United States Patent (19) 11) 4,338,343 Vidal et al. 45 Jul. 6, 1982

(54) LIQUID ANTI-MICROBIAL TREATMENTS Chemical Abstracts, vol. 53, 1959, Columns FOR STORAGE GRAN WITH AMMONUM 22.770-22771. BISULFITE AND A Chertkov, B. A., Zhur. Priklad, Khim, 32, pp. PRODUCT THEREOF 1732-1742, 1959. Catalysis, Kinetics, vol. 78, p. 309, 1973, Abst. No. (75). Inventors: Frederick D. Vidal, Englewood 20686s. Cliffs; Anantharaman Jayaraman, Chemical Abstracts, vol. 83, p. 600, 1976, Abst. No. Nutley, both of N.J. 187726v. 73) Assignee: Pennwalt Corporation, Philadelphia, Mizoguchi, T. et al., Bulletin of the Chemical Society of Pa. Japan, vol. 49, No. 1, 1976, pp. 70-75. Chertkov, B. A. et al.; Soviet Chemical Industry, vol. 49, (21) Appl. No.: 163,413 No. 6, 1973, pp. 383-387. Kirk-Othmer, Encyclopedia of Chemical Technology, 22 Filed: Jun. 26, 1980 2nd ed., pp. 90–91. M. Goehring, Ergebnisse and Probleme der Chemie der Related U.S. Application Data Schwefelstick stoffverbindungen, Akademie Verlag, (60) Continuation-in-part of Ser. No. 156,501, Jun. 4, 1980, Berlin, 1957, pp. 138-141. Pat. No. 4,309,451, and Ser. No. 38,739, May 14, 1979, Nickless (ed.), Inorganic Sulfur Chemistry, (1968), p. abandoned, said Ser. No. 156,501, is a division of Ser. 377, pp. 515-517. No. 50,162, Jun. 20, 1979, abandoned. Primary Examiner-Thomas G. Wiseman (51) Int. Cl3...... A23B 9/00; A23L 3/34 Assistant Examiner-Elizabeth J. Curtin 52 U.S. Cl...... 426/331; 426/335; Attorney, Agent, or Firm-Woodcock, Washburn, 426/532; 422/28; 424/164 Kurtz, Mackiewicz & Norris 58 Field of Search ...... 426/321, 331, 335, 312, 57 ABSTRACT 426/319, 320, 532, 442,618; 424/317, 161, 162, Materials are disclosed for treating moist grains to pre 164, 166, 175, 127, 149; 422/28 vent the growth of microorganisms during storage. 56). References Cited These materials comprise aqueous solutions of ammo U.S. PATENT DOCUMENTS nium bisulfite (NH4HSO3) and at least one acidification compound for at least lowering the pH of the solution 1,222,830 4/1917 Werner ...... 424/317 1,524,494 1/1925 Warth...... 424/162 to between about 2.5 to 4.0, preferably 3.0. Preferred 1,777,044 9/1930 Legendre ...... 426/319 acidification compounds include acidic ammonium salts 2,132,786 - 10/1938 Hockenyos ...... 424/162 of inorganic acids, such as sulfuric or phosphoric acids, 2,735,775 2/1956 Bronstein, Jr. et al...... 426/164 and of organic acids such as acetic, propionic or other 2,799,583 7/1957 Harris...... 426/321 short chain organic acids. Alternatively, the disclosed 2,912,793 11/1959 Stone et al...... 424/162 preservative materials comprise disproportionation 3,404,987 10/1968 Kooistra et al...... 426/9 products of ammonium bisulphite solutions, such as 3,928,577: 12/1975 Kochurova et al...... 426/335 ammonium, or alkaline mineral salts of metabisulfites, 3,962,475 6/1976 Forest et al...... 426/331 trithionates, thiosulphates, tetrathionates, dithionates 4,083,999 4/1978 Drury et al...... 424/317 and others. Natural and artificially disproportionated OTHER PUBLICATIONS solutions of ammonium bisulfite are also disclosed as exhibiting surprising preservative actions. The dis Chemical Abstracts, vol. 66, 1967, Abstract No. 27779k. closed preservative materials are applied as liquids in Chemical Abstracts, vol. 87, No. 19, p. 451, Nov. 1977, treatments at 1% by weight of the grain to be pre Abst. No. 150449p. served. Grain treated in accordance with the present Foods, vol. 72, p. 293, 1970, Abstract No. 2303m. invention exhibits increased resistance to spoilage and Thermodynamics, vol. 88, p. 427, 1976, Abst. No. excellent odor, flavor and color characteristics. Ac 137947x. cordingly, excellent preservatives are disclosed for Chemical Abstracts, vol. 76, p. 329, 1972, Abst. No. treating grains which remains suitable for subsequent 50552.W. human consumption. Air Pollution & Industrial Hygiene, vol. 75, p. 167, 1971, Abst. No. 100985s. 5 Claims, No Drawings 4,338,343 1 2 is effective for inhibiting microbial growth, grain LIQUIDANT-MICROBIAL TREATMENTS FOR treated with these amounts of propionic acid has an STORAGEGRAIN WITH AMMONIUM BISULFITE objectionable taste and color, and therefore may not be AND A DISPROPORTIONATION PRODUCT sold for human consumption. Nonetheless, under THEREOF E.P.A. regulations, grain containing not more than 2% propionic acid can be sold for animal fodder. It is esti CROSS REFERENCE TO RELATED mated that propionic acid treatment is not used on more APPLICATIONS than about 1% of the grains stored in the United States. The present application is a continuation-in-part of It has also been suggested to treat grains during stor our prior co-pending patent application entitled "Liquid 10 age with various gases. According to one process, am Anti-Microbial Treatment for Storage Grain', Ser. No. monia gas is slowly "trickled' through grain to be 156,501, filed June 4, 1980, now U.S. Pat. No. 4,309,451 treated. Unfortunately, this treatment discolors the which is a division of my prior copending application treated grain, producing a darkened product. Accord Ser. No. 050,162, filed June 20, 1079, now abandoned, ingly, grain treated with an ammonia gas trickle process which is a continuation-in-part of Ser. No. 38,739, May 15 is permitted only for animal consumption. 