3,164,480 United States Patent Office Patented Jan. 5, 1965

2 is desired the agglomerated material is ground or com 3,164,480 minuted to a desired fineness short of one which cakes on MANUEFACTURE OF MEATCURING Standing, and preferably to a fineness coarser than the COMPOSITION Louis Sair, Evergreen Park, and George. R. Reschke, particle-size-distribution of the material subjected to com Palos Park, E., assignors to The Griffith Laboratories, ipaction. Comminution is best done and controlled by Inc., Chicago, Ill., a corporation of Illinois passing the cake through the nip of grinding rolls set apart No Drawing. Fied Feb. 19, 1964, Ser. No. 344,464 to control the size. Several passes are preferred, as by 13 Claims. (C. 99-222) passing the material through a bank of such set rolls, for example, three in number, each following set being more The present invention relates to a granular curing salt O closely spaced. Preferably, the comminution is effected composition containing a major proportion of homogene on the caked forms which are dry, or which have not more ous crystals and a minor proportion of than 2%, content of moisture, and preferably-less than 1% nitrogen-containing salt.selected from the group consist content of moisture. M ing of alkali-metal nitrite, alkali-metal nitrate, and mix Caking may be effected in one way by mechanically tures thereof. S. Curing salt compositions are commonly shipped in large squeezing together the particles of a fine-ground mixture. drums from a supplier to a meatpacker, who removes This may be done by mechanically compressing the indi portions from the drums for immediate use... For along vidual original crystals into sheet, cake, pellet, or bri time past, such compositions were made by mechanically quette form. mixing crystals of the separate Salt ingredients. Com 20 One way is to extrude a rod-like form and to chop of plaints by government control authorities arose as a result pellets as extruded. Another way is to pass a mass of the of using such a mixture. The content of the nitrite salt original crystals through the nip of heavy compression used in curing is limited by such authorities. It was ascer rolls, exerting heavy pressure, so that sheet-like forms are tained that in shipping and, in distributing such bulk quan produced of thickness, for example A6 to /8-inch. Such tities of the mechanical mixture, gravitational separation 25 forms may be further fragmented to facilitate further frequently took place with the result that there were conminution as described. formed portions relatively deficient and relatively richer In curing meat a considerable quantity of sodium chlo in nitrite salt. Use of the richer portions resulted in ride is used with a small quantity of curing salt. It is a excess use of nitrite in the curing process. conventional practice to compound sodium-chloride-and It is known that when such a mixture, is very finely 30 the curing salt for use as an ingredient in processing meat, ground, the danger of separation is minimized, but other difficulty is encountered. Very fine particles tend to cake usually supplemented by additional sodium chloride. merely due to their size. This tendency, makes the par Therefore, the composition of the present invention has ticles less mobile, thus minimizing separation. The longer no more sodium chloride combined with the curing salt Such a fine-ground mass stands, the harder it cakes, making 35 than is to be used for the meat with the curing salt it more difficult to remove a portion of the cake for use. content. - It has been found that the ingredients as a mechanical A typical curing salt composition permitting use of Sup mixture can be bonded to a unified form by effective me plemental sodium chloride is chosen for the purpose only chanical pressure, so that the unified form may be reduced of illustration, as follows: to desired sizes for various commercial practices without 40 a change of composition. - - ... - Parts by weight It is the general object of the invention to produce a Sodium chloride ------90 granular mass of polycrystalline aggregates consisting ------6 essentially of homogeneous sodium chloride crystals and ------4. the selected nitrogen-containing curing salt. 45 It is a particular object of the invention to prepare a This composition is hereinafter referred to as "90-6-4.” granular salt composition of the type described with a Nitrite salt is the chief ingredient with which certain particle-size-distribution such that all the size-fractions Federal regulations are concerned, and the uniformity of thereof are substantially uniform in chemical composition. the composition as referred to in the present application is It is a particular object of the invention to produce a 50 measured by reference to the nitrite content. In the free-flowing granular form of such a composition. typical composition given above, the theoretical content The preferred process is to prepare a finely-divided or . of nitrite is 6%. The Federal regulations, in recognition fine-ground uniform mixture containing the salt ingredi-. of problems in manufacture, permit deviations up to 10% ents, mechanically to apply pressure in a manner to pro from the theoretical content, when the theoretical amount duce caked forms of the mixture, and then comminute the 55 mixture to provide. a granular mass of heterogeneous par is 6%, but permits greater deviation when the theoretical ticles of the caked forms of size such that all the particles amount of nitrite is less, being for example, 15% when have a composition substantially like that-of-the initial the theoretical amount is 2%. mixture. - Commercial homogeneous sodium chloride (NaCl) To achieve the desired results a uniform mixture, which 60 crystals are available in different grades of fineness, identi is suitably finely-divided or fine-ground, is purposely caked fied as fine salt, fine , and flake salt. Table I or agglomerated to eliminate the small-size particles and below shows the particle-size-distribution of these three to bond the mass to a unified whole. Cake or caked forms salt grades and of commercial sizes of nitrate and nitrate are thus produced. When a granular free-flowing product salt crystals. 8,164,480 Table I The following Table V shows that a substantially uni form composition may be made by very fine grinding of Percent of Fractions a 90-6-4 composition No. 7. However, such a fine --- ground mixture cakes and is commercially unsatisfactory. Ingredient Mesh Sieve 5 Table V shows the particle-size-distribution in percent for ------each fraction and the nitrite content of each fraction. On 50 On 100 On 200 Thiru 200 Table V

