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Packaging methods – modified atmosphere
packaging and super chilling of farmed cod
Morten Sivertsvik
Research manager
Nofima mat, Nofima Norconserv as
Måltidets Hus; Stavanger
morten.sivertsvik@nofima.no / www.nofima.no
Visittkort til mobil: send <nofima 85> til 2077
Contents
Content • Background
– Why modified atmosphere packaging
Background – Why super chilling
- raw material
- spoilage
• Effect of temperature and rigor-state on the shelf life of
Rigor-state farmed cod
Temperature
• Extending the shelf life of farmed cod using modified
atmosphere packaging
MAP – Optimal gas composition
-optimal – Specific spoilage organisms
-microbiology
– Combination with super chilling
Combinations – Combination with brining
-superchilling
– Combination with salting/desalting
-brining
-other • Concluding remarks
Conclusions
Raw material
Content
Background
- raw material
- spoilage
Rigor-state
Temperature
MAP
-optimal
-microbiology
Combinations
-superchilling
-brining
-other
Conclusions
Loin cut
Content
Background
- raw material
- spoilage
Rigor-state
Temperature
MAP
-optimal
-microbiology
Combinations
-superchilling
-brining
-other
Conclusions
Modified atmosphere packaging
Content
Background
- raw material
- spoilage
Centralized
Rigor-state
Packaging
Temperature
MAP
-optimal
-microbiology
MAP
Combinations
-superchilling
-brining
-other
Conclusions
Characteristic odour changes of cod stored in ice
Content Prime quality
Superchilling
Background
- raw material Phase Period Description
- spoilage
Rigor-state I 0 to 6 days No marked sign of spoilage
Temperature
MAP
II 7 to 10 days No odour production
-optimal
-microbiology
III 11 to 14 days Production of some sour,
Combinations slightly sweet to fruity odours
-superchilling
-brining IV Greater than Production of H2S and other
-other
14 days sulphide compounds, fecal,
Conclusions and strong ammonia odours
Shewan (1970)
Quality of filleted farmed cod stored on ice
Post-rigor vs. pre-rigor
Content
Background
- raw material
- spoilage
Rigor-state
Temperature
MAP
-optimal
-microbiology
Combinations
-superchilling
-brining
-other
Conclusions
Quality of filleted farmed cod stored on ice
Post-rigor vs. pre-rigor
Content
Background
- raw material
- spoilage
Rigor-state
Temperature
MAP
-optimal
-microbiology
Combinations
-superchilling
-brining
-other
Conclusions
Effect of superchilling and MAP on pre-rigor farmed
cod, retail package: (Gas mix 60% CO2:40% N2 g/p: 1)
Content
Background
- raw material
- spoilage
Rigor-state
Temperature
MAP
-optimal
-microbiology
Combinations
-superchilling
-brining
-other
Conclusions
Gas mixture optimising at 0 C.
Pre-rigor filleted cod loins, retail, g/p 2:1
Content
Mixture design
Background
- raw material
- spoilage
Rigor-state
Simplex Design Plot in Amounts
Temperature
CO2
1
MAP
-optimal
-microbiology
Combinations 0 0
-superchilling
-brining
-other
Conclusions 1
O2
0 1
N2
Gas mixture optimising
Pre-rigor filleted cod loins, retail, g/p 2:1
Content
Exudate formation / drip loss
Background (as % of initial weight)
- raw material
- spoilage
Rigor-state
Temperature
MAP
-optimal
-microbiology
Combinations
-superchilling
-brining
-other
Conclusions
Gas mixture optimising
Microbial: Psychrotrophic bacteria
Content
(as logarithm of colony forming unit per gram cod)
Background d7-lpsb
< 3
- raw material
3 - 4
- spoilage 4 - 5
CO2 5 - 6 CO2 CO2
Rigor-state 1 6 - 7 1 1
> 7
Temperature
MAP
-optimal 0 0 0 0 0 0
-microbiology
Combinations
-superchilling
1 0 1 1 0 1 1 0 1
-brining
O2 N2 O2 N2 O2 N2
-other 10 days of storage 14 days of storage
7 days of storage
Conclusions
Gas mixture optimising
Pre-rigor filleted cod loins, retail, g/p 2:1
Content
TMA (left) – TMAO (right) (mg N/100 g cod)
Background
- raw material
- spoilage
Rigor-state
Temperature
MAP
-optimal
-microbiology
Combinations
-superchilling
-brining
-other
Conclusions
Gas mixture optimising
Content
Raw odour score
(point scale for 10 (seafresh) to 1 (totally rotten))
Background 14 days of storage
- raw material (component amounts)
- spoilage CO2
1
d14-lukt
Rigor-state < 5
5 - 6
6 - 7
7 - 8
Temperature > 8
0 0
MAP
-optimal
-microbiology
Combinations 1 0 1
-superchilling O2 N2
-brining
