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5) Post-Harvest > Lecture 14: > Flashcards

Lecture 14: Flashcards

1
Q

describe micro level of F&V structure

A

individual cells w/ specific functions (Pro, CHO, fat synth)

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2
Q

descrie macro level of F&V structure

A

collective functions, formation of large group of similar cells

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3
Q

describe cell wall

A
  • outermost layer of cell
  • comp of cellulose and other polymeric materials
  • main functions: structural support and containing all cell components
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4
Q

describe middle lamella

A
  • cell membrane more rich in pectic substances
  • pliable
  • has role in holding and binding cell components
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5
Q

describe plasmaderma

A
  • communicates w/ adjoining cells
  • semi permeable membrane w/ selective permeability
  • imp in plant water relationship (osmosis)
  • responsible for turgidity of plant cell
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6
Q

describe vacuole

A
  • fluid reservoir of cell
  • contains soultes
  • surrounded by semi-permeable membrane called tonoplast
  • has a role in cell turgidity
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7
Q

describe cytoplasm

A
  • fluid matrix
  • where all major metabolic activities take place
  • functions controlled by nucleus and coordinated through organells
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8
Q

describe endoplasmic reticulum

A
  • responsible for synthesis and transport b/w nucleus and cytoplasm
  • implicated in protein synthesis
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9
Q

describe the golgi complex

A
  • implicated in cell wall synthesis

- modification and transporation of proteins and fats built in the ER

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10
Q

describe nucleus

A
  • overall control of all metabolic activities, esp protein synthesis and DNA/RNA transformation
  • control center
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11
Q

what does the ribosome contain?

A

RNA rich organnel responsible for protein synthesis

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12
Q

what are 3 types of plastids?

A

chloroplast (photosynthesis)
chromoplast (color)
amyloplast (starch)

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13
Q

what are 3 systems in plant tissue at a macro level?

A
  1. dermal system
  2. ground system
  3. vascular system
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14
Q

describe the dermal system

A
  • protective tissue belonging to outer surface of produce
  • offers protection from: loss of H2O, invasion of pathogens, mechanical injuries, temp stress, volatilization of aromatic compounds, texture loss
  • facilitates gas exchange (O2 in; CO2 out)
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15
Q

what are types of dermal cells?

A
  1. cuticle (cutin or wax)
  2. epidermis
  3. corky tissue
  4. stomata
  5. lenticels
  6. peel
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16
Q

describe cutin

A
  • polymerized pdt of hydroxycarboxylic acids and their esters
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17
Q

describe wax (dermal cell)

A

ester of aliphatic wax alcohols and their corresponding FAs

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18
Q

fruits has ___ (more/less) wax/cutin than veg

A

more

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19
Q

leafy veg have ____ (more/less) wx/cutin than root veg

A

more

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20
Q

describe epidermis

A
  • cells along outermost layer of the organ
  • fits together compactly
  • cell walls have lipid like materials
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21
Q

describe the cuticle or cuticular membrane

A
  • extracellular water impermeable surface layer
  • cutinization dictates functional properties
  • consists of cutin or waves
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22
Q

describe corky tissue

A
  • surface of underground storage organs
  • contains lipid-like material called suberin
  • found in serial fruits (eg. apples)
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23
Q

describe stomata

A
  • small pores in epidermal layer
  • surrounded by specialized guard cells
  • serve as minute valves for gas exchange
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24
Q

describe lenticels

A

pores in corky tissues

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25
Q

describe peel

A

modification of outer protective cell

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26
Q

what is the role of collenchyma and sclerenchyma cells?

A

supports tissues

provides mechanical support to the cell

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27
Q

describe collenchyma

A
  • series of separate longitudinal strands
  • cells elongated parallel to long axis
  • unevenly thickened
  • cell walls rich in petin and hemicelluloses
  • have unusual pliability
28
Q

what are functions of ground system?

A
  • major metabolic activities
  • chief edible portion of produce (~80% of plant tissue)
  • provides mechanical support for the tissue
29
Q

describe parenchyma cells

A
  • most common ground tissue
  • has mostly undifferentiated cells
  • has a large vacuole
30
Q

describe schlerenchyma tissue

A
  • have uniform thickened walls
  • 60-80% cellulose
  • normally lignified
  • low tensile strength
  • greater rigidity and hardness
  • provides better impact resistance
31
Q

what are 2 types of sclerenchyma cells?

