Abstract:
A bag formed of flexible thinwall sheet material for washing and/or dewatering comestibles having an upper compartment and a lower compartment connected by at least one opening. The bottom of the lower compartment is formed by a zipper-type closure. The members of the closure resist separation under elevated hydrostatic pressure generated in the lower compartment by centrifugal force. The closure may include a slider for providing controlled engagement and disengagement of the members, to permit use of the bag both for washing and dewatering.

Description:
RELATED APPLICATION 
     This application is based on, and claims benefit of, U.S. Provisional application Ser. No. 60/119,813, filed on Feb. 12, 1999now abandoned. 
    
    
     The present invention relates generally to articles for food preparation and, more particularly, to an article for washing and/or removing excess liquid from the surface of comestibles such as salad greens. 
     BACKGROUND OF THE INVENTION 
     Many comestibles need to be washed prior to serving to remove undesired sand, grit, etc. Typical are salad greens, and the present invention will be described in connection therewith, although it should be understood that it may also be used with a variety of fruits and vegetables, either whole, sliced or diced. Washing of salad greens is usually done by rinsing the greens with running water. After washing, it is usually necessary to remove the excess water remaining on the surface of the greens. The retained water is difficult to remove, being held tenaciously on the surface of the greens. Various means are employed to remove the adhering water, including manually shaking the greens, or placing the greens on absorbent paper or cloth to remove the liquid by capillary action. Both methods of removal have shortcomings; shaking the greens tends to broadcast water in all directions, and absorbing the water is time consuming and requires substantial counter space and a large amount of absorbent paper or cloth. 
     Another situation in which it is desirable to remove excess liquid from salad greens is after dressing has been added to the greens. Frequently, an amount of dressing is added in excess of that necessary in the finished salad, in order to ensure that the dressing will coat most of the greens. In such instances, it is desirable to remove the excess liquid to avoid oversaturation and unsightliness due to the excess liquid. The same difficulties are encountered in removing the excess liquid as already described. 
     THE PRIOR ART 
     To overcome these difficulties, various mechanical devices have been devised to wash and/or remove the excess water. Mechanical devices for this purpose typically include a perforated bowl for receiving the greens, the bowl being rotatably received in an outer stationary bowl. The greens in the inner bowl are rinsed with water, following which the inner bowl is spun to impel the excess water from the greens through the perforations and into the outer bowl. Such mechanical devices are costly, cumbersome to use, take up a large amount of storage space between uses, and require cleaning and drying after each use. 
     U.S. Letter Pat. No. 4,715,963 discloses a simple and inexpensive means for dewatering salad greens. The article disclosed in that patent is a bag formed of thin walled sheet material having an upper compartment and a lower compartment separated by a seal which extends across most of the bag, but is discontinuous in at least one region so as to provide an opening between the upper compartment and the lower compartment. Washed salad greens are placed in the upper compartment, after which the bag is manually twirled so that, under the influence of centrifugal force, the surface water is impelled from the salad greens against the heat seal line separating the compartments, and thence through the opening or openings into the lower compartment. The water removed from the salad greens is collected in the lower compartment, where it remains until the dewatered salad greens are removed from the upper compartment. The bag is then disposed of, either with the water still in place in the lower compartment or, if desired, the water may first be drained from the lower compartment by cutting open the bag, after which the bag is discarded. 
     The dewatering method and device of the &#39;963 patent perform commendably, and provide an exceedingly convenient and inexpensive solution to the problem of dewatering salad greens and other comestibles. One disadvantage is that the device is designed for a single use, after which the bag is discarded. Inasmuch as the bag is made of inexpensive plastic film, and produced economically, this is entirely feasible. Nevertheless, it would be desirable to provide a similarly convenient and inexpensive article which would be suitable for multiple use. 
     Another disadvantage of the &#39;963 method and device is that they are not readily adapted for washing salad greens. The amount of water needed for adequate removal of foreign material is substantial, and ordinarily would exceed the volumetric capacity of the lower compartment. 
     Another type of bag designed for use in dewatering salad greens in accordance with the method of the 1963 patent is disclosed in U.S. Pat. No. 5,380,093. In accordance with the &#39;093 patent, washed salad greens are placed in an upper compartment, and the bag is revolved to drive water into a lower compartment through a plurality of holes. After collecting in the lower compartment, the water may be poured out through a channel extending along the side of the bag from the lower compartment to the top of the bag. The bag is thereafter used for refrigerated storage of the washed salad greens. There is no teaching in the &#39;093 patent that the bag may be reused and, indeed, the patent teaches that the bag is disposable. Moreover, the bag of the &#39;093 patent has dead spots in the lower compartment and in the side channel which are not susceptible to effective sanitization between uses, and which can harbor undesired microorganisms and lead to their proliferation. Neither is the &#39;093 bag adapted for use in washing greens, inasmuch as the lower compartment would quickly fill with wash water. 
