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FoodMicroLecture 21
Final Exam
Describe the hurdle concept. | One preservative isn't enough for all microbial safety and stability. |
T or F: Growth, survival, and inactivation of microorganisms in foods are not reproducable responses. | False |
A _____ model can quantitatively describe the combined effect of environmental parameters. | mathematical |
What are two types of tests used in predictive microbiology? | Challenge testing, storage trials. |
Define a primary model. | Describe changes in microbial numbers with type (eg. D-value). |
Define a secondary model. | Describe how parameters in a primary model change with different environmental parameters (eg. Z-value). |
Define a tertiary model. | Describe secondary models with user-friendly interface for non-modelers. |
What is the flow from data generation to modeling? | Data generation, primary modeling, secondary modeling, product validation, tertiary modeling. |
Define thermal death time. | The time necessary to kill a given number of microorganisms at a specified temperature. |
T or F: Thermal death is first order process. | True |
Microbial death rate due to heat can be expressed as a function of____ and ____ under a given condition. | time, temperature |
T or F: Rate of cell death is directly dependent on the number of viable cells present at a given lethal temperature. | True |
Define decimal reduction time (D-value). | Time at a given temperature for a microbial population to be reduced by 1-log. |
Define Z-value. | Temperature change which results in a 1-log change in D-value; calculated from log-D versus temperature. |
How would the thermal death curve appear if the population contained a mix of species? | Tailing would be observed. |