buccinum undatum L.). L'evaluation objective de la tendrete a ete faite a I'aide de l'Universital Testing Machine (lNSTRON) et en prenant comme parametre de tendrete Ie module d'elasticite (Me) de la courbe force-deformation. L'analyse de variance nous a montre que Ie temps de cuisson a un effet significatif sur la tendrete (P ~ 0,01). Alors que la variation de la taille de buccin n'a pas d'effet significatif, la concentration de papalne affecte significativement la tendrete de la chair de buccin. La determination des differents parametres d'optimisation de la tendrete de la chair de buccin permettra I'amelioration de la texture caoutchouteuse de cette chair.
DUREE DE MATURATION ET QUALITE DE LA VIANDE DE BOUVILLON STIMULE ELECTRIQUEMENT. C. Gariepy* et J. Amiot, Departement de Sciences et technologie des aliments et Centre de recherche en nutrition de I'Universite Laval, Sainte-Foy, Quebec. La qualite du longissimus dorsi (LD) provenant de carcasses stimulees electriquement (SE) et conservees pendant 24, 48 et 72 h, a ete comparee a celie d'un temoin (144 h. non stimule). La S.E. a 600V/1 min. fut appliquee a la moitie gauche de 24 carcasses de bouvillons commerciaux. En plus des pertes de poids durant Ie ressuage, la conservation et la cuisson, la qualite du L.D. des longes courtes fut evaluee par des mesures instrumentales de tendrete (W.B. modifie), de couleur (L.a.b. Hunter) de retention d'eau (pression) et de pH, completees par une evaluation organoleptique de la tendrete, la jutosite et la saveur. Ce dispositif en split-plot fut repete 6 fois. Seulle temps influence les pertes de poids. Meme si I'effet de la S.E. sur la couleur est moins evidente, les viandes S.E. de 24 et 48 h. sont aussi tendres, juteuses et savoureuses que Ie temoin (p ~ .05). Les viandes S.E. ont toutefois une retention d'eau inferieure (p ~ .05) pour des memes valeurs de pH. En plus des economies de poids et d'energie, la S.E. permettrait la commercialisation de viande agee de 24 h. ayant la meme qualite que celie du temoin. Can. [nsf. Food Sci. Technol. J. Vol. 19. No.4. 1986
EFFECTS OF ELECTRICAL STIMULATION ON CALCIUM DEPENDENT PROTEASES IN ELECTRICALLY STIMULATED BEEF. Sharon Dubetz*, Cecilia Shiu and Fred Wolfe, Department of Food Science, University of Alberta, Edmonton, Alberta. Calcium dependent proteases from both electrically stimulated and control beef carcasses were purified through four successive chromatography columns: Celex D, phenylsepharose, sephacryl S-3OO, DE52. Both JIm and mM Ca2 + requiring forms of CDP from both aged and fresh samples were isolated. The enzymes showed differences in elution profiles and specific activity after each purification step. Subunit molecular weights were estimated by SDSpolyacrylamide gel electrophoresis. The effects of pH and Ca 2 + ion concentration on proteolytic activity was measured. Autolysis of mM Ca 2 + requiring CDP's results in a decreased Ca2 + requirement. Electrical stimulation has a greater effect on JIm than on mM forms. COMPARISON OF CALCIUM DEPENDENT PROTEASES FROM NORMAL AND PSS SUSCEPTIBLE PIGS. Cecilia Shiu*, Sharon Dubetz and Fred Wolfe, Department of Food Science, University of Alberta, Edmonton, Alberta. Calcium dependent proteases from both normal and PSS susceptible pork carcasses were purified through four successive chromatography columns: Celex D, phenylsepharose, sephacryl S-3OO, and DE52. Both JIm and mM Ca 2 + requiring forms of CDP were isolated. The enzymes showed differences in elution profiles and specific activity after each purification step. Sub-unit molecular weights were estimated by SDS-polyacrylamide gel electrophoresis. The effects of pH and Ca 2 + ion concentration on proteolytic activity was measured. The differences observed may reflect different physiological states in the muscle of PSS pigs. PROPERTIES OF Z-DISC ACTIN FROM CHICKEN PECTORAL MUSCLE. Kevin Swallow*, Department of Food Science, University of Alberta, Edmonton, Aberta; Sam Chang, North Dakota State University, Fargo, North Dakota, and