US2203033A - Lettuce pack and method of packing lettuce - Google Patents

Description

June 4, 1940; E. H. SPIEGL 2,203,033

LETTUCE PACK AND METHOD oF PACKINQLETTUCF Filed Dec. 19, 1958 .ATTORNEY Patented June 4, 1940 UNITED. STATES PATENT OFFICE LETTUCE PACK AND METHOD OF Claims.

ing of lettuce for shipment, all of the steps are very carefully controlled so that the lettuce harvested from the field will-be presented to the market in the best possible condition, not only insofar as its inherent value is concerned but also insofar as its appearance is concerned since lettuce heads which can be made to arrive onthe market in good physical condition, and especially with a highly attractive, fresh appearance, command a considerable premium over the usual market price. It is therefore of immediate commercial value in any wise toimprove upon the technique or apparatus, involved in the handling of lettuce between the growing eld and ultimate presentation on the market. This' usually involves a great deal of care betweentheactual removal of the lettuce from the growing field up to the time it is packaged and shipped-which time is usually within a very few hours of the same day. The shipment time, however, often extends over a number of days since the lettuce customarily is shipped the majority of the way or entirely across the continent, so that often, despite extra care` exerted by the picker and the packer of the produce, the conditions of transit are such as to negative the otherwise beneficial results to be obtained. vThe universal practice at the present time, so far as I am aware, is to pack the lettuceheads, after stripping Ithe outside leaves and trimming the stem, into rectangular shipping crates made up of a number of spaced wooden slats secured together. Into the container so formed, a lining of parafned paper is placed and the heads of lettuce are'then introduced along with a quantity of crushed ice.

After the maximum number of lettuce .heads have been placed in the crate, a final charge of crushed ice is heaped upon the top, the ends of the waxed paper are folded over on top of the heaped crushedice, and a springy, resilient, slatted wooden lid is by pressure finally nailed in position. The bulged crate, along with many others like it, is put into a refrigerator car until the car isv approximately three-quarters full, crushed ice is then blown into the car on top of the entire load, and the car is sealed and sent to its destination. Hundreds of thousands of cars of lettuce areshipped in this way each year,

Upon arrival at destination it is found that a certain number of the packages of lettuce yare not in good order, for the reason that some of the heads have been mechanically squeezed l against the sharp Iedges of the crate slats, due 5 to the initial pressure of the resilient lid exerted through the crushed ice, and the heads have been squeezed into or against the slatted sides of the crates and into the corners thereof, so that material mechanical injury follows. 'Ihis mel0 chanical injury is particularly apparent upon the heads which have been forced into the crate corners and against the sharp edges of the crate slats. The pressure when the crates are initially packed -is large since, to compensate at 15 least partially for ice meltage within the crate during shipment, the crate is customarily greatly overbuilt with ice so that when the lid is nailed on deformation and bruising of the heads ensue. Bruising of the leaves is-followed by a milky 20 exudation which oxidizes red and ruins the appearance of the produce. For resale, therefore, all the outer bruised leaves must be stripped off, thus reducing the head size so much as greatly to lower the retail price, or to make the head un- 25 salablysmall. This retail loss is of the nature of 25% of the crate but heretofore has not been overcome.

There is also mechanical injury to the crates themselves amounting to about 2% to 5%, im- 30 portant in that recoopering is required and damage claims against the carrier arise. This v condition is aggravated by the soaking the crate wood gets from the ice melt so that repair is diicult or impossible and further use of the 35 crate is impossible.

But the chief economic loss probably arises from the inability to display or keep thelettuce for very long after its arrival on the re tail ,market That which is not` immediately sold may keep for another days display or it may have deteriorated so badly that it must be discarded. The addition of each days keeping time is of tremendous value. But the keeping 45 time depends largely upon, how soon afterpicking the field heat in the lettuce head can be extracted. Even with ice in the crate, the lettuce in the customary paper-lined wooden crate requires from twenty-four to fortyf-eight hoursl 50 injury to the lettuce in packing and in shipment Y will b e materially reduced.

' an improved lettuce'pack which can be shipped with greater 'facility and with' at least equal ease of handling from the standpoint of size. contourv and weight, as compared with the present package.