Fine Salt------0 53 37 10 - Fine Flake Salt 1. 84 4 10 Fine Mixture Flake Sat.---- 86 i 1. 2 SEG N.E. - - 4g É s is Fraction Composition No. 7

as The above salt supplies were blended to a 90-6-4 com- ... PercentWhole of PercentNitrite position and the blend fractionated on the same set of 15 screens. The nitrite contents of the fractions are given 3. 38 Mesh. i 6. : in Table II which shows poor uniformity in chemical On 270. Mesh 22 6.5 composition, indicative of separation in shipping. Thru 270 Mesh. 66 6.05 Table II 20 According to the present invention, a fine-ground caking mixture such as Composition No. 7 (Table V) can be Percent Nitrite Satin Fractions compacted or agglomerated into caked forms, which caked Composi forms may be comminuted to particle sizes coarser than tion No. NaCl. On 50 On 100 on 200 Thru 200 the original mass. Compaction is illustrated by use of - . . . . 25 those ingredients of which the particle-size-distribution is 1------Fine------79 9.8 1.2 1. shown in Table i. Compositions Nos. 8, 9 and 10 were 2------Fine Flake.-- 11.7 4.4 2.7 2.2 made with the ingredients of Table I, and were compacted 8------Flake------4.0 8.6 6.0 3, 6 and then ground to sizes having particle-size-distributions with fractions of nitrite salt content shown in Table VI. Mechanical mixtures of 90-6-4 were made using the 30 same grades of sodium chloride crystals and finer grades Table VI of the nitrite and nitrate , of which the particle-size Percent Nitrite Salt in Fractions distributions are given in Table III. ERS NaCl. On 50 On 100 On 200 Thru 200 Table III 35 --|--|-- 8------Fine.------6.9 6.4 3.5 4.7 , . -- Fine Flake-- 6. 5.8 4.3 5.8 Ingredient Percent--- in Fractions Flake------6.4 6.0 4.7 4, 8 ... On 50 On 100 On 200 Thru 200 The nitrite uniformity of Table V does not meet said --- 40 Federal standards, but it is greatly improved over that Fine Salt------0. 29 63 8 shown in Table II. Elisat. s ES i.2 The present invention may be used to eliminate the Sodium Nitrite-- 0 0.3 7 93 tendency to cake of a mixture such as Composition No. 7 Sodium Nitrate------0 2 13 85 of Table V. The finely ground Composition No. 7 was 45 divided into four batches. These were compacted dry, These mechanical mixtures were then fractionated on with 1% added water, with 2% added water, and with 4% the same screens and the nitrite contents of the fractions added water. The four compositions were then dried to determined. The compositional uniformity of the frac not more than 1% moisture and ground to a size coarser tions was improved by the finer grinding of the nitrite than the original mass. The four dried comminuted com and nitrate salts, but not sufficiently for the required 50 positions of 90-6-4 have weight-fractions with nitrite con standards, as shown in Table IV. tent as shown in Table VII. Table VII

