Degradable drinking straw

Abstract

A disposable degradable drinking straw made of chitin contains water-activated degrading enzymes. Initially in inactive lyophilized (dry) form, the enzymes upon exposure to ambient water in environment degrade chitin-based drinking straw to chitosan, a benign compound.

Claims

1. A degradable tubular article comprising a combination of an inner tube and an outer tube, whereby inner diameter of said outer tube is larger than outer diameter of said inner tube, said inner tube coaxially disposed inside said outer tube, said inner tube comprising lumen of said article, said inner tube further comprising chitin-type polysaccharide compound or compounds, said inner tube and said outer tube comprising at least one cavity between them, said at least one cavity further comprising chitin-degrading enzyme or enzymes, said enzyme or enzymes being present in inert form.

2. The article in claim 1 wherein said outer tube and said inner tube are longitudinally connected by at least one radial spacer, said spacer in conjunction with said outer tube and said inner tube comprising said at least one cavity.

3. The article in claim 1 wherein said outer tube comprises compound or compounds containing chitin-degrading type of enzyme or enzymes.

4. The article in claim 1 wherein said at least one cavity is sealed at at least one of its ends.

5. The article in claim 1 wherein said outer tube is shorter than said inner tube.

6. The article in claim 1 wherein said outer tube comprises compound or compounds containing chitin-type polysaccharide.

7. The article in claim 1 wherein said outer tube comprises at least one water ingress aperture, said aperture communicating with environment outside said outer wall.

8. The article of claim 7 wherein said aperture further comprises at least one water ingress retardation element.

9. The article of claim 8, wherein the retardation element further comprises a plug located inside said aperture.

10. The article of claim 9, wherein said plug further comprises polyvinyl alcohol.

11. The article of claim 9, wherein said plug further comprises a porous compound, said compound permeable by water, said compound comprising bio- or photo-degradable material or materials.

12. A degradable article comprising a tube, said tube further comprising chitin-type compound or compounds, said tube further comprising at least one enclosed compartment, said compartment located outside of lumen of said tube, wherein said compartment further comprises chitin-degrading enzyme or enzymes, said enzyme or enzymes being present in inert form, wherein said compartment further comprises at least one aperture, said aperture in communication with environment outside said article, wherein said aperture being capable of providing water ingress into said compartment, and wherein said aperture further comprises at least one water ingress retardation element.

13. The article of claim 12, wherein said retardation element comprises a plug.

14. The article of claim 13, wherein said plug further comprises a polyvinyl alcohol.

15. The article of claim 13, wherein said plug further comprises a porous compound, said compound permeable by water, said compound comprising bio- or photo-degradable material or materials.

16. The article of claim 15, wherein said porous compound is capable of controlling the rate of water ingress.

17. A degradable article, said article comprising elongated tubular shape, said article comprising lumen, said article further comprising at least one chitin-containing compound, said article further comprising at least one enclosed compartment, said compartment further comprising at least one type of enzyme, said enzyme supplied in lyophilized form, said enzyme configured to upon exposure to aqueous solution capable of degrading said chitin-containing compound of said article, said compartment further comprising at least one aperture communicating with environment outside said lumen of said article, said aperture permitting water ingress into said compartment from outside of said article, said enzyme configured to be activated by said aqueous solution, said enzyme subsequently degrading said chitin-containing compound of said article, said article consequently configured to be degraded upon exposure to said aqueous solution from outside of said article.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a perspective view of the degradable drinking straw with enzyme compartments.

(2) FIG. 2 is an elevation view of the degradable drinking straw inserted into a beverage holder.

(3) FIG. 3 is a partial perspective of a drinking straw.

(4) FIG. 4 is a cross-section of the degradable drinking straw taken along line A-A on FIG. 3.

(5) FIG. 5 is a partial perspective of the degradable drinking straw with infiltration retardation features.

(6) FIG. 6 is a cross-section of an alternative embodiment of the degradable drinking straw.

DESCRIPTION OF THE EMBODIMENTS

(7) In the foregoing description like components are labeled by the like numerals.

(8) Referring to FIG. 1 drinking straw 100 comprises a straw body 135 which in turn comprises the free end 110 which is inserted into user's mouth and submersible end 120 containing degrading enzymes 125.

(9) Referring to FIGS. 3 and 4 straw's submersible end 120 comprises essentially convex hemispheric hollow enzyme compartments 130 positioned longitudinally on straw body 135 while leaving straw's lumen 105 unoccluded for unobstructed liquid flow. Each compartment 130 is sealed at the end proximal to the edge of straw body 135 by end cap 115. Each compartment 130 is open at its distal end to allow water ingress when the straw is discarded. Each compartment 130 further contains enzyme 125 within it.

