Attachment 1
to MPR#4
Project 2010-707
Investigations into use of PET lined
cardboard cartons as replacement for
expanded polystyrene boxes for
packing cooked, chilled farmed
prawns.
Prepared by
Carl Paulo, Yasmina Sultanbawa & Sue Poole
February 2012
CRC 2010-707MPR 4
1.
Attachment 1
Investigation into use of PET lined cardboard cartons as replacement for
expanded polystyrene boxes for packaging cooked, chilled farmed prawns
Introduction
Expanded polystyrene boxes have been the method of choice for bulk distribution of
cooked, chilled farmed prawns due to their insulation properties. Though still
acceptable within the catering sector, there is pressure from the retail sector for a
better alternative. This push stems from inherent problems arising from the current
practice of packaging 5kg prawns topped with 1kg shaved ice. The use of wet ice by
industry is two-fold; to limit bacterial growth by maintaining a chilled environment
and to retain quality at point of sale, with a focus on the moist glossy outer
appearance imparted by melting ice. Unfortunately, this melted ice water is of major
concern within retail chains. During handling and distribution polystyrene is prone to
crack and break with subsequent leakage of melt water. Another major cause for
rejection of polystyrene by retailers is the lack of systems for disposal and adequate
recycling of the bulky boxes. At retail level, the preferred material for packaging
would be either cardboard or recyclable plastics.
Some farms have recently trialled cardboard cartons for commercial product.
However, similar issues to polystyrene were encountered. The design of the cartons
allowed for capture of about 5cm of melted ice water. Anything more, or any slight
angle of placement, would result in leakage of melt water from carton. Tilted boxes
invariably occur during handling especially at the wholesale points in the distribution
chain where individual cartons are added to a pallet of other mixed chilled goods, in
various sizes, to be transported to specific retail stores. Commonly, prawn cartons
are added to the top of pallets and may not sit flat depending on the shapes of the
other goods loaded on the pallet. Consequently the likelihood of prawn ‘juice’
contaminating other chilled product (for example dairy) placed beneath prawn
cartons is ever present.
Hence the industry is seeking alternative packaging for the transportation of
produce. To date, the most practical alternative is plastic polypropylene containers
with a fitted lid. Successful trials have been carried out by the APFA confirming that
containers are leak proof and capable of maintaining chilled temperatures during
transportation. From these trials a storage life of 12-14 days was achieved. The
polypropylene packaging meets the requirements for recyclability however issues
remain surrounding correct disposal. A requirement for recycling is that the
containers must be thoroughly rinsed for inclusion in the plastics-recycle load. If not
adequately cleaned the resulting odour negates the recyclability of the entire
plastics load.
The APFA requested that we investigate alternative packaging options to replace
expanded polystyrene. Here we document trials to determine the viability of design
improvements made by manufacturers of cardboard carton boxes. To date, plastic
tubs were unavailable to us for trialling. Fortunately, we have now obtained samples
and will be incorporating tubs into future trials to establish their effectiveness and
the actual storage life of product in combination with synergistic benefits derived
from incorporating antimicrobial treatments.
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CRC 2010-707MPR 4
2.
Attachment 1
Investigation into use of PET lined cardboard cartons as replacement for
expanded polystyrene boxes for packaging cooked, chilled farmed prawns
Materials and Methods
Processing and shelf life
Trial was conducted at Seafarm’s prawn processing facility near Cardwell (QLD,
Australia). Banana prawns (Fenneropenaeus merguiensis) were all from the same
pond harvest. Prawns used in the various packaging options trialled were from a
single cooked batch and modified atmosphere packed (MAP) prawns from the batch
previous. Post processing, cooked chilled prawns were packed into 5 kg boxes with a
total of six boxes for each of the packaging options trialled. Boxes had hygienic
Thermocron TC temperature loggers (OnSolution, NSW, Australia) placed internally
at top and bottom. Loggers had a sampling rate every 15 minutes. Six 4 kg bulk MAP
trays were also sourced from Seafarm’s stock of retail products. Boxes and MAP
trays were transported to Brisbane (QLD, Australia) through Seafarm’s logistics
chain. Three days post-harvest, boxes were transported from truck depot to the
research facility inside iced one tonne insulated bins. On arrival at research facility
boxes were held at 3°C ± 0.5°C until sampling on days 3, 6, 10, 13, 14 and 17 postharvest. On sampling day a box from each of the packaging options and an MAP tray
were analysed for microbial and sensorial changes.
