Yazar "Yildirim, M" seçeneğine göre listele

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    Factors affecting the adsorption of buchnericin LB, a bacteriocin produced by Lactocobacillus buchneri
    (Urban & Fischer Verlag, 2002) Yildirim, Z; Avsar, YK; Yildirim, M
    Buchnericin-LB adsorbs to gram-positive but not to gram-negative bacteria. The tested gram-positive bacteria were species of Lactobacillus, Pediococcus, Leuconostoc, Enterococcus, Lactococcus, Listeria, Bacillus, Staphylococcus; gram-negative bacteria belonged to the genera Salmonella, Escherichia, Yersinia and Pseudomonas. Buchnericin-LB adsorption depended on pH but not on time and temperature. Also some anions of salts and lipoteichoic acid reduced or inhibited its adsorption. Treatment of cells and cell walls of sensitive bacteria with detergents, organic solvents or enzymes did not affect subsequent binding of buchnericin-LB. Treatment with buchnericin-LB caused sensitive cells to lose high amounts of intracellular K+ ions and UV-absorbing materials and became more permeable to o-nitrophenol-beta-D-galactopyranoside. Buchnericin-LB (640-2560 AU/ml) decreased the colony forming units (99%) and absorbance values of Listeria monocytogenes and Bacillus cereus. These results indicate that the mode of action of buchnericin-LB is bactericidal and its lethal effect is very rapid.
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    Use of retentate powder in the production of white-brined cheese by the direct recombination system. 1. Effect of different protein levels an the ripening behaviour
    (A V A Agrarverlag, 2001) Avsar, YK; Yildirim, M; Yildirim, Z
    In this study, a white-brined cheese with different protein content (similar to 12.5, 14.0, 15.5 or 17.0%) but the same total solids (similar to 40%) was produced by the direct recombination system, using retentate powder, skim-milk powder and anhydrous milk fat. For cheese-making, cheese milk composition was adjusted to the equivalent to that of cheese. During a 30 day of ripening period, changes in the gross composition, nitrogen fractions and ripening indices of cheese samples were monitored at 10 day intervals. It was found that there was no significant effect of the protein level on the final composition of the experimental cheese although a fluctuation in the composition of the cheese samples was observed during the early days of ripening. Results also showed that it was possible to produce a white-brined cheese with a defined composition. Owing to the limited syneresis and the use of milk powders, considerable amounts of whey protein nitrogen (0.17 to 0.26%) and lactose (1.6 to 5.9%) were retained in the experimental cheese at the end of the ripening. For this reason, whey proteins should be excluded in the calculation of ripening degree. In addition. increasing the protein content appeared to hinder the proteolysis.
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    Use of retentate powder in the production of white-brined cheese by the direct recombination system. 2. Effect of different protein levels on the rheological properties
    (Volkswirtschaftlicher Verlag, 2002) Avsar, YK; Yildirim, Z; Yildirim, M
    In this study, the effect of protein contents on the textural properties of white-brined cheese produced by the direct recombination system (DRS) using retentate powder was investigated. The total solids and fat content of cheese was kept same, but the samples differed in protein content (12.5, 14.0, 15.5 and 17.0%, respectively). A compression test was applied and elasticity modulus, yield stress and yield strain were obtained from force-time curves. Samples were analysed for a period of 30 d at 10 d intervals. Increasing the protein content up to a certain level (14.0%) increased the elasticity modulus and yield stress. However, beyond that level (i.e. 15.5 and 17.0%) no effect of additional protein was observed suggesting that after a critical level is reached the additional protein increased the viscous component of the cheese rather than the elastic one. Unlike the other parameters, the protein levels did not affect the yield strain since this parameter is closely related to pH and proteolysis. Yield stress and yield strain values decreased, and the cheese samples became considerably shorter during maturation as an indication of breakdown of the bonds holding the structure.