14, 1979, now abandoned which applications are hereby Another gas which has been suggested for use in incorporated by reference as if fully set forth herein. preserving grains is . Not surprisingly, The present application is also a continuation-in-part sulfur dioxide gas, while exhibiting preservative effects, of our prior co-pending patent application entitled may produce some odor and flavor problems in the "Gaseous Antimicrobial Treatment of Storage Grains", 20 treated grain. Additionally, treatments with sulfur diox Ser. No. 06/038,739, filed May 14, 1979, now aban ide gas are extremely corrosive on storage equipment, doned which application is hereby incorporated by presumably as the result of sulfurous and sulfuric acids reference as if fully set forth herein. which are formed within the moist treatment environ The present application is also related to our co-pend ment. . ing patent application entitled "Gaseous Anti-Microbial 25 The above described treatments, and other chemical Treatments of Storage Grain', Ser. No. 163,410, filed materials, have been described in various publications as June 26, 1980, which application is also a continuation exhibiting preservative or pesticidal effects: in-part of the above mentioned applications. For various patents referring to the use of gases, such BACKGROUND OF THE INVENTION 30 as ammonia gas or sulfur dioxide gas, please see U.S. The present invention relates to the field of preserva Pat. No. 1,777,044 (Legendre) (Grain preserved . tive treatments of grains during storage, and more par through treatment with ammonia gas, sodium carbonate ticularly, to treatments applied to grains containing or alkaline-reacting gas by adjusting the hydrogen more than about 15% moisture, to prevent microbial concentration of the adherent moisture to a point within spoilage which might otherwise result, as for example 35 the range pH 7–10); U.S. Pat. No. 3,928,577 (Ko due to the growth of various fungi, molds, etc. churova et al.) (vegetable food products, flower bulbs, It is often advantageous to store grains such as corn, plants, etc. preserved with tablets containing potassium wheat, sorghum and the like after harvest and prior to metabisulfite, gelatin or starch, stearic acid and salts their eventual conversion into products such as flour, thereof which are described as replacing use of sulfur molasses, etc. Unfortunately, without some form of 40 dioxide, potassium metabisulfite, and treatment after harvest, most grain will spoil, particu sodium bisulfite prior art techniques); U.S. Pat. No. larly when stored in semi-closed conditions, such as 1,524,494 (Warth) (sulfur dioxide or other gases such as grain storage bins, elevators, etc. After harvest, most hydrocyanic acid gas, carbonic acid gas, and grain contains approximately 20% to 25% moisture. disclosed as treatments for composition cork to destroy This moisture content is sufficient to promote microbial 45 or prevent the development of mold spores, bacteria, growth, such as fungi and mold growth, which may fungus growths, yeasts, insect larvae, etc.); U.S. Pat. very rapidly cause spoilage of the stored grain. No. 2,132,786 (Hockenyos) (sulfur dioxide intermixed One treatment for preserving grain during storage with carbon dioxide for use as fumigant for carpet bee which has achieved considerable success is the rapid tles, moths, bedbugs, etc.); U.S. Pat. No. 2,912,793 drying of grain through the application of heat, such as 50 (Stone et al.) (soil treatment to reduce nematode popu hot air, which reduces the moisture content of that lations comprising injection of sulfur dioxide substan grain to below about 15%. At this moisture content, tially below the surface of the soil followed by a soil pH grain may be stored for extended periods of time while adjustment by application of an alkaline fertilizer, such retaining suitable odor, flavor, and color characteristics. as anhydrous ammonia, calcium oxide, etc.). Unfortunately, this technique normally requires the 55 Organic acids, such as decanoic, undecylenic, and consumption of substantial amounts of energy which is acetic acids, have also been suggested in the literature as used to provide the heat necessary for quick drying of treatments for storage grains: grain to be preserved in this manner. Accordingly, a In U.S. Pat. No. 3,962,475 a method is disclosed for substantial need has arisen for alternative preservative preserving high moisture content agricultural grains treatments which may be used either alone or in combi 60 comprising treating grains with, (1) a composition con nation with ambient air drying techniques, to thereby sisting essentially of an organic food-grade acid or phos provide an energy efficient method of treating grain for phoric acid, (2) a water soluble, noncorrosive, nontoxic, storage. alkali or alkaline earth metal sulfate salt, and (3) a syn Another treatment for preserving grain which has thetic organic cationic or anionic surfactant for enhanc achieved some commercial success is the use of propi 65 ing the penetration of said acid into said grains. In ac onic acid. This treatment normally entails the provision cordance with this disclosure, exemplary organic acids of less than 2%, usually about 1%, by weight of propi include propionic and acetic acids, while exemplary onic acid to the grain to be treated. While this method alkali or alkaline earth metal sulfate salts particularly 4,338,343 3 4. include such sulfate salts as sodium and potassium sul following articles, each of which are hereby incorpo fates. rated by reference: . . . In U.S. Pat. No. 3,404,987 (Kooistra et al.), a preserv Landrooth et al, Thermodynamics, Vol. 88, 