CA1168078A - Intermediate moisture food preservation - Google Patents

Abstract

INTERMEDIATE-MOISTURE FOOD PRESERVATION ABSTRACT The object of the invention is to provide a new preservation system for intermediate-moisture foods. Current intermediate-moisture food stabilizers have characteristics of taste, effectiveness, and cost which are often considered negative factors depending upon the particular food product and the nature of the intended consumer, be it man or lower mammal. The present invention identifies monobuty-rin and monopropionin as alternative preservation materials which can be employed as total or partial replacements for known antibacterial and antimycotic agents. According to a preferred embodiment of the invention, the monopropionin, monobutyrin, or a combination of these, is employed at a level of from 1 to 5%, based on total composition weight, in addition to other preservatives to stabilize a nutritionally balanced dog food against bacteriolog-ical and mycotic spoilage.

Description

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Case 2758 : DESCRIPTION

INTERMEDIATE-MOISTURE FOOD PRESFRVATION

Technical Field The present invention relates to intermediate-05 moisture foods, and particularly to an improved preservation system for intermediate-moisture foods.
A significant advance in food preservatio~ was made with the development of intermediate moist~re foods for both human and animal use. Typically, these foods will have moisture contents of greater than 15% and less than 70% and would spoil if not aseptically packaged or treated with preservatives.
It has always been a challenge to workers in this art to find presexvatives which are palatable, and preferably are compatible with the intended food product. Many of the known preservatives, such as propylene glycol and glycerol, are palatable in limited amounts, but tend to take on objectionable taste characteristics at higher concentrations.
Further, many of the known preservatives are palat-able in their own rights, but tend to be incompat-ible with certain flavors. For example, sugar is quite pleasing in taste but does not taste good with many meat dishes, especially when used at levels ., ~r ., . ~ i ~L ~680~8 effective to impart a significant preservative effect.
The need to balance flavor and effectiveness is further complicated by the need to produce the 05 intermediate-~moisture food at a cost which is com-petitive with other forms of the same or substitute products. The cost factor in the balance is con stantly changing and presents the posssibility that, at any given time, the preferred preservative system might become uneconomical.
It would be desirable to provide additional, effective preservatives for use in intermediate-moisture food systems to provide a wider range of choice in striking the balance between taste, effect-iveness and cost.

Back~ound Art The art has produced a wide number of inter-mediate-moisture food products. U.S. Patent 3,202,514 to Burgess et al for example, describes a pasteurized intermediate-moisture animal food based principally upon proteinaceous meaty materials which product is shelf-stable and re~istant to microbial decomposition withou~ the need for sterilization, refxigeration or aseptic packaging. The meaty animal food is stabilized by "water soluble solutes", principally sugar. The function of these solutes is to bind up available water in which microorganisms grow.
In U.S. Patent 3,769,042 to Kaplow et al there is described a process for making an intermediate-moisture beef stew and similar products for human consumption. Briefly stated, meat and vegetable pieces are stabilized by infusion with solutes ~y immersion in a measured excess of an a~ueous stabil-j--1 ~680~

izing solution, and the excess spent infusion solu-tion can be retained to form a stabilized gravy. The water activities of the liquid and solid phases will be the same and within the range of from 0.6 to 0.9.
05 In U.S. Patent 3,753,734 to Kaplow et al, there is described the preparation of shelf-stable pancake batters and pancakes. The batter includes water-soluble solids at least equal in weight to the moisture content, with edible polyhydric alcohols constituting the principal source of the water soluble solids.
These patents are merely representative of the various types of foods which have been rendered shelf-stable by the use of intermediate-molsture technology. Because of the well known taste and cost limitations of the known stability systems for products of this type, the search for alternatives has been active as evidenced by a large number of patents and other technical publicatlons. For 2Q example, in U.S. Patent 3,658,548 to Haas, caproic and caprylic acids are taught to be effective pre-servatives for meat and meat-like pet foods of the intermediate moisture variety. Similarly, in U.S.
Patent 4,0~8,342 to Haas et al, it is suggested that packaging intermediate-moisture foods in an atmos-phere of carbon dioxide will increase the effect-iveness of edible aliphatic acids, such as sorbic, caproic and caprylic, and their salts.
In an article appearing in the publication Antimicrobial Agents and Chemotherapy! Kabara et al investigated the "Antimicrobial Action of Esters of Polyhydric Alcohols" (Vol. 4, No. 5, at pages 501 to 506, Nov. 1973). They determined the minimal inhib-itory concentration of a series of fatty acid esters of polyhydric alcohols against gram-positive and , 1 ~80~8 gram-negative organisms by a broth dilution method.
Of the monoglycerol esters, monoglycerol laurate was found to be the most active, while monoacetin and monobutyrin were not found to have any activity at 05 all. In fact, no activity was found until the acid moiety had a carbon chain length of at least six.

