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4) Food Processing > Lecture 8: Quality Optimization in Thermal Processing > Flashcards

Lecture 8: Quality Optimization in Thermal Processing Flashcards

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Gourmet Food flashcards
1
Q

what is the aim of techniques in quality enhancements?

A

improving heat transfer to the product

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2
Q

what is heat transfer in canned foods driven by?

A
  1. convective heat transfer: the rate of heat transfer from the heating medium to the can
  2. heat transfer within: can be mixed convection and conduction rate heat transfer
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3
Q

what factors are involved with a shorter rate of heat transfer?

A
  • shorter process time/quicker turnover
  • more uniform temp
  • less overcooking of product
  • bettwe quality retention
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4
Q

what is the heat transfer equation?

A

q= h * A * deltaT = k * A * deltaT * x

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5
Q

the graph of relative D value vs. temperature provides what data?

A

relative resistance of bacteria to thermal destruction

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6
Q

in the relative D vs temp graph, what has the highest D value? why?

A

nutrients b/c they are more stable than microorganisms

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7
Q

do nutrients or microorganisms have a higher z value?

A

nutrients have a higher Z value

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8
Q

are nutrients or microorganisms less sensitive to changes in temperature? how can this be seen?

A

nutrients are less sensitive, which can be seen by their flatter slope in the relative D vs temp graph

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9
Q

in the relative D vs temp graph, what does a steeper slope indicate?

A

more sensitive to change in temp

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10
Q

vegetative bacteria has a very ___ slope

A

steep

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11
Q

what does HTST stand for?

A

high temperature short time

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12
Q

what does UHT stand for?

A

ultra high temperature

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13
Q

everything on the left of the thermal destruction curve is _____

everything on the right of the curve is ____

A

underprocessed

overprocessed

(process times should be right on the curve)

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14
Q

what are some different types of heat exchangers?

A
  • plate and frame
  • tubular
  • swpet (Scrapped) surface
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15
Q

what are some process benefits from HTST and UHT?

A
  • hats rapidly for liquids
  • involves packaging in thin profile forms
  • for cans that undergo agitation during processing (either liquids or semi-solids)
  • for aseptic processing and packaging
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16
Q

what is HTST not suitable for?

A

conduction heating type of products in large containers

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17
Q

what does HTST do in thin profile processing?

A
  • increases surface area

- reduces thickness

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18
Q

what is thin profile processing use for?

A

conduction heating foods

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19
Q

what are the three layers in a retort pouch used in thin profile processing?

what is the role of each layer?

A
  1. outer layer: strength and printability
  2. middle layer: barrier properties
  3. inner layer: heat sealability and food contact
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20
Q

in the retort pouch used in thin profile processing, which layer is used for heat sealability?

A

inner layer

21
Q

in the retort pouch used in thin profile processing, which layer is used for strength and printability?

A

outer

22
Q

in the retort pouch used in thin profile processing, which layer is used for barrier properties?

A

middle

23
Q

what is over pressure processing used to process?

A
  • retort pouches
  • flexible containers
  • glass containers
24
Q

what is over-pressure processing used for?

A
  1. to protect package integrity (prevents pressure build up in packages at the beginning of cooling)
  2. promotes better heat transfer during heating (better contact between package and contents)
25
Q

what determines the degree of over pressure?

A

proportion of steam and air

26
Q

in over pressure processing, higher steam content provides _____

A

better heat transfer

27
Q

in over pressure processing, higher air content provides ____

A

better overpressure protection

28
Q

what kind of turbulent conditions are used in over-pressure processing to achieve better heat transfer?

A
  1. continuous venting (positive flow retorts)

2. turbo fans (through mixing)

29
Q

how does overpressure processing change the pressure profile of a process?

A

pressure profile with NO overpressure has higher pressure than the retort during cooling. Thus, this creates a danger zone

pressure profile WITH air overpressure has lower pressure than the retort during cooling. Thus, the whole process is in the safe zone

30
Q

what happens when there is no over-pressure to compensate for the high pressure inside a pouch compared to if overpressure is present?

A

if no overpressure: pouch will expand from the inside

if overpressure is present: expansion will be supressed

31
Q

what are advantages of HTST?

A
  • high quality
  • easy opening and disposal
  • easy reheating
  • easy storage
32
Q

what are disadvantages to HTST?

A
  • slow speed (sealing limitation)
  • incomplete air removal
  • package failure (fragility)
  • more manual labor
  • needs overpressure processing
33
Q

why is rotational/agitation processing is used to optimize food processing?

A

to improve heat transfer by improving mixing and heat transfer coefficient

34
Q

what are the type types of rotation and agitation processing?

A
  1. end over end
  2. axial agitation
  3. reciprocation agitation
35
Q

what kind of operation is axial rotation used for?

A

continuous operation

36
Q

what kind of operation is end over end rotation used for?

A

batch operation

37
Q

what are advantages of rotation/agitation processing?

A
  • results in mixing of content
  • rapid heat transfer
  • uniform temperature
  • less overcooking of product
  • better quality retention
  • shorter process time/quicker turnover
38
Q

what type of container is end over end good for?

A

cans, semi rigid containers, glass containers

39
Q

what type of container is axial rotation good for?

A

only for cans

40
Q

what type of container is reciprocation agitation good for?

A

all types

41
Q

what are factors that influence rotary sterilization?

A
  • product viscosity
  • can size
  • type of product
  • agitation speed
  • retort temp
  • head space
  • ratio of liquid to particles
42
Q

what is aseptic processing applied to?

A

liquid and acidic foods

43
Q

what is the main concept behind aseptic processing?

A

heat, hold and cool concept

44
Q

what are advantages to aseptic processing?

A
  • high speed
  • continuous process
  • less damage to product
  • shorter processing time
  • uniform and high quality
  • reduced energy consumption
45
Q

what needs to be sterilized for aseptic processing?

A
  • equipment
  • container
  • product (HTST)
  • environment
46
Q

what are disadvantages of aseptic processing?

A
  • high initial capital investment
  • complexity of system
  • sophisticated instrument
  • need highly qualified personnel
  • can’t be used for solid food or conductive products
  • process is not long enough to inactivate enzymes
47
Q

what is SSHE?

A

security, safey, health, environment management

48
Q

what is laminar and turbulent flow?

A

laminar: slow
turbulent: high speed

49
Q

which fluid viscosity gives better flow for particulates: lower or higher viscosity?

A
  • low density moves along top surface and has resistance with the bottom
  • high density moves along the bottom and has resistance with the top
  • fluid with equal density with liquid moves down the middle and moves fastest

4) Food Processing (18 decks)

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