Packaging options
Two different packaging materials were trialled:
 Expanded polystyrene approved for seafood air transport (internal
dimensions 350x250x165 mm (LxWxH)) (Polyfoam, QLD, Australia), and
 PET lined cardboard carton (internal dimensions 350x250x165 mm (LxWxH))
(AMCOR, QLD, Australia)
Three different internal chilling agents were trialled for each packaging material:
 Plastic bag lining with 1 kg ice placed on top of prawns prior to sealing bag
 Plastic bag lining with 1.2 kg ice pack (Gel Ice Company, NSW, Australia)
placed on top of sealed prawns, and
 Absorbent pads (Thermasorb, VIC, Australia) and rigid plastic board placed at
the bottom of prawns with 1 kg ice on top.
Microbial analysis
Prawn samples. Two samples of five whole prawns were taken from each box, one
sample from top layer and other from bottom. Prawns were aseptically placed in a
stomacher bag (Biocorp, Australia) and homogenized at room temperature for 60 s
using a Lab Blender 400, Stomacher (Seward Medical, UK). A sub-sample (10 g) of
homogenized whole prawns was transferred aseptically into a filter stomacher bag
(PX0020S, Elmex, Japan) containing 90 ml of 0.1% peptone water and homogenized
for 60 s using a Lab Blender 400. For microbial enumeration a 1.0 ml sample of serial
dilutions (1:10, diluent, 0.1% peptone water) were mixed with 10 ml molten agar
using the pour plate method [AS 5013.5-2004]. For Total viable counts (TVC)
enumeration, Plate Count Agar (PCA, CM0463, Oxoid, Basingstoke, UK) was used and
counts were determined after incubation for 72 h at 30°C. For H2S-producing
bacteria (including Shewanella putrefaciens) Iron Agar (IA, CM 867, Oxoid,
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Attachment 1
Investigation into use of PET lined cardboard cartons as replacement for
expanded polystyrene boxes for packaging cooked, chilled farmed prawns
Basingstoke, UK) was used. After setting a 10 ml overlay of molten medium was
added. Iron agar plates were incubated for 72 h at 30°C and black colonies formed by
the production of H2S were enumerated. Two replicates of appropriate dilutions
were enumerated. Microbiological data were transformed into logarithms of the
number of colony forming units (CFU/g). All plates were examined visually for typical
colony types and morphology characteristics associated with each growth medium.
Drip loss and melted ice. 25 ml of liquid was drawn from each box using a sterile
plastic pipette into a sterile container. A sub-sample (1 ml) was transferred
aseptically into 9ml of 0.1% peptone water and mixed. Microbial, TVC and H2S
enumeration was performed as per prawn samples.
Sensorial analysis
Sensorial qualities of banana prawns were assessed using the Quality Index Scheme
for black tiger prawns (cooked) (Australian Seafood Quality Index Manual, 2009) with
appropriate modification with respect to colour. Through repeat trials, a preliminary
quality index scheme can be developed specific for banana prawns although this has
not yet been done. A group of 3-5 panellists trained in the Quality Index method
assessed prawns individually and held round table discussions until consensus on
each assessable parameter. Any notable changes not described on the black tiger
prawn QI Scheme were documented and monitored during storage.