Disclosùre of Invention ~ n accordance with the present invention, it has been discovered that two non-toxic compounds have a high de~ree of efectiveness as preservatives in intermediate-moisture food compositions. Both the food compositions and the method of preparing the food compositions, as improved by the use of these compounds, namely monopropionin and mono-butyrin, are disclosed. The improved intermediate-moisture food composition is of the type, containing at least 15% moisture, which .is normally subject to bacterial and mold growth, and has incorporated therein a preservation system effective to control bacterial and mold growth, wherein the improvement comprises: an amount of monopropionin, monobutyrin, or a combination of these, which is effective to protect the food against bacterial and mold growth.
According to the method, an intermediate-moisture food product is prepared by adding, as part of the preser~ation system, monopropionin, monobutyrin, or a combination of these, in an amount which is effec-tive to protect the food against bacterial and mold growth.
The ~ood compositions can be made fox human or animal consumption. The particular type of food product is not critical to the invention which resides in the discovery that monopropionin and monobutyrin are very effective antibacterial and 116807~

antimycotic agents for preserving intermediate-moisture food compositions.
In general, to be considered "intermediate-moisture", a food composition will have less mois-05 ture than its natural counterpart, if any, and havemore than would be acceptable from a microbiological stability standpoint in the absence of preservatives.
Typically, the art has set a lower moisture limit of 15% of product weight. The upper limit, as a strict percentage is less well defined, but will almost always be less than 70%. Preferably, the upper limit on moisture will be 50% of the weight of the food composition.
The mo~opropionin and monobutyrin are employed to prevent mold and bacterial growth in intermediate-moisture food compositions which would otherwise be subject to such growth. Monopropionin is defined as the l-monopropionic acid ester of glycerol. Mono-butyrin is defined as the l-monobutyric acid ester of glycerol. These food compositions may contain other preservatives in addition to the monopropionin and monobutyrin, so that no one preservative flavor becomes so pronou~ced that it impairs the usefulness of the food ~or its intended purpose. The amount of the monopropionin, monobutyrin, or combination of these will be that which is ef~ective, in the pres~
ence of the other preservatives and at the given product moisture and pH to stabilize the food again~t mold and bacterial attack.
The preservation of moisture-containing foods from microbial decomposition is dependent upon a variety of factors and mechanisms. There are some generally well accepted preservation mechanisms and systems which have evolved in the art, and any preservation system effective when employing either ~168 or both monopropionin and monobutyrin for achieving shelf stability in the final product, which is acceptable for the particular end use, can be employ-ed according to the present invention.
05 Typical preservative systems employ antimicro-bial agents as well as materials which control the amount of moisture in a system available as a growth medium, The expression typically employed for defining the amount of water available to support microbial growth is the water activity, aw, of a product. The aW is equal to the vapor pressure of water in the sys-tem divided by the vapor pressure of pure water at the same temperature, Theoretically, the aW of a given system can be lowered to such a degree that the water is not su~iciently available to support any microbial growth, However, to achieve the proper taste and te~ture for inter-mediate-moisture dog food products, it is not poss-ible as a practical matter to obtain these low aW
values~ Thus, antimicrobials are also added to control mold growth which is not sufficiently re-tarded at the aW val~Ies :involved, IJseful intermediate-moisture products have water binding ingred;ents dispersed throughout in amounts sufficient to achieve aW values of below about 0,93, pre~erably within the ran~e of from 0.80 to 0,90, and further have added or in contact there-with an antimicrobial agent. ~he level of the water binding ingredients and antimicrobial agent is sufficient to keep the product resistant to micro-~ 8~7~

