Evaluating performance of beef,lamb, pork & poultry system€¦ · Confidential Client Report...

Evaluating performance

of beef,lamb,

pork & poultry

in the FoodCap

system

Sept 2015

Confidential Client Report 15-707

Client name: FCI

Final report: Sept 2015 of 37

This report has been prepared for the CLIENT and is CONFIDENTIAL to that organisation and Carne

Technologies Ltd. Carne Technologies Ltd will not disclose its contents to third parties unless directed to

do so by the client.

Every effort has been made to ensure this report is accurate. However, because research and

development can involve extrapolation and interpretation of uncertain data, Carne Technologies will

not be responsible for any error or omission in this report unless specifically agreed otherwise in writing. To

the extent permissible by law, neither Carne Technologies nor any person involved in this report accepts

any liability for any loss or damage whatsoever that may directly or indirectly result from any advice,

opinion, representation, statement or omission, whether negligent or otherwise, contained in this report.

Dr Nicola Simmons

General Manager

Enquiries or requests to:

Carne Technologies Ltd

4 Matos Segedin Drive 3495

PO Box 740, Cambridge 3450

New Zealand

Email: [email protected]

Phone: +64 7 827 0731


Client name: FCI


Contents

Executive summary .................................................................................................................................... 5

Declaration .................................................................................................................................................. 8

Background to the FoodCap system ..................................................................................................... 8

Meat storage in FoodCaps using modified atmospheres ......................................................... 9

Outline of trial design ............................................................................................................................... 10

Sample collection and packing ................................................................................................... 11

Microbiological assessments ......................................................................................................... 12

Purge losses ....................................................................................................................................... 13

Retail display ..................................................................................................................................... 13

Tenderness measurements............................................................................................................. 13

Manufacturing Trim - Mince trials .................................................................................................. 13

Chicken Portion trials ....................................................................................................................... 14

Results ......................................................................................................................................................... 14

Pre-packing ........................................................................................................................................... 14

Oxygen measurements .................................................................................................................. 14

APCs ................................................................................................................................................... 15

EBCs .................................................................................................................................................... 15

Conclusion......................................................................................................................................... 16

Post storage microbiology – beef, pork & lamb. ........................................................................... 16

Aerobic plate counts (APCs) ......................................................................................................... 16

Enterobacteriaceae counts (EBCs) ............................................................................................. 18

Effects of reducing CO2 concentration. ..................................................................................... 20

Conclusions ....................................................................................................................................... 21

Purge losses ........................................................................................................................................... 22

Conclusion......................................................................................................................................... 25

Product appearance during retail display ..................................................................................... 26

Beef retail display performance ................................................................................................... 27

Pork retail display performance .................................................................................................... 28

Lamb retail display performance ................................................................................................. 29

Conclusion......................................................................................................................................... 30

Tenderness ............................................................................................................................................. 30

Conclusion......................................................................................................................................... 32

Results – Beef and Pork Trim ............................................................................................................... 32

Microbiology ..................................................................................................................................... 33

Conclusion......................................................................................................................................... 35

Results – Poultry ..................................................................................................................................... 36


Client name: FCI


Microbiology ..................................................................................................................................... 36

Purge losses ....................................................................................................................................... 37

Conclusion......................................................................................................................................... 37


Client name: FCI


Executive summary

The FoodCap chilled meat storage system offers a radical alternative to the traditional system

that is based on vacuum packaging individual primals and packing them into cardboard

cartons or plastic crates for storage and transport (VP system). The FoodCap system is based

on bulk packaging up to 170 kg of primal cuts into individual FoodCap containers, a system

that is intended to allow new opportunities and efficiencies in materials handling.

An essential requirement for any novel meat storage system is to demonstrate that it can at

least match or surpass existing systems in terms of product storage life, food safety and product

quality. To this end, FoodCap International Ltd contracted Carne Technologies to undertake

an extensive comparison between the FoodCap system and a conventional vacuum packing

storage system: this comparison considers a range of species (beef, pork, lamb, poultry), a

range of primal cuts within each species, and a range of storage times for each of the primals

(up to 63 days in beef and lamb, 35 days in pork, 21 days in beef and pork trim and 16 days in

poultry). After storage, the assessment evaluated microbiological status of the product, the

magnitude of purge losses during storage, effects on retail display life and on the tenderness

of the product.

Two forms of the FoodCap system have been developed:

The P1 (primal compression system) is limited to boneless product and applies and maintains

a mechanical compression of the product to remove air voids. It is then vacuumed and gas

flushed to sustain an oxygen free environment for the meat. CO2 is only used to gas the head

space above the compression platen to avoid spoilage of meat exposed to the head space.

In the P1 configuration, individual FoodCaps can store up to 170kgs of chilled primals or

manufacturing trim.

The P2 (deep vacuum gas flush system) can be used for both bone-in and boneless product

and places the primals on a shelving system that fits inside the FoodCap. The shelves prevent

compression of the product during storage. Atmospheric oxygen is removed via FoodCaps

deep vacuum process and replaced with a modified atmosphere. This report evaluates the

P2 gas flushed system, based primarily on a 50% CO2/50% N2 gas mix. In the P2 configuration

individual FoodCap’s can store up to 150kgs of primals and 170kgs of chicken portions.

Effective chilled storage of meat depends critically on maintaining the product in very low

oxygen. This requires that oxygen is thoroughly removed from the FoodCap after packing, and

that oxygen is effectively prevented from diffusing into the FoodCap during storage. Direct

measurements of oxygen in 8 FoodCaps showed levels below 1 ppm (the limit of detection)

immediately after packing and gas flushing at the start of the storage period. After storage

periods of 21 to 35 days, the concentrations were still below 1 ppm in 7 FoodCaps, and

increased to 14 ppm in the remainder. These results indicate a better exclusion of oxygen than

conventional barrier bags, which typically allow transmission of 10-15 cc O2/m2/24hrs/atm.

The control of microbial growth during storage was assessed by measurements of aerobic

plate counts (APCs) to provide a non-specific count of organisms, and of Enterobacteriaceae

(EBCs) to provide a more specific measure of a class of spoilage organisms. None of the

product reached the point of overt spoilage with either the FoodCap or VP systems after any

of the storage periods evaluated. However, generally the FoodCap system consistently

resulted in lower APCs and EBC’s in all species and cuts than the VP across all periods of

storage.


Client name: FCI


The slower bacterial growth in the FoodCap system can be attributed to the presence of CO2

in the modified atmosphere of the FoodCaps. A preliminary comparison of bacterial growth

with alternative gas mixes found that 30% CO2/70% N2 continued to show improvements

relative to VP, but 100% N2 was equivalent.