Thermal properties
Preparation of trial was conducted at 3°C ± 0.5°C. Thermocouple wires were
attached to the inside top and inside bottom of two polystyrene and two cardboard
carton boxes. 5 kg cooked tiger prawns (Penaeus monodon) sourced from various
farms (QLD, Australia) were placed in each box and either 1 kg ice or an ice pack as
chilling agent placed on top. Boxes were closed and lids securely taped as per
commercial practices. Temperature was recorded with a DataTaker Data Logger
DT800 (Thermo Fisher Scientific, VIC, Australia) with a sampling rate of 1 minute. A
single thermocouple wire was freely recording ambient room temperature. Boxed
prawns were relocated to room temperature for 48 hours. Trial was replicated.
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3.
Attachment 1
Investigation into use of PET lined cardboard cartons as replacement for
expanded polystyrene boxes for packaging cooked, chilled farmed prawns
Results and Discussion
To limit contamination, and to ensure a starting microbial profile inline with product
in the retail sector, packaging of prawns was conducted onsite at Seafarm’s
processing facility. No changes were made to Seafarm’s processing practices with
the exception of substituting their current packaging material with the various
options being trialled. To maintain identical bacterial profiles within boxes prawns
used were all sourced from the same cooked batch. Unfortunately, due to the
processing setup of the farm, prawns for MAP had to be sourced from the batch
previous. However, since MAP prawns were from the same pond harvest and
processed identically in the same production line, the starting bacterial profile
should be near identical. Effects of handling and temperature on flora changes
during the distribution chain were kept identical to those experienced within retail
products by utilising Seafarm’s logistic network to transport samples to the research
facility.
The various packaging options presented were tested on their suitability to meet key
industry issues, namely recyclability, maintaining low microbial counts and
eliminating leakage. The custom designed PET lined cardboard cartons were
proposed by packaging company AMCOR, based on claims that they would solve
such issues. An improvement to previous designs, carton boxes were made from a
single piece of non-perforated cardboard and PET lined on both sides, affording
waterproof capacity to the rim. Dimensions were matched to polystyrene boxes
trialled to maintain equal headspace and surface area between packaging materials
and product. Chilling agents trialled were aimed towards removing either the use of
ice or the melted ice water.
On arrival at the research facility some polystyrene boxes were leaking because of
splitting and breakage sustained during distribution, confirming industry claims that
this malfunction is a frequent occurrence. Continued leaking was observed
throughout the shelf life storage trial. No such issues were identified from any of the
PET lined cardboard boxes. Though cardboard boxes did not leak other issues
inherent in their design were encountered. Carton boxes were devised as a two
component system; waterproof casement with fitted lid. This meant that a relatively
upright position must be maintained to prevent liquid from pouring over the lip of
the casement and running down the side of the lid. Though an improvement to the
current carton boxes used by industry, boxes of this design need careful handling
and stacking in an upright position and further development work is needed to
overcome this.
During chilled storage no obvious difference could be identified between microbial
counts from polystyrene and cardboard carton boxes but, variations were noticed
within individual boxes. It should be noted that microbial counts depicted are best
observed as a trend over the total storage period rather than absolute for any one
sampling time. This is because the count achieved by the plating method may vary
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CRC 2010-707MPR 4
Attachment 1
Investigation into use of PET lined cardboard cartons as replacement for
expanded polystyrene boxes for packaging cooked, chilled farmed prawns
by ±0.5 log cfu due to metabolic and physiological factors associated with solid agar
plating.
Total volatile counts from prawns located on the top layer of the majority of boxes
were found to be higher than prawns located at the bottom (Figure 1- Figure 4). This
pattern was consistently encountered and found to be independent of packaging
material or chilling agents used. However, counts were only marginally different and
could be representative of the standard error within laboratory analysis or the result
of a limited sampling size or localised concentration in flora populations within
prawn samples analysed. Further replicates would need to be performed to confirm
if this profile is the naturally prevalent pattern. It is also interesting to note that
many of the microbial populations showed a ‘drop’ in organisms present between
day 14 and day 17 of storage. This currently is unexplained but does not appear to
be directly related to chilling agent nor box type. Again replication of trial would add
more information. Very similar trials are being designed in which microbial
population shifts are to be determined.