Fred Wolfe, Department of Food Science, University of Alberta, Edmonton, Alberta. Z-disc actin was isolated from chicken pectoral muscle using a modification of the G actin isolation procedure described by Spudich and Watt in 1971. Comparison of Z-disc and thin filament actin have revealed several different properties. Purified Z actin has an amino acid composition and molecular weight similar to G actin, but differs in solubility, isoelectric point, ultraviolet spectrum and susceptibility to enzymatic proteolysis. The two actins exhibit markedly different superprecipitation behavior in the presence of myosin and ATP. The results suggest that the differences observed may be related to differences in covalently or otherwise bound nucleotides. OCCURRENCE OF A PINK COLOR IN COOKED TURKEY BREAST. B. Girard* and J. Vanderstoep, Department of Food Science, University of British Columbia, Vancouver, British Columbia. A particular problem involving cooked turkey products is the appearance of a generated pink color which consumers often associate with undercooking. The attribution of this phenomenon to undenatured oxymyoglobin has been questioned in the past. Using transmission spectrophotometry, thin cooked slices of turkey breast have been scanned. The spectral characteristics obtained suggest the involvement of myoglobin as well as cytochromes b, Cl and c. The oxidation states of these heme proteins in relation to cooking timetemperature programs and anaerobic/aerobic environments will be presented with the help of differential spectra. Results indicate that pink color in cooked turkey breast muscle doesn't necessarily imply undercooked meat. FRACTURE BEHAVIOUR OF COOKED MEAT. A QUALITATIVE STUDY. V.M. Bernal* and D.W. Stanley, Department of Food Science, University of Guelph, Guelph, Ontario. Microscopic techniques showed that cooking temperature affects the rupture behaviour of meat and confirmed the role of the perimysium/endomysium (P/E) interface as the primary fracture site. Fractures occurred along the undenatured perimysium core or through the endomysium, in meat cooked at temperatures 45°C,
Institute Affairs / xli
EFFECT OF METHOD OF CATCHING AND TIME OF YEAR ON COMPOSITION OF ATLANTIC COD (GADUS MORHUA). J .R. Botta*, K.M. Kennedy, B.E. Squires, Inspection Division, Canada Department of Fisheries and Oceans, St. John's, Newfoundland. During the normal commercial fishing season in Newfoundland, June-October, in 1983 and 1984, the effects of method of catching and time of year on the composition of Atlantic cod (Gadus morhua) were investigated. Relationships between gear type (gillnet, longline, handline, trap, ottertrawl) time of catching, pH, physical characteristics and composition were examined. While similar trends in protein, fat, ash, and moisture values were observed with each gear type over time, actual protein and moisture values significantly differed (Pr ~ 0.05) with gear type. Fat and ash content showed significant interaction with gear type.
OPTIMISATION DE LA TENDRETE DE LA CHAIR DE BUCCIN. Lucien Adambounou*, CRESALA, Universite du Quebec a Rimouski, Quebec; Jean Lavallee et Francois Castaigne, Universite Laval,Sainte-Foy, Quebec. Dans ce travailles auteurs ont etudie les effets de la taille des buccins, du temps de cuisson et de la concentration de papalne sur la tendrete de la chair de buccin (Buccinum undatum L.). L'evaluation objective de la tendrete a ete faite a I'aide de l'Universital Testing Machine (lNSTRON) et en prenant comme parametre de tendrete Ie module d'elasticite (Me) de la courbe force-deformation. L'analyse de variance nous a montre que Ie temps de cuisson a un effet significatif sur la tendrete (P ~ 0,01). Alors que la variation de la taille de buccin n'a pas d'effet significatif, la concentration de papalne affecte significativement la tendrete de la chair de buccin. La determination des differents parametres d'optimisation de la tendrete de la chair de buccin permettra I'amelioration de la texture caoutchouteuse de cette chair.