A further object of my invention is in general to improve aA lettuce pack and the method of packing lettuce. l

The foregoing and other objects are attained in the embodiment of the invention illustrated in the drawing, in which- Fig. 1 is a longitudinal cross-section on a vertical piane, of a diagrammatically illustrated refrigerator car packed in accordance with my inv vention;

Fig. 2 is a cross-section the plane of which is indicated by the line 2'-2 of Fig. 1; f

Fig. l3 is a cross-section on a diametral. vertical plane, of a lettuce pack in accordance with my invention; andl Y' Fig. 4 is a cross-section the plane of which is indicated by the-line l-I of Fig. 3. Y In its preferred form, the lettuce pack of my invention includes a circular cylindrical container, substantially airand water-tight and 4fabricated of material having high thermal conductivity, within which are symmetrically ar-.`

ranged a plurality of heads of lettuce, the majority-of the heads being in immediate contact with the material of the container and under s. some circumstances being interspersed with crushedwatereice, there'being'a closure means for maintaining the heads of lettuce in position within the container. The method includes arranging the-heads of lettuce in a predetermined form, confining them to such form sometimes in the presence .of a refrigerant and in the subystantial absence of air by a means having a high thermal conductivity, and iinaily extracting the eldheat from the lettuce rapidly through a c onning means.

In following out lthe conduct of I my inven--I tion, from which both the new pack and theV method willnappearl I shall dcribe-.the par- 60 ticular manner of practicing it -which has resulted in securing a premium over the marketl price. In this instance I have taken a container G which is fabricatedA preferably of a vmaterial having a relatively high thermal conductivity, such as sheet iron or steel, coated with aV suitable material inside and outside to preclude deterioration or undesired chemical action in connection with the contents. The precise thermal ccnductivity of the material isnot critical. but I have found that metal has a relatively high conductivity with respect tothe field heat within the\ lettuce, as contrasting with the relatively low thermal conductivity of the wooden containers at lpresent universally used, particularly when such. containers are lined with one or more bruising or other damage.

layers of waxed paper, in which event it is very.

diicult for eld heat within the lettuce to be transferred to a refrigerant which surrounds the package as a whole.

In the present instance, the container 6 is preferably a right circular cylinder having in one embodiment a diameter of substantially eighteen and one-quarter inchesand a height of approximately twelve and one-half inches. The container has a similar metal bottom 1 which is secured by any 4suitable inter-folding 8 with the side walls 9, so that the container is water-tight. A: container 6 of about the indicated size and proportions is `readi1y handled by an operator since its weight is not far different from that of the present wooden crate and since it can readil be put on a present packing stand. r 1

When a container is so positioned, lettuce heads 4which have been ltrimmed are arranged on the bottom 1 in a predetermined vand preferably symmetrical geometrical order, as clearly disclosed in Figs. 3 and 4. vIn this way each of the lettuce heads Il is in direct and immediate thermal conducting relationship with the walls 1 .and 9, yet there are no sharp edges or corners to groove or bruise the produce. Since the con-- tiner is round and the lettuce head is of similar curvature, whatever pressure there is between them is exerted over alarge area of contact, so that the unit pressurejis so low as to obviate The large area o f contact is also veryfavorable for thermal transfer. This condition is further assisted since the metal walls 6 of the container are quite thin and are somewhat deformable so that when a layer of lettuce is packed, the .container cross-section can '1 form so that the container wall yields to provide uniform pressure instead of locally pressing upon and bruising the lettuceg In the arrangement .sho'wn 'especially in Fig. 4, most of the ten headsV oflettuce in the bottom layer are in immediate depart from circular into a partially polygonal l thermal contact withthe sides 9 as well aswith the bottom 1, and the remaining central heads are in good thermalcontact with the bottom 1,

vso that a' majority ofthe heads of lettuce in the lower layer arein direct and immediate thermall Of course, the numcontact with the container. ber of heads of lettuce in a'particular layer, .and

the arrangement of the layer, will vary notcnly f with the size of the .heads of lettuce but 'with the diameter of the container; but the arrangement shown is calculated to result in a standard number of heads of lettuce inmy new container.