Purge losses were also generally better in the FoodCap compared with VP. An explanation for

this improvement is not obvious, but may relate to the absence of physical contact with the

surface of a significant portion of the primals when they are placed on shelves, compared with

complete contact when encased in a vacuum bag. The physical contact may be

contributing to the movement of purge to the surface of the primals through surface tension

effects.

Retail display was assessed in overwrap and MAP retail tray systems. In general, little difference

was evident between the storage systems. Some beef topsides discoloured sooner in the MAP

system after storage in the FoodCaps, but this is attributed to the release of CO2 from the meat

after retail packing, leading to restricted oxygenation of the surface of the cut. Pork cuts

showed a marked improvement in appearance during retail display after storage in the

FoodCaps, particularly when displayed in overwrap, an effect attributed to better exclusion of

O2 during storage in the FoodCaps compared to VP.

The suitability of the FoodCap system for bulk storage of trim was assessed for periods of

between 7 and 21 days. APCs and EBCs increased minimally during this interval and averaged

less than 1000 cfu’s (< log 3), demonstrating that microbial growth was effectively controlled

during this period.

Purge losses were too low to measure accurately. Mince manufactured from the trim

continued to show good colour and retail colour stability once removed from the FoodCap

storage and assessed for retail display in either overwrap or MAP packs, although the 21 day

product was reaching the limit of colour acceptability after 10 days in MAP retail display.

Bulk chilled storage of poultry pieces (skinless/boneless breasts, skinless/bone-in thighs and skin

on/bone-in drumsticks) were also assessed for periods of between 8 and 16 days. By 16 days,

APCs and EBCs were still within very acceptable values, averaging approximately 3000

cfu’s/cm2 (log 3.5) and EBC approximately 70 cfu’s/cm2 (log 1.8). Purge losses in the breasts

and thighs were very low, averaging between 0.15 and 0.5%. Drumsticks showed much higher

losses, averaging up to 4.2%. The purge from the drumsticks also had a much lower viscosity

than purge from the breasts and thighs, possibly suggesting some of the fluid is actually water

from the immersion chilling of the carcasses that was being lost, rather than just losses from the

leg meat itself.

Tenderness, as assessed by cooked shear force, was not affected by the method of storage.

Summary:

• The FoodCap system provided very effective exclusion of atmospheric oxygen at the

start of the storage period, and was very effective at preventing oxygen ingress

during chilled storage. This is a critical requirement to delay spoilage and protect

quality attributes during extended chilled storage.

• The use of a 50% CO2/50% N2 modified atmosphere in the FoodCaps provided the

expected bacteriostatic effect that resulted in better microbial control than the VP

system.


Client name: FCI


• The FoodCap system also provided an unexpected (and as yet unexplained) benefit

in purge losses in the red meat primals, while some improved retail colour in pork can

probably be attributed to better control of oxygen ingress during storage.

The FoodCap provides a very effective bulk storage medium for extended chilled storage of

trim and chicken portion, through effective control of microbial growth and management of

purge losses.


Client name: FCI


Declaration

FoodCap International contracted Carne Technologies to evaluate the FoodCap system and

compare its performance with the conventional vacuum packaging system.

All the trials reported here were carried out by Carne Technologies staff. This includes collecting

the trial samples in the boning room and packing the samples in either FoodCaps or vacuum

packs. After packing, the product was transported to, and stored at, the Carne Technologies

laboratory. All product was unpacked and measurements of microbiology, meat quality and

residual oxygen in the FoodCaps were carried out at the Carne Technologies laboratory.

Background to the FoodCap system

The FoodCap system constitutes a meat packaging, preservation and material handling

system for fresh meat. The FoodCap system differs fundamentally from the procedures

currently in use in the fresh meat supply chain, where the industry standard is based on sealing

individual primal cuts in disposal barrier bags and packaging these in cardboard cartons or

plastic crates.

The FoodCap system is based on 3 key components:

1. The FoodCap provides a rigid and re-useable bulk storage container able to store up

to 170 kgs of meat in each FoodCap

2. The FoodCap employs either an anaerobic or carbon dioxide (CO2) -enriched

environment to control the growth of spoilage organisms and provide extended

storage life for fresh meat

3. The design of the FoodCap provides the basis for an alternative material handling

system to the conventional cardboard carton or plastic crate.

Both the FoodCap and conventional meat storage systems employ the same underpinning

principle to control the growth of spoilage organisms and extend chilled meat storage life. The

key requirement in these systems is to produce and maintain an essentially oxygen-free

environment to discourage aerobic spoilage organisms and encourage the growth of low

spoilage-potential lactic acid bacteria. This process of creating an environment that selects

for the most beneficial microorganisms is combined with low temperatures during storage to

maximise storage life by slowing microbial metabolic activity and growth rates.

Beyond using an anaerobic and low temperature environment, a further option to increase

chilled storage life is to employ a modified atmosphere enriched with CO2. Elevated CO2

concentrations directly suppress microbial growth compared with a solely anaerobic

environment, and the slower growth of microorganisms extends chilled storage life. An

example of this technology is the CapTech gas flush pouch system that uses a 100% CO2

atmosphere.

The FoodCap system can be configured for chilled storage of meat in two ways: the first

involves packing meat cuts in the FoodCap and then applying and maintaining mechanical

compression of the packed meat to create a single ‘block’ of meat; this compression

evacuates air from voids between the packed cuts and create an anaerobic environment.

The compression also contributes to reducing purge losses by equilibrating pressure around the

cuts and reducing void spaces between the cuts. The head space above the top platen that


Client name: FCI


is used to apply the mechanical compression is then evacuated and replaced with 100% CO2.

This CO2 atmosphere in the head space is used to remove O2 and avoid spoilage of the top

layer of meat around the platen, but the CO2 does not diffuse beyond the top layer.

The second alternative is to place individual primals on a proprietary shelving system designed

to fit within the FoodCap; the shelves separate the cuts into multiple levels and avoids

compression of the cuts during storage. After packing, the atmosphere in the FoodCap is

evacuated and replaced with an appropriate modified atmosphere, typically based on a

CO2 -enriched atmosphere.

The general principles that underpin the ability of either anaerobic or high CO2 environments

to manipulate microbiological ecology and extend the storage life of chilled meats are

generally well defined, and these principles are common to both the bulk FoodCap storage

system and barrier bag packaging of individual primal cuts. However, it is essential to

understand how these principles interact with the packaging systems and how they are

implemented, as these interactions can have important effects on the quality of the meat and

its microbial status at the end of a chilled storage period.

This report describes the results of a direct comparison of the effects of chilled storage in the

modified atmosphere FoodCap system with storage in conventional vacuum packed barrier

bags. A range of chilled storage periods was compared for beef, lamb, pork and chicken

product.

