US2302639A - Method of packaging and refrigerating perishable commodities - Google Patents

Description

Nov. 17, 1942. w MOORE 2,302,639

METHOD OF PACKAGING AND REFRIGERATING PERISHABLE COMMODITIES Filed Jan. 31, 1939 2 Sheets-Sheet 1 F I I Z] 3 I f 5 W n/lgl ENToRx ATTORNEY.

Nov. 17, 1942. w. E. MOORE METHOD OF PACKAGING AND REFRIGERATING PERISHABLE COMMODITIES 2 Sheets-Sheet 2 Filed Jan. 31, 1959 IN ENTDR.

ATTORNEY- Patented Nov. 17, 1942 METI IOD OF PACKAGING AND REFRIGER- ATING PEBISHABLE COMMODITIES William E. Moore, San Francisco, Calif.

2 Application January 31, 1939, Serial No. 253,762

3 Claims.

This invention relates to a, method of packaging and refrigerating perishable commodities such as fresh fruits, vegetables, flowers, fresh fish, meats, etc., the present invention being an improvement on my co-pending, application entitled "Package refrigeration, filed July 28, 1937, Serial No. 156,093, now Patent No. 2,210,946, issued Aug. 13, 1940.

In the co-pending application above referred to, a refrigerated heat-absorbing body is devide an efllcient method of packaging and refrigerating-perishable commodities, in which the use of a heat absorbing body of the type referred to is employed; to provide a method' of preserving the freshness of perishables, in which moisture derived from the melting of a primary refrigerant is applied to the perishable at a predetermined rate substantially under the control of a secondary or booster refrigerant; to provide a self-refrigerated package, having a wateproof or water-resistant liner, in which is placed a layer of absorbing material such as sawdust with sufficient capacity to absorb excess water or moisture liberated in the package; to provide a substantially sealed self-refrigerated package which will be, practically speaking, dry on the exterior, from which odors will not escape, which is relatively inexpensive to produce, and which is capable of shipping perishables long distances without the necessity of being placed in refrigerator, cars; and further, to provide a simple, compact, portable refrigerating unit of small size which is adapted to be placed within a standard container for cooling and preserving in fresh condition such products as flowers, etc.

The package and method of refrigeration are described in more detail in the accompanying specification, and are shown by way of illustration in the accompanying drawings, in which Fig. 1 is a central vertical longitudinal section of the refrigerated package;

Fig. 2 is .a horizontal section taken on 11-11 of Fig. 1; v

Fig. 3 is a cross section taken on line III-III of Fig. l;

Fig. 4 is a central longitudinal vertical section of a package, showing a slightly modified form line thereof;

Fig. 5 is a horizontal section taken on line V-V of Fig. 4;

Fig. 6 is a cross section similar to Fig. 3, showing the manner in which lettuce heads and similar vegetables are packed for shipment.

A number of perishable commodities, such as fresh fruit, vegetables, fresh fish, etc., are'materially benefited by modern methods of cold storage and/or refrigeration, at least to the extent of prolonging or increasing their keeping properties, but they are at the same time detrimentally affected as far as quality and appearance is concerned, this being particularly true where the method of cold storage or refrigeration employed permits the-more or less free circulation of cold air through the commodity, as cold air has a great affinity for moisture, and causes rapid dehydration and hence a withered or dried-up appearance of such commodity.

If commodities of this character can be maintained at a substantially uniform temperature of, for instance, 36 to 40 F., air circulation substantially eliminated, and water ormoisture supplied rather than removed from theproduct, keeping qualities are materially prolonged, and quality and appearance of the commodity are maintained. The present invention involves a method of packaging and refrigerating commodities of this character whereby a substantially uniform temperature ismaintained throughout the body of the commodity over a period of several days, air circulation is substantially eliminated, and the required water or moisture to maintain freshness is continuously supplied to the product. The manner in which this is accomplished is as follows.

Referring to the accompanying drawings, and particularly Figs. 1 to 3, A indicates a box or similar container constructed of wood, fiber board or any other suitable material. Placed within the box is a liner 2 which covers the sides, ends and bottom. This liner may be constructed of several layers of paper orsimilar material which is waterproofed to prevent escape of water or moisture. A suitable insulating material is introduced between the sheets of material, and

hereinafter be more fully described.

