Is meat really fresh when Modified Atmosphere Packaging (MAP) is used?
Modified Atmosphere Packaging (MAP), also known as Controlled-Atmosphere Packaging (CAP) or Gas Flushing involves modifying the gaseous atmosphere and packaging of meat with blends of Nitrogen, Oxygen and Carbon Dioxide. This has been used as a solution in major retailers in Australia and overseas to reduces spoilage and preserve pre-packaged meat.
The primary reason for using MAP in major retailers is to extend shelf-life out to 11 days in chilled form, allowing retail supply chains to centrally-package product in state-based warehouses and distribute out to outlying retail sites. The goal is to extend the shelf life and work within a complicated production and distribution system. This modified atmosphere artificially controls chemical, enzymatic and micro-biological reactions in meat to extend storage life.
However, the question needs to be asked:
“What impact is this having on the meat you are eating?” and
“How fresh is the meat you are buying?"
The History of MAPs in Australia
The Sydney Morning Herald (SMH) reported in 2011 thanks to advances in technology, meat was now able to sit on supermarket shelves for 8 days. This was then updated to news that in 2023, technology had extended this up to 11 days.
The SMH article went on to state that the major retailers admitted to pumping Carbon Dioxide and Oxygen into their fresh meat packs to limit bacterial growth and extend the shelf life of their meat.
Choice spokeswoman, Ingrid Just said “The techniques being used to allow meat to stay on the shelves longer begs the question: is it really fresh?”
In the past, the major retailers contained in-house butchers and used standard clingfilm packaging and so these meat cuts were not treated with oxygen or carbon dioxide. However, they have now removed all of these in-house butchers and prepare meat off site with modified atmosphere packaging.
Ingrid Just also noted that the supermarkets used carbon monoxide to prolong their meat’s redness so it would look fresher.
What is the impact of MAPs on meat quality?
In 2016, Meat Standards Australia conducted a trial on Modified Atmosphere Packaged beef products at 9 days and found there was an extremely significant sacrifice in tenderness index points. This effect was identical, across tenderloins, striploins and rumps.
Meat & Live Stock Australia’s (MLA’s) General Manager for Producer Consultation and Adoption, Michael Crowley, said that it was “just surfacing now that this (MAP Packaging) is an issue in eating quality. We’re still learning about the extent of the impact, what’s causing it and the possible solutions.”
Prior to this in 2015, MLA Meat & Livestock Australia published a report that was prepared by the CSIRO titled “Impact of high oxygen packaging on MSA lamb loin and topside eating quality”.
The report pointed out that overseas studies mainly in beef had shown that the eating quality of high oxygen modified packaging was less than optimal due to toughening of meat and negative flavour changes.
The research conducted by the CSIRO in this study demonstrated that the resulting toughening of meat under High Oxygen MAP occurs primarily due to intermolecular cross-linking or other mechanisms.
In 2016, Beef Central News in Australia reported that the red meat industry had been rocked by an unexpected discovery that MAPS in retail meat packaging appeared to have a serious negative impact on tenderness performance in both beef and lamb.
They cited the Meat Standards Australia-backed trial which unearthed startling data suggesting that typical MAP-packed beef products at nine days sacrifice 12 MSA tenderness index points. The effect was identical across three cuts tested in the trial — tenderloins, striploins and rumps — and was consistent across different vacuum-packaged ageing periods prior to placement in the retail packaging.
In essence, the research findings suggest that:
• Virtually any item that would otherwise have been an MSA five-star eating quality item effectively becomes a four-star product when packed in MAP and held for nine days
• Anything that was a four-star item becomes a three-star, and
• Any product that was not in the top half of MSA three-star for tenderness becomes a fail.
Controversy over the Toxic Effect of MAPs
PubMed published a paper in January 2018 titled "Carbon Monoxide in Meat and Fish Packaging: Advantages and Limits” by Djamel Djenane, Pedro Roncalés
They stated that:
“The use of CO for meat and seafood packaging is not allowed in most countries due to the potential toxic effect, and its use is controversial in some countries. The commercial application of CO in food packaging was not then considered feasible because of possible environmental hazards for workers. CO has previously been reported to mask muscle foods’ spoilage, and this was the primary concern raised for the prohibition, as this may mislead consumers.”
“The use of CO in the food industry is controversial. Some countries approve the application such as the U.S., Canada, Australia and New Zealand, while the EU member states ban it from food processing. CO has previously been reported to mask meat spoilage, and this was the primary concern raised for the prohibition as this may mislead consumers.”
Safety of MAP
Djenane and Roncales added:
“Maintaining the quality and safety of muscle foods from slaughter to consumption is highly important in the modern food supply. Concerns have been expressed about the risk of pathogens in meat packaging under MA. The increase in shelf-life of MAP meats through inhibition of spoilage bacteria may provide sufficient time for stimulated pathogens to grow to dangerous levels while the food still remains attractive to the consumer. Whatever the packaging system, keeping the continuous chill chain throughout all of the storage period is the most important key factor influencing the storage life of fresh meat.”
How does CO2 Gas Flushing Work?
The spoilage bacteria often found on meat is called pseudomonads. It can be inhibited by Carbon Dioxide levels above 20%. Brocothrix thermospacta requires a 60-70% carbon dioxide level to begin inhibiting growth. Then at an atmosphere of 100% Carbon Dioxide, Lactic Acid bacteria are selected at the competitive expensive of other spoilage bacteria. It is then only after extended storage, that spoilage occurs.
How to Spot MAPs
MAP packs of red meat on retail shelves use a deeper tray and a tightly-stretched film — under which is injected a combination of inert gasses to eliminate pathogen growth and lengthen shelf-life. A conventional cling-film over-wrap tray has a shelf-life of just 2-3 days. This will primarily be inserted into shelf trays of chilled meat.
About the Author
Steven Hines is one of the owners and co-founders of Stockman Steaks. His family has been in the meat business for over 5 decades and 3 generations. He has a passion for eating great quality meat and researching the health benefits behind it.
