Food Safety: Food Spoilage And Preservation

Front 1

What is food spoilage?

Back 1

Deterioration in quality of food (colour, odour, texture, flavour) making it aesthetically unpleasant or unsafe

Front 2

What causes food spoilage?

Back 2

Microbial growth and/or chemical changes eg. enzyme activity

Front 3

What is food quality?

Back 3

Aesthetics: colour, odour, flavour, texture

Front 4

What does safety of a spoiled food product depend on?

Back 4

Whether pathogens are present initially and how they behave in product during/after shelf life

Front 5

What is the significance of food spoilage?

Back 5

Global problem

Front 6

What 7 costs are associated with food spoilage?

Back 6

Production, processing, distribution, storage, retailing, disposal, environmental cost

Front 7

How much food is discarded?

Back 7

~25-30%

Front 8

What are the 2 major types of food spoilage organisms?

Back 8

Psychrophilic and mesophilic

Front 9

What temp do psychrophiles like?

Back 9

=7*C

Front 10

What are the 2 main psychrophiles involved in food spoilage?

Back 10

Listeria monocytogenes, Aeromonas hydrophila

Front 11

What temp do mesophiles like?

Back 11

>/= 8*C = 45*C

Front 12

What type of microorganisms are mesophiles?

Back 12

zoonotic

Front 13

What is the main mesophile involved in food spoilage?

Back 13

Staphylococcus aureus

Front 14

What temp do thermophiles like?

Back 14

>/= 46*C

Front 15

What causes variation of the dominant species in meat?

Back 15

meat composition, storage and packaging conditions (eg. gas permeable vs vacuum packed)

Front 16

How do food spoilage bacteria proliferate?

Back 16

binary fission

Front 17

What influences replication time?

Back 17

composition and storage conditions

Front 18

What 5 intrinsic factors affect microbial growth?

Back 18

pH, moisture content, nutritional profiles, antimicrobial constituents and biological structures

Front 19

What unit is used to measure moisture content?

Back 19

Aw water availability

Front 20

What nutrients are intrinsic factors affecting microbial growth?

Back 20

carb and protein profiles

Front 21

What antimicrobial constituents are found in milk and eggs?

Back 21

Lactoferrin (milk), Lysozyme (milk and eggs)

Front 22

What 4 extrinsic factors affect microbial growth?

Back 22

Storage temp, relative humidity, presence comp and conc of gases, presence and activity of other microorganisms

Front 23

What 3 gases affect microbial growth?

Back 23

O2, CO2 and N2 (ratio)

Front 24

What does LAB produce?

Back 24

bacteriocin

Front 25

Which microorganism in food spoilage is a poor competitor?

Back 25

S. aureus

Front 26

What are the 4 stages of bacterial growth?

Back 26

Lag phase, exponential phase, stationary phase, death phase

Front 27

What makes lean meat susceptible to spoiling?

Back 27

high Aw

Front 28

What protects meat?

Back 28

pH goes from 7 to 5.5-5.8, inhibiting growth

Front 29

What are the 5 results of spoilage of meat?

Back 29

Putrefaction, rancidity, odours, slimes, discolouration

Front 30

What type of meat fat is especially susceptible to spoilage?

Back 30

Abdominal and surface fat

Front 31

What type of meat fat is less susceptible to spoilage?

Back 31

intramuscular marbling

Front 32

What 4 prevention technologies are used to prevent microbial growth on meat?

Back 32

hygiene, cold line controls, chilling, freezing

Front 33

What does freezing do?

Back 33

Freezes water, lowers Aw, Increases osmotic stress

Front 34

What does freezing physically damage?

Back 34

cells

Front 35

What does chilling do?

Back 35

Prevents microbial growth and enzyme activity

Front 36

What temp should red meat be chilled at?

Back 36

= 7*C 24hrs PM, = 4*C thereafter

Front 37

What temp should poultry be chilled at?

Back 37

= 4*C ~2hrs PM

Front 38

What are the 4 methods of preservation used on meat?

Back 38

Curing, drying, smoking, fermentation

Front 39

What 3 ways is salt added to meat during curing?

Back 39

rubbing, immersing in brine, injecting brine

Front 40

What does addition of salt result in?

Back 40

Decreased Aw

Front 41

What do nitriles do?

Back 41

Colour and inhibit clostridia

Front 42

What 2 things are added to meat for curing?

Back 42

salt and nitriles

Front 43

What does drying of meat cause?

Back 43

Decreased Aw, increased osmotic stress

Front 44

What is smoking?

Back 44

Wood chip buring

Front 45

What 3 things does smoking produce?

Back 45

Phenols, aldehydes and furans

Front 46

What does smoking time depend on?

Back 46

Smoke temp

Front 47

What does fermentation cause?

Back 47

LAB, decreased pH, increased lactic acid

Front 48

What are the 4 packaging technologies?

Back 48

gas composition, gas permeable packaging, vacuum packaging, modified atmosphere packaging (MAP)

Front 49

What concentrations of gases are used in MAP?

Back 49

60-70% CO2 / 10-15% O2 / 15-30% N2

Front 50

What is the shelf life of fresh meat?

Back 50

7-10 days at -1 - 1*C

Front 51

What is the shelf life of vacuum packed meat?

Back 51

>70 days at -1 - 1*C

Front 52

What is the shelf life of MAP red meat at 60% CO2?

Back 52

Up to 70 days at -1 - 1*C

Front 53

What is the shelf life of MAP poultry at 60% CO2?

Back 53

Up to 25 days at -1 - 1*C

Front 54

What chemicals are used to preserve foods? 4

Back 54

nitrates in bacon and ham, sulphites in beverages, sorbates in cheeses and beverages, salt in cured meats

Front 55

What is an example of a natural food 'additive' used for preservation?

Back 55

Bacteriocins (nisin) produced by LAB

Front 56

What are the 5 main pathogens in raw milk?

Back 56

L. mono, M. bovis, Campy, Salmonella, E. coli

Front 57

What pathogen of raw milk is capable of growth a refrigeration temp?

Back 57

Pseudomonas

Front 58

What is curdling?

Back 58

Protein precipitation and souring lactic acid, rancidity

Front 59

Which microorganisms survive pasteurisation?

Back 59

Thermodurics

Front 60

What are the 8 steps in yogurt production?

Back 60

Pasteurise, homogenise, pre-heat 40-46*C, add starter cultures, incubate 40-46*C for 4-5 hours, stir and cool 5*C, add fruit/flavours/colours, filling/packing

Front 61

What pH is yogurt?

Back 61

~4.3