Figure 1 - Total viable count on prawns in polystyrene and carton boxes with ice as chilling agent.
8
Polystyrene top
Polystyrene bottom
Carton top
7
Carton bottom
Log CFU/g
6
5
4
3
0
2
4
6
8
10
12
14
16
18
Days from harvest
If symbolic of flora evolution during cold storage, these results would run contrary to
general industry belief that pooled liquid at the bottom of packaging (composed of
melted ice water and drip loss) imparts a higher bacterial count in soaked prawns
(pers. comms.). Analysis of liquid from all boxes during the storage trial (Figure 5)
found this not to be the case. Microbial loads remained relatively constant at around
105 CFU/g until day 13 where a sharp increase was noticed. Towards end of storage
micro counts from several prawn samples were found to be well above 106 and some
over 107 CFU/g. Contrarily, micro loads of liquid from corresponding boxes were
found to be lower with some counts upwards of a log scale different.
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CRC 2010-707MPR 4
Attachment 1
Investigation into use of PET lined cardboard cartons as replacement for
expanded polystyrene boxes for packaging cooked, chilled farmed prawns
Figure 2 - Total viable count on prawns in polystyrene and carton boxes with ice pack as chilling
agent.
8
Polystyrene top
Polystyrene bottom
Carton top
Carton bottom
7
Log CFU/g
6
5
4
3
0
2
4
6
8
10
12
14
16
18
Days from harvest
(Fig 2. The Day 17 data point for polystyrene is missing as was incorrectly packaged on-farm)
Figure 3 - Total viable count on prawns in polystyrene and carton boxes with ice as chilling agent
and absorbent pads.
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Polystyrene top
Polystyrene bottom
Carton top
7
Carton bottom
Log CFU/g
6
5
4
3
0
2
4
6
8
10
12
14
16
18
Days from harvest
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CRC 2010-707MPR 4
Attachment 1
Investigation into use of PET lined cardboard cartons as replacement for
expanded polystyrene boxes for packaging cooked, chilled farmed prawns
This documentation of flora evolution supports the idea that there will be potential
benefits gained by topical applications of an antimicrobial solution during packaging.
As generally expected, microbiological counts for MAP prawns were lower than for
prawns from other packaging options. Shelf life extension through MAP was quite
obvious with counts < 106 CFU/g throughout storage. Unfortunately, due to the high
capital required to install and maintain a MAP system this option would only be
viable for a select few growers/processors within the industry.
Figure 4 - Total viable count of MAP prawns.
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MAP top
MAP bottom
7
Log CFU/g
6
5
4
3
0
2
4
6
8
10
12
14
16
18
Days from harvest
Comparisons between chilling agents identified a distinct suppression of microbial
growth during cold storage when gel packs were substituted for ice. Differences in
counts of up to one log unit were identified towards end of storage. This result
highlights that ice is a secondary source for bacterial contamination and is a less
efficient inhibitor of growth, most likely due to a relatively faster melting time.
With sensorial analysis, no discernable difference could be found by visual
comparison of prawns chilled by ice or with gel packs. Prawns from boxes containing
gel packs were described as having superior flavour and texture. This has been
attributed to the fact that no melting ice water is present to leach out flavours and
salt. Though an extension in shelf life whilst maintaining quality was achieved, when
the idea was presented to industry, the cost of implementation was found to be
unviable. A cheaper alternative to the polyethylene sealed gel packs trialled are dry
sheets requiring hydration prior to freezing. However, previous trials conducted by
industry (Lewis, APFA, pers. comm. 2011) resulted in an inferior product when
incorporating hydrating ice sheets. Prawns were described as having a ‘dry’
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CRC 2010-707MPR 4
Attachment 1
Investigation into use of PET lined cardboard cartons as replacement for
expanded polystyrene boxes for packaging cooked, chilled farmed prawns
appearance, most likely due to the continual absorption of these sheets, which led to
the abandonment of further research. Unfortunately this leaves wet ice as still the
only feasible option to provide a chilled environment within packaging during cold
storage. A suitable replacement for wet ice is an issue being worked on globally with
no commercially viable alternatives found to date (Paw Dalgaard, Denmark,pers
comm, 2011). Inclusion of pads to absorb melted ice water with a floating semi-rigid
plastic sheeting to separate prawns from pads and ice water was also trialled.