Composition Percent Particle Size No. EI2O On 50 On 100 On 200 Thru 200 I 0 (Eercent 99ntent-- 54 28 5 3. ------Percent Nitrite---- 6.0 5.99 6.05 6.05 1. Percent Content- 61 . 24 4. O Percent Nitrite 6,05 6.06 5.95 5.95 2 {E:Percent Content.--Nitrite... 55.6. 06. 245, 98 76.05 146.05 14. 4. {E: Content 57 23 7 3 - - - r - - - - - Percent Nitrite 6.03 5.99 6.04 6.02 Table IV By finely grinding a mixture of sodium chloride, sodium nitrite and sodium nitrate, followed by compaction to bonded caked forms, and then by size-reduction of the Composi Percent Nitrite Salt in Fractions caked forms which have not more than 2% by weight of tion No. - 70 water, it is possible to produce a product having particles NaC On 50 On 00. On 200 Thru 200 which preferably are coarser than the original particles

5.7 5. 3.9 7.0 compacted, which have substantially the same composi 5, 6 4. 3.6 7.6 tion in the coarsest fraction and in the finest fraction. The 5, 0 4, 5 4.4 8.2 uniformity meets the most rigid requirements and can 75 be within 2% deviation from the theoretical content. 3,164,480 5 -6 The mesh data shown in Table V is typical of a fine Another illustration of the effect of water is shown-in grind which will cake on standing, while the mesh data of Tables XI and XII. A composition 90-6-4 is ground to Table VII shows a particle-size-distribution of sufficient the size shown in Table XI, having fractions which are coarseness so that the composition is free-flowing indefi non-uniform in nitrite content. nitely. 5 The compositions shown in Table VII were compacted Table XI between rolls urged together by a force of 5400 pounds per linear inch of roll. In Table VIII below, the same Mesh Percent Salt SE Composition No. 7 of Table V was compacted at a higher pressure corresponding to a force of 9000 pounds per 0 O linear inch of roll, otherwise using the same conditions. ... 2 23.0 The products of Table VIII are also acceptable. Tables SS 3. VII and VIII show that with a suitably fine original mix Table VIII

. Particle. Size Composition Percent No. H2O On 50. On 100 . On 200 Thru 200

5 O (E: Content.-- 50 15 14 21 ...... - r r- Percent Nitrite--- 5.85 5.85 5.85 5.85 16 1. {E. Conten 49. 17 4. 20 ------Percent Nitrite--- 6.05 6.05 5.85 6.30 17 2 {E: Content-- 48 4. 13 24 -- a rare all as a Percent Nitrite 5.95 5.95. 6.00 6.00 ture, the pressure of compaction and the content of water Table XII shows the sizes and nitrite content of the are not critical. . . . above mixture of Table XI, compacted dry and with 2% Experience has shown that as the original mix is made added water, and then dried and ground, all under the coarser, the tendency is to make unacceptable products, 30 same conditions except as to water. Table XII .. Particle size Comgition0. FirstEO v On 50 On 100 On 200 - 200

25 O (East: Content.-- 46 5 17 22 ------Percent Nitrite- 5.80 5.55 4.0. 690 26 2 {E: Content. 55 6 4. 6 a ------Percent Nitrite--- 5.30 6.05 5.40 6.5 and that this tendency may be compensated for by in Composition No. 26 is acceptable in uniformity. creasing the moisture content, or by increasing the pres From the foregoing it is to be understood that the trends sure, or by both. This is shown in Tables IX, and X. 45 for a uniform product are (1) the finer, the grind of the Table IX shows a coarser original mix than is shown in original mixture, (2) the presence of some water content, Table V. - and (3) the increase of pressure in compaction. All Table IX "...these factors are so related that critical bounds for all of them cannot be set, because a variation of only one Percent in Fractions factor shifts the ranges for the other factors. Mesh 50 Although it is preferable to grind the compacted ma Salt ... Nitrite terial to a particle-size-distribution which is coarser than

0.2 ...that of the original mass for certain uses, it may be de g------i.00 sirable to grind it to a form finer than that of the original Thru 200------63.15.4 . it;2.70 55 mixture--4. for other uses. The references herein to the - particle-size-distribution of the original mass must be In Table X, Compositions Nos. 23 and 24 are sub considered in connection with the fact that during com stantially uniform in chemical composition in all size paction crystals are fractured by the high pressure in fractions. order to produce forms to fill the intercrystal voids. Table X

'Particle Size Composition . ...No. E.O. Pressure 1 oJ. : . . . O On Th 50 OO 200 200

O 9,000: {E:Percent Content--Nitrite.- . 52, 5.50 165.30 4.305 6.6.60 . . 9,000v. (EEEPercent NitriteContent-- -- 485.95 155.89.495. 16 2.6.60 2 9,000s {EPercent Nitrite.-Content : 445.93 14- 6.08 164.90 256.25 O 4,500 (EEPercent Content:Nitrite. 465.75 75.30 4307 206.65 14,500 (EN:Percent Nitite.Coatent 425.85 165.85 4.907. 2 6.65 2 1,500 (EercentPercent Stent--Nitrite--- 45.85 156.08 155.45 226.60

