Midterm 2

Question 1

Pasteurization

Answer 1

Specifically designed to destroy enzymes to destroy vegetative pathogens and extend shelf life from a microbial and enzymatic pov

Question 2

Commercial sterility or “Sterile”

Answer 2

All pathogenic organisms are destroyed as well as all other organisms which if present could grow in the product and produce spoilage under normal handling and storage conditions

Question 3

Sterilization

Answer 3

Complete destruction of all microorganisms

Question 4

How to select heat treatments

Answer 4

Heat product to sufficiently destroy MO and enzymes that generally adversely affect the specified food

Question 5

Why be precise with heat?

Answer 5

Energy is expensive
Excess heat could deteriorate quality
Must cool after heating

Question 6

Time and temperature

Answer 6

Have inverse relationship

Specific for inactivating target organism in a particular food

Question 7

Conduction in cans

Answer 7

Cold point in the middle. Longer to heat up and longer to cool down.

Question 8

Convection in cans

Answer 8

Cold point near bottom. Quicker to cook and cool down.

Question 9

Target lethal range of vegetative cells

Answer 9

Above 60C or 140F

Question 10

Target lethal range of Spores

Answer 10

Above 100C or 212F

Question 11

Heat resistance

Answer 11

Depends on organism
Method of sterilization
Product (water activity, pH, composition)

Question 12

D value

Answer 12

Heat resistance expressed as time in minutes of the given temperature in a given food required to destroy 90% of the population (reduce by one log) of a specific MO

Question 13

Surrogates

Answer 13

Usually more heat resistant to ensure the death of pathogenic and less heat resistant MO

Question 14

Less heat resistant

Answer 14

Lower pH and more water tend to be less heat resistant and kill the pathogens quicker at the D value

Question 15

Z value

Answer 15

The temperature change needed to change the D value by one decimal

Question 16

Thermal Processes

Answer 16

Low acid foods-12 D process

High acid foods-5 D process

Question 17

F value

Answer 17

Total time required to achieve a stated reduction in the microbial population at a given temperature

Question 18

Where do D and Z come from?

Answer 18

Thermal Death Time studies (TDT)
Graphed log CFU/g by heating time; D value is -1/slope
Graph log D value by temperature; Z value is -1/slope

Question 19

Blanching reasons

Answer 19

Inactivate oxidative enzymes, undesirable changes in color, flavor, and nutritive value
Remove gases
Wilts tissue to help packaging
Fixes color and texture

Question 20

Foods to blanch

Answer 20

Solid foods with active enzymes or sensitive colors

Question 21

Blanching efficiency

Answer 21

Measured by assaying the heat resistant enzyme peroxidase

Question 22

Types of blanching

Answer 22

Steam and hot water

Question 23

Hot water Blanchers

Answer 23

Rotary/reel or tunnel

Question 24

Steam blanchers

Answer 24

Tunnel

Question 25

Steam/hot water blanchers

Answer 25

Steam/hot water spray-hot

Water immersion

Question 26

Factors influencing blanch process

Answer 26

Product (different enzyme systems)
Product size
Product thermal conductivity 
Heating medium (temperature and contact)
Water soluble nutrients/flavor compounds
Quality attributes less sensitive to thermal treatments than enzymes

Question 27

Factors when blanching nutrients

Answer 27

Maturity/pre blanching prep
Surface area to volume
Blanching medium
Time/temp

Question 28

Pasteurization facts

Answer 28

Heating and cooling sections
Temperatures used are below boiling point
Liquids so heat exchanger is plate, shell and tube or tube in tube
Prepackaged=heated and cooled requires refrigeration
Inpackage=may not require refrigeration (CO2 and pH)

Question 29

Milk

Low Temperature Long Time (LTLT)

Answer 29

63C for 30 seconds
D value = 2.5 min
Z value = 4.1C

Question 30

Milk

High Temperature Short Time (HTST)

Answer 30

72C for 15 seconds

Question 31

Milk pathogens

Answer 31

Brucella abortis, Mycobacterium tuberculosis, and Coxiella burnetti

Question 32

Juice pathogens

Answer 32

E. coli, Salmonella, Listeria

Question 33

Juice process

Answer 33

FDA required HACCP plan
Process must achieve 5 log reduction
pH 4 or less means 3 seconds at 71.1C

Question 34

Beer pasteurization

Answer 34

1 pasteurization unit is 1 minute at 60C

Typically target 15-30 PU

Question 35

Blanching

Answer 35

Inactivation of natural food enzymes