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Factors Influencing Microbial Ecology in Stored Meats
antibiotics and off-f1avour/ odour compounds, and permitted extensive reuse of the water under good quality control. NMR T, MEASUREMENTS IN THE ASSESSMENT OFTHE STATE OF WATER IN POSTMORTEM MUSCLE. Currie, R. W. and F. H. Wolfe, Department of Food Science, University of Alberta, Edmonton, Alberta T6G 2N2. The state of water in muscle cells during rigor development and resolution is not well understood. Recently, spin lattice relaxation times (TJ of those muscle water protons which have a slow relaxation rate have been shown to be related to the rate of postmortem rigor development. It is the purpose of this paper to report correlations between the rates of various postmortem physiological and biochemical events (e.g., pH fall, ATP degradation, water holding capacity, non-freezable water content) and changes in T, for beef semitendinosus. FOOD RHEOLOGY. De Kee, D., Department of Chemical Engineering, University of Windsor, Windsor, Ontario N9B 3P4. In this presentation we will review some properties of timeindependent and time-dependent foodstuffs, pseudoplastic materials, thixotropic and yield stress characteristics, as they relate to the design and control of processes where pumping and mixing are present. In particular, the suitability of several test instruments and rheological equations will be discussed. INITIAL MICROFLORA AND SPOILAGE PATTERNS OF VACUUM-PACKED TABLE-READY POULTR Y PRODUCTS CONTAINING NO NITRITE. Dodds, K.L. and A.G. Kempton, Department of Biology, University of Waterloo, Waterloo, Ontario N2L 3GI. Vacuum packages of sliced turkey roll containing no nitrite undergo two types of spoilage. In addition to the conventional pattern of delayed spoilage by lactic acid bacteria, early spoilage by Serratia liquefaciens, Enterobacter agglomerans and other Gramnegative bacteria is accompanied by a hydrogen sulfide odour and gassy packages. Rapid methods were assessed for detecting and predicting the Gram-negative spoilage pattern, including the LimuIus Lysate assay and a test for catalase. RETENTION OF SPARINGLY SOLUBLE FLAVOURING COMPOUNDS DURING SPRAY DRYING. Elgar, J.W. and T.G. Smyrl, School of Food Science, Macdonald Campus of McGill University, Ste. Anne de Bellevue, Quebec H9X ICO. Retentions of carvone, a sparingly soluble flavouring compound, were measured during spray drying of model solutions containing corn syrup solids. Carvone retention was found to increase with increased initial dissolved solids, elevated feed temperatures, elevated inlet air temperatures, increased air flow rates and the presence of gelatin, gum arabic, hexanol, octanol and corn oil. Factors which led to a decrease in volatile retention were increased feed rates and increased initial carvone concentrations as well as the presence of sucrose or glucose. The pH of the feed and the presence of ethanol or butanol had little effect on carvone retention. A CONTINUOUS ANION EXCHANGE PROCESS FOR DESALTING CHEESE WHEY. I. EQUILIBRIUM AND RATE STUDY. Fadd, S.M., E. Lee and S. Nakai, Department of Food Science, University of British Columbia, Vancouver, British Columbia V6T 2A2. The factors affecting the efficiency of a continuous countercurrent process were studied. Equilibrium data, e.g., contact time and maximum fractional saturation of Rexyn 202 resin in OH form, were obtained and it was found that an equilibration time of 20 min was required. Breakthrough concentrations, contact efficiency and pH change were satisfactory during 90 min continuous operation on a lab-scale system for continuous countercurrent fluidization. Elimination of over 80% chlorides was attained without exceeding pH 8.0 during treatment. Of detergents, oxidants and reductants tested for removing phenolic resin odour, countercurrent washing of resin simply with water was most efficient. FACTORS INFLUENCING MICROBIAL ECOLOGY IN STORED MEATS. Farher, J. and E.S. Idziak, Department of
166/ Affaires de I'Institut
