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During the stowage part of the evaluation, it was determined that the flexibility differences of the three material types did not have an impact on ease of stowage or vacuum sealability. The clear materials were desirable to see how the food looked inside the bulk overwrap package throughout the evaluation, but the foil laminate would be the recommended material for its superior barrier properties. The smaller fixture that was originally built did not allow for easy stowage of the foods because the pouches were slightly wider than the fixture. The larger fixture solved the stowage problem and worked very well with the gusseted pouches. The current Accu-Seal sealer had trouble sealing the gusseted pouch because it is designed for sealing through only two layers of film, rather than the four layers in the gusseted pouches. Therefore, it is recommended that a more appropriate sealer be purchased for improved sealability and vacuum sealing of the gusseted pouches.
The pie shaped fixture did not yield desirable results. The two side pouch formed to the pie shape well but it created a lot of waste material in certain areas because it had to be folded to conform to the shape. Also, the shape did not allow for optimal stowage since most of the packages are rectangular, so there was considerable wasted volume. There were a lot of issues with sealing the pouch because it created a large and an almost round diameter, opening that was hard to lay flat inside the seal bar without creating any fold in the material. Folds in the seal area were unavoidable without having to seal the pouch at least one foot above the food, which created additional material and volume waste. Any folds in the seal caused the pouch to lose its vacuum. A large two sided pouch formed to an odd shape is not recommended for this application.
The foil bulk overwrap pouch provides significant food packaging time savings versus the individual overwrap system and considerable volume and mass savings. By using the bulk overwrap system the time required for packaging of food is reduced by about 50% because the primary food package no longer has to be inserted and sealed in a secondary package. The time required to stow and seal the food in the bulk overwrap package may increase slightly due to the vacuum and gas flushing of the package versus stowing the food directly into the Collapsible US Food Container (CUFC).
The CUFC has internal dimensions of about 14.75”x 11.75”x 4.75”, which is approximately 825 in3 in volume. The removal of the individual overwrap pouches and vacuum packaging of the bulk overwrap from the Sweets Snacks and Yogurts (SSY) container reduced the volume inside the CUFC by 154 in3, which is approximately 18.7% of the total volume of the container. This is very significant because it would allow for increased food supply in the same amount of volume.
The foil bulk overwrap pouch weighs 65g after being cut down to 4 inches above the food, the shortest allowed distance due to equipment constraints. There are currently a total of eight different standard menu containers, six of which contain overwrapped foods.
The current ISS stowage system consists of the use of rigid aluminum food containers that collapses to approximately 1/6 of its assembled configuration. The containers weigh 700g each and are not typically used post food consumption, yielding a considerable amount of wasted volume and mass. The bulk overwrap system could potentially be used as the primary containment system and significantly reduce the upmass. The bulk pouches could be reused for trash or other storage post food consumption. Typically, a resupply flight consists of at least 40 containers of food, which would mean a savings of 28 kg of upmass per flight.
The disadvantage to using the bulk overwrap as a stowage container would be that the food would have less protection against impact or sharp objects. Other means of protection could be incorporated into the vehicle stowage to minimize damage to the food. One issue that was discovered during bulk sealing of containers that included MRE pouches, was that the sharp corners of the tear notch on the pouch could pierce through the bulk overwrap package. This caused the package to lose vacuum and its cuboid shape. Also, a loss of packaging integrity would open the contents to the external environment substantially decreasing the shelf life of the food. The recommended solution to this issue would be to research a more robust bulk overwrap material or to purchase MRE type pouches that exclude the tear notch, to prevent piercing.
A new Accu-Seal sealer with biactive sealer bars, that seal from both sides, and improved mechanism for vacuum/gas flushing has been ordered to improve the testing capabilities. The new sealer will be used for further optimization of the vacuum and gas flush parameters to reduce the oxygen content in the headspace to the lowest level possible while retaining the cuboid shape. Once the final vacuum level and oxygen content are determined, the proper oxygen scavenger system will be selected. Additionally, samples of various reclosable systems will be researched and acquired during the annual Pack Expo conference in October 2009.
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