-other
Conclusions
Post-rigor filleted, retail packaged:
Effect of temperature and gas mixture on
Content
Psychrotrophic bacteria
Background
- raw material 10,0
- spoilage 9,0
Rigor-state 8,0
7,0
Temperature
6,0 AIR (0°C)
log CFU/g
CO2:N2 (0°C)
MAP 5,0 CO2:N2 (4°C)
-optimal CO2:O2 (0°C)
4,0 CO2:O2 (4°C)
-microbiology
3,0
Combinations 2,0
-superchilling
-brining 1,0
-other 0,0
0 2 4 6 8 10 12 14 16
Conclusions Storage time (days after filleting) (+5 d after slaughter)
Post-rigor filleted, retail packaged:
Effect of temperature and gas mixture on
Content
TMA
Background
- raw material
60
- spoilage
50
Rigor-state
40
Temperature AIR (0°C)
mg N/100 g
CO2:N2 (0°C)
30 CO2:N2 (4°C)
MAP CO2:O2 (0°C)
-optimal CO2:O2 (4°C)
20
-microbiology
10
Combinations
-superchilling 0
-brining 0 2 4 6 8 10 12 14 16
-other Storage time (days after filleting) (+5 d after slaughter)
Conclusions
Post-rigor storage; retail:
Effect of temperature and gas mixture on
Content
QIM score
Background
- raw material 12
- spoilage
10
Rigor-state
Temperature 8
AIR (0°C)
CO2:N2 (0°C)
score
MAP 6 CO2:N2 (4°C)
-optimal CO2:O2 (0°C)
-microbiology CO2:O2 (4°C)
4
Combinations
-superchilling 2
-brining
-other 0
0 2 4 6 8 10 12 14 16
Conclusions Storage time (days after filleting) (Days after slaughtering = + 5 d)
Microbial growth
• Total viable count (TVC) and psychrotrophic bacterial count followed same
Content pattern
– Increase bacterial inhibition with increased CO2 content
Background • After 14 days combinations of CO2 and O2 gave lowest bacterial
- raw material counts
- spoilage
• No H2S producing bacteria was detected!
Rigor-state – Shewanella putrefaciens ?
• Generally regarded as the SSO in air stored cod
Temperature • Not present or in very low level at elevated temperatures in all trials
with farmed cod
MAP – Photobacterium phosphoreum
-optimal • SSO of MAP and vacuum packaged wild cod
-microbiology • Characterisation of the bacterial flora of modified atmosphere packaged
farmed Atlantic cod (Gadus morhua) by PCR-DGGE of conserved 16S
rRNA gene regions (Hovda et al. 2007a):
Combinations – Pseudomonas spp. were found to be the predominant bacteria in
-superchilling oxygen enriched atmospheres,
-brining – spoilage bacteria Photobacterium sp., S. putrefaciens and
-other Pseudomonas spp. dominated in CO2:N2 and air packaged samples.
– PCR-DGGE can be applied to examine bacterial diversity and
Conclusions population shifts among different MA-packaged products.
Super chilling as pre-treatment:
farmed cod (pre-rigor filleted)
Content
Superchilled 4 min -38 C
Background
- raw material JBT Impingement freezer
- spoilage Equal. temperatur -1 C
Rigor-state
Temperature
MAP
-optimal
-microbiology
Combinations
-superchilling
-brining
-other
Conclusions
Super chilling as pre-treatment: farmed cod
Content
(pre-rigor filleted): Drip loss
Background
Performed correctly super-
- raw material chilling can reduce drip loss
- spoilage
Rigor-state
Temperature
MAP
-optimal
-microbiology
Combinations
-superchilling
-brining
-other
Conclusions
Super chilling as
pre-treatment:
Content farmed cod
Background (pre-rigor filleted)
- raw material
- spoilage
Sensory evaluation
Rigor-state
Temperature
MAP
-optimal
-microbiology
Combinations
-superchilling
-brining
-other
Conclusions
Pre-rigor filleted, retail packaged:
Effect of brining and gas mixture on
Content
Psychrothrophic bacteria
Background
- raw material
10
- spoilage
9
Rigor-state 8
Temperature 7
6 AIR (0°C)
log CFU/g
MAP CO2:N2 - Brined
5 CO2:O2 - Brined
-optimal CO2:N2 - Natural
-microbiology 4 CO2:O2 - Natural
3
Combinations
-superchilling 2
-brining 1
-other
0
0 2 4 6 8 10 12 14 16
Conclusions Storage time (days)
Pre-rigor storage; retail:
Effect of temperature and gas mixture on:
Content
Drip loss / exudates
Background
- raw material
- spoilage
• Increased during
Rigor-state
storage
• Less in brined samples
Temperature • No difference between
gas mixes
MAP
-optimal
-microbiology
Combinations
-superchilling
-brining
-other
Conclusions
Pre-rigor storage, retail:
Effect of brining and gas mixture on
Content
Hydrogen sulphide producing bacteria
Background
3,5
- raw material
- spoilage
3
Rigor-state
2,5
Temperature AIR (0°C)
log CFU/g
2 CO2:N2 - Brined
