No description available.

Microbial safety and quality attributes were evaluated for frankfurters formulated with potassium lactate/sodium diacetate (0 or 3%) and inoculated with a four-strain Listeria monocytogenes cocktail before and after treatment with pasteurizing doses of irradiation (0, 1.8, or 2.6 kGy). Frankfurters were inoculated after irradiation and stored aerobically for 4 wk at 4 °C to simulate the product becoming contaminated after opening, or they were inoculated prior to vacuum packaging and stored for 8 wk at 4 °C. Incorporation of lactate/diacetate into frankfurter formulations with or without irradiation had a strong listeriostatic effect throughout 4 wk of aerobic storage. Total microbial counts for frankfurters formulated with lactate/diacetate remained constant throughout storage while those without increased steadily (5.4 to 9.3 log cfu). Over 4 wk of storage, the outgrowth of L. monocytogenes on frankfurters formulated with lactate/diacetate was effectively suppressed and counts were not significantly different from initial counts (5.2 vs. 5.0 log cfu, respectively). Irradiation treatments alone had significantly higher L. monocytogenes counts after 3 wk of storage. Both treatments together or alone were not detrimental to sensory aroma or flavor attributes. Meaty/brothy complex, smoke, spice aroma, springiness, and cohesiveness attributes were judged slightly lower for frankfurters formulated without lactate/diacetate than those with lactate/diacetate at the end of aerobic storage. Sensory color was not dramatically influenced by either treatment, however, L*a*b* values of all treatments decreased slightly during storage. Both the addition of lactate/diacetate to a frankfurter formulation and irradiation were effective towards controlling microbial growth of L. monocytogenes in an unopened vacuum package after 8 wk of storage. Large and incremental reductions in total microbial counts were seen with irradiation treatment, which were maintained throughout storage with lactate/diacetate treated frankfurters. There were fewer influences on sensory characteristics for vacuum packaged frankfurters compared to those aerobically packaged. Overall, lactate/diacetate addition and irradiation to a lesser extent were effective towards retarding the outgrowth L. monocytogenes on frankfurters while maintaining quality attributes throughout aerobic storage. The combination of irradiation and lactate/diacetate were effective for reducing and retarding growth of L. monocytogenes and especially during the last two weeks of vacuum packaged storage.

Lactate dehydrogenases from an abyssal fish, a dogfish, a tidepool sculpin, and a mammal have been found to differ in their ability to bind substrate analog and coenzyme at varying temperatures and pressures. Affinities for a substrate analog are quite similar for each lactate dehydrogenase at their respective biological temperatures, suggesting temperature-dependent modification of enzyme-substrate binding for optimal function. Binding of coenzyme by the three ectothermic enzymes is less affected by changes in temperature than is coenzyme binding by the mammalian enzyme, and coenzyme binding by the abyssal fish enzyme is considerably less sensitive to high hydrostatic pressure than it is in the case of the other three lactate dehydrogenases. The total free energy change involved in binding coenzyme and substrate analog is only slightly higher for the endothermic than for the three ectothermic enzymes, but the enthalpic and entropic contributions are quite different. The ectotherms appear to have minimized the enthalpic contribution and hence minimized temperature effects on binding. The relationship between enthalpy and entropy for each of the binding interactions studied is a straight line of slope within the limits found by other workers for water-solute interactions and/or weak bond formation and is presumed to be a result of the conformational changes accompanying ligand binding. The contributions to binding of the AMP and nicotinamide subsites of the coenzyme binding site give a good estimate of many of the binding interactions of the coenzyme as a whole, and appear to compensate one another to maintain low AH and AS values for coenzyme binding to the ectothermic enzymes. This same type of compensation in volume change can be seen between the substrate and coenzyme binding sites for the abyssal fish lactate dehydrogenase, resulting in a net volume change very close to zero. The observed temperature and pressure effects on binding cannot be explained solely in terms of the types of weak bonds involved, and known homologies between dogfish and pig LDH make major differences between the active sites unlikely. Conformational changes occurring simultaneously with binding may be of considerable importance in modifying the observed responses to both temperature and pressure. / Science, Faculty of / Zoology, Department of / Graduate

Thesis (doctoral)--Lund University, 1994. / Added t.p. with thesis statement inserted.

Thesis (doctoral)--Lund University, 1994. / Added t.p. with thesis statement inserted.

PURPOSE: To compare the effects of recovery intensity on performance of a bicycle sprint task and blood La⁻ clearance. METHODS: On three separate days twelve trained male subjects (27.4 ± 3.9 yrs) performed three supramaximal exercise (SE) bouts at 120% of maximum aerobic power (MAP) for 60% of the time to exhaustion (TTE). Bouts were separated by 5 mm of passive recovery (PR), active recovery (AR) or combined active recovery (CAR). The third bout was followed by a 14 mm recovery. Recovery intensities were: PR (rest), AR at 50% of the workload difference between the individual anaerobic threshold (IAT) and the individual ventilatory threshold (IVT) below the IVT ( ₋50%ΔT), or CAR at the IAT workload for 5 mm and at the ₋50%ΔT workload for 9 mm. Five 10 s sprints were performed 2 mm post-recovery. Blood lactate (La⁻) concentration, power parameters (Peak Power (PP), Mean Power (MP), Fatigue Index (Fl), and Total Work (TW)), Heart Rate (HR), and Oxygen Uptake (VO₂‚‚) were compared using repeated-measures ANOVA. Pairwise comparisons and dependent T-tests were performed to analyze differences. RESULTS: Mean La⁻ values for AR and CAR were lower than PR (9.7 ± 3.5, 9.5 + 3.5, 11.7 + 3.6, respectively, p≤0.05). La⁻ was significantly lower with CAR versus PR at the 3rd, 6th, 9th, and 14th mm of recovery (p≤0.05). AR versus PR La⁻ was lower at the 3rd, 6th, 9th, and 14th min of recovery (p≤0.05). Mean MP was greater in the AR group compared to the PR group (800.1 ± 114.5 vs 782.2 ± 111.7 W, p≤0.05). TW during AR was greater than PR (p≤0.05) but not CAR (p≤0.05, 40003.3 ± 5110.2, 39108.3 ± 4852.9, 39335.8 ± 5022.6 J, respectively). CONCLUSIONS: AR and CAR both demonstrated improved La⁻ clearance when compared to PR, but differences in La⁻ clearance did not determine performance on the sprint task. AR resulted in more TW than PR and greater maintenance of power over the sprints.