When the box is to be prepared for shipment of commodities, for instance fish or crabs, the next step is to provide a layer of dry sawdust or a similar water-absorbing substance such as indicated at 3, by placing it in the bottom; and

on top of that a supporting platform is provided which maintains the fish out of contact with the sawdust. The supporting platform here illustrated may be composed of a series of spaced wooden slats such as indicated at l, which are held by cross-slats 5 or the like. or other commodity to be shipped is placed on top of the slatted support, as indicated at 6, and on top of that is placed a layer of crushed ice, such as shown at I, hereinafter to be known as the primary refrigeran On top of again is placed one or more refrigerated heat-absorbing pads 8, hereinafter to be referred to as the secondary refrigerant. On top of that is placed an insulating liner 9, which may be formed from the side walls of the liner, instead of separate as shown, the box or container being finally closed by the application of a cover In by means of nails, bands or the likes thus packed is ready for shipment, and in order to describe fully the benefits of the method and the results that take place, fish-will be particulanly referred to.

It is generally conceded that crushed or shaved ice has a certain beneficial effect on fish, especially as the melting allows a flow of water to pass over the fish, which flow positively carries or conducts the temperature throughout the load; it also supplies moisture and at the same time carries off any surface secretions or products of decomposition developed in the fish during transit.

The problem of icing and re-icing fresh fish in order to ship them commercially over long distances has never been satisfactorily solved. For instance, at present the most generally employed commercial method of packing fish for shipment consists of placing a quantity of fis'h in a large .wooden box of heavy construction, together with a sufficient quantity of cracked ice to cover the fish completely so as to provide cooling for the journey. If the distance to be shipped is greater than a single icing of the fish will last, then re-icing is necessary at some point during transit, to keep the fish from spoiling.

- Naturally, the cost of providing additional icing "and handling increases the total cost of the shipment. Another serious objection to the use of cracked ice as a means of preserving the fish is that the temperature maintained by it is not Thejsh.

employed is the special pad or. pads indicated at}. These are composed of sawdust pressed into cake form and saturated with calcium chloride or a similar solution capable of reaching a low temperature before freezing into a' solid.. These cakes are frozen to a temperature well below zero, for instance 20 below or more,

and when placed on.'top of.the ice as shown in' Figs. 1 and 2 supplement the cooling effect of the ice and,prevent the too rapid melting thereof. The supplementary amo'unt of heat absorption provided by the pads 8 is suflicient to maintain The box or container a predetermined or desired uniform temperature for a period of several days.

During theshipment of a package of this character the crushed ice in immediate contact with the top layer of fish will slowly melt. The water liberated thereby fiows down through the several layers of fish and, first, acts as a conductor to maintain a uniform temperature throughout the load of fish; secondly, as it fiows over the fish it dissolves or absorbs any prodiicts of decomposition 'or surface secretions which may develop during transit. The water finally fiows through the slatted supporting platform and is readily absorbed by the sawdust. This absorption causes diffusion of the water throughout the body of the sawdust, and to.that extent also has a coolconstant enough to guarantee proper condition of the fish upon arrival at a distant point, and many times spoilage occurs en route. Ice alone gradually loses its heat-absorbing capacity as it melts, due to gradual loss of its latent heat, and the water resulting from the melting flows down through the fish and soaks the box with water and drains out, where it must be taken care of or cause damage to other packages in the vicinity. For these reasons fish can only be shipped by certain carriers and under special regulations. If, therefore, a method could be found for packing fish and other sea foods that will retain the beneficial efifects of crushed ice while remedying the bad features of the same, the shipment of fresh fish and other products todistant markets ing effect. The sawdust layer-also acts as an efiicient insulating wall against the entrance of heat, and as the water is absorbed by the sawdust it becomes so spread as to prevent shortcircuiting of heat and cold; thereby excess loss of the refrigerant, and riseiin temperature, are prevented.

The low temperature, to wit, 20 below zero, or less, maintained in the.pads 8 when they are first introduced into the package would cause freezing of the fish during the first period of 1 ingly important for the reasons already stated;

that is, supplying moisture or water flow over the fish, and in addition functioning as a conductor to cause uniform heat flow. Furthermore, it acts as an insulator between the pads and the fish, and therebymaterially resists or retards the heat fiow from the fish to the pads, as well as acts to insulate the pads from too rapid heat flow from the walls of the package. That is, the crushed ice in immediate contact with the heat absorbing pads assumes, practically speaking, the temperature of the pads, for instance 20 below ,zero, but the layer immediately adjacent the fish is maintained at substantially melting temperature. The temperature gradient thus ranges through the layer of the ice from a point considerably below zero to the melting point.