DUREE DE MATURATION ET QUALITE DE LA VIANDE DE BOUVILLON STIMULE ELECTRIQUEMENT. C. Gariepy* et J. Amiot, Departement de Sciences et technologie des aliments et Centre de recherche en nutrition de I'Universite Laval, Sainte-Foy, Quebec. La qualite du longissimus dorsi (LD) provenant de carcasses stimulees electriquement (SE) et conservees pendant 24, 48 et 72 h, a ete comparee a celie d'un temoin (144 h. non stimule). La S.E. a 600V/1 min. fut appliquee a la moitie gauche de 24 carcasses de bouvillons commerciaux. En plus des pertes de poids durant Ie ressuage, la conservation et la cuisson, la qualite du L.D. des longes courtes fut evaluee par des mesures instrumentales de tendrete (W.B. modifie), de couleur (L.a.b. Hunter) de retention d'eau (pression) et de pH, completees par une evaluation organoleptique de la tendrete, la jutosite et la saveur. Ce dispositif en split-plot fut repete 6 fois. Seulle temps influence les pertes de poids. Meme si I'effet de la S.E. sur la couleur est moins evidente, les viandes S.E. de 24 et 48 h. sont aussi tendres, juteuses et savoureuses que Ie temoin (p ~ .05). Les viandes S.E. ont toutefois une retention d'eau inferieure (p ~ .05) pour des memes valeurs de pH. En plus des economies de poids et d'energie, la S.E. permettrait la commercialisation de viande agee de 24 h. ayant la meme qualite que celie du temoin. Can. [nsf. Food Sci. Technol. J. Vol. 19. No.4. 1986
EFFECTS OF ELECTRICAL STIMULATION ON CALCIUM DEPENDENT PROTEASES IN ELECTRICALLY STIMULATED BEEF. Sharon Dubetz*, Cecilia Shiu and Fred Wolfe, Department of Food Science, University of Alberta, Edmonton, Alberta. Calcium dependent proteases from both electrically stimulated and control beef carcasses were purified through four successive chromatography columns: Celex D, phenylsepharose, sephacryl S-3OO, DE52. Both JIm and mM Ca2 + requiring forms of CDP from both aged and fresh samples were isolated. The enzymes showed differences in elution profiles and specific activity after each purification step. Subunit molecular weights were estimated by SDSpolyacrylamide gel electrophoresis. The effects of pH and Ca 2 + ion concentration on proteolytic activity was measured. Autolysis of mM Ca 2 + requiring CDP's results in a decreased Ca2 + requirement. Electrical stimulation has a greater effect on JIm than on mM forms. COMPARISON OF CALCIUM DEPENDENT PROTEASES FROM NORMAL AND PSS SUSCEPTIBLE PIGS. Cecilia Shiu*, Sharon Dubetz and Fred Wolfe, Department of Food Science, University of Alberta, Edmonton, Alberta. Calcium dependent proteases from both normal and PSS susceptible pork carcasses were purified through four successive chromatography columns: Celex D, phenylsepharose, sephacryl S-3OO, and DE52. Both JIm and mM Ca 2 + requiring forms of CDP were isolated. The enzymes showed differences in elution profiles and specific activity after each purification step. Sub-unit molecular weights were estimated by SDS-polyacrylamide gel electrophoresis. The effects of pH and Ca 2 + ion concentration on proteolytic activity was measured. The differences observed may reflect different physiological states in the muscle of PSS pigs. PROPERTIES OF Z-DISC ACTIN FROM CHICKEN PECTORAL MUSCLE. Kevin Swallow*, Department of Food Science, University of Alberta, Edmonton, Aberta; Sam Chang, North Dakota State University, Fargo, North Dakota, and Fred Wolfe, Department of Food Science, University of Alberta, Edmonton, Alberta. Z-disc actin was isolated from chicken pectoral muscle using a modification of the G actin isolation procedure described by Spudich and Watt in 1971. Comparison of Z-disc and thin filament actin have revealed several different properties. Purified Z actin has an amino acid composition and molecular weight similar to G actin, but differs in solubility, isoelectric point, ultraviolet spectrum and susceptibility to enzymatic proteolysis. The two actins exhibit markedly different superprecipitation behavior in the presence of myosin and ATP. The results suggest that the differences observed may be related to differences in covalently or otherwise bound nucleotides. OCCURRENCE OF A PINK COLOR IN COOKED TURKEY BREAST. B. Girard* and J. Vanderstoep, Department of Food Science, University of British Columbia, Vancouver, British Columbia. A particular problem involving cooked turkey products is the appearance of a generated pink color which consumers often associate with undercooking. The attribution of this phenomenon to undenatured oxymyoglobin has been questioned in the past. Using transmission spectrophotometry, thin cooked slices of turkey breast have been scanned. The spectral characteristics obtained suggest the involvement of myoglobin as well as cytochromes b, Cl and c. The oxidation states of these heme proteins in relation to cooking timetemperature programs and anaerobic/aerobic environments will be presented with the help of differential spectra. Results indicate that pink color in cooked turkey breast muscle doesn't necessarily imply undercooked meat. FRACTURE BEHAVIOUR OF COOKED MEAT. A QUALITATIVE STUDY. V.M. Bernal* and D.W. Stanley, Department of Food Science, University of Guelph, Guelph, Ontario. Microscopic techniques showed that cooking temperature affects the rupture behaviour of meat and confirmed the role of the perimysium/endomysium (P/E) interface as the primary fracture site. Fractures occurred along the undenatured perimysium core or through the endomysium, in meat cooked at temperatures 45°C,
Institute Affairs / xli