(10) Alternatively, as shown on FIG. 5 each compartment 130 can include water infiltration-control plug 140 on its distal end. Control plugs 140 can be made of a PVA (polyvinyl alcohol) or similar aqueously-soluble materials, or a porous filter-type degradable paper.

(11) Straw body 135 and enzyme compartments 130 are made of chitin. Enzymes 125, preferably in the form of free-flowing powders, are loosely retained in compartments 130, so there are numerous capillary pathways for dissolved enzymes and water to propagate through the entire lengths of compartments 130.

(12) Alternatively, enzymes 125 can be formed into pressed elongated shapes fitting inside compartments 130. Such shapes can be made to have smaller cross-sections than compartments' 130, to create capillary channels for water and dissolved enzyme propagation.

(13) End caps 115 can be made of chitin or can be eliminated altogether by crimping or sealing enzyme compartments 130.

(14) Enzymes 125 are preferably chitochinase-type enzymes or a combination of enzymes, initially in an inactive dry (‘lyophilized’) state. The chitochinase-type enzymes are well known in the art.

(15) For example, some of the mostly studied chitochinase-type enzymes are those extracted from the fungi Mucor rouxii, Absidia coerulea, Aspergillus nidulans and Colletotrichum lindemuthianum. All these enzymes are glycoproteins.

(16) The chitochinase-type enzymes in lyophilized powder form are commercially available, for example Product C6137 ‘Chitinase from Streptomyces griseus’ and Product C8241 ‘Chitinase from Trichoderma viride’, both by Sigma-Aldrich, Inc. of Saint Louis, Mo., USA.

(17) A cross-section of an alternative embodiment 300 of the straw is depicted on FIG. 6. It essentially comprises a double-walled tube comprising the inner shell 135 and the outer shell 137 interconnected with internal radial dividers 139. The spaces defined by the inner and the outer shells and dividers are filled with enzymes 125. Embodiment 300 also contains elements 115 and 140 of embodiment 100.

(18) Both straw embodiments 100 and 300 can be fabricated by extrusion. Fabrication of multi-lumen tubes, similar to straw 100 and 300, and their respective enzyme compartments 130 and radial dividers 139 integrated into a complete part, is well known in the art. Such multi-lumen tubing and extruded parts are widely used in diverse applications and are commercially available from numerous suppliers.

OPERATION

(19) As shown on FIG. 2, during use drinking straw 100 is placed into a beverage container 200 containing beverage 202, so that the upper edge of submersible section 120 of straw 100 is not submerged below level 210 of beverage 202, lest beverage 202 enters enzyme compartments 130 and causes premature degradation of straw 100 by activating enzymes 125.

(20) The straw can remain in a beverage virtually indefinitely (provided the beverage does not enter enzyme compartments 130), since the chitin material of straw 100 is impervious to water. When discarded, the straw is exposed to the environment where it will be eventually exposed to water which will enter enzyme compartments 130 and degrade the straw.

(21) Upon exposure to environmental water, the lyophized enzymes 125 are activated and proceed to decompose wall 135 and enzyme compartments 130 of straw 100 via hydrolysis of N-acetamido bonds in chitin which break down (acetylate) chitin and convert it to chitosan.

(22) If a straw contains retardation devices such as plugs 140 made to dissolve or having controlled porosity, the ambient water first dissolves the plugs or slowly penetrates them before reaching the enzyme. This prevents premature enzyme activation from accidental contact with water or aqueous substances (e.g. user spilling a beverage onto a straw) during straw use.

(23) The total amount of enzymes 125 is sufficient to degrade not only the enzyme-containing portion 120 of straw 100, but also the short free end 110 which is inserted into user's mouth.

ADDITIONAL EMBODIMENTS

(24) Although descriptions provided above contain many specific details, they should not be construed as limiting the scope of the present invention.

(25) Disposable degradable beverage and food containers and their corresponding lids and covers are also possible with the underlying technology described hereinabove.

(26) Various enzyme containment means, such as internal ribs, dividers, pockets and depressions can be added to the straw.

(27) The shape and number of enzyme compartments can vary as well.

(28) Also, depending on the catalytic efficiency of the selected enzyme(s), rather than covering most of the straw's length, the enzyme-containing portion of the straw may be limited to only its part between the level of the beverage and the user's mouth.

(29) Other articles can be made degradable using the technology described herein above, such as packaging and utensils.

(30) Thus, the scope of this invention should be determined from the appended claims and their legal equivalents.