Meat storage in FoodCaps using modified atmospheres

The industry standard for storage of chilled meats is based on vacuum packaging using barrier

bags. The flexible barrier bags means that the atmosphere can be easily removed from the

bag using a vacuum, which reduces residual O2 concentrations to trace levels. The barrier

material has very limited permeability to O2, and the vacuum pack (VP) system therefore

provides a simple process to create the anaerobic environment that allows extended chilled

storage of meat.

Although an effective storage system, the VP system requires individual packaging of each

cut and further packaging into cartons or crates. Bulk storage systems exist that use rigid

thermoform trays but, because the tray cannot be collapsed, reducing residual O2 to

adequately low levels (less than 0.05% or 500 ppm) is more difficult. Without adequate control

of O2, the residual oxygen can discolour the meat surfaces by oxidising myoglobin to the brown

metmyoglobin, and can allow faster growth of spoilage organisms. As a result, additional steps

are needed to protect the product, either by chemical oxygen scavenging, or use of carbon

monoxide to protect the meat myoglobin against oxidation.

The FoodCap system uses a proprietary gas evacuation and injection system that overcomes

the difficulty of residual O2 in a rigid container. The design of the FoodCap allows a rapid

evacuation of atmospheric gases to very low residual pressure and replacement with a

modified atmosphere. This procedure results in residual O2 concentrations below the 1 ppm

limit of detection.

The further consideration in using a rigid container such as a FoodCap in conjunction with high

CO2 atmospheres is the high solubility of CO2 in meat: approximately 1 L of gas dissolves in

each kilogram of meat. This creates significant volume changes that are easily

accommodated by collapsible barrier bags, but a rigid container such as a FoodCap will be


Client name: FCI


subjected to negative internal gas pressures that could, potentially, affect its ability to seal out

atmospheric oxygen.

A gas that has low solubility in meat, such as nitrogen (N2), is an alternative to CO2 that can

maintain an anoxic environment comparable to VP while causing only minimal pressure

changes. This option lacks the additional bacteriostatic benefit offered by CO2. Alternatively,

the CO2 concentration can be reduced by mixing with a less soluble gas.

However, there is limited information on the effects of reducing the CO2 concentrations in

anoxic gas mixtures on microbial growth and overall storage life during extended chilled

storage, although 20-30% CO2 are recognized to produce a bacteriostatic benefit in high

oxygen modified atmosphere retail packs. For the trials reported here, the principle gas mix

was 50% N2 and 50% CO2, which avoided excessive pressure changes associated with CO2

dissolving into meat while still obtaining some bacteriostatic benefits of CO2.

Outline of trial design

The objective of this evaluation of the modified atmosphere FoodCap system is to

demonstrate suitability of the FoodCap system as an alternative to vacuum packaging

systems for extended storage of chilled meats. The suitability of the FoodCap system is based

on the following indicators:

1. Effect on microbial growth during storage

2. Effect on purge losses during storage

3. Effect on colour and colour stability during subsequent retail display

4. Effect on tenderness, as measured objectively by shear force

Throughout the trials (with the exception of trim and chicken pieces), the comparisons were

made between pairs of primals from the same carcass, using one as the FoodCap sample and

the contralateral side as the VP sample. This design was to minimise variability caused by

intrinsic differences between different carcasses.

After vacuum packing, the VP samples were placed on shelves inside FoodCaps and

maintained under the same storage conditions as the test FoodCaps. This arrangement was

designed to maintain equivalent temperature conditions for the two packaging systems. All

the FoodCaps (containing either the FoodCap test product or VP product) were transferred

to a storage chiller where they were held for the duration of the storage period.

The performance of the FoodCap system was assessed in 4 species:

1. Beef

2. Pork

3. Lamb

4. Chicken

For each species, a number of different primal cuts were assessed at a range of storage

periods. In addition to whole primals, the trials included an evaluation of the effects of storage

on beef and pork trim (Table 1).


Client name: FCI


Table 1. Summary of trial design

Species

Storage duration Primal

Beef 21, 42 & 63 days

Striploin

Scotch fillet (ribeye)

Rump

Topside

Pork 14, 21, 28 & 35 days

Bone-in loin

Rump

Topside

Belly

Lamb 21, 42 & 63 days

Bone-in shoulder

Bone-in leg

Bone-in short loin

Beef and Pork

Trim 7, 14 & 21 day Trim

Chicken 8, 10, 12, 14 & 16 days

Skin-off boneless breast

Skin-off boneless thigh

Skin-on drumstick

Sample collection and packing

For the trials involving beef, pork and lamb, a direct comparison was made between product

stored in FoodCaps and VP. In the cases of trim (beef and pork) and chicken portions, the

comparison with VP was not made: the storage trials only evaluated performance in the

FoodCaps, and all measurements were assessed on their own merits rather than with reference

to a VP product.

Where both primals were collected from the same carcass, the cuts were marked on the

carcass in the side chillers before the boning room and collected after boning and trimming.

Any additional product used solely to fill the remaining space in the FoodCaps was collected

at random from the boning line.

The pH of all test product was measured prior to packing in the FoodCaps and any samples

with a pH of greater than 5.8 were not included in either the FoodCap or vacuum pack

treatments.

The packing and storage of the test product was carried out as close as possible to

commercial conditions. The trials were carried out in a commercial boning room that currently

uses the FoodCap system alongside a conventional VP storage system. Separate lines in a

single boning room provided beef, lamb and pork primals. Chicken portions were processed

in the chicken boning room; carcasses were supplied directly from an external supplier as


Client name: FCI


whole chilled carcasses, and the chicken carcasses were then boned into pieces that were

transferred directly into the FoodCaps.

All product selection and packing into either FoodCaps or VP took place during normal

commercial processing.

Because of the multiple shelves in the FoodCaps, test samples were distributed at different

levels to ensure that all the positions within the FoodCap were represented in the trials. The

FoodCaps were filled to a standard, commercial final weight with additional product

collected at random. The typical final weight of meat in the FoodCaps was approximately

130-150 kg.

The atmosphere in the FoodCap was then evacuated and refilled with a modified

atmosphere, in most cases a 50% CO2/50% N2 gas mix. Tests measurements of residual O2

showed that the residual concentrations after flushing were less than 1 ppm.

The vacuum packing was carried out using the plant equipment and Cryovac A600 high shrink

barrier bags (50µm) for boneless product, and Cryovac Z1 (75µm) for bone-in pork and lamb

primals. These barrier bags provide medium to high barriers to oxygen permeability

(depending on the heat shrinking conditions); manufacturer data specify oxygen permeability

rates of less than 40 ml/24 hours/m2 before shrinking, and an expected permeability of 12-15

units after shrinking.