Though enough pads were used to absorb the melted ice water twice over, liquid
was still pooling at bottom of boxes. On further investigation, pads were observed to
release captured moisture when excessive force is applied on top, such as 5kg of
prawns. To be of functional benefit to industry an absorbent pad robust enough to
retain moisture under pressure would need to be developed. Consultation with
manufacturers yielded no such product available.
Figure 5 - Total viable count of pooled liquid at bottom of boxes.
8
Polystyrene with ice
Carton with ice
Polystyrene with ice pack
Carton with ice pack
7
Polystyrene with absorbent pad
Carton with absorbent pad
MAP
Log CFU/g
6
5
4
3
0
2
4
6
8
10
12
14
16
18
Days from harvest
Another major requirement for packaging materials of chilled products is to offer an
acceptable level of insulation from temperature abuse. Figure 6 and
document the changes in internal temperatures between chilled polystyrene
and carton boxes when subjected to thermal abuse.
Figure 7
Once exposed to room temperature an immediate rising of internal temperatures in
both packaging materials was noticed. Polystyrene quickly rose to an internal
temperature of 5-7°C and cardboard cartons rose to 10-13°C. Though the initial rise
in temperature experienced inside carton boxes was higher than that of polystyrene
the rate at which the internal temperature was warming remained relatively
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CRC 2010-707MPR 4
Attachment 1
Investigation into use of PET lined cardboard cartons as replacement for
expanded polystyrene boxes for packaging cooked, chilled farmed prawns
constant between packaging materials irrespective of chilling agents used. This
constant rate of warming suggests that the carton boxes used offer similar insulation
to that of polystyrene under certain environments. However, further design
improvements by AMCOR will need to occur to reduce the initial spike in internal
temperatures experienced during first exposure to thermal abuse. Comparison of
chilling agents identified ice packs as the better performer in maintaining a chilled
environment.
Figure 6 - Insulation profile of polystyrene and carton boxes with either ice or ice packs as chilling
agents (Replicate 1).
30
25
20
Temperature (°C)
Ambient
15
Polystyrene ice top
Polystyrene ice bottom
Carton ice top
10
Carton ice bottom
Polystyrene ice pack top
Polystyrene ice pack bottom
5
Carton ice pack top
Carton ice pack bottom
0
0
4
8
12
16
20
24
28
32
36
40
44
48
-5
-10
Time (hrs)
Figure 7 - Insulation profile of polystyrene and carton boxes with either ice or ice packs as chilling
agents (Replicate 2).
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CRC 2010-707MPR 4
Attachment 1
Investigation into use of PET lined cardboard cartons as replacement for
expanded polystyrene boxes for packaging cooked, chilled farmed prawns
30
25
Temperature (°C)
20
Ambient
15
Polystyrene ice top
Polystyrene ice bottom
Carton ice top
10
Carton ice bottom
Polystyrene ice pack top
5
Polystyrene ice pack bottom
Carton ice pack top
Carton ice pack bottom
0
0
4
8
12
16
20
24
28
32
36
40
44
48
-5
-10
Time (hrs)
An 8 to 10 hour exposure at room temperature (Figures 8 and 9) was sufficient
enough to melt ice and induce a dramatic increase in temperature within the
headspace of carton boxes in both replicates and in polystyrene during one of the
replicates. It took until the fourteenth hour for ice to melt in polystyrene within the
other replicate. This created a large differential in temperatures between the top
and bottom of boxes utilising ice. This dramatic change in the rate of warming was
not observed in boxes containing ice packs. Instead, a consistent increase in
temperature was logged and limited temperature differentials between top and
bottom was noticed. An unexplainable observation was the similar melting times of
ice within both packaging materials despite the difference in temperatures.
