unit 9A

Question 1

how is sterility achieved?

Answer 1

heating ALL parts of a product to 121C for 15 minutes

Question 2

is sterility a requirement for food?

Answer 2

no, nutritional value decreases and food becomes unacceptable under these conditions

more suitable for hospitals & labs

Question 3

what is commercial sterility?

Answer 3

all pathogenic and toxin-forming vegetative organisms are killed and their spores are inactivated, to the extent that they cannot reproduce

Question 4

vegetative cells are (more/less) susceptible to heat than spores

Answer 4

more

Question 5

what pH range constitutes a low acid food?

Answer 5

greater than 4.6

Question 6

can C. botulinum spores germinate in high acid foods (pH < 4.6)?

Answer 6

no

Question 7

what kind of temperatures are required to inactivate C. botulinum spores in low acid foods?

Answer 7

greater than the boiling point of water

Question 8

expand psi

Answer 8

pounds per square inch

Question 9

what temperature is achieved at the following pressures? 10 psi, 15 psi, 20 psi

Answer 9

10 psi = 116C
15 psi = 121C
20 psi = 127C

Question 10

commercial sterility yields a shelf life of….

Answer 10

> 2 years

Question 11

what kind of cells does pasteurization target?

Answer 11

vegetative that are relatively thermally resistant

Question 12

what is the most important thing for thermal processing?

Answer 12

safety

Question 13

describe the 4 steps of thermal processing

Answer 13

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

Question 14

what microorganisms can be used instead of C. botulinum during the validation of the efficacy of a thermal process? why?

Answer 14

• Clostridium sporogenes
• Bacillus stearothermophilus
  they are even more heat resistant but less toxic than C. botulinum

Question 15

what does 12D mean?

Answer 15

it’s the amount of decimal (log) reductions required to achieve commercial sterility

Question 16

what shape does a hydrostatic cooker/cooler take on?

Answer 16

U shape

Question 17

what’s the use of a thermocouple?

Answer 17

stuck in the cold points of cans to observe their change in temperature over time

Question 18

where are the cold points of cans for solid and liquid foods?

Answer 18

solid: center
liquid: on third from the bottom

Question 19

how does starch gelatinization affect heat transfer?

Answer 19

slows

Question 20

what’s the difference between use of heat penetration studies in principle vs in practice?

Answer 20

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