Microbiology, Macdonald College of McGi11 University, Ste. Anne de Bellevue, Quebec H9X ICO. The factors which limit, stimulate or impede the growth of meat spoilage organisms are poorly defined. The effects of several factors on the microbial ecology of meats have been studied. Slight variations in oxygen tensions from 0.1 to 1.0% resulted in 4- and 3-log differences in the Pseudomonas and Brocothrix thermosphacta numbers after 12 days at 4° C The supernatants and lysed cells of the different spoilage organisms grown in meat juice medium had little effect on the growth of each other. Only Moraxella sp. growth was inhibited by the supernatant from several of the spoilage organisms. During storage at 4°C the concentration of several metal ions was also monitored. Storage resulted in an increased ratio of bound/ free Mg++ from 1.53 (day 0) to 23.3 (day 16). Differences in this ratio were also observed with depth, e.g., 23.0,4.3 and 2.7 at 0-3,3-6 and 6-9 mm, respectively, at day 16. Studies concerned with redox potential. oxygen tension in meats, as well as the fate of nutrients in muscle foods is continuing. THE MICROSTRUCTURE AND TEXTURE OF COOKED SCALLOP. Findlay, CJ. and D.W. Stanley, Department of Food Science, University of Guelph, Guelph, Ontario NI G 2WI. The striated portion of the adductor muscle of the mollusc Pecten is consumed as the seafood known as scallop. The effect of boiling and microwave cooking on the texture and microstructure of this material was studied. Frozen commercial scallop of 7.5 g average weight were heated to different internal temperatures in boiling water; compression, extension and shear tests were performed using an Instron Universal Testing Machine. Scanning electron microscopic examinations of the raw and treated samples were performed. It was found that the scallop toughened with increased heating. A matrix of heat coagulated protein was observed in microwaved scallop. IMPROVING THE WHIPPING PROPERTIES OF UHT HEA VY CREAM. Foster, Cherise, Palm Dairies Limited, Edmonton, Alberta, and Pavel Jelen, Department of Food Science, University of Alberta, Edmonton, Alberta T6G 2N2. Parameters such as temperature, homogenization, pH and additives were examined to determine a method of improving the whipping properties of U HT heavy cream. Little effect of temperature was found; homogenization significantly increased whip time while giving a product with a longer shelf life. The additives were examined to determine if their use would be beneficial for cream from the Alberta region. An acceptable whipped cream was produced by adjusting the pH between 6.2and 6.4. Further lowering of pH decreased whip time and increased whip strength. Further investigation is required on the role of low pH to arrive at an industrially acceptable product. BUTTER WRAPPING MATERIALS AND LIGHT-INDUCED OXIDIZEE> FLAVOUR. Froehlich, D.A., D.B. Emmons, G.J. Paquette, D.C. Beckett and H. W. Modler, Food Research Institute; G. Butler, Engineering Station Research Service, and P. Brackenridge and G. Henne, Dairy, Fruit and Vegetable Division, Agriculture Canada, Ottawa, Ontario K IA OC6. Eleven wrappers were tested for protecting butter from CoolWhite fluorescent light. The critical exposure was 2,000 Ix for 2 days; others were 2,000 Ix/4 days, 400 Ix/6 days, 400 Ix/ I day. An expert panel scored the surface and interior of exposed butter for intensity of oxidized flavour on a 15 cm unstructured scale and for overall flavour (federal grade score). There was a close correlation among peroxide values, oxidized flavour and flavour scores, using differences between surface and interior of exposed butter, the sensory and peroxide data being mutually confirmatory. Mean differences of 1.0 meq of peroxide, 2.0 cm on the oxidized flavour scale and 0.5 points on the federal grade scale were approximately equivalent. INFLUENCE OF CARCASS FAT LEVEL ON SENSORY EATING PROPERTIES OF COOKED CHICKEN MEAT. Froehlich, D.A., E. Larmond, J.R. Chambers and A. Fortin, Agriculture Canada, Ottawa, Ontario K I A OC6. The influence of carcass fat level on eating quality of broiler meat, and eating properties of meat from obsolete vs. modern strains of broilers slaughtered at a (i) similar age, and (ii) similar body weight were evaluated using sensory evaluation. Ten experienced 1.
In~/.