CO2:O2 - Brined
MAP 1,5 CO2:N2 - Natural
-optimal CO2:O2 - Natural
-microbiology 1
Combination 0,5
-superchilling
-brining 0
-other 0 2 4 6 8 10 12 14 16
Storage time (days)
Conclusions
Pre-rigor filleted, retail packaged:
Effect of brining and gas mixture on TMA
Content
Background
- raw material 12
- spoilage
Rigor-state 10
Temperature 8
mg N/100 g Cod
AIR (0°C)
MAP 6
CO2:N2 - Brined
CO2:O2 - Brined
-optimal CO2:N2 - Natural
-microbiology CO2:O2 - Natural
4
Combination
-superchilling 2
-brining
-other
0
0 2 4 6 8 10 12 14 16
Conclusions Storage time (days)
Pre-rigor filleted, retail packaged:
Effect of brining and gas mixture on
Content QIM score during storage
Background 10
- raw material 9
- spoilage
8
Rigor-state 7
6 AIR (0°C)
Temperature CO2:N2 - Brined
score
5 CO2:O2 - Brined
MAP CO2:N2 - Natural
4
-optimal CO2:O2 - Natural
-microbiology 3
2
Combinations
-superchilling 1
-brining 0
-other 0 2 4 6 8 10 12 14 16
Storage time (days after slaugthering and filleting)
Conclusions
Other MAP combinations
Content • Ozone (Hovda et al. 2007b)
Background – Pre-treatment with ozone prior to MAP of pre-rigor farmed
- raw material cod did not affect shelf life or other quality indices
- spoilage
Rigor-state • Rehydrated/desalted salted farmed cod in MAP (Rotabakk et
al., 2009)
Temperature
– De-salting changes the characteristics of the product
MAP – Limited shelf-life due to microbial activity and autolytic
-optimal proteolysis during chilled storage
-microbiology – Chilled MAP increases the shelf-life of desalted cod from 6 to
Combinations 10 days
-superchilling – Minor effect of pre-treatments with phosphate brine or
-brining steaming prior to MAP storage
-other
– 50% oksygen combined with 50% CO2 decreased drip
Conclusions loss; no additional effect of high oxygen vs anoxic MAP
Concluding remarks
• Storage temperature is still the most important parameter
Content
– even for farmed cod
Background • Filleting pre-rigor increases the fillet shelf-life
- raw material – Not the total shelf-life
- spoilage • Modified atmosphere increased shelf-life
– Increased effect on pre- compared to post-rigor
Rigor-state – Increased effect at 0 C and superchilled conditions
• High oxygen mixed with carbon dioxide -> optimal gas mixture
Temperature – Inhibits TMA formation (more pronounced on pre-rigor)
MAP
• Superchilling has potential as a pre-treatment
-optimal
-microbiology – Extends shelf-life; longer prime quality
– Makes ice superfluous – built-in cooling; increased transport efficiency
Combinations – Additional effect combined with MAP
-superchilling
-brining • Phosphate brined pre-rigor farmed cod fillets kept better than those not
-other brined under MA
Conclusions • MAP increases shelf-life of rehydrated salted farmed cod
Acknowledgement
Content
• This work was kindly funded by the Norwegian Research Council
Background – ConCod: minimally processed convenience products from farmed cod
- raw material (SIP-PRIM)
- spoilage – Marinepack (BIP MAT)
• Thanks to You and my co-authors:
Rigor-state – Maria Befring Hovda, Jan Thomas Rosnes, Bjørn Tore Rotabakk & Sveinung
Birkeland, Nofima
Temperature
• Our publications related to MAP and farmed cod:
MAP – Hovda, MB, Lunestad, BT., Sivertsvik, M., Rosnes, JT. 2007a. Characterisation of
the bacterial flora of modified atmosphere packaged farmed Atlantic cod (Gadus
-optimal morhua) by PCR-DGGE of conserved 16S rRNA gene regions. International
-microbiology Journal of Food Microbiology 117(1):68-75
– Hovda MB., Sivertsvik, M, Lunestad, BT, Rosnes, JT. 2007b. The bactericidal
Combinations effect of ozone on farmed cod determined by PCR-DGGE. Journal of Food
Protection 70(11)2460-2465
-superchilling
– Rotabakk, BT., Sivertsvik, M., Birkeland, S. 2009. Microbial quality of de-salted
-brining cod in consumer packages - Effects of storage atmospheres and pre-treatments.
-other Journal of Aquatic Food Product Technology 18(1)(in press)
– Sivertsvik, M. 2007. The optimized modified atmosphere for packaging of pre-rigor
Conclusions filleted farmed cod (Gadus morhua) is 63 ml/100 ml oxygen and 37 ml/100 ml
carbon dioxide. LWT – Food Science and Technology 40: 430-438
Nofima Norconserv a/s is now located in Måltidets Hus in Stavanger