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CRC 2010-707MPR 4
Attachment 1
Investigation into use of PET lined cardboard cartons as replacement for
expanded polystyrene boxes for packaging cooked, chilled farmed prawns
Figure 8 - First 8 hours insulation profile of polystyrene and carton boxes with either ice or ice packs
as chilling agents (Replicate 1).
30
25
20
Temperature (°C)
Ambient
Polystyrene ice top
15
Polystyrene ice bottom
Carton ice top
10
Carton ice bottom
Polystyrene ice pack top
Polystyrene ice pack bottom
5
Carton ice pack top
Carton ice pack bottom
0
0
1
2
3
4
5
6
7
8
-5
-10
Time (hrs)
Figure 9 - First 8 hours insulation profile of polystyrene and carton boxes with either ice or ice packs
as chilling agents (Replicate 2).
30
25
20
Temperature (°C)
Ambient
Polystyrene ice top
15
Polystyrene ice bottom
Carton ice top
10
Carton ice bottom
Polystyrene ice pack top
Polystyrene ice pack bottom
5
Carton ice pack top
Carton ice pack bottom
0
0
1
2
3
4
5
6
7
8
-5
-10
Time (hrs)
Drip water loss was not measured in these trials as the prawns were packed out onsite according to farm standard practice. Hence accurate and initial weight of prawns
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CRC 2010-707MPR 4
Attachment 1
Investigation into use of PET lined cardboard cartons as replacement for
expanded polystyrene boxes for packaging cooked, chilled farmed prawns
or ice added to the boxes could not be obtained without severe interference with
the production line operation.
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CRC 2010-707MPR 4
4.
Attachment 1
Investigation into use of PET lined cardboard cartons as replacement for
expanded polystyrene boxes for packaging cooked, chilled farmed prawns
Situation Summary
Historically, chilled prawns were packed out and transported in polystyrene boxes
for distribution within the supply chain. The advantages of this packaging form are:
boxes are inexpensive; light-weight which minimises transport costs; provided
excellent temperature insulation during different stages of transport; and are
available in different polymer grades with concomitant differential in cost per unit;
the heavier grades demonstrated good integrity of pack though the multiple
handling steps in the supply chain. However, polystyrene boxes have several
disadvantages: when lighter grade and cheaper polymers are chosen package
integrity is easily lost through prawn rostrum damage as well as transport handling
damage; medium to light grade polymer material also is porous and so allows
leakage of meltwater where flake ice is used as coolant. The major problem with
polystyrene packaging is that the box is not recyclable and hence use can incur heavy
disposal costs at receival end of the chain. Primarily due to this latter issue, the retail
sector is demanding alternative packaging formats, with the major retailers not
accepting product if received in polystyrene, although polystyrene boxes currently
remain acceptable within the food service sector. Therefore, the industry is seeking
alternative packaging options to polystyrene.
Cardboard cartons were viewed as a likely functional alternative as they are used
widely, and highly successfully, within the horticultural product industry. Packaging
companies have developed a range of practical carton types, including products with
and without wax coatings to prevent moisture leakage. The latter appears to be a
feasible option for the prawn industry however, again they are not readily recyclable
and therefore not acceptable to the major retailers. Hence the focus turned to plain
cardboard boxes which are available commercially as a two-part product – base and
lid – and in flat-pack format to minimise cost of transporting and storage while
empty. However, several issues are associated with this packaging format. Inherently
cardboard cartons exhibit poor temperature insulation capacity and so there is a
need for use of a chilling agent within the pack to hold temperature. The Prawn
Industry wish to use flake ice as the chilling medium for maintaining chill
temperature along the chain as it is readily available on-farm at packout point,
relatively cheap and has excellent chilling properties. Flake ice does have the
disadvantage of adding to total package weight which can be significant for air
transport although a minor issue in road transport.
Flake ice has an added benefit of keeping the prawn product moist during
distribution. This causes another issue however, as moisture from melting ice
reduces cardboard integrity and results in leakage during transport and storage.