The-plurality of lettuce heads il in immediate contact with the bottom 1 constitute the lower layer, generally designated I2. At this point twov alternatives are possible. 'I'he pack may be inelusive 'of water-ice, termed a "wet pack, or ice -V may bev omitted, resulting in a' dry pack. To -make the wet pack, upon nishing the lower layer l2, the packer introduces al charge .of crushedV water-ice into the container.

Thev

water-ice spreads itself over the heads of lettuce and lls the interstices therebetween, vso that an adequate bed is made for the reception of a superposed, .intermediate layer Il constituting. a'nother plurality of lettuce heads I6 which are arranged either in the same geometrical pattern as was the layerv II or in' a variation thereof', delpending somewhat upon 'the fancy of the packer, Y

butin any case a majority of the heads are in immediate contact with the wall 'I'he layer A I4 is in turn subjected to-a charge ofcrushed water-ice and `upon it is superposed a top layer I1 on which an ice charge is placed, substantially filling the container.

This procedure may be varied, if desired, by first completely filling the container with layers of heads of lettuce and finally charging the container with crushed water-ice in a quantity suf- Iicient to 'fill all of the interstices and also the container. In this instance the heads of lettuce will be in immediate contact with each other rather than spaced by layers of water-icc. In either event the top layer I1 of heads of lettuce is just below the rim I9 of the container 6, and a Iinal charge of refrigerant in the form of crushed water-ice is introduced.

To follow the dry pack alternative, the heads of lettuce are arranged as described but no ice is added to the container. For a given size container preferably larger heads are used with the dry pack so that a reasonably firmly filled packl age results.

With either the wet pack or the dry pack, when the container is full, a closure 2|, preferably of metal comparable to that of the sides 9, is engaged with the rim I9 and is effective to retain the contents in position. The closure 2I can be frictionally retained, can be lightly crimped in place, as shown in Fig. 3, can be tack welded in position, or can be otherwise secured. The metal closure is put on the container at substantially room temperature 'and before the interior ice, if used, has had much opportunity to reducel the temperature. But subsequently, as the temperature of the closed package and contents is reduced, the metal is contracted, as is the contained air, so that the closure is subsequently removable only with some diiculty. I have found that practically the package is substantially water-tight and, although not hermetically sealed, is nearly airtight. Of c'ourse, the package can be sealed, and evacuated of air, or can be charged with an inert gas, but this renement is not ordinarily necessary.

The practical exclusion of air or air circulation is commercially effective greatly to reduce or prevent redness of the lettuce, which rednessv is- .very undesirable. What oxygen is trapped in the container is converted into carbon-dioxide by a slight reaction with the lettuce, after which oxidation practically ceases. Whenever a lettuce leaf is bruised and where the lettuce butt' the container and the closure 2l is put on, either dimensions of the car.

by hand or by machine, the container 6 is placed within its shipping compartment, such as the load compartment of a refrigerator car 23. The arrangement of the container 6 and a plurality of its fellows within the car will vary somewhat with the size of the container and the interior A typical arrangement is illustrated, in which the containers are disposed in rows and files and in superposed layers virtually to the capacity of the car, following which interior bridging or bracing 24 is utilized to retain the containers in position, and the interior of the car is charged with crushed waterice 26 which not only lls the interstices between the adjacent containers 6 but is introduced in suiliicent quantity to form a blanket over the top of the load. This refrigerant is introduced with the customary ice-slingers now utilized to blow crushed ice into the interior vof cars.