It is a known fact that the lower the temperature of ice the greater its resistance to heat conduction; hence the crushed ice layer between the heat absorbing pads and the fish, and between the fish and the walls of the container, functions as an insulator. or retarder to slow down the heat flow, and it also acts as a dis tributor whereby the heat flow is maintained uniformly throughout the body of the container and the fish contained therein. 'The quantity of sawdust maintained in the bottom of the package is' more than enough to absorb all the water liberated by the ice, hence when the package is opened there is no spilling of water; the fish is clean and fresh and may be readily removed; and as a waterproof liner is provided in addition to the moisture or water absorbing sawdust, danger of leakage and spoiling of other adjacent goods during transit is entirely eliminated. In addition to all the advantages so far pointed out, it should also be understood that a package of this character does not require exterior refrigeration and as such can be shipped in ordinary express cars, as refrigeration from within the package is all that is'necessary, and is entirely depended upon.

Where flowers or similar commodities are to be shipped, a uniform cool temperature and the application of water or moisture has been found to be of great advantage. In order to prevent the weight of the ice and the heat absorbing pads 8 from crushing or otherwise damaging flowers or similar goods, a perforated partition member (see Fig. 4) is placed between the crushed ice and the flowers. This partition member may be constructed .of .any suitable material, but it should be uniformly perforated throughout to permit the water produced by the melting ice to be uniformly sprinkled over the flowers during transit.

In Fig. 6 the same type of package as that dis-' closed in Figs. 1 to 3 is shown, but the drawing illustrates'a practical method of packing lettuce heads and other vegetables of this character. As a substitute for the wood or slatted supporting platform interposed between the sawdust and the fish or crabs, it has been found that a perforated platform made of paper or wood, such as shown at 26, is sufficient. On top of this a suitable number of layers of lettuce heads are packed, as shown at 21, and on top of these the crushed ice and the final heat-absorbing pads are placed. With certain vegetables and flowers it has been found that direct contact with the crushed ice is not desirable, as it has a tendency to burn them, or in other words cause frost marks which result in dark spots or discoloration; hence the desirability of placing the spacer l5 between the ice and the uppermost layer of vegetables or flowers.

While a layer of perforated cardboard I5 is shown as being interposed between the crushed ice and the vegetables or flowers proper, I wish it understood that any other suitable material may be employed, for instance, one or more layers of paper which is adapted to become saturated with water liberated by the melting ice, so as to permit the water to flow through; again, paraflined sheets of paper which are perforated to permit the water to pass through may be employed. The important feature, with certain commodities, is to keep the ice out of direct contact with the commodity by an interposed material which permits a free flow of water and at the same time functhe commodity but alsothe refrigerant whereby a desired temperature is maintained within the package throughout a predetermined'period of time. Another important feature of the invention is the provision of two refrigerants, to wit, a primary and a secondary refrigerant, the primary being placed adjacent or in immediate contact with the commodity to absorb heat therefrom. and the secondary refrigerant functioning to absorb heat from the primary, to prevent too rapid melting thereof. It is also important that the two refr gerants shall have different melting points, so that a comparatively w de range of temperature may be maintained between the primary and the final heat-absorbing unit, in other words the secondary refrigerant, as this determines the total amount of B. t. u. which the two refrigerants are capable of absorbing before their refrigerating capacity becomes totally spent. In fact. the difierence in melting point between the two refrigerants is the reason why it becomes possible to package and refrigerate commodities of the character described without danger of actually freezing them, and further, why it is possible to ship perishable commodities to destinations re- A quiring several days in transit without replenishing the refrigerant.

While certain features of my invention have been more or less specifically described and illustrated, I nevertheless wish it understood that changes may be resorted to within the scope of the appended claims.

Having thus described and illustrated my invention, what I claim and desire to secure by Letters Patent is: I

l. A method of packaging and refrigerating perishable commodities which consists in placing the commodity in-a container, placing crushed ice in contact with the commodity to conduct heat away from the commodity, placing a refrigerated material of lower melting point than the crushed ice in contact with the ice to conduct heat away therefrom, placing an absorbent in the container to absorb water liberated by melting of the ice, insulating the container to retard heat flow from the exterior of the container to the interior thereof, and closing the container for storage or shipment.

2. A method of packaging and refrigeratin perishable commodities which consists in placing a layer of water absorbing material in the bottom of a heat-insulated containenplacing a perishable commodity above the absorbent material, placing a refrigerated heat-absorbing body above the commodity, interposing a layer of crushed ice between said-heat-absorbing body and the commodity and in contact with both, and closing the container with a heat-insulated cover.

3. A method of packaging and refrigerating perishable commodities which consists in lining a container with a waterproof heat-insulating material. placing a layer of water-absorbi material in the bottom of the lined container, placing a perishable commodity above the absorbing material, placing crushed ice on top of the commodity and in contact therewith, placing a refrigerated heat-absorbing body on top of the ice and in contact therewith, and finally closing the container with a heat-insulated cover.

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