In order to maintain a storage environment for the VP product as equivalent as possible to the

FoodCap product, the VP product were stored on shelves, one layer deep, inside a FoodCap,

and these FoodCaps were stored together with the FoodCap trial samples.

In general, for each storage duration (time point) 3 or 4 separate FoodCaps were used. Within

each FoodCap, typically 2-3 primals were labelled and used for comparison with the

contralateral cut packaged as VP.

All FoodCaps were stored in chillers maintained at between 0 and 2°C. Temperature

conditions at every stage of the trial were monitored using temperature loggers.

Microbiological assessments

Surface swabbing over a 25 mm2 area was used for all samples, except with chicken pieces

and trim where a 5 mm2 swab area was used.

Measurements were made for Aerobic Plate Counts (APC) and for Enterobacteriaceae

Counts (EBC). The APCs provide a relatively non-specific measure of the total number of

colony-forming organisms, while the EB measurements provide a more specific measure of a

family of organisms that make an important contribution to meat spoilage.

On each packing day, 5 randomly selected cuts of the type being packed on the day were

sampled in the boning room to provide a measure of the initial microbial counts before

packing. In addition, the paired samples (used for direct comparison of FoodCap with VP)

were also tested before packing.

Microbial measurements were made again at the end of each storage period. In these cases,

measurements were made from the paired test samples to allow a direct comparison of the

FoodCap and VP storage systems.


Client name: FCI


Purge losses

Each of the paired test cuts were weighed before packaging. At the end of the storage

period, the cuts were reweighed and the weight difference was taken as the purge loss during

storage.

Retail display

At the end of the storage period, the test product was assessed for appearance in simulated

retail display. Retail display of the product used either a conventional PVC overwrap on

Styrofoam trays, or a sealed modified atmosphere pack using a mixture of 80% O2 and 20%

CO2. Beef and boneless pork primals were sliced into 20 mm individual steaks. Bone-in lamb

loins and pork loins were boned out, then sliced into 20 mm steaks.

As an indicator of the effects of the storage periods on lamb legs, the topside was boned out

from each pair of lamb legs and sliced through the main body of the muscle to produce a 20

mm steak. The lamb shoulder was not used for retail display.

In all cases for beef, pork and lamb, the retail display directly compared the retail appearance

of the FoodCap portions with the contralateral portion from the same carcass stored in VP. The

retail packs were displayed at 5°C for the period of retail display. At the end of the designated

display period, a colour measurement was made using a Minolta Colourmeter, together with

a subjective assessment of appearance and odour.

Tenderness measurements

Product tenderness was measured using a shear force measurement of cooked product. The

shear force was measured using the Carne Technologies Tender-o-meter, which is based on

the shear force measurement principles developed by the Meat Industry Research Institute of

New Zealand (MIRINZ).

The Tender-o-meter uses a mechanical tooth to shear through a prepared sample of cooked

meat. Samples were cooked in bags in a 100°C waterbath to a core temperature of 75°C,

then immediately cooled in ice. The samples were then cut into 10 ‘bites’: each bite comprised

a slice of the original sample with a 10x10mm cross section parallel to the muscle fiber

direction. The tenderness value for the samples was calculated from the average of the forces

needed to shear through each of the 10 bites.

Manufacturing Trim - Mince trials

A VP comparison was not made for the trim/mince trials.

For the manufacturing trim, two packing methods were used to fill the FoodCaps:

Method 1 - involves packing trim in the FoodCap and using the same mechanical compression

technique described previously, followed by vacuum gas flushing to create an anaerobic

environment. The head space above the top platen that is used to apply the mechanical

compression is then evacuated and replaced with 100% CO2.


Client name: FCI


Although 100% CO2 was avoided for primals because of the pressure changes when the CO2

is absorbed, its use for trim is possible as the mechanical compression process eliminates voids,

and the volume of added CO2 is therefore relatively small (mostly confined to the head space

above the product); this means that the pressure changes caused by CO2 dissolving into the

meat is manageable.

Method 2 – involves the same packing process, but in this technique, no mechanical

compression is applied. Instead the packed FoodCap’s are deep vacuumed and gas flushed

with 50% CO2/50% N2.

After the designated storage time, representative samples were taken from three positions

through the depth of the FoodCap (near the surface, midway and near the bottom) for

microbiological assessment.

The beef trim was minced twice while the pork trim was minced once. The minced product

was transferred directly from the mincer onto retail trays without any intermediary handling.

Chicken Portion trials

A VP comparison was not made for the chicken storage trials.

FoodCaps were filled with chicken portions, without the use of shelves: the product was

collected directly off the end of the belt conveyor and packed in the FoodCaps following the

standard operational process.

When the FoodCaps were full, the residual atmosphere was evacuated and replaced with the

modified atmosphere of 50% CO2/50% N2. After the designated storage time, representative

samples were taken from three positions through the depth of the FoodCap (near the surface,

midway and near the bottom) for microbiological assessment.

Purge losses in the chicken trials were measure as the residual fluid in the FoodCap after the

chicken portions were removed. This was expressed as a % of the total weight of product in

the FoodCap. Purge losses from the beef and pork trim was negligible and could not be

measured.

Chicken pieces were placed in retail display trays as whole portions.

Results

Pre-packing

Oxygen measurements

Eight FoodCaps were fitted with valves that allowed internal O2 measurements to be made.

Initial measurements were made immediately after gas flushing the FoodCaps, and a

subsequent measurement was made after the period of chilled storage.

All the FoodCaps had O2 values below the limit of detection of 1 ppm immediately after gas

flushing.


Client name: FCI


After storage periods of 21 to 35 days, 7 FoodCaps did not have measurable levels of O2 (<1

ppm). The remaining FoodCap had 14 ppm of O2.

The results show that the initial evacuation of the FoodCap is highly effective at removing the

residual atmosphere after packing, and that the FoodCap is very effective at preventing

diffusion of O2 into the FoodCap during chilled storage.

APCs

The slaughter and carcass dressing were carried out in an export-licensed New Zealand meat

processing facility, where good manufacturing practice and process hygiene is of a high

standard. In keeping with standard red meat carcass dressing practices in New Zealand,

additional sanitation steps after dressing, such as hot water or acid washes, were not used.

Beef and lamb counts from primals ex the boning room were generally less than 1000 – or log3

- cfu/cm2. Pork typically has higher counts after dressing, and the measured counts were

mostly between 1000 and 5000 (log 3 – 3.6) cfu/cm2). Chicken portions performed well, possibly

reflecting the sanitation steps that are routinely used in chicken carcass dressing (average log

1.7 cfu/cm2) (Figure 1).