4 4500 (EEPercent Content-Nitrite--- 5.906 546.0 305.80 1 Force in pounds perlinear inch of roll. 8,164,480 7 3. Since it is not possible to determine the extent to which the melting point is lower than when the metal base is the the original mixture is thus changed in particle size by same for both salts. compaction, it is obvious that the pressure employed in The following example shows the invention practiced compaction fractures to a greater extent as the pressure with a fusion to provide a 90-6-4 composition. is increased. Therefore, in using, say a coarser mixture A solid fusion of 6 parts of sodium nitrite and 4 parts and very high pressure, the result may be the same as of sodium nitrate is mixed with 90 parts of sodium chlo some other circumstance in which a finer original mixture ride. The two components may be separately ground, or and a lower pressure are employed. the mixture may be ground so that all passes a 100-mesh By specifying that the bonded cakes are reduced to a screen. The fine ground mass is then compacted to cake granular form coarser than the original mixture, it is form. When the irregular caked forms are desired in practically assured that the desired uniformity of com O a granular free-flowing state, they are so ground that all position in the size-fractions will be achieved, because of passes a 30-mesh screen, 50% remains on a 50-mesh the fracturing of the original mixture, to smaller size by screen, and about 10% passes a 200-mesh screen. Such compacting as described above. fractions are substantially uniform in nitrite content. The invention is not limited in saleable products to In carrying out the invention, the caked forms need those which contain the entire product of grinding a not be ground or comminuted to produce a granular compacted mass. Since the final product has fractions of product, there being no limit to the maximum size. For graded sizes, any grind may be fractionated to select from example, the chopping off of pellets from a continuous its fractions a composition of one or more fractions with extrude can be accomplished so that the pellets, being in a predetermined range of particle sizes. Such frac 20 fractured caked forms, are all of substantially the same tions as are rejected in doing this may be used as a raw size, so as to form a granular mass. When pellets are material for recycling through the compaction procedure, so formed, any water in the pellets may be removed whether they be at the coarser end or at the finer end. thereafter, and then if sizes smaller than said pellets are in consequence, the original mass may be, or may in desired the dried pellets may be reduced to the desired clude, particles which are aggregates of the component granular form. When a free-flowing granular form is salts. . . . . desired, the caked forms may be ground to coarse sizes, The invention is not limited to mixing the separate even such as rock salt, to serve the mechanical purposes crystals of sodium chloride, separate crystals of nitrite of the users. It is noted, however, that the invention has salt, and separate crystals of nitrate salt. However, that been explained and exemplified by reference to an ulti is preferred because such salts are commercially available 30 mate fineness much greater than need be practiced. to supply the raw materials. The presence of a limited A granular form of curing salt of moderate fineness amount of water is preferred to facilitate the bonding. is the form desired by the meat packers, not only for The nitrite and nitrate salts are more readily dissolved mixing it directly in products for ground meat and for by added water than are the sodium chloride crystals. rubbing onto meat, but also for ready weighing and dis Thus, the original mixture when compacted may con solution in forming brine. tain a dissolved quantity of the selected salt. The solu The composition which is the subject of the present tion lubricates the mass for compaction and provides bond invention may contain additives, such as cane sugar, corn on drying to hold the several different homogeneous par sugar, phosphate salts, alkaline agents, and seasoning, ticles in a bonded agglomerate. However, excess water which function in the treatment of meat. should be avoided. The maximum amount is controlled 40 The invention is not limited to or by the details and so that it is not exuded during compaction. examples given above to illustrate and explain the inven The nitrite and nitrate salts may be combined into tion, and numerous changes and modifications are con a physically homogeneous fusion product, and that prod templated as falling within the scope of the invention as uct used to supply the two salts. expressed in the appended claims. The following Table XIII gives the fusion points of This application is a continuation-in-part of Serial No. such salts, and of certain mixtures thereof. 