US2567010A - Fungistatic wrapper - Google Patents

Description

24?? Zafiigllli) UNl'i nu a IAIL'D' PAI'ENT OFFICE" I I I t t H 52,567,010 Y t FUNGIS TATIC WRAPPER V GeraldH. Coleman and Paul A. Wolf, Midland,

Mi ch assignors to The Dow Chemical Company, Midland, Mich., a corporation of Delaware No Drawing. Application January 13, 1947, Serial No. 721,880

3'Claims. (01. lei-38.6)

. This invention relates to fungistatic wrappers, especially paper or regenerated cellulose wrappers, containing or coated with an agent which prevents or retards the growthoi-molds and other fungi. It relates in pa icular to sucli'f'a wrapper adapted for use in protecting foodstuffs from fungus attacks. I

Many foods are kn own to be subject to spoil age and become unmarketable or unacceptable for table use because of the growth thereon of molds and other fungi. The modern tendency is to reject most molded foods as unfit for use. To reduce the wastage which results from this practice, the more perishable foods are commonly wrapped, in an attempt to exclude molds. This is only partially eifective, and the protection is reduced when the wrapper is opened to remove part of the contents. Wrappers containing various fungicides or fungist-ats have been proposed, but none of them have been found to be as effective as desired. The principal, though by no means the only, foods which might benefit'fro-n'i' such wrappers are breadstuffs and cheeses. For such use, the antifungus agent in the wrapper must be odorless, and should also be tasteless, i. e. it should not impart any discernible flavor to the wrapped food, "andit must be harmless for humans to handle or to ingest; at use concentrations. Such agent should be reasonably longlived in the wrapper.

- It is among the objects ofthe presentinvention to provide a iungistatic sheet, suitable for wrapping purposes. A related object is to provide such 'a wrapper for use on foodstuffs, containing a fungistat which is odorless, tasteless, and non-hazardous to humans at use concentrations. A particular object is to provide a wrapper suitable for use in contact with breadstuffs or cheese.

The fungistatic wrapper of the present invention is a flexible wrapping sheet (usually paper or celloph-ane) treated to bear from 0.3 to 10 per cent, and usually from 1 to 3 per cent of dehydroacetic acid as the fungistatic agent. Dehydroacetic acid has the formula Ha C O l l r H- CHa ll 0 and is also known as 3-acety1 S-methyl pyrandione-2,4. It has a very limited solubility in water will Other objects may appear hereinafter.

V v 2 (about 0.1 per cent at room readily soluble in a variety of organic solvents, in,-. cluding ethyl alcohol and, the glycols, and is come, patible with paraflin wax and other coating ma.- terials. It is also soluble in. alkaline aqueous solu: tions .and may bereprecipitated therefrom by acidification. These properties make it possible to incorporate dehydroacetic acid in paper onthe machine, or. to coat paper or cellophane in a number of ways withdehydroacetic acid or compositions containing it. The agent is essentially neutral, and forms a neutral sodium salt, from which it may be recovered by acidification,-

When using relatively porous papers to make the new fungistatic wrapper, the dehydroacetic acid may be introduced into the body of. the paper, either by addition of the agent to the fibers during paper making or, more economically, by treating the paper withasolution of the agent or one of its-soluble salts, anddepositingv the agent .on the fibers. Such fibrous papers may also be coated with lacquers or hot-melt coatings containingndea hydroacetic acid, using. the methods known in the paper coating art. When the wrapper is to comprise a fparchmen paper, glassine paper, or regenerated cellulose sheet, the fungista-tic agent is applied thereto asan ingredient of a surface coating composition which mayv be a lacquer or a melt. The coating composition. may contain the usual filmf-orming ingredients or the usual heat sealing agentsor moisture-proofing agents, in any combination known to be suitable for the intended application. The composition of suchcoatings, apart from the fungistatic ingredient, forms no part of the present invention. The fungistat should be contained in the coating composition at a concentration to provide from 0.3 to 5per cent of dehydroacetic acid, based on the dry weight of the final coated sheet.