EBCs

EBs counts were also within the expected range. Beef and lamb were typically 10-20 cfu/cm2,

while pork were a little higher at approximately 60 cfu/cm2, and chicken had negligible levels

(Figure 1).

Figure 1: Microbial counts pre-packing for all primals

0

0.5

1

1.5

2

2.5

3

3.5

4

Beef Lamb Pork Chicken Beef Trim Pork Trim

Log

co

un

ts

Species

APC EBC


Client name: FCI


Conclusion

Variable initial counts will have an important influence on the final counts after a period of

storage as well as on the maximum storage life for a product. For this reason, extensive testing

of all the product was carried out before packing to gain a clear indication of the variability

and range of counts likely to be encountered. The measurements, carried out across a number

of different packing days, showed values that were consistently within an acceptable range,

and unlikely to introduce large variations in counts following the various storage periods and

treatments.

The results of storage of the primal cuts of beef, pork and lamb will be considered first. Trim and

chicken will be addressed separately because of their distinctly different processing and

storage requirements.

Post storage microbiology – beef, pork & lamb.

All the assessments of the microbiology after varying periods of storage are based on

comparing paired samples from the same carcass, using one side for packaging in FoodCaps

and the other in VPs.

Aerobic plate counts (APCs)

The APCs after the shortest storage periods for beef and lamb (21 days) were often found to

have comparable or lower values than the initial measurements made in the boning room,

and this applied to both the FoodCap and VP product.

Part of the explanation for this relates to the latent phase that typically occurs soon after

packing, during which growth is slow as the organisms adjust to the imposed anaerobic

environment. This phenomenon can account for limited increases in counts during the shorter

storage periods, but doesn’t adequately account for the frequent incidences of measured

values that are lower after the shorter storage period compared with the initial values. This

result probably reflects a systematic difference in the efficiency of the swabbing process in

recovering the organisms in the test area on fresh product in the boning room compared with

aged product.

However, the key comparison is between the FoodCap samples and VP samples collected at

the same time and under identical conditions. Figures 2, 3 and 4 show the APCs after each

storage period for beef, pork and lamb. On average, the counts on the different primals types

(within a species) did not show any differences, so the subsequent results combine all the

primals for each species.


Client name: FCI


Figure 2: Beef APC’s. All Primals

Figure 3: Lamb APC’s. All Primals

0.0

2.0

4.0

6.0

8.0

21 42 63

LOG

AP

C

Days storage

Foodcap Vac pack

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

21 42 63

LOG

AP

C

Days Storage

Foodcap Vac Pack


Client name: FCI


Figure 4: Pork APC’s. All primals

The increase in counts as the storage period was extended are broadly in keeping with

expectation for each species and largely reflect differences in the initial microbial loads: pork

loins had the highest values of log 7-8 after 35 days of storage of VP, and values of log 7 after

42 days in lamb. In beef Log 7 was reached after 63 days storage.

The APC counts were consistently slightly lower in the FCs compared with the VPs. These

differences did not reach statistical significance: a large number of measurements would be

needed to show a statistical difference, given the inherent variability of microbial counts on

meat samples. Nevertheless, the consistent pattern across species and storage timepoints

does show a very probable tendency for slower microbial growth in the FoodCaps compared

with VPs.

Enterobacteriaceae counts (EBCs)

As in the case of the APCs, the growth of EBC’s during storage was consistently slower in the

FoodCap compared with vacuum packs. This was also apparent across species and different

periods of storage.

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Client name: FCI


Figure 5: Beef EBC’s. All primals

Figure 6: Pork EBC’s. All primals

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Client name: FCI


Figure 7: Lamb EBC. All Muscles

Effects of reducing CO2 concentration.

A possible explanation for the difference between the FoodCap and the VP storage systems

is the bacteriostatic effect of 50% CO2. As a preliminary assessment of this possibility, some

limited comparisons were made using 30% CO2/70% nitrogen (N2) or using 100% N2, using beef

product only. The average log APCs and EBCs of beef primals packed in the different gas

concentrations are shown in Figures 8 & 9 below.

Reducing the CO2 concentrations to 30% continued to show the trend of lower counts in the

FoodCaps compared with the vacuum packs for both APCs and EBCs. At 100%N2, the effect

is less clear: although a benefit is apparent for APCs on 21 days, the effect was minimal at 42

days and EBS also showed limited if any benefits.

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Client name: FCI


Figure 8: Effects of different modified atmospheres in the FoodCap (CO2 & N2 mix)

Figure 9: Effects of 100% N2 in the FoodCap on microbial growth

Conclusions

The improved microbial counts in the FoodCap system are likely to be the result of the

bacteriostatic effect of 50% CO2. Although the conclusion is tentative at this stage, it seems

likely that there continues to be some bacteriostatic benefit down to 30% CO2 in the FoodCap,

but this is probably lost at 100% N2, at which point the microbial counts in the FoodCap can be

expected to be equivalent to that of the VP system.


Client name: FCI


Purge losses

How much purge is lost during storage is generally considered to be due more to intrinsic

factors of the meat rather than the choice of packaging systems, although 100% CO2 storage

systems have been reported to increase the amount of purge under some circumstances.

Different primals produce different levels of purge, independent of any effects from packaging

systems. The causes of varying purge losses are complex but ultimately relate to how tightly

water is bound by proteins in meat. Purge derives from the proportion of water that is loosely

bound by muscle proteins, and this loosely bound water can migrate to the surface of the cut

through channels between muscle fibres and bundles that form after meat enters rigor mortis.

Intrinsic factors that are recognised to influence water binding in meat include in particular

the final pH attained by the meat at rigor mortis (high pH meat binds more water and purges

less), and the interaction of muscle pH with temperature during the prerigor period; conditions

where low muscle pH develop while muscle temperatures are still high reduces the ability of

proteins to bind water so purge increases resulting in the so-called Pale Soft and Exudative

condition (PSE), a particularly problem which can be prevalent in pork. In beef, this condition

accounts for the generally higher purge losses in deep leg muscles of beef carcasses, such as

the topside, where the rate of carcass side cooling is much slower than more superficial cuts

such as the striploin.

Purge losses were measured from the difference in weight between the start and end of the

storage period. To minimise intrinsic variation, the two primals from the same carcass were

allocated to either the FoodCap or VP system.

Figure 10 shows the average purge losses for the different beef primals. To simplify the

presentation, the different storage timepoints for each primal were combined. The results show

that the FoodCap generally produces less purge than the vacuum pack.

Figure 10: Beef purge

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How much the FoodCap can reduce purge losses in beef can be estimated from Figure 11.

