I am in need of some advice on MAP.
We currently use nitrogen to gas flush snack trays that contain crackers, sliced ready to eat meat, cheese and olives.
Our critical limit is 1.0% oxygen as a recommendation from another manufacturer of similar goods. I have not been able to find a regulation that states what the maximum gas level should be. Our critical limit was 2.0% but a customer asked us to reduce it due to shelf life concerns. We have not had any issue with the trays growing out pathogens.
Can anyone point me in the direction of a regulation or validation? I have tried google and cannot find a specific statement on levels except for fruits/veg. Our MAP process is NOT currently a CCP, but I am concerned it might be questioned in our upcoming SQF audit.
Any advice will be appreciated, thank you.
Dear Destinee,
I didn’t quite understand why yr O2 level is a “critical limit” if yr MAP aspect is not a
CCP. Maybe you meant “target” ??
Your main question was regarding a maximum O2 level in the case of gas-flushed nitrogen. I have not found any official regulations on this as predicted by Mesophile
. I hv seen a variety of opinions on “targets” ranging from zero to 2%, particularly depending on the product (and including variations within the ones you mentioned). See (1-5 below)
In addition I hv noticed some opinions (see 7-8) on operational equipment limitations which made me re-think a little regarding the "exactness" of the quoted target values in this post. You will probably be better able to assess these “comments” than I.
IMO the MAP / BC interactions can be quite complex. Hv posted some extracts for clarity.
(1)
General Objective (Not Restricted to Nitrogen)Oxygen (O2 )
Food deteriorates due to physical, chemical and microbiological factors. Oxygen is probably the most important gas in this context being used metabolically by both aerobic spoilage mic ro organisms and plant tissues and taking part in some enzymic reactions in food including the compounds such as vitamins and flavours. For these reasons, in modified atmosphere packaging, oxygen is either excluded or the levels set as low as possible. The exceptions occur where oxygen is needed for fruit and vegetable respiration, colour retention as in the case of red meat or to avoid anaerobic conditions in white fish (Parry, 1993). In MAP, oxygen levels are normally set as low as possible to reduce oxidative deterioration of foods. Oxygen will generally stimulate the growth of aerobic bacteria and can inhibit the growth of strictly anaerobic bacteria, although there is a very wide variation in the sensitivity of anaerobes to oxygen. One of the major functions of O2 in MAP meats is to maintain myoglobin in its oxygenated form, oxymyoglobin. This is the form responsible for the bright red colour, which most consumers associate with fresh red meat (Farber, 1991).
g01 - MODIFIEDATMOSPACKAGING.5-1.pdf 31.54KB
168 downloads (pg4)
(1a)
General (Not Restricted to Nitrogen)Generally, the share of residual oxygen in each package should be less than 1–2 %. In the case of higher oxygen values, MAP cannot be used to its best advantage as far as oxidation protection is concerned. Exceptions to this rule are special MAP atmospheres, e.g. for fresh meat, which work with high concentrations of oxygen. If carbon dioxide, in a concentration which allows it to unfold its bacteriostatic effect, is part of the modified atmosphere, the minimum concentration of this gas should be 20 %.
g01a - MAPAX brochure17-4683-1.pdf 3.9MB
121 downloads(pg 11)
(2) deli meat – absolutely zero (!)