209,216, filed July 11, 1962, now abandoned. We claim: Table XIII 1. The method of producing a curing salt composi tion which method comprises forming an initial free-flow Approxi 50 ing particulate mass having up to 4% by weight of water Substance mate Melt ing Point, which mass is substantially uniform in composition by o C. combining with a major proportion of homogeneous so dium chloride crystals a minor proportion of salt selected ------337 from the group consisting of alkali-metal nitrite, alkali Potassium nitrite. 297.5 55 Sodium nitrate- 308 metal nitrate, and mixtures thereof, the sodium chloride Sodium nitrite- 27 being present in amount not over that to be used with the Sodium chloride 804 curing salt content, bonding said mass to cake forms by "SiumSodium00lum nitriteIlliflenitrate 60%6UVo------40%------} 230 - application of effective mechanical pressure, and reducing Mixed: the size of said caked forms which have not more than Sodium nitrite 60%. 60 Potassium nitrate 40%. 2% by weight of water to provide a granular mass of Begins to melt at------26. compaction-bonded agglomerates of such particle-size and is completely liquid and transparent at------56 Mixed: distribution that all the size-fractions thereof have a sub Potassium nitrite 60%. stantially uniform content. - Sodium nitrate 40%. Begins to melt at------139 2. The method of claim 1 in which the caked forms are and is completely liquid and transparent at------172 substantially dry when reduced in size. 3. The method of claim 1 in which said initial mass is characterized by a particle-size-distribution of which the There are some peculiar facts about the fusion points size-fractions are non-uniform in chemical content. of mixtures. When dry nitrites and nitrates are mixed 4. The method of claim wherein the initial mass for fusion, the melting point is sharp when the same contains from 1 to 4% by weight of water. metal base, such as sodium, is used in both salts. When 5. The method of claim 1 in which said selected salt the metal bases differ, the melting point is spread over comprises physically homogeneous particles thereof. a wide range. This is believed due to a shifting of the 6. The method of claim 1 in which said initial mass is equilibrium between the two salts forming perhaps four formed from physically homogeneous particles of said se salts. It is also noted that where the metal bases differ 75 lected salt and from 1 to 4% by weight of water. 3,164,480 9. 10 7. The method of claim 1 in which the initial mass is of water is present in the initial mixture subjected to in finely divided granular form and in which the caked mechanical pressure. - forms are reduced in size to a particle-size-distribution 12. The method of claim 10 in which not over 2% of much coarser than said mass. moisture is present in the caked forms when reduced in 8. The method of claim 1 in which the selected salt SZC. comprises separate crystals of alkali-metal nitrite and of 13. The method of claim 10 in which a small amount alkali-metal nitrate. - s of water in excess of 2% is present in the mixture sub 9. The method of claim 1 in which the selected salt jected to mechanical pressure, and in which the caked comprises particles of a physically homogeneous fusion forms are dried to not over 2% of moisture for reducing mass of alkali-metal nitrite and alkali-metal nitrate. 10 the sizes thereof. 10. The method which comprises forming an initial free-flowing finely-divided granular curing salt mixture References Cited by the Examiner of substantially uniform composition, which composition UNITED STATES PATENTS comprises salt components consisting essentially of a 2,054,624, 9/36. Griffith ------99-159 X major proportion of homogeneous sodium chloride crys 2,054,625 9/36 Griffith ------99-159 X tals and a minor proportion of physically homogeneous 2,054,626 9/36 Griffith ------99-159 particles of salt selected from the group consisting of 2,145,417 1/39 Hall ------99-222 alkali-metal nitrite, alkali-metal nitrate and mixtures 2,400,292 5/46 Dalton. thereof, the sodium chloride being present in amount not 2,668,770 - 2/54 Hall ------99-159 X over that to be used with the curing salt content, said 20 2,668,771 2/54 Hall 99-159 X initial mixture having a particle-size-distribution of 2,770,548 11/56 Hall et al. ------99-159 X which graded fractions differ greatly in content of selected 2,770,549. 11/56 Hall ------99-159 X salt, bonding said mixture to caked forms of the same 2,770,550 - 11/56 Hall et al. ------99-159 X composition by application of effective mechanical pres 2,770,551 11/56 Hall et al. ------99-159 X sure, and reducing the size of said caked forms to a gran 2,828.212 3/58 Sair.99-159 X ular mass of compaction-bonded heterogeneous agglom 2,935,3875/60 Phillips ------71-64 X erates of different physically homogeneous particles which 2,977,214 3/61 McLellan ------. 71-64 mass has a substantially uniform composition and a par 3,098,767 7/63. Bush ------127-63 ticle-size-distribution of average size greater than that of 80 A. LOUIS MONACELL, Primary Examiner. said initial mixture. 11. The method of claim 10 in which a small amount HYMAN LORD, Examiner.