1976, p. ing agent, such as propionic acid, sorbic acid, benzoic 427, 'Thermodynamics of the reaction of ammonia and acid (and its methyl- and ethyl esters) and a potentiating sulfur dioxide in the presence of water vapor': agent, typically an edible mineral salt, such as the phos Zelionkaite et al, Chemical Abstracts, Vol. 76, 1972, phates, carbonates, chlorides, nitrates, , pyro p. 329, "Decomposition of Ammonium hydrosulfite phosphates and hydroxides of iron, manganese, zinc, tin solutions under the action of thiosulfate'; and silver, are disclosed as being effective in inhibiting Scargill, Air Pollution and Industrial Hygiene, Vol. microbial growth in food systems. In this patent, the 10 75, 1971, p. 167, "Dissociation constants of anhydrous cooperative effect between the preserving agent and ammonium and ammonium pyrosulfite prepared potentiating agent is described as exhibiting outstanding by gas phase reactions'; activity against microorganisms. Chertkov, Chemical Abstracts, Vol. 53, 1959, Cols. Another chemical which has been reported in the 22770-22771, (citing Zhur. Priklad. Khim. 32, literature as exhibiting a preservative effect is ammo 5 1695-1707, 1959), "Kinetics of the autodecomposition nium bisulfite. In Chemical Abstracts, Vol. 87, No. 19, p. of ammonium bisulfite-sulfite solutions'; 451 (1977) preservation with 0.4% ammonium bisulfite Chertkov, Zhur. Priklad. Khim. 32, 1732-1742, 1959, (NH4HSO3) of oat-pea, corn, clover-timothy, or alfalfa "Kinetics of Spontaneous Decomposition of Ammo silage containing 72-84.6% water was described as nium Sulfite-Bi-sulfite Solutions'; improving feed quality. Preservation was described as Najbar et al, Catalyst, Kinetics, Vol. 78, 1973, p. 309, increasing the soluble sugar, nitrogen and lactic acid "Kinetics and stoichiometry of the heterophase reaction content of the feeds and of preventing butyric acid sulfur dioxide with ammonia'; formation. Good results were also reported by mixing Hisatsune, Chemical Abstracts, Vol. 83, 1976, p. 600, corn with straw (5:1, 67.3% moisture) and treating the 25 "Infrared spectroscopic study of the ammonia-sulfur mixture with 0.4% ammonium bisulfite. Similarly, in dioxide-water solid state system'; Chemical Abstracts, Vol. 66, No. 7, p. 2616 (1967) (Ab Mizoguchi et al, Bulletin of the Chemical Society of stract 27779K) selected preservatives were tested to Japan, Vol. 49(1), 1976, pp. 70-75, "The Chemical Be determine the pH of a 1% solution, acidity or buffer havior of Low Valence Sulfur Compounds. X) Dispro value, and the preserving properties of selected preser 30 portionation of Thiosulfate, Trithionate, Tetrathionate vatives. The preserving capacity was determined by the and Sulfite under Acidic Conditions'; degree of suppression of germination of moist grain, the Chertkov et al, Soviet Chemical Industry (English growth of mold, the activities of oxidative-reductive, Translation), Vol. 49(6), 1973, pp. 383-387, "Spontane proteolytic, and amylolytic enzymes. Thiourea, ammo ous Decomposition of Concentrated Ammonium Sul nium bisulfite (NH4HSO3), a mixture of urea and NH4 35 fite-Bisulfite Solutions'; pyrosulfate, and ammonium bisulfate (NH4HSO4) were Encyclopedia of Chemical Technology, Vol. 14, pp. described as good preservatives which enriched green 90-91, edited by Raymond E. Kirk and Donald F. Oth matter with nitrogen and sulfur. Other ammonia con mer, published by The Interscience Encyclopedia, Inc., taining compounds were described as weak preserva New York, “Thionic Acids'; tives. Of these compounds, ammonium bisulfite, ammo Goehring et al., Zeitschrift fuer anorganische und nium bisulfate, and ammonium chloride (NH4Cl) were allgemeine Chemie, Vol. 263, 1950, pp. 138-144, recommended for further study and industrial tests. “Ueber die Einwirkung von Schwefeldioxyd auf Am Finally, in Chemical Abstracts, Vol. 72, No. 1 (1970), p. moniak'; 203 (Abstract No. 2303m) various sulfur preparations M. Goehring, Ergebnisse and Probleme der Chemie were described as preserving green fodder. Among 45 these, liquid sulfur dioxide, NaHS2O3 and an 80% solu der Schwefelstickstoffverbindungen, Akademie Verlag, tion of NH4SO3 were tested at given doses. Upon com Berlin, 1957. parison with "conventional methods', strong decompo These "disproportionation' reactions apparently sition of all soluble carbohydrates was inhibited, the cause ammonium bisulfite to be oxidized and dispropor latent phase of fermentation was prolonged, total trace 50 tionated into several other compounds, which contrib able acidity was decreased, and the formation of volatile ute to a solution exhibiting a lowered pH. Analysis of and non-volatile organic acids was suppressed. The ammonium bisulfite which had aged for several years resultant silage was considered to be superior to con indicated that up to 20-30% may have been converted ventional silages in organoleptic properties, as well as in to ammonium bisulfate, and minor amounts of thiosul maintenance of its structure. Preservation with sulfur 55 fate, metabisulfite, dithionate, imidodisulfonate, and preparations was described as reducing the loss of nutri various polythionates. In addition to a lowered pH, a tive substances by 50%. disproportionated solution of ammonium bisulfite ex It is known to commercially prepare ammonium bi hibits a yellow-greenish color which is not exhibited by sulfite by bubbling ammonia and sulfur dioxide into a "fresh' (undisproportionated) aqueous solution of water, forming