g02 - Deli-Tech-lo-1.pdf 5.11MB
104 downloads(pg 4)
(3) Nuts - <1%
See g01 - (pg4)
(4) Cheddar Cheeese - <0.5% (mould related)
g04 - 01chapter1.pdf 4.1MB
88 downloads(pg2)
(5) Cured meats - <0.5%
(Sebranek, 2006)
17.5.2
NITROGENNitrogen is an inert gas that is colorless, odorless, and tasteless (Mullan and McDow-ell 2003). The gas is nonflammable, has a lower density than air, and has a low solubility in water and fat. Nitrogen can affect meat product shelf life indirectly because when nitrogen is used to completely displace oxygen, the atmosphere will not allow growth of aerobic micro-organisms. Because aerobic organisms are the fastest growing organisms normally present on fresh meat and poultry, preventing aerobic growth will improve shelf life. However, nitrogen has no direct effect on microbial growth and, consequently, has no impact on anaerobic bacteria. The low solubility of nitrogen is advantageous for use as a filler gas with carbon dioxide to prevent package collapse that can occur when carbon dioxide is absorbed by the product. Nitrogen gas, usually 100%, is most often used for flush-and-fill packages of cooked, cured meats, particularly sliced items where slice adhesion is to be prevented. In these packages, oxygen must be reduced to 0.5% or less for good cured color stability (Møller, Jensen, Olsen, Skibsted, and Bertelsen 2000). For uncured, cooked products, exclusion of oxygen is critical to suppression of rancidity and flavor losses. It is important to remember that fully cooked products, either cured or uncured, typically have low microbial numbers. For these products, prevention of flavor changes during storage is often more critical to shelf life of these products than microbial inhibition. The use of 100% nitrogen can extend shelf life of the products by preventing the chemical changes and flavor losses induced by exposure to oxygen. Carbon dioxide is seldom used for packaging these products because microbial control has been achieved by other means.
(6) Comment : the
optimal oxygen level for growth (21% for aerobes, 0-2% for anaerobes)
(
http://www.foodsafet...d=1955&sub=sub1 )
(7) Comment :
Production of Gas-flushed packaging (ca.2001)
The gas flush technique is normally accomplished on a form fill-seal machine. The replacement of air inside a package is performed by a continuous gas stream. This gas stream dilutes the air in the atmosphere surrounding the food product. The package is then sealed. Since the replacement of air inside the package is accomplished by dilution, there is a limit on the efficiency of this unit. Typical residual oxygen levels in gas flushed packs are 2-5% O2 . Therefore, if the food item to be packaged is very oxygen sensitive, the gas flush technique is
normally not suitable. So when considering a packaging system it is important to consider the oxygen sensitivity of the food product.
See g01 - (Pg 5)
(8) Comment : (Morales-Castro, 2010) -
10.2.1.4
Residual Oxygen and Other Applications
Even with modified atmospheres of 60% N2 and 40% CO2 and vacuum packages, small amount of oxygen is left on the packages and care should be taken because residual oxygen inside the package can promote adverse reactions such as lipid oxidation. On MAP and VP, raw and cooked, beef O2 levels between 1.15% and 1.26% were detected (Smiddy et al. 2002a). Similar findings were reported for cooked chicken patties, with concentrations of 0.9%–1.1% and 0.11%–0.15% for MAP and VP, respectively, with the most oxidized samples for MAP products (Smiddy et al. 2002b). This can be explained by the fact that gaseous environment within MAP is not static since product respiration, microbial metabolism, and gas exchange act continuously to change the composition of the atmosphere. Concentrations of residual oxygen in MAP packs can be attributed to a number of factors such as oxy-gen permeability and poor sealing ability of packaging film (package leaks), food ability to trap air, and ineffective gas flushing. A study for processed cooked meats concluded that in 88% of packs oxygen was present after only 24 h of package with concentration up to 1.2% O 2 at day 1 and after 21 days of storage, which indicates that MAP is dynamic changing constantly due to the factors mentioned above with the consequent quality deterioration (Smiddy et al. 2002c).
Hope the above helps a bit.
Rgds / Charles.C
PS - My (previously) recollected old post is here –
http://www.ifsqn.com...dpost__p__17782(anecdotal data but still interesting)
PPS I didn't notice any articles where MAP itself was a
CCP although the 2009 US Food Code doesn't exactly specify that it couldn't be.
The above post rather underplays the priority
haccp safety issue which demands the implementation of parallel control measures / hurdles. For details, see this link -
http://www.fda.gov/F...9/ucm188201.htm