Con. Sd. T(;'chnvl. Aliment. Val. 14. No. 3, Juillet 1981
166/ Affaires de I'Institut
Microbiology, Macdonald College of McGi11 University, Ste. Anne de Bellevue, Quebec H9X ICO. The factors which limit, stimulate or impede the growth of meat spoilage organisms are poorly defined. The effects of several factors on the microbial ecology of meats have been studied. Slight variations in oxygen tensions from 0.1 to 1.0% resulted in 4- and 3-log differences in the Pseudomonas and Brocothrix thermosphacta numbers after 12 days at 4° C The supernatants and lysed cells of the different spoilage organisms grown in meat juice medium had little effect on the growth of each other. Only Moraxella sp. growth was inhibited by the supernatant from several of the spoilage organisms. During storage at 4°C the concentration of several metal ions was also monitored. Storage resulted in an increased ratio of bound/ free Mg++ from 1.53 (day 0) to 23.3 (day 16). Differences in this ratio were also observed with depth, e.g., 23.0,4.3 and 2.7 at 0-3,3-6 and 6-9 mm, respectively, at day 16. Studies concerned with redox potential. oxygen tension in meats, as well as the fate of nutrients in muscle foods is continuing. THE MICROSTRUCTURE AND TEXTURE OF COOKED SCALLOP. Findlay, CJ. and D.W. Stanley, Department of Food Science, University of Guelph, Guelph, Ontario NI G 2WI. The striated portion of the adductor muscle of the mollusc Pecten is consumed as the seafood known as scallop. The effect of boiling and microwave cooking on the texture and microstructure of this material was studied. Frozen commercial scallop of 7.5 g average weight were heated to different internal temperatures in boiling water; compression, extension and shear tests were performed using an Instron Universal Testing Machine. Scanning electron microscopic examinations of the raw and treated samples were performed. It was found that the scallop toughened with increased heating. A matrix of heat coagulated protein was observed in microwaved scallop. IMPROVING THE WHIPPING PROPERTIES OF UHT HEA VY CREAM. Foster, Cherise, Palm Dairies Limited, Edmonton, Alberta, and Pavel Jelen, Department of Food Science, University of Alberta, Edmonton, Alberta T6G 2N2. Parameters such as temperature, homogenization, pH and additives were examined to determine a method of improving the whipping properties of U HT heavy cream. Little effect of temperature was found; homogenization significantly increased whip time while giving a product with a longer shelf life. The additives were examined to determine if their use would be beneficial for cream from the Alberta region. An acceptable whipped cream was produced by adjusting the pH between 6.2and 6.4. Further lowering of pH decreased whip time and increased whip strength. Further investigation is required on the role of low pH to arrive at an industrially acceptable product. BUTTER WRAPPING MATERIALS AND LIGHT-INDUCED OXIDIZEE> FLAVOUR. Froehlich, D.A., D.B. Emmons, G.J. Paquette, D.C. Beckett and H. W. Modler, Food Research Institute; G. Butler, Engineering Station Research Service, and P. Brackenridge and G. Henne, Dairy, Fruit and Vegetable Division, Agriculture Canada, Ottawa, Ontario K IA OC6. Eleven wrappers were tested for protecting butter from CoolWhite fluorescent light. The critical exposure was 2,000 Ix for 2 days; others were 2,000 Ix/4 days, 400 Ix/6 days, 400 Ix/ I day. An expert panel scored the surface and interior of exposed butter for intensity of oxidized flavour on a 15 cm unstructured scale and for overall flavour (federal grade score). There was a close correlation among peroxide values, oxidized flavour and flavour scores, using differences between surface and interior of exposed butter, the sensory and peroxide data being mutually confirmatory. Mean differences of 1.0 meq of peroxide, 2.0 cm on the oxidized flavour scale and 0.5 points on the federal grade scale were approximately equivalent. INFLUENCE OF CARCASS FAT LEVEL ON SENSORY EATING PROPERTIES OF COOKED CHICKEN MEAT. Froehlich, D.A., E. Larmond, J.R. Chambers and A. Fortin, Agriculture Canada, Ottawa, Ontario K I A OC6. The influence of carcass fat level on eating quality of broiler meat, and eating properties of meat from obsolete vs. modern strains of broilers slaughtered at a (i) similar age, and (ii) similar body weight were evaluated using sensory evaluation. Ten experienced 1.
In~/.
Con. Sd. T(;'chnvl. Aliment. Val. 14. No. 3, Juillet 1981