an essentially 100% yield of pure ammo 60 ammonium bisulfite. nium bisulfite solution having a pH of about 5.5. Aque As seen from the above, while many efforts have ous solutions of 47-50 weight percent of ammonium been made to provide preservatives which are suitable bisulfite are thus readily available. Upon extended stor for use in preserving grains, no chemical preservative age, particularly when exposed to air, ammonium bisul has yet been found which provides an efficient, low cost fite is known to spontaneously undergo various "dispro 65 method of preserving grains, while maintaining or en portionation' reactions. For various discussions of hancing the color, odor and flavor characteristics of these disproportionation reactions, their kinetics, and those grains so that the treated grains remain suitable the products which result therefrom, please refer to the for human consumption. 4,338,343 5 6 preservative solutions, as are propionic, acetic, benzoic, SUMMARY OF THE INVENTION sorbic and other organic acids having less than 10 car Quite surprisingly, applicants have found that bon atoms. Preferred acidic ammonium salts include "aged', i.e., substantially "disproportionated', solutions mono-ammonium dipropionate and/or mono of ammonium bisulfite are superior materials for use in ammonium diacetate. The resultant solutions provide preserving grains during storage. Disproportionated grain preservatives which are effective, economical and ammonium bisulfite solutions, that is, solutions contain do not impair the odor, color or flavor characteristics of ing ammonium bisulfite and effective amounts of ammo the grains treated therewith. - nium bisulfite disproportionation products, which ex Through the above methods, novel preservative ma hibit a pH of between 2.5 and 4.0, preferably below 3.5 10 terials are provided which prolong grain storage times and about 3.0, are better preservatives than aqueous to up to ten times the length obtained through corre solutions of ammonium bisulfite. Disproportionated sponding aqueous ammonium bisulfite treatments. ammonium bisulfite solutions do not adversely effect Accordingly, a primary object of the present inven the color, taste or odor of grains treated therewith and tion is the provision of novel grain preservatives. thus produce preserved grains which are fit for human, 15 Another object of the present invention is the provi as well as animal consumption. sion of grain preservatives which do not adversely af. In accordance with alternate embodiments of the fect the color, taste or odor of the grains treated there present invention, "synthetic' preservatives are pro with. vided which consist essentially of ammonium bisulfite A further object of the present invention is the provi and effective amounts of at least one ammonium bisul 20 sion of grain preservatives which produce preserved fite disproportionation product. These "synthetic” pre grain suitable for human consumption. servatives are preferably adjusted in pH through the A further object of the present invention is the provi addition of an acid, or acidic ammonium salt of an acid, sion of a peanut preservative which controls at least A. to achieve a pH of between 2.5 and 4.0, preferably about flavus, and thus, levels of aflatoxin. 3.0. In accordance with these embodiments, suitable 25 These and other objects of the present invention will disproportionation products include ammonium dithio become apparent from the following more detailed nates, trithionates, tetrathionates, bisulfates, metabisul description. fites, imidodisulfonates, and polythionates. Hexameta phosphates, such as sodium hexametaphosphate, may DESCRIPTION OF THE PREFERRED also be added to ammonium bisulfite solutions to obtain 30 EMBODIMENTS a suitable preservative. In these preservatives, the molar While particular examples have been selected for the ratio of the ammonium bisulfite to its disproportionation purposes of illustration, one of ordinary skill in the art product(s) should range from about 1:0.10 to about 1:1. will recognize from the information set forth herein that In accordance with these embodiments of the present the materials and methods of the present invention are invention, sulfuric, hydrochloric or phosphoric acids 35 applicable to a wide variety of grains in a wide variety are suitable inorganic acids for use in adjusting the pH of treatment concentrations. Accordingly, one of ordi of the preservative solutions. Propionic, acetic, and nary skill in the art will recognize that various modifica other organic acids having less than 10 carbon atoms, tions may be made to the specific materials and concen are suitable organic acids for use in adjusting the pH of trations described hereinafter without departing from these preservative solution(s). More particularly, pH 40 the scope of the present invention, which is defined adjustment through the addition of an acidic ammonium more particularly in the appended claims. salt, such as mono-ammonium dipropionate and/or In testing the materials and methods of the present mono-ammonium diacetate, are believed to be effective. invention, various methods were employed to deter The resultant grain preservatives are effective and eco mine the effectiveness of control and test compositions nomical and do not exhibit deleterious color, odor or 45 upon samples of moist wheat, corn, and sorghum. As an flavor effects on grains treated therewith. experimental technique, it has been