This graph plots the measured weight loss in the FoodCap against the weight loss from the

contralateral primal stored in VP, and the result shows that the purge loss in the two storage

methods are significantly correlated to each other – more purge in the FoodCap means more

purge in VP. In addition to this, the line that best fits the datapoints can be used to compare

the losses in the two storage systems and calculate the relationship between the purge losses

produced by the two storage systems:

Purge loss produced in VP = 0.78* purge loss in FoodCap + 1.4

Figure 11: Comparison of FoodCap vs VP purge losses

The result of this calculation is shown in Table 2 below.

Table 2. Calculated purge losses comparing

FoodCap with VP storage treatments

% FoodCap purge % VP purge

1 2.2

2 3.0

3 3.8

4 4.6

5 5.3

This relationship shows that the FoodCap offers a particular benefit in reducing purge under

conditions where purge isn’t excessive (<3%), but the benefit becomes less under conditions

where purge is very high. High levels of purge are associated with large cuts from the hind

quarter, such as the topside, particularly when these are stored for long durations. This

conclusion is supported by the measurements shown in Figure 12.

y = 0.78x + 1.4

R² = 0.58

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Client name: FCI


Purge losses from lamb were very low in both FoodCaps and VPs, largely because the primals

were bone in and the primals were minimally processed. The leg and shoulder cuts continued

to show slightly less purge in the FoodCap compared with the VP.

Figure 12: Lamb purge

Pork purge losses were highly variable in both the FoodCap and VPs and cuts from the same

carcass did not show any relationship between storage systems for any of the primal types.

However, the pattern of purge loss continued across all the primals with the losses from the VP

treatment being consistently higher than those from the FoodCaps.

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Figure 13: Pork purge

Conclusion

Purge losses were consistently lower in the FoodCap system compared with the VP storage

system across all the primal cuts and for all three species.

The explanation for how the FoodCap system provides this benefit is not obvious. Once

vacuum packed, the VP samples were placed on trays inside FoodCaps and held under

essentially identical conditions to the meat in FoodCap storage, which means the only real

difference is exposure of the bare meat to the CO2/N2 gas mixture in the FoodCap, compared

to continuous contact with the barrier bag in the case of the VP samples. It was evident during

unpacking of the FoodCaps that the surface of the FoodCap samples were drier than the VP

samples, and a possible explanation for the difference is the absence of any physical contact

with the meat surface over large areas of the primal when meat is placed on shelves in the

FoodCap. In contrast, the entire meat surface is in continuous contact with the barrier bag in

the VP system: this contact may encourage the migration of purge to the surface and result in

more overall purge accumulation.

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Product appearance during retail display

The retail display life of meat is generally defined by discolouration of the meat surface rather

than from accumulation of surface microorganisms and product spoilage. Exposure of meat

to O2 converts purple meat myoglobin into the desirable cherry red oxymyoglobin form, but

discolouration develops subsequently from the gradual chemical oxidation of myoglobin to

the brown metmyoglobin form.

The chemistry involved in the changes between the myoglobin, oxymyoglobin and

metmyoglobin forms are complex, but the key requirement of a storage system for meat

critically depends on ensuring sustained very low O2 during the storage period, since even low

levels of O2 over extended periods of time allows oxidation reactions to propagate (as well as

encourage the growth of spoilage organisms).

An assessment of retail display performance of meat after storage therefore provides a test of

how effectively oxygen was excluded during the storage period.

Barrier bags are designed to have very limited permeability to O2, but they are also very thin

and therefore do have measurable oxygen transmission rates. This oxygen transmission value

varies depending on the material used, and is also affected (usually increased) by contact

with moisture from the meat, an effect that is not always reflected in the published oxygen

permeability values for barrier bag materials. The specific barrier bag used in the present

comparison (Cryovac A600 and Z1 barrier bags) are rated as medium to high barrier material,

with oxygen transmission rates around 12-15 ml/m2/24hrs after heat shrinkage.

The FoodCap used in these trials are constructed from a proprietary FDA approved plastic,

which has very low oxygen transmission rates but, also, because the plastic provides the

structural integrity for the FoodCap, is manufactured to a thickness of 6mm.

Published values for oxygen transmission through the plastic are 2-3 cm3/mm/m2.atm/24hrs, or

0.3-0.5 units for a 6 mm thick FoodCap wall, which is as much as 100 x less than a vacuum bag.

Accordingly, the oxygen transmission through the walls of the FoodCap can be expected to

be better than the very best barrier bag and provide a very effective protection from oxidation

during storage. This was confirmed from measurements of oxygen inside the FoodCaps after

storage (described earlier) that found O2 concentrations to range from below the level of

detection (< 1ppm) and, to a maximum of 10 ppm even after the longest storage period.

Steaks from each primal were packaged using either overwrap or modified atmosphere retail

display packs. Overwrap film is O2 permeable and allows atmospheric O2 to diffuse into the

meat and develop the cherry red bloom in the meat surface during retail display. However,

central retail preparation of meat generally requires longer retail display life because of the

additional transport time to the retail stores, and using high oxygen modified atmospheres in

sealed, oxygen impermeable retail packs remains one of the most common options to extend

retail shelf life: by increasing the atmospheric oxygen to between 70 and 80% O2, a deeper

layer of oxymyoglobin forms in the meat surface, and the greater oxygenation has the effect

of delaying discolouration. CO2 concentrations are also normally between 20 and 30% in the

modified atmosphere as this assists with reducing the rate of microbial growth.

The effects on retail display life after varying periods of chilled storage in either the FoodCap

or VP systems were compared. As before, to minimise the risk of intrinsic differences attributable

to animal or carcass processing effects, primals were collected from both sides of the same

carcass and each side was allocated to either FoodCap or VP storage.


Client name: FCI


The product was tested in overwrapped retail trays or in modified atmosphere retail packs

using 80% O2 and 20% CO2. To align with standard commercial practices, the period of retail

display used for overwrap product was 3 days, while the period of retail display for the MAP

product was 10 days.

Beef retail display performance

Consumer responses to beef colour during retail display typically reaches a limit of

acceptability when the a* values of the colour meter fall to approximately 16. Values above

20 generally correlate to a bright red colour that is highly acceptable to consumers.

Different cuts have different colour stabilities: loins and ribeyes are relatively colour stable,

topside is intermediate and rump is one of the more unstable cuts. These differences are

reflected in the a* values after a defined period of retail display, where rumps show consistently

lower values than the other cuts (Figure 14).

Figure 14: Measured a* values in beef steaks packed in

either overwrap or MAP retail display

After 3 days in overwrap or 10 days in MAP, the differences between the FoodCap and VP

product was generally minimal (Figure 14). The rump colour had deteriorated most,

particularly after 10 days in MAP, but ribeye and loins were still showing good colour by the

end of the display period.