The following example illustrates the preparation of one form of the new wrappers, and describes its use in the protection of foodstuffs:

Ewample A series of melts was prepared consisting of microcrystalline wax and from 0.5 to 2 per cent of its weight of dehydroacetic acid. Regenerated cellulose sheet was coated with these melts at the standard rate of 40 pounds of coating for each 20 pounds of the cellulosic sheet. For preliminary test purposes, measured samples were cut from the coated sheet and were placed with their coated face down on the surface of previously inoculated malt yeast agar nutrients in petri dishes. After a suitable period had elapsed for maturity temperature) but is 3 of the microorganism, the area of effective protection was measured. The results are given below, in terms of the relative areas of the zone of inhibition, larger values representing greater protection. The corresponding value for an untreated control sheet is taken as unity.

Concentration of The coated sheet containing 2 per cent of dehydroacetic acid in its coating was used to wrap loaves of commercial bakers bread, both sliced and uns'licecl. Other loaves, of the same bread 1 were wrapped in untreated wrappers while still wrappers. Non-fibrous thermoplastic films, for wrapping purposes, may be made to contain dehydroacetic acid, though it is considered more advantageous to apply the compound to the surface of such films. Examples of this class of wrapper are the films made of rubber hydrochloride, vinyl chloride-vinyl acetate copolymer, the vinylidene chloride copolymers, ethyl cellulose, and the like.

The utility of the new wrappers is not limited to the protection of bread and cheddar cheese, as they may be used to wrap baked goods of all types and cheeses of both hard and soft varieties, candies, fruit cakes, citrus fruits and many other mag 15 terials subject to attack by fungi. In its broader aspects the invention comprises not only flexible wrappers of the types suggested above, but also the relatively stifier fiber board cartons commonly used in the packaging and shipment of perishable items. Suchcartons may have their fibrous walls coated or impregnated with gerr droacetic acig to provide resistance to attack y otherslwere wrapped ina coated sheet which was purchased as being antimycotic. The wrapped loaveswere all stored for 7 days, at 85 F. and 90 per cent relative humidity. The untreated control wrapped loaves had heavy growths of black and blue-green molds on their crusts; especially along the side, just under the crown. The loaves wrapped in the commercial antimycotic sheet had healthy but smaller growths of similar molds along their sides. The loaves whose wrappers contained the dehydroacetic acid showed no mold growth on their outer crusts.

A similarly coated sheet of regenerated cellulose, in which the wax-coating contained 0.5 per cent of dehydroacetic acid, was used to wrap slabs of cheddar cheese. The wrapper was not sealed, so that airwas not excluded from the cheese. Other pieces of thesame cheese were wrapped in the same. way in regenerated cellulose containing no antimycotic agent. The samples were stored at, jC. an atmosphere havingabout 80 per. cent, relative humidity. The cheese in. the untreated wrapper had a heavy growth of blue-green mold in 7 days, while that in the treated wrapper was free from any visible mold growth for the several. vweeks vdurationof the test. I

'In, addition to the regenerated cellulose described in the example, the described melt of ,wax and dehydroacetic acid has beenapplied to other wrapping sheets, including fibrous sheets such as sulfite, and kraft sheets; and non-fibrous plastic sheets, and these have value as fungistatic wrappers., Lacquers containing dehydroacetic acid, are similarly useful inv coating orimpregnating cellulosic and other sheets. suitable for use as microorganisms.

The method of protecting foods b'y wrapping them in the new wrappers is disclosed and claimed by the present inventors in two applications filed concurrently herewith, Serial Nos. 721,877 and 721,378, new U. S. Patents 2,474,227 and 2,474,228, respectively.

We claim:

1. A cellulosic wrapping sheet carrying an effective fungistatic amount, at least 0.3 per cent of the weight of the article, of dehydroacetic acid integral therewith.

2. A coated cellulosic wrapping sheet carrying an effective fungistatic amount, at least 0.3 per cent of the weight of th'e'article, of dehydroace'tie acid in the coating on said sheet.

3. A sheet of coated regenerated cellulose whereof the coating contains from 0.3 to about 5 per cent by weight of dehyd'roacetic acid.

GERALD H. COLEMAN. PAUL A. WOLF.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS July 15, 1941.

Jour. Textile Institute, March 1944, page A Review of Report, by W. Colman.

Claims (1)

1. A CELLULOSIC WRAPPING SHEET CARRYING AN EFFECTIVE FUNGISTATIC AMOUNT, AT LEAST 0.3 PER CENT OF THE WEIGHT OF THE ARTICLE, OF DEHYDROACETIC ACID INTEGRAL THEREWITH.