'I'he car so iced is then ready for shipment, but the result ensuing is materially different from vthat following the use of standard wooden crates with waxed paper lining. In accordance with my invention, the field heat of the lettuce heads II which are in intimate thermal contact with the highly conductive walls of the container 6 is dissipated from the heads of lettuce directly through the Walls of the container to the surrounding crushed ice 26. Hence extraction of the eld heat results in` a large melt of the external crushed ice 26 which virtually surrounds each container and can be replaced if necessary, rather than in a rapid melt of interior ice as occurs with wooden crates. Otherwise stated, whereas with wooden crates the crushed ice contained within the package melts very rapidly in extracting the eld heat from the lettuce and discharges indiscriminately from the package during shipment and even after unloading, in the disclosed dry pack arrangement there is no interior melt, with the wet pack the melt within the package is relatively slow, and with both of my packs the melt of ice in the car is relatively rapid. Under comparable practical conditions the ice melt lwithin a crate is at least fifty percent, giving rise to large initial overbuilding in an endeavor to compensate for it in advance, whereas with my arrangement the internal melt, where interior ice is used, is not over ten to fifteen percent. While the external, car melt is much greater, the ice can, if necessary, be easily replenished. When the containers 6 are finally taken from the car at the end of the journey, the contained lettuce is in good condition, and with the wet pack there is considerable crushed ice remaining for further refrigerationand preservation of the lettuce heads when the package is placed on display in a retail store. Whatever melt occurs from the contained ice I3 does .not escape from the package but remains as cold water in contact with the lettuce, helping to prevent access of air thereto even though the closure is not completely air-tight or has been removed, and preventing desiccation of the lettuce heads. With the dry pack the heads are cold, dry, fresh in appearance and ready for immediate sale.

When the container contents are to be inspected either within the car or at a market, removal of the closure 2| is reasonably easy and exposes immediately one-third of the lettuce' heads, while removal of the center heads 22 and 23 exposes all of the remaining heads in the container. Replacement of those heads removed, if any, and of the closure leaves the package in substantially its original condition before inspection. 'I'his contrasts with the crate, the wood of which becomes water-soaked during several days` subjection to ice melt'and if opened for inspection cannot be repacked and recoopered to be accepted as anything but rehandled merchandise of greatly lowered value.

This inspection feature is'valuable to the retailer, since he may place the opened but watertight container directly upon his display stand and expose the produce while it is still in contact with the the remaining refrigerant, if any, the melt from which is confined to the container fone-half of a crate. It vis, therefore possible,v

where space is at a premium, to display.` the original package instead of unpacking part of the contents from time to time. Half-crates are not feasible since thereare twicelas many corners' as with a wh'oe crate and hence twice as many opportunities for bruised and damaged heads so that the percentage of first-grade heads uneconomically reduced.

Finally, after the lettuce heads have been re"- moved from the container, the container either is reusable under the same circumstances or has a salvage value for other purposes. The weight of the package and the ability to handle it are substantially comparable with the present wooden crate, but the ability to retain the melted ice, if any, but especially to conduct the field heat of the lettuce rapidly through the material of the container, vamong other attributes, has resulted in making the dry pack feasible and in reducing the interior icing so that the heads of lettuce arrive at the market in so much better than usual state that a premium is obtainable.

The example described herein has illustrated zine use of water-ice as the internal and the exernal refrigerant, but other refrigerants, such as solid carbon-dioxide, are usuable. If Aprecooling facilities are available, it is entirely feasible to pack the lettuce heads dry and then to precool the containers` and contentsprior to loading them into cars. The car cooling utilized after loading 'may involve placing ice around and on the loaded containers or may involve simply the circulation of chilled air. n

Furthermore, while the example speaks particularly of lettuce and is peculiarlyI adapted to meet theproblems involved in the marketing of lettuce, it is also usable and beneficial in connection with carrots, peas, artichokes, cauliflower, broccoli andcomparable produce.

claim:

1. A lettuce pack comprising a circular-cylhidr- Y ment' with material having a high thermal con- I ductivity, introducing ice into confinement with said heads of 1ettuce,and then subjectingsaid heads of lettuce and said ice to a rapid extraction of field heat from' said heads of lettuce through said material.

' 3. A lettuce pack comprising a substantially watertight container fabricated of material having a high thermal conductivity, a plurality of Aheads of lettuce packed in layers within and in thermal contact with said container, crushed water-ice within said container in heat-transferring relationship with said lettuce heads, and a removable closure for said container.

4. A lettuce pack comprising a-metal container capable of retaining water, a plurality of heads of lettuce packed in layers within and in thermal contact with said container, and crushed water-ice within said containerv in heat-transferring relationship with said lettuce heads'.

5. A lettuce pack comprising a metal container, a plurality of heads of lettucefpacked in layers within and in thermal contact with said container, and crushed water-ice exteriorly of and in heat-transferring relationship with said container. 1

. ELLIS H. SPIEGL.

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