PURPOSE: To compare the effects of recovery intensity on performance of a bicycle sprint task and blood La⁻ clearance. METHODS: On three separate days twelve trained male subjects (27.4 ± 3.9 yrs) performed three supramaximal exercise (SE) bouts at 120% of maximum aerobic power (MAP) for 60% of the time to exhaustion (TTE). Bouts were separated by 5 mm of passive recovery (PR), active recovery (AR) or combined active recovery (CAR). The third bout was followed by a 14 mm recovery. Recovery intensities were: PR (rest), AR at 50% of the workload difference between the individual anaerobic threshold (IAT) and the individual ventilatory threshold (IVT) below the IVT ( ₋50%ΔT), or CAR at the IAT workload for 5 mm and at the ₋50%ΔT workload for 9 mm. Five 10 s sprints were performed 2 mm post-recovery. Blood lactate (La⁻) concentration, power parameters (Peak Power (PP), Mean Power (MP), Fatigue Index (Fl), and Total Work (TW)), Heart Rate (HR), and Oxygen Uptake (VO₂‚‚) were compared using repeated-measures ANOVA. Pairwise comparisons and dependent T-tests were performed to analyze differences. RESULTS: Mean La⁻ values for AR and CAR were lower than PR (9.7 ± 3.5, 9.5 + 3.5, 11.7 + 3.6, respectively, p≤0.05). La⁻ was significantly lower with CAR versus PR at the 3rd, 6th, 9th, and 14th mm of recovery (p≤0.05). AR versus PR La⁻ was lower at the 3rd, 6th, 9th, and 14th min of recovery (p≤0.05). Mean MP was greater in the AR group compared to the PR group (800.1 ± 114.5 vs 782.2 ± 111.7 W, p≤0.05). TW during AR was greater than PR (p≤0.05) but not CAR (p≤0.05, 40003.3 ± 5110.2, 39108.3 ± 4852.9, 39335.8 ± 5022.6 J, respectively). CONCLUSIONS: AR and CAR both demonstrated improved La⁻ clearance when compared to PR, but differences in La⁻ clearance did not determine performance on the sprint task. AR resulted in more TW than PR and greater maintenance of power over the sprints.

PURPOSE: To compare the effects of recovery intensity on performance of a bicycle sprint task and blood La⁻ clearance. METHODS: On three separate days twelve trained male subjects (27.4 ± 3.9 yrs) performed three supramaximal exercise (SE) bouts at 120% of maximum aerobic power (MAP) for 60% of the time to exhaustion (TTE). Bouts were separated by 5 mm of passive recovery (PR), active recovery (AR) or combined active recovery (CAR). The third bout was followed by a 14 mm recovery. Recovery intensities were: PR (rest), AR at 50% of the workload difference between the individual anaerobic threshold (IAT) and the individual ventilatory threshold (IVT) below the IVT ( ₋50%ΔT), or CAR at the IAT workload for 5 mm and at the ₋50%ΔT workload for 9 mm. Five 10 s sprints were performed 2 mm post-recovery. Blood lactate (La⁻) concentration, power parameters (Peak Power (PP), Mean Power (MP), Fatigue Index (Fl), and Total Work (TW)), Heart Rate (HR), and Oxygen Uptake (VO₂ ) were compared using repeated-measures ANOVA. Pairwise comparisons and dependent T-tests were performed to analyze differences. RESULTS: Mean La⁻ values for AR and CAR were lower than PR (9.7 ± 3.5, 9.5 + 3.5, 11.7 + 3.6, respectively, p≤0.05). La⁻ was significantly lower with CAR versus PR at the 3rd, 6th, 9th, and 14th mm of recovery (p≤0.05). AR versus PR La⁻ was lower at the 3rd, 6th, 9th, and 14th min of recovery (p≤0.05). Mean MP was greater in the AR group compared to the PR group (800.1 ± 114.5 vs 782.2 ± 111.7 W, p≤0.05). TW during AR was greater than PR (p≤0.05) but not CAR (p≤0.05, 40003.3 ± 5110.2, 39108.3 ± 4852.9, 39335.8 ± 5022.6 J, respectively). CONCLUSIONS: AR and CAR both demonstrated improved La⁻ clearance when compared to PR, but differences in La⁻ clearance did not determine performance on the sprint task. AR resulted in more TW than PR and greater maintenance of power over the sprints. / Education, Faculty of / Kinesiology, School of / Graduate

No description available.

No description available.