found desirable to Further alternate embodiments of the present inven conduct comparative tests on wheat and sorghum utiliz tion provide "artificially disproportionated' ammonium ing sterilized and subsequently innoculated grain sam bisulfite solutions wherein one or more physical treat ples. Unless otherwise specified hereinafter, all wheat ments are applied to ammonium bisulfite solutions to 50 and sorghum samples have been inoculated with spores produce artificially disproportionated solutions exhibit of A. flavus in concentrations of 108 spores per gram of ing enhanced grain preservative actions. In accordance grain. This procedure enables rapid testing of various with these methods, ammonium bisulfite solutions are preservative substances and produces reliable results subjected to one or more steps of UV-irradiation, ul due to the fact that A. flavus is recognized to be a major trasonication, or heating, to artificially disproportionate 55 source of spoilage which is extremely difficult to con these ammonium bisulfite solutions to produce addi trol. Further, particularly in peanuts, by controlling A. tional novel preservatives. flavus populations, concentrations of aflatoxin may cor Still further alternate embodiments of the present respondingly be controlled. invention provide acidified ammonium bisulfite solu It is within the scope of the present invention to apply tions which have been found to be more active as grain 60 the disclosed preservative solutions in weight percent preservatives than aqueous ammonium bisulfite solu ages ranging from 0.05 to 5 weight percent, preferably tions of higher alkalinities. In accordance with these 0.5 to 1.5 weight percent, or about 1 weight percent of embodiments of the present invention, acidic ammo the grain to be treated. Similarly, it is within the scope nium salts of an inorganic or organic acid are preferred of this invention to utilize aqueous solutions containing to achieve a pH of between about 2.5 and 4.0, preferably 65 between 5 and 60 weight-percent, preferably 20 and 50. less than 3.5 and about 3.0, in the acidified ammonium weight-percent ammonium bisulfite. Those of ordinary bisulfite solution. Sulfuric, hydrochloric or phosphoric skill in this art will recognize that, due to the ionic acids are also suitable for use in adjusting the pH of the nature of the disclosed perservative solutions, other 4,338,343 7 8 materials, such as sodium and potassium salts, which are comparative purposes. As seen from Table I, these addi ionic in solution, may be added to achieve the chemical tional materials, even though in many instances includ equivalence of these weight percentages of ammonium ing ammonium and having been similarly adjusted bisulfite. In the following examples, treatments with the to preservative properties. Example 20 includes several indicated test solutions were applied at 1% by weight of 5 disproportionation product equivalents which, in ab the grain to be treated, unless otherwise indicated. Any sence of ammonium bisulfite, show only moderate required adjustment of pH has been accomplished acitivity. through additions of ammonium bisulfate to the test The general antimicrobial effects of test substances on solutions, unless otherwise indicated. As seen from the a wide range of bacteria, fungi, and molds which are following table, test materials in accordance with the 10 likely to develop in unpreserved grains has also been various above described embodiments exhibit marked investigated. In particular, preservative materials in preservative effects on the moist (i.e. 25% H2O) test accordance with the present invention have been found grain samples. to be effective against bacteria, yeasts and molds such as TABLE I aspergillus, penicillium, alternaria and fusarium. Indeed, Effec- 15 no fungi believed to contribute to natural grain spoilage tive has yet been found which is not effectively controlled Ex- Period a- In through the use of the herein disclosed treatments. ple Treatments' Grain pH Days In the following examples, 20 grams of wheat were 1 47% NH4HSOs Wheat 5.0 2 20 adjusted to have a moisture content of 25% and steril 2 46.8% NHHSO3 Wheat 4.5 2 ized. These samples were then inoculated with 108 3. 46% NHHSO3 pH adjusted Wheat 40 4. spores of A. flavus per gram of wheat. After four days of . 4 45% NHHSO3 with solid Wheat 3.5 8 5 44% NHHSO3 NHHSO4 Wheat 2.9 4. incubation at room temperature, the infected samples 6 5% NH4HSO4; pH adjusted with Wheat & 3.0 2 were subjected to various treatments at 1% by weight 40% NaOH Sorghum 25 of the grain. In Table II, the treatments and the mini 7 4N H2SO4 Wheat & 3.0 2 Sorghum mum periods for which such treatments were deemed 8 4N HC Wheat & 3.0 2 effective in preventing spoilage are indicated. Sorghum TABLE II 9 4N H3PO4 Wheat & 3.0 2 Sorghum Ex- Effective 10 40% NaHSO3; pH adjusted with Wheat & 3.0 8 3O al- Period solid NHHSO4. Sorghum ple Treatment" pH (in Weeks) 11 6% H2SO3; pH adjusted with Wheat 3.0 3 21 47% NH4HSO3 "old" ammonium bisul- 3.0 s 60 40% NaOH fite (stored at ambient tempera 2 1% Na2S2O6 Sorghum 3.0 ture for several years) 13 1% Na2S3O6 pH adjusted with Sorghum 3.0 22 100% Propionic Acid - > 60 solid NHHSO4. 35 14 1% K2S506 pH adjusted with Sorghum 3.0 23 20% Propionic Acid - 2 solid NHHSO4. 24 47% NH4HSO3 (Fresh) 5.3 < 1 Moldy 5 1% K2S606; pH adjusted with Sorghum 3.0 l 25 45% NH4HSO3 (Fresh) -- 3.0 2 Moldy solid NHHSO4. 4.8% NHHSO4 6 i0% K2S3O6 Wheat 3.4 l 26. 