Lecture 7: Thermal Processing Equipment

Question 1

what are preliminary operations?

Answer 1

preparation
blanching
filling
exhausting
double seaming
processing (cooling, labelling, storage)

Question 2

what is a retort?

Answer 2

• pressure vessel
• cylindrical shell
• vertical or horizontal

Question 3

what are essential features in all retorts?

Answer 3

1. temp and pressure control

2. temp and pressure uniformity

Question 4

temp differences in a retort can compromise _____

Answer 4

safety

Question 5

how does temperature fluctuations compromise product quality?

Answer 5

can result in product overcooking when adjusted for giving the required lethality

Question 6

what are two major issues of temperature fluctuations on product quality??

Answer 6

temperature variation and stability with respect to:

1. Time (eg. system limitations)
2. space (eg. loading pattern limitations)

Question 7

what are pressure controllers used for?

Answer 7

to establish temp and control stability

Question 8

what are two important factors to consider with pressure controllers and retort temp?

Answer 8

1. temp distribution

2. heat (lethality) distribution

Question 9

temperature establishment in retorts is based on relationships of what?

ie. what is compared in steam tables?

Answer 9

steam temperature and pressure

Question 10

what happens if air is present in the retort?

what can you do to solve this problem?

Answer 10

1. steam pressure will be much lower
2. the drop in pressure will cause a drop in temp

can solve this be venting (getting rid of air from the retort)

Question 11

why is venting important?

Answer 11

to avoid drop in pressure and temperature inside the retort

need to get rid of air to have saturated steam inside

Question 12

what are vent valves?

Answer 12

a part of a retort which can allow for venting

Question 13

when do vent valves stay open until? why?

Answer 13

until retort reaches 200F

because incoming steam helps to expel air in the retort, which helps to keep saturated steam in the retort (so that the pressure and temp relationship in the retort is the same as in the steam tables)

Question 14

venting is very energy _____

Answer 14

intensive

Question 15

how does the presence of air in the retort affect rate of heat transfer?

Answer 15

air acts as an insulator and interferes with condensation

Question 16

what are two modes of condensation?

Answer 16

1. dropwise (hydrophobic surface)

2. filmwise (hydrophillic)

Question 17

what are the modes of condensation influenced by?

Answer 17

the presence of air in the retort, since air acts as an insulator. Thus, it is important to get rid of the air

Question 18

what is the best choice for heating and rapid heat transfer?

Answer 18

steam

Question 19

retort control can be based on ____ or ___

Answer 19

T or P

Question 20

compare differences between steam heated water and steam with air overpressure

Answer 20

steam heated water

• good for cans and jars
• water circulation increases heat transfer

steam with air overpressure

• good for all containers
• heat transfer rate is increased by fans inside the retort

Question 21

what is the function of the bleeder in the retort?

Answer 21

directs the medium in the right direction

Question 22

what is the function of the vent in a retort?

Answer 22

allows air to come in to protect from a drastic change in pressure

Question 23

what happens when the pressure in the retort increases too high?

Answer 23

safety valve will open and released pressure

Question 24

what is the function of the controller in a retort?

Answer 24

controls temp and pressure

Question 25

describe the steristar steam/air retort

Answer 25

- fan at back wall - no venting - conservation of energy - used for cans and flexible containers

Question 26

describe the lagarde steam/air retort

Answer 26

- fan at back - can be operated in water-spray mode and spray cooling - horizontal 4-car system

Question 27

describe the water spray retort by lagarde

Answer 27

- 4 car system - efficient and conserves water usage - heat exchanger is used for heating and cooling water

Question 28

describe the FMC overpressure retort barriquand steriflow

Answer 28

- has Weir type water flow - can be vertical or horizontal - overhead reservoir for preheating - short CUT - good for glass and flexible containers - water spray - high flow rate - small volume of water (efficient recycling and heat exchangers) - insulated shell

Question 29

describe a Lagarde ful water immersion retort

Answer 29

- good liquid contact - more effluent - preheat chamber conserves heat and reduces CUT

Question 30

describe the malo crateless retort system

Answer 30

- the crateless retort reduces amount of labour needed since cans can be put straight into the cooker - conveyer on bottom transports contents across the bottom - higher capacity and less handling

Question 31

describe efficiency of rotary retort

Answer 31

containers go through a rotating motion so process time can be reduced (better quality and faster)

Question 32

describe a hydrostatic sterilizer (FMC)

Answer 32

- saves space - high capacity operation - mild agitation which prevents thermal shock for glass - level of water in legs determines steam temp

Question 33

describe the FMC continuous turbo cooker

Answer 33

- continuous operation - pressure cooking and cooling - high speed operation - extensively used for soups

Question 34

describe flame sterilization

Answer 34

- high speed operation - excellent quality - high vacuum - constant headspace

Question 35

what is cook chex?

Answer 35

cardboard tags with purple heat sensitive ink, which changes color on heating

Question 36

what compound causes color change in cook chex?

Answer 36

chromium compound changes color on heating can be formulated to be sensitive to different times and temperature combinations

Question 37

with cook chex, what color is it when dry and cool? what color is it when wet and heated?

Answer 37

pink: dry and cool green: wet and heated

Question 38

what does a pink retort check mean?

Answer 38

unexposed to heat

Question 39

what color is a pass retort check?

Answer 39

green

Question 40

what color is a failed retort check?

Answer 40

grey