     It is a principal object of the present invention to provide a dewatering device for washing and/or removing excess liquid from salad greens and other comestibles which overcomes the described problems. It is a further object of the present invention to provide a bag formed from flexible film which performs as a washing and dewatering device and which is readily reusable. It is a more specific object of the present invention to provide a washing and dewatering bag formed from flexible film which is adapted to be readily sanitized after use. These and other objects will be apparent from the following description and drawing. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, there is provided an improved washing and dewatering device for comestibles, formed from flexible thinwall film, which is capable of substantial reuse. The article may be thoroughly cleansed between uses, with substantially no dead spaces where undesired microorganisms may accumulate. Even so, the dewatering device is relatively inexpensive, and retains all of the other advantages of the dewatering method and device disclosed in the &#39;963 patent. 
     Briefly, the dewatering bag of the present invention comprises a bag formed of thermoplastic thinwall sheet material divided into a first, upper compartment, and a second, lower compartment. The upper compartment is adapted to receive food items, such as salad greens, and has an open top to enable their insertion. The upper compartment is separated from the lower compartment by a discontinuous weld line, the discontinuity being such as to form at least one throat sized to permit passage of water therethrough, but substantially to prevent passage of the washed salad greens. The lower compartment is designed to function as a temporary storage space for wash water impelled from the salad greens placed in the upper compartment. The bag is used to dewater the greens by grasping the open end of the upper compartment and revolving, spinning or twirling the dewatering bag from the open end. Radial acceleration generated by revolving the bag and its contents results in the imposition of radial forces on water droplets, impelling them from the greens and thence through the throat and into the lower compartment. 
     An important feature of the present invention is means by which water collected in the lower compartment is selectively releasable therefrom, and by which the lower compartment may be sanitized after use so that the dewatering bag may be reused one or more times. Alternatively, if desired, the dewatering bag is sufficiently inexpensive that it may be discarded after a single use. 
     This feature is enabled by the surprising discovery that the bottom of the lower compartment may be formed in whole or in part by an openable longitudinal fastening means formed from two interlocking components, commonly known as a zipper-type fastener. The provision of a zipper fastener at this site has not heretofore been suggested or taught, no doubt because it was not appreciated that a zipper fastener can withstand the elevated “g” forces generated by revolving the bag without parting. For example, the &#39;093 patent referred to above discloses the use of a releasable locking strip such as sold under the brand name “ZIPLOC®” to seal the top of the upper compartment, but that site is not subjected to elevated “g” forces. The &#39;093 patent clearly does not teach or suggest the use of a zipper fastener to seal the bottom compartment. 
     The provision of a zipper fastener forming the bottom of the lower compartment permits draining and washing of the lower compartment after use to sanitize it and thereby inhibit growth of undesired microorganisms. In a more preferred embodiment, the fastener is provided with a slider to enable controlled opening of the zipper for only a portion of its length, so that collected water may be drained through a bottom corner of the lower compartment. The zipper may thereafter be reclosed, to permit additional water to be collected in the lower compartment. This enables the volume of the lower compartment to be minimized with respect to the volume of the upper compartment thereby decreasing the overall dimensions of the bag. 
     In a most preferred embodiment, the bag is used as a receptacle for washing the greens prior to dewatering. In this embodiment, the slider of the zipper is positioned so as to fully open the bottom compartment so that it acts as a sleeve to guide wash water flowing by gravity from the upper compartment. After the greens are thoroughly washed, the slider is moved to closed position, whereupon the dewatering function described above may be performed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a plan view of a first embodiment of a flexible film dewatering bag constructed in accordance with the present invention; 
     FIG. 2 is a plan view of a second embodiment of a flexible film dewatering bag also constructed in accordance with the present invention; 
     FIG. 3 is an enlarged fragmentary cross-sectional view taken along lines  3 — 3  of FIG. 1; 
     FIG. 4 is an enlarged fragmentary perspective view of the lower right hand corner of the dewatering bag of FIG. 2; and 
     FIG. 5 is an enlarged fragmentary cross-sectional view taken along lines  5 — 5  of FIG.  2 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to FIG. 1, a bag  11  is provided having an open top  13  and a bottom closure  15 . The bag is made from a thin-walled thermoplastic material such as low density or high density polyethylene. The bag  11  is divided into an upper compartment  17  and a lower compartment  19  by a discontinuous weld line  21 , the discontinuity providing at least one throat or opening  23 . In the illustrated embodiment, the weld line  21  is vee-shaped, with a single throat  23  at the point of the vee and generally at the centerline of the bag. It should be understood that the weld line may be discontinuous at a plurality of locations to provide a plurality of throats, and that the illustrated embodiment constitutes only one weld line embodiment. 
