Drying and gas or vapor contact with solids – Process – Gas or vapor contact with treated material
Reexamination Certificate
2000-02-11
2001-07-10
Gravini, Stephen (Department: 3749)
Drying and gas or vapor contact with solids
Process
Gas or vapor contact with treated material
C034S516000, C034S218000
Reexamination Certificate
active
06256905
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the invention
The present invention relates to a system, method and apparatus for shipment/storage of perishable products, such as fresh vegetables and fruit, fresh fish, etc. in a controlled atmosphere environment, and more particularly to a novel method in which the controlled atmosphere is provided throughout the shipment and/or storage of the product, and the apparatus associated therewith.
2. Background Art
It has long been known that temperature, humidity and the composition of the surrounding atmosphere can effect the useful life of food products. Products that have benefited greatly using controlled atmosphere storage and controlled atmosphere transport include fruits, vegetables, orchids and flowers, meats, poultry, fish, and also grains and seed, among many others.
For many decades perishable food products (e.g. fresh meat) had been shipped in a refrigerated environment. When these have been shipped by rail, specially constructed refrigerated freight cars would be supplied with a quantity of ice periodically along the route to maintain the desired low temperature. Later, mechanical refrigeration units were supplied for freight cars, over the road trucks, trailers, etc.
With regard to the atmospheric conditions affecting the shelf life of such food products, it has long been known that with the use of “controlled atmosphere” techniques, the shelf life of fresh post-harvest product can by extended by two, or three times or more in comparison with the conventional air storage techniques, when used as a supplement to good temperature and humidity protocols. Also, it has been a practice to have fruits and vegetables ripen to an optimum point prior to sale in a controlled atmosphere and then shipped using controlled or conventional atmospheric techniques. The term “modified atmosphere” refers to replacement of ambient air with a particular gas mix, and then sealing the container holding the mixture. No further controls are generally employed to maintain this particular gaseous mix.
The controlled atmosphere process in one where gas replacement of ambient air is accomplished in a similar manner to modified atmosphere. However, there is a mechanism to continually refresh the gas mix so that the levels don't fall out of proper proportions due to biochemical and enzymatic reactions between the gases and the product being housed. The continual modification is termed “controlled atmosphere”.
The controlled atmosphere process usually involves reducing the oxygen level in the immediate environment to inhibit oxygen loving and putrefying bacteria as well as the chemical oxidation processes. Controlled atmosphere techniques are commonly used to store vegetables and fruits in warehouses over many months. Without controlled atmosphere techniques in such warehouses, the product would perish quickly and all consumption would be seasonal only.
Ambient air is generally about 0.3% CO
2
, 20% O
2
and 78% N
2
with remaining 1.7% comprised of many other gases. Generally, the gas environment used in controlled atmospheric techniques is composed of CO
2
, O
2
, and N
2
. The proportions (or partial pressures) for optimum storage periods differ depending on the product. For lettuce, it may be only 2% CO
2
, 3% O
2
and 95% N
2
. For cantaloupe it may be 18% CO
2
, 5% O
2
and 70% N
2
. For poultry it may be 95% CO
2
, 1% O
2
and 4% N
2
. For some fish it may be 85% CO
2
, 5% O
2
and 10% N
2
.
However, when the food products are enclosed, the natural bacteriological and chemical processes that occur can alter the atmosphere around the enclosed products greatly. For fruits and vegetables the ripening process is very active, and to maintain the desired atmospheric conditions, some actively produced CO
2
and ethylene must be constantly removed and regulated. For post-harvest meats, poultry and fish, there is less active emission of generated products, but the post-rigor breakdown of the protein and fats is hastened in the presence of high levels of O
2
. Too little O
2
, however, will provide a different set of concerns such as allowing the toxic anaerobic bacteria to potentially flourish. Thus, it is highly desirable to change the atmosphere for protein products due to bacteriological and chemical processes, and this can be accomplished by constant purging of the aged air, and replacement with new, properly proportioned gases.
Most packaging materials used in food manufacture such as corrugated cartons, sbs fiberboard, styrofoam and polyethylene bags have a porosity that enables the gradual exchange of gases. Therefore, product that has been prepared and packaged in a standard method and with standard materials is generally very amenable to the benefits of controlled atmosphere storage and shipping.
For these reasons, equipment has been developed to maintain a controlled atmosphere for such food products when these are being stored for extended periods of time, or when these are being shipped by boat. Thus, specialized ocean shipping containers have been developed.
Specialized ocean containers are boxes that measure approximately 40 feet long, 8 feet wide and 9 feet high. The containers are available uninsulated-insulated or insulated with refrigeration units. Some units are available that are half this size, or 20 feet long, 8 feet wide and 9 feet high. Some companies have altered insulated refrigerated containers to permit the infusion of alternative gaseous atmospheres, and displacement of an ambient air atmosphere. Additionally they have placed into the containers extra seals to prohibit rapid gas exchange with outside air or loss of the gas or mixture. Some of these altered, refrigerated containers are also altered to install a railing just inside the doors that accepts a plastic curtain which serves to provide an additional seal against gas exchange.
However, there is an expense in modifying the basic design to incorporate the controlled atmosphere system, and one effect of this is that obtaining such specialized containers in a routing system used by shipping companies is often a time consuming process and can cause significant delays to acquire such containers. Normally, these are not used in routes involving most ports world wide, but instead are cycled in routes that are centers for fruit and vegetable production. Further, the controlled atmosphere techniques are often used in conjunction with refrigeration of the containers. All ocean shipping containers that use refrigeration have periodic defrost cycles. The periodicity may be as often as four hours or can be every 24 hours. The defrost cycles raise the interior of the containers several degrees for several minutes. Even small temperature changes on products have deteriorating effects.
One specialized ocean shipping container is provided by Transfresh Corporation. This system provides a sealed container with gas ports. The required gas is injected into the container, and the container is then sealed. There are mechanical processes that remove undesired levels of some gases such as ethylene and carbon dioxide. The system is primarily passive and is not capable of maintaining high levels of CO
2
for meat, poultry and fish products over time. It functions primarily as a modified atmosphere control system as will be described below. This container requires that a plastic curtain be fitted into specialized tracks at the entrance (the back door), and the curtain must be removed to ventilate the container for access of the product.
Another ocean shipping container is manufactured by C. A. Global Express L. L. C. Their shipping container contains the gas cylinders, nitrogen systems and dispensing systems. It dispenses controlled levels of gaseous atmosphere to product held in sealed (transfresh- type) containers.
As another example, Carrier Transicold Corporation manufactures refrigerating systems, and modifies ocean shipping containers to provide these in somewhat the same manner as Transfresh Corporation. A nitrogen making module is placed in the container which allows the purging of unwan
Gravini Stephen
Hughes Robert B.
Hughes & Schact, PLLC
LandOfFree
Controlled atmosphere shipping/storage system and method does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Controlled atmosphere shipping/storage system and method, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Controlled atmosphere shipping/storage system and method will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2547234