unit 9A Flashcards
how is sterility achieved?
heating ALL parts of a product to 121C for 15 minutes
is sterility a requirement for food?
no, nutritional value decreases and food becomes unacceptable under these conditions
more suitable for hospitals & labs
what is commercial sterility?
all pathogenic and toxin-forming vegetative organisms are killed and their spores are inactivated, to the extent that they cannot reproduce
vegetative cells are (more/less) susceptible to heat than spores
more
what pH range constitutes a low acid food?
greater than 4.6
can C. botulinum spores germinate in high acid foods (pH < 4.6)?
no
what kind of temperatures are required to inactivate C. botulinum spores in low acid foods?
greater than the boiling point of water
expand psi
pounds per square inch
what temperature is achieved at the following pressures? 10 psi, 15 psi, 20 psi
10 psi = 116C
15 psi = 121C
20 psi = 127C
commercial sterility yields a shelf life of….
> 2 years
what kind of cells does pasteurization target?
vegetative that are relatively thermally resistant
what is the most important thing for thermal processing?
safety
describe the 4 steps of thermal processing
1) understanding time/temp combos & their effect on microorganisms of concern
2) understanding heat penetration characteristics of products
3) calculating an appropriate thermal process based on 1 and 2
4) validation of the efficacy of the process
what microorganisms can be used instead of C. botulinum during the validation of the efficacy of a thermal process? why?
- Clostridium sporogenes
- Bacillus stearothermophilus
they are even more heat resistant but less toxic than C. botulinum
what does 12D mean?
it’s the amount of decimal (log) reductions required to achieve commercial sterility
what shape does a hydrostatic cooker/cooler take on?
U shape
what’s the use of a thermocouple?
stuck in the cold points of cans to observe their change in temperature over time
where are the cold points of cans for solid and liquid foods?
solid: center
liquid: on third from the bottom
how does starch gelatinization affect heat transfer?
slows
what’s the difference between use of heat penetration studies in principle vs in practice?
in principle, they should be done for every change in container, packaging characteristics, and product formulation.
in practice, there are standardized products and packages to choose from