39% NH4HSO3 (Fresh) + 3.0 - 60 17** 40% K2SOs pH adjusted with Wheat 3.0 12 40 17% Propionic Acid solid NHHSO4. 27 29% NH4HSO3 (Fresh) -- 31% Na2S2Os 3.0 s 60 18 10% K2S3O6; pH adjusted with Wheat 3.0 28 31% NHHSO3 (Fresh) -- 33% Na2S2O5 5.3 6 Moldy NH4HSO4. 29 45% NHHSO stored at ambient 3.0 50 19 10% Na2S4O6; pH adjusted Wheat 3.0 2 temperature for several months. with NHHSO4. Heated at 55C, for 2 days. 20 2% Na2S2O6 - 2% K2S3O6- Wheat 3.0 7 45 30 41% NH4HSO3 (Fresh) + 9% K2S3O6 3.0 s 41 2% Na2S4O6 -- 2% (NH4)2S2O3: 31 28% NHHSO3 (Fresh) -- 6% K2S3O6 -- 3.0 - 41 pH adjusted with solid NH4HSO4. 29% (NH4)2S2O3 32 42% NH4HSO3 (Fresh) -- 3.0 - 55 All treatments are 1 g per 100 g of the grain 11% 6N H2SO4 Metabisulfites are known preservative agents 33 45% NH4HSO3 (Fresh) irradiated 3.0 12 Moldy with UV light for 24 hours From Table I it may be seen that the aqueous ammo- 50 34 45% NH4HSO3 subjected to ultra- 3.0 8 Moldy nium bisulfite solutions adjusted to within a pH range of sonication 35 46% NH4HSO3 (Fresh) -- 1% thiodi- 3.0 9 Moldy between 2.5 and 3.5, are effective grain preservatives. propionic acid Examples 1-5 of Table I clearly demonstrate the effects 36 46% NH4HSO3 (Fresh) -- 1% benzoic 3.0 9 Moldy of acidified ammonium bisulfite solutions applied to acid wheat. Examples 1 and 2 indicate that a "fresh' or a 55 37 46% NH4HSO3 (Fresh) + 1% sorbic 3.0 9 Moldy slightly acidified ammonium bisulfite solution is not acid 38 39% NHHSO3 (Fresh) -- 8% acetic 3.0 55 particularly effective as a wheat preservative when acid + 8% propionic acid applied at 1% by weight. An improvement in preserva 39 39% NHHSO3 (Fresh) -- 4% K2S3O6 3.0 55 tive effect is exhibited by Example 3, wherein the pH of -- 4% Na2S4O6 an ammonium bisulfite solution has been adjusted to 4.0. 60 40 43% NHHSO3 (Fresh) + 4.5% K2S3O6 4.9 4 Moidy A further improvement in preservative effect is exhib -- 4.5% Na2S4O6 41 39% NH4HSO3 (Fresh) + 8% Na2S2O6 3.02 Moldy ited by Examples 4 and 5, which have been adjusted in 42 40% NH4HSO3 (Fresh) -- 1.7% Na2S2O6 3.0 s 38 pH to 3.5 and 2.9 respectively. Accordingly, when -- 1.7% K2S3O6 - 1.7% Na2S4O6 - ammonium bisulfite solutions are adjusted to within the 1.7% (NH4)2S2O3 preferred pH range, preservation periods are prolonged 65 43 42% NH4HSO3 (Fresh) + 1% ammonium 3.0 3 Moldy polysulfide to between 4 and 7 times the preservative periods exhib 44 21% NHHSO3 (Fresh) + 6% M 3.0 2 Moldy ited by regular ammonium bisulfite solutions of higher anmonium diacetate alkalinity. Examples 6-9 and 11-20 are provided for 45 20% NHHSO3 (Fresh) -- 7%. 1 M 3.0 3 Moldy 4,338,343 9 10 TABLE II-continued periods. The results are set forth in Examples 46 Ex- Effective through 71 in Table III. am- . . Period TABLE III ple Treatment" pH (in Weeks) Treatments of Yellow Corn ammonium dipropionate Effec "The treatment solutions for the different examples contained also varying amounts tive of water to obtain a total of 100%. Ex- Period al- (in As seen from Table II representatives of each of the ple pH Weeks) preferred embodiments of the present invention are set 10 Treatments 46 47% NH4HSO3 stored at ambient tem- 3.0 19 forth. With respect to the use of disproportionated (old) perature for several years ammonium bisulfite solutions as preservatives, compare 47 45% NH4HSO3 (Fresh) 3.0 2 Example 21 to Example 24, whereupon it will be seen 48 47% NHHSO3 (Fresh) 5,3 l that naturally disproportionated ammonium bisulfite 49(a) 42% NH4HSO3 + 11% H2SO4(4N) Corn 3.0 2 15 49(b) 42% NHHSO3 + 11% HCl (4N) Corn 3.0 2 extends the effective preservative period by more than 49(c) 42% NH4HSO3 + 11% H3PO4 (4N) Corn 3.0 2 60 times. Similarly, representative mixtures of ammo 50 45% NH4HSO3 (Fresh) heated 2 days 3.0 23 nium bisulfite and at least one additional ammonium at 50 C. bisulfite disproportionation product (or its equivalent 51 100% Propionic Acid - 40 52 41% NHHSO3 (Fresh) -- 9% K2S3O6 3.0 5 potassium or sodium salt) exhibited various improve 20 53 44% NHHSO3 (Fresh) -- 4.7%. 1,2- 5.5 20 ments in the effective preservation periods for the Propanediol -- 1.9% undecylenic treated samples (see Examples 27, 28, 30, 31, 39, 40, 41, acid 54. 46% NH4HSO3 (Fresh) + 1% ammonium 4.3 15 and 42). In each instance, ammonium bisulfite and an polysulfide effective amount of one or more of its disproportion 55 29% NH4HSO3 (Fresh) -- 31% (NH4)2S2O3 3.0 15 ation products, particularly when adjusted in pH to be 25 56 45% NH4HSO3 (Fresh) + irradiated 3.0 6 within a preferred range of 2.5 to 3.5, exhibited at least with UV light for 24 hours 57 45% NH4HSO3 (Fresh) ultrasonicated 3.0 6 twice the preservative effect of a fresh (un-dispropor 58 45% NHHSO3 (Fresh) used at 1.5% by 3.0 5 tionated) ammonium bisulfite solution (Example 24). weight of grain sample In Table II artificially "disproportionated' ammo 59 45% Na2S2O5 . 