Food or edible material: processes – compositions – and products – Packaged or wrapped product – Packaging structure cooperating with food generated gas
Reexamination Certificate
1998-10-08
2001-05-15
Bhat, Nina (Department: 1761)
Food or edible material: processes, compositions, and products
Packaged or wrapped product
Packaging structure cooperating with food generated gas
C426S129000, C426S316000, C426S319000, C426S324000, C426S332000, C426S396000, C426S404000, C426S410000, C426S415000
Reexamination Certificate
active
06231905
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to systems and methods of making modified atmosphere packages for extending the shelf life of raw meats or other food. More particularly, the invention relates to such a system and method that is significantly faster than prior art techniques.
BACKGROUND OF THE INVENTION
Containers have long been employed to store and transfer perishable food prior to presenting the food at a market where it will be purchased by the consumer. After perishable foods, such as meats, fruits, and vegetables, are harvested, they are placed into containers to preserve those foods for as long as possible. Maximizing the time in which the food remains preserved in the containers increases the profitability of all entities in the chain of distribution by minimizing the amount of spoilage.
The environment around which the food is preserved is a critical factor in the preservation process. Not only is maintaining an adequate temperature important, but the molecular and chemical content of the gases surrounding the food is significant as well. By providing an appropriate gas content to the environment surrounding the food, the food can be better preserved when maintained at the proper temperature or even when it is exposed to variations in temperature. This gives the food producer some assurance that after the food leaves his or her control, the food will be in an acceptable condition when it reaches the consumer.
Modified atmosphere packaging systems for one type of food, raw meats, exposes these raw meats to either extremely high levels or extremely low levels of oxygen (O
2
). Packaging systems which provide extremely low levels of oxygen are generally preferable because it is well known that the fresh quality of meat can be preserved longer under anaerobic conditions than under aerobic conditions. Maintaining low levels of oxygen minimizes the growth and multiplication of aerobic bacteria. Heretofore, low-level oxygen systems, such as the systems proposed in U.S. Pat. No. 3,574,642 to Weinke and U.S. Pat. No. 5,115,624 to Garwood, have obtained extremely low levels of oxygen by relying solely upon oxygen evacuation techniques to initially reduce the oxygen level around the raw meat to approximately zero percent.
In typical prior art systems, a package composed of flexible or rigid gas barrier materials is loaded into an evacuation chamber. The package in the evacuation chamber is subjected to a vacuum which reduces the oxygen level to approximately zero percent. After the package is evacuated, the raw meat either can be maintained in a “zero” atmosphere environment (commonly referred to as vacuum packaging) or can be refilled with a gas or mixture of gases to provide a modified atmosphere environment. To provide a modified atmosphere environment, the air-evacuated package is typically filled with a mixture of gases consisting of about 30 percent carbon dioxide (CO
2
) and 70 percent nitrogen (N
2
). Refilling the air-evacuated package with such a mixture of gases is believed to suppress the growth of aerobic bacteria. At this point the package is sealed. The meat in the modified atmosphere package takes on a less desirable purple-red color which few consumers would associate with freshness. This purple-red color, however, quickly “blooms” to a bright red color generally associated with freshness when the package is opened to oxygenate the fresh meat by exposure to air. The package is typically opened immediately prior to display of the fresh meat to consumers so as to induce blooming of the fresh meat just prior to display to the consumers.
Low-level oxygen systems relying solely upon evacuation techniques to diminish the oxygen level to approximately zero percent suffer from several disadvantages. For example, such systems operate at exceptionally slow speeds because they rely solely upon the use of an evacuation device along the packaging line to reduce the oxygen level to zero percent. The evacuation process is time-consuming, and the manufacture of the package cannot be completed until after the package has been fully evacuated. Furthermore, the evacuation techniques render it difficult to remove any oxygen within a previously wrapped package, such as an overwrapped meat tray, without creating vents in the package to allow the oxygen to escape. Trapped oxygen raises the residual oxygen level in the package and can also cause billowing and subsequent damage to the package during evacuation.
A need therefore exists for a system and method of making a modified atmosphere package which overcomes the aforementioned shortcomings associated with existing techniques of making those packages.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a system and method of making a modified atmosphere package which is significantly faster than prior art techniques. The packaging system effectively extends the allowable time period between cutting and purchase of retail cuts of raw meat. The raw meat can be cut and packaged several weeks prior to being purchased at the store and yet remains fresh during this time period.
To achieve the foregoing objectives, the packaging system and method utilizes a modified atmosphere package including a first package and a second package. The first package includes a non-barrier portion substantially permeable to oxygen, while the second package is substantially impermeable to oxygen. After a food product such as raw meat is placed within the first package, the first package is sealed and then inserted into the second package without sealing the second package so as to create a pocket between the first and second packages. Next, the oxygen level in the pocket is reduced to a first level greater than zero percent using one or more techniques, including but not limited to evacuation, gas flushing, and oxygen scavenging. The pocket is preferably flushed with one or more gases to create a modified atmosphere therein suitable for suppressing the growth of aerobic bacteria.
To reduce the oxygen level in the pocket from the first level to approximately zero percent, an oxygen scavenger is positioned to absorb any residual oxygen within the package. The oxygen scavenger is activated with an oxygen uptake accelerator to increase the rate at which the oxygen is absorbed. The activated oxygen scavenger aggressively absorbs any residual oxygen within the package after it is sealed.
The above system and method of making a modified atmosphere package is advantageous because it does not rely solely upon time-consuming evacuation techniques to reduce the oxygen level to zero percent. Rather, an oxygen reduction technique such as evacuation, gas flushing, and/or scavenging is only used to quickly reduce the oxygen level to the first non-zero level, while an activated oxygen scavenger is used to further reduce the oxygen level to zero percent. By activating the oxygen scavenger, the scavenger has the aggressiveness required to rapidly move the oxygen level in the package through the pigment sensitive oxygen range of about 0.05 percent to two percent oxygen. In this pigment sensitive range, metmyoglobin can form very quickly. Metmyoglobin is a substance that causes meat to change to an undesirable brown color. Metmyoglobin forms very slowly at oxygen levels above about two percent and below about 0.05 percent but very quickly between these oxygen levels. Accordingly, it is important to pass the meat in the package through the pigment sensitive range very quickly. Activation of the oxygen scavenger insures that such rapid passage through the pigment sensitive range is achieved, thereby preventing discoloration of the meat.
It has been found that the use of evacuation for only part, but not all, of the oxygen reduction process significantly increases the throughput of the manufacturing process relative to prior art systems. The manufacturing process of the present invention is completed after the package is sealed. The oxygen scavenger essentially operates outside the manufacturing process because it continues to
DelDuca Gary R.
Deyo Alan E.
Luthra Vinod K.
Wu Wen P.
Bhat Nina
Jenkens & Gilchrist P.C.
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