     The closure  15 , defining the bottom of the lower compartment  19 , comprises a continuous zipper-type closure having a female element  25  (FIG. 3) and a male element  27  interlocking with the female element. The female element  25  is welded to the front wall of the bag  11  and includes a lip  29  extending downwardly from the lower compartment. The male element  27  is welded to the back wall of the bag  11  and includes a lip  31  which extends under and around lip  29  of the female element. 
     This configuration of the interlocking lips of the male element  27  and the female element  25  resists separation of the elements even under the elevated hydrostatic pressure conditions generated in the lower compartment when the bag and its contents are vigorously twirled or revolved. This is a feature not disclosed or suggested in the prior art. 
     When the lower compartment becomes partially or fully charged with liquid removed from the food items in the upper compartment, the closure  15  may nevertheless readily be opened by grasping the male and female elements below the closure and pulling them apart. The lips are readily separable when manipulated from the underside of the closure  15 , and the liquid contained in the lower compartment may be drained away through the opened closure. The elements may thereafter be re-engaged by pressing them together with finger pressure, enabling dewatering to be resumed if not yet complete. 
     Upon completion of dewatering, the closure  15  may be fully opened, making the bottom compartment  19  completely accessible for cleaning and sanitization so that the bag may be used again at a later time. Closures suitable for the embodiment of FIGS. 1 and 3 are commercially available in polyethylene bags sold under the brand name “ZIPLOC®” by S.C. Johnson and Co., Racine, Wis. 
     A preferred embodiment of the bag of the present invention is shown in FIGS. 2,  4  and  5 , in which the same reference numerals are used with a “prime” symbol to identify components corresponding or analogous to those of FIGS. 1 and 3. A bag  11 ′ is provided having an open top  13 ′ and a bottom closure  15 ′. The bag  11 ′ is divided into an upper compartment  17 ′ and a lower compartment  19 ′ by a discontinuous weld line  21 ′, and in the illustrated embodiment, the weld line  21 ′ is discontinuous in four regions to provide four throats or openings  23 ′. 
     The closure  15 ′, defining the bottom of the lower compartment  19 ′, comprises a continuous zipper-type closure having a female element  25 ′ (FIG. 5) and a male element  27 ′ interlocking with the female element. The female element is welded to the front wall of the bag  11 ′ and includes a lip  29 ′ extending downwardly from the lower compartment  19 ′. The male element  27 ′ is welded to the rear wall of the bag  11 , and includes a lip  31 ′ which extends under and around the lip  29  of the female element. 
     As in the embodiment of FIGS. 1 and 3, the configuration of the matching lips of the male element  27 ′ and the female element  25 ′ resists separation of the elements under the elevated hydrostatic pressure conditions generated in the lower compartment  19 ′ during dewatering use. The closure also provides the other benefits and advantages described in connection with the embodiment of FIGS. 1 and 3. 
     A further important feature of the embodiment of FIGS. 2,  4  and  5  is the provision of a slider  33  straddling the interlocking male and female elements  25 ′ and  27 ′ which permits precisely limited separation thereof. The slider  33  is of the type illustrated in U.S. Pat. No. 5,161,286, which is incorporated herein by reference. 
     When the lower compartment  19 ′ becomes charged with liquid removed from food items in the upper compartment, the closure may be partially opened by sliding the slider to a position away from the end stop (shown in two different positions in FIGS.  2  and  4 ), and the liquid drained away through the resultant gap. Because the slider enables rapid and precise opening and reclosing of the closure, draining can be effected several times during the course of dewatering and this, in turn, permits the volume of the bottom compartment to be substantially less than if it were sized so as to hold all of the liquid to be removed. For example, the volume of the bottom compartment may comprise as little as ten percent or less than that of the upper compartment. 
     Bags with closures suitable for the embodiment of FIGS. 2,  4  and  5  are exemplified by those available under the previously mentioned ZIPLOC® brand name, as well as under the brand name HEFTY ONE ZIP® from Tenneco Packaging, Pittsford, N.Y. 
     A further feature of the present invention is the capability of the bag  11  or  11 ′ to be used as a device for washing salad greens as well as dewatering after washing. By fully opening the closures  15  and  151 , the lower compartments  19  and  191  become sleeves through which wash water may freely pass. Thus, unwashed salad greens may be placed in the upper compartments  17  and  17 ′, and running water may be introduced through the open tops  13  and  13 ′. The greens may be manipulated under the running water, with the wash water running freely through the openings  23  and  231  and thence to a sink drain. After washing, the closures  15  and  15 ′ are closed, and the washed greens dewatered by twirling the bag as described above. 
     As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description should be interpreted as solely illustrative and not in a limiting sense.