3.0 5 nium bisulfite solutions are also represented which are 60 29% NHHSO3 (Fresh) + 31% Na2S2O5 3.0 30 30 61 39% NH4HSO3 (Fresh) + 17% propionic 3.0 30 seen to have preservative effects which are enhanced acid over those of fresh (undisproportionated) ammonium 62 28% NHHSO3 (Fresh) + 29% (NH4)2S2O3 3.0 - 1 bisulfite solutions. The artificial techniques employed to + 6% K2S3O6 accelerate disproportionation reactions include storage Temperatures 63 39% NH4HSO3 (Fresh) + 8% sodium 3.0 9 plus heat (Example 29), ultraviolet irradiation (Example 35 hexametaphosphate 33), and ultrasonication (Example 34). In accordance 64 31% NHHSO3 (Fresh) + 33% (NH4)2S2O3 3.0 17 with the methods of the present invention, heating & SO2 bubbled thru till the pH should be conducted at between 35 C. and 100 C., reached 3.0 65 39% NHHSO3 (Fresh) -- 8% diammonium 3.0 9 preferably 45 C. to 60° C. for at least about 8 hours, imidodisulfonate preferably 2 days or more. Ultrasonication should be 66 39% NH4HSO3 (Fresh) + 8% K2S3O6 3.0 9 conducted for at least 15 minutes, at cps of 18-20 kHz, Treatments of Sorghum preferably 20 kHz. Irradiation should be conducted Effec using a UV light source for at least 15 minutes, and tive preferably 24 hrs. or more, at 50-200 Joules/sec/m2. Ex- Period . As seen in Table II, representative acidified ammo 45 8- (in nium bisulfite solutions continue to show enhanced ple pH Weeks) preservative effects when compared to ammonium bi Treatments sulfite solutions having higher alkalinities. Examples 25, 67 100% Propionic Acid - 28 68 45% NHHSO3 (Fresh) 3.0 9 26, 32, 35, 36-38, and 43-45 clearly indicate that the 69 39% NHHSO3 (Fresh) + 8% sodium 3.0 24 antimicrobial properties of aqueous solutions of ammo 50 hexametaphosphate nium bisulfite may be enhanced through additions of 70 47% NH4HSO3 stored at ambient 3.0 15 indicated materials. temperature for several months The novel preservatives of the present invention 71 29% NHHSO3 (Fresh) + 31% (NH4)2S2O3 3.0 7 were also tested as preservatives for yellow corn and sorghum. In these tests, the moisture content of un 55 Once again, the test substances indicated in Table III inoculated 1 kg samples of yellow corn, and sorghum are representative of the various embodiments of the were adjusted to 25% and incubated at room tempera present invention. Substantially disproportionated am ture for four days to increase initial microbial loads. monium bisulfite, that is, an ammonium bisulfite which These samples were then sprayed with various aqueous has aged until its pH has dropped below 4.0, and prefer solutions as indicated in Table III at 1% by weight of 60 ably below 3.5 to about 3.0, is substantially more effec the grain and stored in brown bottles with the caps tive than a corresponding fresh ammonium bisulfite placed loosely thereon to simulate a partially closed solution (compare Example 46 with Example 48). Simi system. The initial microbial load was about 108 organ larly, as compared against a fresh ammonium bisulfite isms per gram of the grain. Propionic acid treated grain solution (Example 48), ammonium bisulfite solutions was considered as a control to compare the efficacies of 65 additionally comprising at least one disproportionation the treatments. The treated samples were analyzed at product (or its alkaline metal equivalent) showed sub various time intervals for their microbial loads by the stantial improvements in the effective periods in pre Total Plate Count Method to determine the effective serving both corn and sorghum. See Examples 52, 55, 4,338,343 ... 1 12 60, 62, 64, 65, 66, and 71. Similarly, acidified ammonium bisulfite solutions evidenced an increased effective per TABLE V-continued iod when compared to fresh ammonium bisulfite. See Treatments Color Odor Taste Examples 47, 49a, 49b, 49c, 53,54, 61, 63, and 69. Artifi NH4HSO3 + propionic acid 4.7 5.2 4.6 cially disproportionated ammonium bisulfite solutions 5 exhibited characteristic increases in effective preserva From the above Table it may be concluded that pro tive periods for corn and sorghum. See example 50 pionic acid exhibits the worst color, odor, and flavor of (heated two days at 50° C.), 56 (irradiated with UV light any of the samples tested. The other samples tested do for 24 hours), 57 (ultrasonicated), and 70 (several not differ substantially from the control. Although ann months storage at ambient temperature). O monia gas treated samples were not presented to the test In order to investigate the effect of varying initial panel, corn which was treated with ammonia gas microbial loads on the effectiveness of acidified ammo looked greenish brown and had a slight bitter taste. nium bisulfite materials, the moisture content of samples Treatments of 1% by weight of a solution of 39% of white corn was ajusted to 25% and incubated at ammonium bisulfite and 17% propionic acid have also room temperature for varying periods of time to 15 been compared to similar 100% propionic acid treat achieve preselected initial microbial loads. The samples ments to determine, their apparent corrosiveness. The were then sprayed with various treatments at 1% by corrosiveness of the given treatments were compared weight of the grain and stored at room temperature in by determining the percent change in the weights of cylindrical glass jars with 24 square inches of open top metal pieces buried in the corn subject to these treat surface to simulate an open system. The treated samples 20 ments. Propionic acid was found to exhibit a 0.31% were analyzed periodically for their microbial loads. In corrosion, while a solution of 39% ammonium bisulfite Table IV, the effectiveness of ammonium bisulfite solu and 17% propionic acid was found to have a percent tions acidified with various acids and methylene-bis corrosion of 0.24%. This improvement in corrosiveness propionate (Examples 73-75) compare favorably to is believed to be of substantial commercial significance. treatments of 100% propionic acid (Example 72), re-2 Since aged ammonium bisulfite solutions were ob gardless of the tested initial microbial load. (Methylene served to have an altered yellow-green