A
  1. fibers:
    - long and pointed
    - unchanged after cooking
    - nutrition importance
  2. sclereids
    - not long or pointed
    - abundant in hard structures
    - occurs as scattered clusters in parenchyma tissue
    - responsible for grittyness or grainyness
32
Q

what are the 6 diff types of cells in plant tissue?

A
  1. phloem
  2. parenchyma
  3. sclerenchyma
  4. collenchyma
  5. xylem
  6. protective
33
Q

describe the vascular system

A
  • transport tissues (eg. transport of H2O and minerals)

- highly specialized

34
Q

what is the role of xylem?

A

conducts H2O and minerals

35
Q

what is the role of phloem?

A

conducts organic pdts of metabolism and photosynthesis

36
Q

what contributes to texture?

A
  • physical properties and structual organization of tissue constituents
  • relative proportions and distribution of types of tissues
  • cell wall, cellulose, hemicellulose…
37
Q

firmness results from what?

A
  1. turgidity of thin walled parenchyma tissue

or 2. high proportion of thick walled mechanical tissue

38
Q

crispiness results from what?

A
  • turgidity of the cells (extent to which the cells are burst open by teeth during mastication)
39
Q

define turgidity

A

balance between elastic nature of cell wall and the hydrostatic pressure of the cell (resulting from osmotic process within)

40
Q

fibrousness of stringiness results from what?

A

presence of bundles of mechanical tissues that resist shearing forces applied by the teeth

41
Q

grittiness results from what?

A

by the presence of small particles or clusters of cells with thick and rigid walls (sclereids)

42
Q

what does turgidity depend on?

A
  • cell wall strength to counter hydrostatic pressure within the cell
  • hydrostatic water pressure is moderated by the osmotic process (composition). Thus turgidity is influenced by structure and composition of the produce
43
Q

turgidity is synnonymous with what?

A

freshness

44
Q

define osmosis

A

selective movement of active components like h2o across a semi permeable membrane

45
Q

define a semi permeable membrane

A

allows free passage of solvent molecules but retains solutes

46
Q

what are the most imp membranes controlling osmosis?

A

tonoplast and plasmalemma

47
Q

____ plays a key role in making produce turgid

A

osmosis

48
Q

describe the osmosis phenomenon

A
  • one side of semi permeable membrane has high kinetic energy while the other side has low kinetic energy
  • water/active component must move from higher to lower kinetic energy region for equilibrium
49
Q

describe how h2o moves into a plant cell

A
  • h2o is sucked in from roots
  • h2o moves into cell and increases hydrostatic pressure (HP) of the cell
  • cell inflates
  • pressure is exerted against cell wall
  • turgidity increases but is limited by turgor pressure
50
Q

what is HP

A

hydrostatic pressure

increased when h2o moves into cell

51
Q

what is TP

A

turgor pressure

52
Q

what limits the turgidity of a cell?

A

turgor pressure

53
Q

what is OP

A

osmotic pressure

when applied, causes influx/efflux of water

54
Q

weak cells rupture due to what?

A

high osmotic inflation

55
Q

normal cells have a balance between what?

A

HP and TP

56
Q

strong cells have cell wall strength greater than ____

this allows what?

A

HP

allows more resistance to moisture loss

57
Q

describe the transpiration process

A

results in

  • loss of h2o from the cell
  • loss in HP
  • incr conc of solutes
  • incr osmotic potential
  • causes pressure difference (OP - TP)
  • establishes dynamic equilibrium
58
Q

OP - TP = ?

A

suction pressure (SP)

59
Q

describe the post harvest behaviour of a cell

A
  • no water influx
  • HP continuously goes down
  • shrivelling when the cell wall collapses
  • turgidity or freshness is lost forever
60
Q

how is an example of how structure influences textural properties?

A

course of ripening

eg. hard green banana becomes soft ripe banana

61
Q

what is instron universal testing machine?

A

texture measuring instrument

62
Q

what is Magnes Taylor Puncture Probe

A

a fruit pressure tester

used to measure firmness of produce

63
Q

hardness = ?

A

max force / max deformation

64
Q

stiffness = ?

A

(force/cross sectional A) / (deformation/initial length)

65
Q

firmness = ?

A

slope of linear section of force x deformation curve

5) Post-Harvest (17 decks)

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