Thermal Processing Equipment

Question 1

The essential features of all retorts:

Answer 1

CONTROL: temperature and pressure
UNIFORMITY: temperature and pressure

Question 2

The 2 types of temperature fluctuations:

Answer 2

time (issues with heating rate provided by system/controls)

space (due to loading pattern/distribution)

Question 3

name the steps in thermal processing operations: (9)

Answer 3

preparation 
blanching
filling
exhausting
double seaming
processing
cooling
labelling
storage

Question 4

Describe a retort:

Answer 4

Pressure vessel
cylindrical shell
Can be horizontal/vertical

Question 5

Why are the temperature and pressure of a retort important?

Answer 5

Lower the temperature, the longer processing needed for required lethality
Pressure will affect temperature

Question 6

True/False: the retort will also have a cold point, like a can

Answer 6

True

Question 7

What is the best heat transfer media? But when is it not applicable?

Answer 7

Steam

Glass (thermal shock), flexible packs (weaken seals)

Question 8

What does heating fluctuations usually result in?

Answer 8

Overcooking

Question 9

What are steam tables?

Answer 9

Tables to relate pressure to temperature in a retort

Question 10

What are the 2 main considerations for retort operations?

Answer 10

1. temperature distribution

2. heat distribution (lethality; ability to transfer heat)

Question 11

temperature establishment in retorts is based upon ___?

Answer 11

steam tables (pressure temperature relationship)

Question 12

What types of condensation heat transfer occur for hydrophilic and hydrophobic products?

Answer 12

hydrophilic: filmwise
hydrophobic: dropwise

Question 13

What heating media are commonly used?

Answer 13

1. steam
2. steam heated water
3. steam with air overpressure

Question 14

What step is necessary to remove air? How is it accomplished?

Answer 14

Venting

Valves remain open as the retort heats up; hot steam drives air out

Question 15

Steam provides ___ heat transfer

Answer 15

condensation

Question 16

True/False: retort control can be based on either temp or pressure

Answer 16

True

Question 17

What happens if air is in the retort? (2)

Answer 17

decreases pressure (subtract from total pressure) -> temperature drop!
act as insulator (poor heating medium)

Question 18

What heating media can be used for all package types?

Answer 18

steam with air overpressure

Question 19

How can the heat transfer of water be increased?

Answer 19

circulating water

Question 20

Types of retorts - Fill in the blank:
Still vs \_\_\_\_\_
\_\_\_\_ vs continuous
\_\_\_\_ vs overpressure
In container vs \_\_\_\_\_

Answer 20

agitated
batch
conventional
aseptic

Question 21

What feature in the retort improves heat transfer of steam+air systems?

Answer 21

powerful fans to circulate

Question 22

Describe flame sterilization process of cans:

Answer 22

HTST continuous operation
Cans rolled along on conveyor (80rpm)
steam heating for uniform initial temp -> burner flame to sterilize (very hot, rapid temp increase) -> holding, then cool with water sprays

Question 23

What are “cook checks?” What do they indicate?

Answer 23

Cardboard tags impregnated with CHROMIUM

change color to indicate reaching certain heat/lethality value - shows that retort contents have been processed

Question 24

What type of continuous cooker uses several different “shells,” and what are their purposes?

Answer 24

continuous turbo cooker
first shell to pre-heat
second shell to steam sterilize
third for cooling

Question 25

Flame sterilization technique is (good/bad) for preserving quality. Why?

Answer 25

good; HTST process, destroy most microbes before damaging quality

Question 26

What are the colors/indication of a cook check tag?

Answer 26

``` purple = cool and dry green = PASS, wet and heated grey = FAIL, Insufficient temp/time ```

Question 27

What are the types of commercial retorts?-(6)

Answer 27

- steam - steam/air - full water immersion - rotary - water spray - crateless

Question 28

What are the types of pilot/production scale cookers? (3)

Answer 28

Flame sterilization, continuous turbo cooker, hydrostatic cooker

Question 29

What product is the continuous turbo cooker commonly used for?

Answer 29

soups

Question 30

what step in processing is not needed in steam/air retorts? Why might this be positive?

Answer 30

Venting; conserves energy

Question 31

Water spray retorts have the advantages of: (5)

Answer 31

``` short come-up time (overhead preheated reservoir) small volume of water can recycle water (more efficient) high flow rate (good exchange) good for glass/flexible containers ```

Question 32

Compared to a steam retort, what additional feature is required in a steam/air retort?

Answer 32

powerful fans to circulate air, increase heat transfer rate

Question 33

True/False: The water for a water spray retort provides both heating and cooling

Answer 33

True; heat exchanger is used to heat/cool water for retort

Question 34

Why would a preheated water reservoir be beneficial for a retort?

Answer 34

shorter CUT

Question 35

What is a large vertical continuous cooker that is especially good for saving space?

Answer 35

hydrostatic cooker

Question 36

How might a full water immersion retort be advantageous over a water spray retort? How might it be disadvantageous?

Answer 36

good: better contact bad: more effluent

Question 37

The steam temperature in a hydrostatic cooker is determined by:

Answer 37

the level of water in the "legs"

Question 38

Both the ____ and ____ retorts make use of a preheated water chamber in order to reduce ____.

Answer 38

water spray; water immersion; CUT

Question 39

To increase the processing time in a hydrostatic cooker, you could increase the:

Answer 39

number of legs

Question 40

Name the benefits of using a hydrostatic cooker (6)

Answer 40

``` Large capacity Easy to maintain No thermal shock (glass) Saves space Conserves steam Mild agitation ```

Question 41

Name the main parts of a hydrostatic cooker. (6)

Answer 41

``` Feed leg Come up leg Sterilization chamber Come down leg Final cooling leg Chain conveyer ```

Question 42

Why is water needed (aside from cooling) in a crateless retort?

Answer 42

"cushion" for when dumping cans in/out, to prevent damage

Question 43

Describe the process of a crateless retort.

Answer 43

``` Retort filled with water Add cans Replace water with steam STERILIZATION Fill with water (cooling) Discharge into water bath ```

Question 44

Why is the crateless retort semi-continuous?

Answer 44

can feed cans in via conveyor, but operates in batches for sterilization

Question 45

What are the heat mediums used in a rotary retort?

Answer 45

Steam, or steam/air

Question 46

What advantage do rotary retorts have?

Answer 46

Agitation