color, experi bis-propionate is a known antimicrobial substance.) ments were conducted to characterize the colors of TABLE IV various ammonium bisulfite solutions, including ammo Treatments of White Corn with Various Initial Microbial Loads 30 nium bisulfite solutions which have been aged, physi Effective Period in Weeks When cally disproportionated, or acidified in accordance with Ex- the Initial Microbial Load is various embodiments of the present invention. It was 3a 2 X 4 x 1.8 x 3.8 x found that by measuring the absorption of ammonium ple Treatment pH 10/g 107/g 108/g 108/g bisulfite solutions at 770 mp, substantial differences in 72 100% Propionic acid - 14 14 14 14 35 percent transmittance (%T) and optical density (O.D.) 73, 39% NHHSO3 were observed. These results are provided in Table VI. 73 (Fresh) -- 3.0 14 14 14 4. 17% propionic acid 74 34% NHHSO3 TABLE VI (Fresh) + 3.0 4 14 14 4 4% acetic 40 Measurement of Absorption of NH4HSO3 Solutions at 770 mp. acid -- 14% % Solid . propionic acid -- NH4HSO3 needed 5 mg to reach indi selenium metal cated pH pH 7%. T. O.D. per 100 45-48% Fresh NHHSO3 m 5.3 32 0.5 ml solution 45-48% Fresh NH4HSO3 2.6 50. 28 0.56 75 39% NH4HSO3 45 45-48% Fresh NHHSO3 5.7 4.5 22 0.66 (Fresh) + 3.0 - 14 14 14 14 45-48%. Fresh NH4HSO3 7.2 4.0 14 0.86 17% methylene-bis 45-48%. Fresh NHHSO3 8.2 3.5 28: 0.55 propionate 45-48% Fresh NH4HSO3 10.9 3.0 23 0.63 45-48% Fresh NHHSO3 18.0 2.5 22 0.65% Several Month Old 3.7 13 0.88 During the above-described tests, the preservative 50 NH4HSO3 - Sample I treatments of the present invention were noted as appar Several Month Old 3.5 28: 0.55 ently not imparting the adverse color, odor, or flavor NH4HSO3 - Sample II NHHSO3, heated at 3.0 23 0.63 characteristics to grains treated with the herein dis 55 C. for 24 hours closed inventive materials. Accordingly, a taste panel NH4HSO3, sonified 4.9 31 0.52 was assembled of untrained judges who were presented 55 15 min. at 20 kHz with coded samples of corn. These judges were asked to NHHSO3, U.V. irrad- 3.0 23 0.63 rank the color, odor, and taste of the samples on a scale iated 50-200 Joules/ of 1-10, with 1 being the best. Odor and taste were sec/m for 30 min. "Measured on 2 times diluted solutions evaluated on cooked samples. The following table pro **Percentages may vary depending upon condition and source of ammonium vides the average rankings of the judges resulting from 60 bisulfite solution this test: As seen from Table VI, the percent transmission at TABLE V the specified wavelength drops substantially as solid Treatments Color Odor Taste ammonium bisulfate is added to solutions of aqueous Control 5.5 5.0 - 4.0 65 Propionic acid 8.8 8.4 8.5 ammonium bisulfite. As the pH of the test solutions SO2 3.5 4.6 4.4 dropped below 4.0, it was necessary to dilute the solu NH4HSO3 3.2 3.2 4.2 tions in order to obtain readable results. From Table VI, NH4HSO3 + Na2S2O5 3.4 3,6 5.0 it will be seen that measurement of absorptions at the 4,338,343 13 14 specified wavelength may be useful in predicting the virtually indefinitely while retaining the properties nec essary to permit human consumption. effectiveness of a given ammonium bisulfite solution. What is claimed is: The treatments and methods of the present invention 1. A method of preserving moist grain to prevent have also been found effective for preserving peanuts, 5 spoilage thereof, comprising the steps of: particularly to control Aspergillus flavus growth, and (a) providing an aqueous ammonium bisulfite solu thus to reduce aflatoxin concentrations therein. These tion; preservatives are also believed useful for treating moist (b) adding to said solution an amount of at least one sunflower seeds to preserve these seeds during storage. ammonium bisulfite disproportionation product 10 effective to improve the antimicrobial effect of said As seen from the above, a number of novel preserva solution, to provide a preservative solution; and tives have been described which are clearly superior to (c) applying said preservative solution to said grain in those heretofore known to the art. The subject preser amounts effective to prevent spoilage of grain. vative solutions may be applied in relatively low weight 2. A method in accordance with claim 1 wherein said percentages to produce products which are fit for 15 ammonium bisulfite disproportionation product is am human consumption. When tested with closed, semi monium bisulfate. closed and open storage systems, the materials of the 3. The method of claim 1 wherein said disproportion present invention demonstrate preservative properties ation product is selected from the group consisting of which enable the subject grains to be stored for substan alkaline salts of, dithionates, trithionates, tetrathionates, tial lengths of time. The preservatives of the present 20 pentathionates, hexathionates, imidodisulfonates, bisul phates, metabisulfites, and sulfides. invention are believed particularly suited for use in 4. The method of claim 1 wherein the molar ratio of open systems. In such systems, ambient air drying may ammonium bisulfite to said disproportionation product reduce the moisture content of the subject grains to is from about 1:0.10 to 1:1. below about 15% moisture during the effective period 25 5. The method of claim 1 wherein said disproportion of preservation. In this manner, grains treated with the ation product is a thiosulphate. novel materials of the present invention may be stored k is k is ak