The MAP topside steaks after storage in the FoodCap did show a difference compared with

the VP samples. In this cut, 5 of the 24 MAP steaks became discoloured during the retail display

period, although the remainder had at least an equivalent or better appearance. The

discoloured samples also showed a number of unusual characteristics: the discolouration

developed rapidly, without showing the first stages of localized areas of discolouration; a

check of the colour through the cross section of the steak found that the discolouration did


Client name: FCI


not penetrate into the meat, and did not show the normal layer of brown metmyoglobin that

develops beneath the surface, where discolouration normally first develops because the

partial pressure of oxygen is lower than at the surface.

None of the topside steaks displayed in the overwrapped trays showed any difference in the

rate of discolouration and this supports the idea that the discolouration is a response to the

MAP system rather than any effect of the storage method on the meat itself.

This anomalous behavior can probably be explained by the release of dissolved CO2 from the

meat after it was packaged, which then pools on the surface of the cut and reduces the

partial pressure of O2 on the surface of the meat. Such conditions of low O2 concentrations

would then cause rapid discolouration, without any changes below the surface.

Why this effect should have happened in only a few topside samples is not clear. It is normal

to delay the retail packing of meat that has been stored in high CO2 conditions in order to

allow dissolved CO2 to diffuse out and avoid distortion of the sealed retail packs caused by

released CO2. This delay was not carried out systematically in this trial, and combining this with

the lack of any movement of the packs once they were put into simulated retail display may

have allowed the accumulation of CO2 on the cut surface.

Pork retail display performance

On the whole, the objective colour measurements did not show large differences in the

appearance of product stored in FoodCaps compared with vacuum packs (Figure 15).

Figure 15: Measured a* values in pork steaks packaged either

as overwrap or MAP for retail display

However, a subjective assessment of the colour did show a consistent enhancement in

appearance of the FoodCap samples, particularly in samples that were in the overwrap

packs. An example of this is shown in Figure 16. In this case, the pork was stored for 21 days in

the FoodCaps and shows a deeper, darker red colour after retail display, as well as a fresher,

less tired appearance. In addition, the rind on the chop was redder and less yellow than its

counterpart that had been stored in VP prior to cutting and retail display.


Client name: FCI


Figure 16: Differences in muscle and subcutaneous fat colour during retail display after 21

days storage

The difference in the rind colour can probably be attributed to the contact of the rind with

accumulating purge in the VP, whereas the purge would not be making contact with the rind

in the FoodCap.

The benefit to colour was not evident in either beef or lamb and an effect of this nature has

not previously been reported in pork. Although this needs to be confirmed with more data, a

likely explanation is the more rigorous exclusion of O2 in the FoodCap during the storage

period. By reducing exposure to O2 during storage, oxidation reactions are delayed and

progress more slowly during retail display because the anti-oxidant properties of the meat as

less depleted during the storage period.

It is likely that beef and lamb are less sensitive to low oxygen levels during storage (for example,

grass-fed cattle and lamb have much higher antioxidant levels of Vitamin E that help to sustain

meat colour during retail display) and the more highly pigmented meat will mean that these

effects are possibly not as apparent in these species.

Lamb retail display performance

Lamb did not show any differences in appearance between the FoodCap and VP product

with either retail packaging systems (Figure 17).


Client name: FCI


Figure 17: Measured a* values in lamb steaks packaged either

as overwrap or MAP for retail display

Conclusion

In general, the retail appearance of product stored in FoodCaps or VP did not differ

significantly. There were two exceptions to this:

First, some topside steaks stored in FoodCaps discoloured much sooner than the VP

counterparts when displayed in MAP trays. This behavior is attributed to the release of CO2

after the steaks were packed into the sealed trays and created conditions of low O2 on the

surface of the meat. This identifies the importance of allowing meat stored in CO2 enriched

environments to release dissolved CO2 before packaging in gas-impermeable retail trays.

Second, the pork stored in FoodCaps consistently showed an improved appearance

compared to the VP samples, although these differences were not captured effectively by

the Minolta Colourmeter measurements. The improved appearance would be expected to

have a significant commercial benefit.

Although the explanation of this benefit is tentative at this stage, the better O2 exclusion during

storage in the FoodCap compared to VP is the likely explanation.

Tenderness

The packaging system used for chilled storage is not generally considered to have a significant

influence on meat tenderness. Nevertheless, in the interest of ensuring that there are not any

unexpected consequence of using the FoodCap system, a comparison was made of the

tenderness of the product after varying periods of chilled storage using shear force

measurements of the cooked product.

The storage timepoints were selected primarily to assess effects on microbial status and were

longer periods than is necessary for meat tenderness to reach its final value, the value beyond

which further storage time does not improve tenderness any further. Accordingly, the


Client name: FCI


tenderness values at the different storage timepoints were combined for each primal and are

shown in Figures 18-20.

The results did not show any significant differences in tenderness between the FoodCap

samples and VP samples in any of the primals.

Figure 18: Beef Tenderness

Figure 19: Pork tenderness

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Figure 20: Lamb Tenderness

Conclusion

The FoodCap system does not have any beneficial or detrimental effects on meat tenderness.

Results – Beef and Pork Trim

Trim can generally be expected to have higher initial microbial counts than primals because

of higher rates of contamination during preparation and the high proportion of cut surfaces

relative to volume. Also, meat with high surface areas relative to volume are also more

susceptible to high levels of purge losses.

For these reasons, trim is normally only stored chilled for relatively short periods. In the absence

of steps to create anaerobic conditions, trim can be stored chilled for a few days (typically no

more than 3 days), but such limited periods can create significant commercial constraints.

Extended chilled storage of trim requires a bulk storage system that also maintains effective

anaerobic conditions to delay spoilage. Conventional vacuum packaging is used, as well as

bulk storage systems that use gas flushing to create an anaerobic environment, but these

approaches can be expensive for a relatively low value product.

The FoodCap system is a potential bulk storage system for trim. When combined with the

proprietary system to evacuate residual atmosphere and inject a modified atmosphere, there

is a potential to create the conditions that will allow extended periods of chilled storage. For

this to happen, the key requirement is to reduce residual O2 to levels low enough to control

microbial growth effectively and protect the product against oxidation reactions, particularly

those that lead to discolouration of the product (oxidation of myoglobin to metmyoglobin).

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Trials were carried out with beef and pork trim to assess the effects of storage in FoodCaps on

microbial growth and purge losses during storage, and on retail colour stability after mincing

the trim.