Within the trials described in this report, use of coolant pads was investigated with
high success with respect to chill temperature maintenance. However, these too
have inherent issues associated: they require pre-freezing prior to packout and use
which for the volumes of product involved during large harvests commandeers a
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CRC 2010-707MPR 4
Attachment 1
Investigation into use of PET lined cardboard cartons as replacement for
expanded polystyrene boxes for packaging cooked, chilled farmed prawns
great deal of freezer space. Additionally, they are quite a bit more expensive than
flake ice hence adding significantly to the cost per kilo of product.
Other issues arising from the use of cardboard cartons include the physical structure
of the box. When held perfectly level leakage is minimal in the short term. However,
cartons maintained in a level position throughout the multiple transport handling
steps is not able to be assured and hence the likelihood of leakage onto other
palleted products during final stages of distribution is high. To combat this issue, use
of a polyethylene liner within the carton was trialled and reduced leakage to some
extent although the heavy gauge material required to be impervious to damage by
prawn rostrums is an expensive option and did not negate leakage when boxes were
tilted beyond a certain point. The use of plastic liners added a new problem – that of
prawns “sweating” during transportation. This phenomenon results in increased
‘slime’ and odour volatiles at package opening creating a negative reaction in the
marketplace. Despite the associated issues, some industry members are using
cardboard cartons for transport of product, but usually only where the distribution
chain is short.
Because of the inherent issues with the packaging forms listed above, the prawn
industry are still seeking a practical and functional alternative. The industry has
recently investigated the use of plastic (polypropylene) tubs with a clip on lid. These
are similar to the 10kg plastic pails used many years ago to transport prawns but the
shape is rectangular rather than the original tall cylindrical pail which resulted in
physically crushed prawns in the bottom 5kgs of product. The advantage of this
packaging format is the high integrity of the packaging material – prawn rostrums
cannot pierce polypropylene and handling damage to the pack is unlikely.
Additionally, leakage issues – even where flake ice is included – are much reduced so
long as the lid stays firmly in place. There remain some potential issues to address
however:

the containers are of solid structure and although stackable still require more
space when empty than flat-pack cardboard cartons hence transport and
storage costs are higher;

in themselves they are not cheap

and the temperature insulation ability needs to be established.
The material used in construction of these tub containers is able to be recycled
within the plastics sector but requires a thorough washing-clean step by the retail
sector staff before inclusion with other plastic recyclables. This will require training
and monitoring by the retailer management.
Currently, some industry members have taken up using these plastic tubs and the
wider industry is keen to gain feasibility data on their use, especially with respect to
temperature holding capacity and overall cost. Consequently, these tubs will be
included in the next storage trials currently being arranged for conduction with
industry on farm sites. These scale-up trials will also include optimised antimicrobial
solutions that are both commercially feasible and all natural (see Attachment 2) to
determine the extension to shelf life of cooked chilled prawns in bulk packs.
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CRC 2010-707MPR 4
Attachment 1
Investigation into use of PET lined cardboard cartons as replacement for
expanded polystyrene boxes for packaging cooked, chilled farmed prawns
On-going discussions with packaging companies will continue to seek alternatives
feasible for the prawn industry. Additionally, continued dialogue with Paw Dalgaard
(Seafood expert, Denmark) is occurring prompted by his raising exactly the same
issues on a Seafood Discussion list (December, 2011) seeking any information of
alternative systems to the use of wet ice. Paw is known to the PI of this project and is
very happy to share information with us and the Australian industry.
5.
References
AS 5013.5-2004. Food microbiology - Microbiology of food and animal feedings
stuffs - Horizontal method for the enumeration of microorganisms - Colony
count technique at 30°C. AS 5013.5-2004. Sydney, N.S.W.: Standards Australia
International
BOULTER, M., POOLE, S. & BREMNER, A. (2009) Australian quality index manual - A
tool for evaluating changes in chilled seafood. Fisheries Research and
Development Corporation and Sydney Fish Market, 2009.
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