Trim was layered in the FoodCap as it was produced in the boning room, with some attention

to ensure that the product was evenly distributed in the FoodCap as it was added. After filling,

two storage treatments were assessed:

1. The FoodCaps were filled with trim and subsequently gas flushed without the use of

mechanical compression of the product or the use of a top platen. In the absence of

compression, removal of residual atmosphere is achieved through the deep vacuum

process, with 50% CO2/50% N2 being injected to create modified atmosphere. The gas

mix has the potential to diffuse through the depth of the FoodCap and contribute

some bacteriostatic benefit.

2. Alternatively, the top platen was fitted and beef trim was mechanically compressed

after the FoodCap was filled. The compression has the effect of removing much of the

atmosphere trapped in the voids between the pieces, but the result is to limit the

opportunity for the CO2 in the modified atmosphere to reach beyond the top layer of

product. The remainder of the FoodCap remains essentially anaerobic but without the

bacteriostatic effect of the CO2.

Microbiological assessments were made using the swabbing method used previously, but

reducing the swab surface area from 25 cm2 to 5 cm2 to accommodate the smaller size of the

product.

Purge measurements could not be carried out as there was insufficient purge in the FoodCap

after the trim was removed to undertake a measurement.

Beef trim was minced twice and pork trim once and the mince patties were tested under

simulated retail display. Six trays were made from each FoodCap: 3 samples were

overwrapped and 3 were gas flushed with 80% O2 and 20% CO2, then placed in simulated

retail display at 5°C.

Microbiology

The APC and EBC counts did not differ between the compressed and uncompressed beef

trim. The results of both procedures were therefore combined in the Figures below.

The increase in APCs and EBCs were remarkably limited over the period of 7 to 21 days of

storage. This result would suggest that the storage environment, and in particular the high CO2

conditions, helped to maintain the growth within the latent phase and produced relatively

little microbial growth within this range of storage period (Figure 21).


Client name: FCI


Figure 21: Pork and Beef Trim

Retail appearance

The effects of the storage periods were further assessed in the retail performance of mince

produced from the trim. Figure 22 shows that increasing the duration of storage from 14 to 21

days did not affect beef mince colour after 4 days in overwrap. The redness of the mince, as

described by the a* values, averaged more than 20 in both cases, and this represents a very

acceptable colour.

Pork mince is more pale and, accordingly, has a much lower a* value, but values above 6-7

represent an acceptable pink colour. Rather surprisingly, pork seems to show a slight

improvement in mince colour with increasing storage time, although this effect was small and

the mince colour was very acceptable in all cases (Figure 23).

The a* values of the overwrapped mince was unaffected by the duration of chilled storage.

In contrast, the longer retail display time in MAP trays showed that the 21 days of storage did

reduce the a* value in both the beef and pork. Although the a* values were lower, subjective

assessment of the product found that some of the product was becoming dull but had not

reached the point of obvious discolouration.

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Figure 22: Beef Mince

Figure 23: Pork Mince

Conclusion

These results indicate that bulk storage of trim in FoodCaps flushed with 50% CO2 and 50% N2

provide an effective storage environment for periods of up to 21 days. Using compression of

the trim before storage to remove air pockets did not produce any measurable benefits,

indicating that the very low pressures used in evacuating the FoodCaps before subsequently

flushing with a modified atmosphere was as effective at evacuating residual oxygen.

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Client name: FCI


The 21 day storage time appeared to reduce the duration of MAP retail display life, but this

was only evident at the end of a 10 day display period while product on retail display for 4

days was still acceptable.

Results – Poultry

As in the case of trim, fresh poultry is not usually stored chilled for extended periods.

Nevertheless, the logistical flexibility afforded by any extended period of chilled storage could

offer significant commercial benefit.

The FoodCap system offers an opportunity for bulk storage after evacuation of atmospheric

O2 and replacing with a modified atmosphere of 50% CO2 /50% N2. To confirm the suitability of

this system, tests were carried out for breasts (skinless and boneless), thighs (skin off, bone in)

and legs (skin on, bone in). Tests were made of the microbial status and purge losses during

storage, and microbiological status of the product after specified periods of retail display.

Microbiology

The microbial status of the three cuts were essentially equivalent to each other after the various

periods of storage. By the end of 16 days of storage, APCs were 3.0, 3.2 and 3.6 log cfu’s for

the breasts, thighs and legs respectively, and the equivalent EBCs were 1.2, 1.2 and 2.4 log

cfu’s.

Figure 24 therefore shows the counts averaged for all three chicken portions.

Increased duration of storage from 8 to 16 days increased APCs and EBCs by approximately 1

log. The maximum counts remained within acceptable limits after 16 days of storage.

Figure 24: Chicken. All primals

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Purge losses

Purges losses from the chicken breast and thighs were very low through all the time points of

storage (Table 3). In contrast, the losses from the drumstick was significantly higher, averaging

4% over all the storage timepoints.

Table 3. Purge losses from different cuts after different storage periods

% Purge

Storage time Breast Thigh Drumstick

Day 10 0.23 0.14 3.67

Day 12 0.30 0.20 4.10

Day 14 0.50 0.25 3.93

Day 16 0.25 0.23 4.23

It was also apparent that the purge from breasts and thighs was highly viscous and did not

flow to the bottom of the FoodCap but accumulated in pockets close to the cuts from which

it originated. In contrast, the purge from the drumsticks had a low viscosity, ‘watery’ property

and pooled at the base of the FoodCap as it accumulated.

The reason for the different viscosities between cuts is difficult to explain. Because the leg

portions were skin on, part of the explanation may be that water used during immersion chilling

of the chicken carcasses may have accumulated and become trapped under the skin, then

migrated out, together with muscle purge, during the storage period.

The relatively high purge loss in the drumsticks may also relate to the inability of this product to

deform and pack effectively inside the FoodCap, due to its shape and high bone content.

Purge losses increase when differential pressure is applied to meat: purge will move quickly

down a pressure gradient when pressure is applied to one area of a cut. A boneless cut such

as breast can be expected to pack together tightly by default with the pressure equilibrating

around the pieces. Although the thigh is also bone-in, the shape is more regular than the

drumstick and the bone is fairly evenly encased in meat. In contrast, the drumstick is an

irregular shape and with some areas minimally encased in bone, which will potentially create

pressure points as the product is stacked in the FoodCap. These physical properties of the

drumstick may contribute to the greater purge losses.

Conclusion

The FoodCap system appears to offer an effective environment for extending the chilled

storage life of poultry. The bacteriostatic effects of the 50% CO2 combined with very effective

O2 removal provided good microbial control. The potential risk of excessive purge losses if the

chilled storage time is increased does not appear to be significant, particularly for the breast

and thigh cuts. Although higher for drumstick, the levels were not excessive.

Evaluating performance of beef,lamb, pork & poultry system€¦ · Confidential Client Report...

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