bial growth and decomposition when packaged in asubstantially moisture-impermeable packaging ma~erial. The level of antimicrobial agents and aW
lowering ingredients will be balanced to achieve 05 stability at the given moisture content and pH. For example, it may be necessary to employ only a minor amount of antimicrobial agent where the aW of a given intermediate-moisture system is at a level nearly precluding all growth. Conversely, larger amounts of antimicrobial agents may be needed in a moisture containing system wherein the aW is closer to 0.93. The compounds monopropionin and monobu-tyrirl which have been identified according to the invention as useful and effective antimicrobials may be ernployed as the sole antimicrobials in some situations; however, in others known antimicrobials such as sorbic acid and its salts, 1,2-propanediol,.
and the like must also be employed.
No precise numer.ical range oF universal appli-cability in defining the effective levels of monobu-tyrin or monopropionin is possible; however, it presently appears that lcvels of from about 1 to about S%, based on the weight of the intermediate-moi.sture product provides a good balance bet~een taste and effectiveness. The narrower range, of from 2 to ~%, can be considered p.referred for food compositions, especially meat-containing pet foods, having moisture contents within the range of from about 20 to 45%, and having sufficient moisture binding agents to maintain an aW within the range of from about 0.80 to about 0.90.

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Useful as water binding ingredients are any of the edible materials which have the ability to tie up water t~ such an extent that it is no longer usable for microbial growth and propagation. Exem-05 plary of this group of materials are sugars, poly-hydric alcohols, mixtures thereof, and mixtures of alkali metal or alkaline earth salts with sugar and/or one or more polyhydric alcohols.
The polyhydric alcohols useful as liquid pre-servatives for use in the slurries are preferablypolyhydric alcohols having from 3 to 7 carbon atoms.
Preferred dihydric alcohols are 1,2-propanediol and 1,3-butanediol. Glycerine, a trihydric alcohol, is a very effective water binder and may be added alone or in combination with a dihydric alcohol. Other useful polyhydric alcohols include tetritols, such as erythritol or the threitols; pentitols, such as ribitol or xylitol; heXitols such as sorbitol or mannitol; and heptitols, such as perseitol or vole-mitol. Certain of these, such as 1,2-propanediol and 1,3 butanediol also have antimicrobial proper-ties.
Sugars useful as water binding agents include the reducing and non-reducing water soluble mono-and polysaccharides; e.g., pentoses such as xyloseand arbinose; hexoses such as glucose, fructose or galactose; and disaccharides such as lactose, suc-rose and maltose. To be effective as a bacterios-tatic agent, the sugars are preferably water soluble and of such a low molecular weight as to be effec-tive in increasing the osmotic pressure of the aqueous system in which it is dissol~ed. Preferred sugars are sucrose, dextrose , fructose and highly converted corn syrups, especially high fructose corn syrups.

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g Various alkali metal and alkaline earth metal halide salts are also effective water binding agents Preferred salts are sodium chloride and calcium chloride.
05 The provision of an acid medium by the addition of acid or acid salts will also aid in preventing microbial decomposition. Preferred acids include phosphoric, citric, malic, fumaric, hydrochloric, sulfuric, lactic, acetic, adipic and the other known non-toxic acids. Phosphoric acid is the most pre-ferred due to its use as a source of phosphorous.
~ he pH of the product will he maintained within the range of from 4.0 to 8.0 to achieve the best results based on a balance of preservative effec-tiveness and taste; however, there are some foodproducts which would taste best and can be prepared outside of this range. The most preferred pH range on this same basis is from 4.5 to 6.5.
To better illustrate the present invention, the following description will focus on the preparation of an intermediate-moisture pet food, and especially one suited to the taste preferences of dogs. It is to be understood, however, that the teachings of this invention are fully applicable to all interme-diate-moisture foods.
The term "pet" as used in this description, means small to moderate-sized carnivorous animals, normally domesticated and maintained as household companions. ~ecause providing proper nutrition is essential, it is important to formulate all pet foods to be nutritionally complete. By nutrition-ally balancing each individual food ration, it is then unnecessary for the pet owner to balance the quantities of different foods supplied. In this manner, the nutritional intake of the pet is assured as long as it intakes a minimum amount of food.
Nutritionally-balanced pet foods contain protein, carbohydrates, fats, vitamins, and minerals in the amounts known in the art and established by feeding 05 tests to be sufficient for the proper growth and maintenance o~ the pet.
Typical of the intermediate-moisture pet foods which can be improved according to the present invention are those disclosed in U.S. Patent No.
3,202,514 to Burqess et al. According to that disclosure, proteinaceous meaty materials are coo~ed with stabilizing solute materials in a first stage and then with the other added pet food materials, which can include farinaceous components, in a second stage prior to shaping and packaging. An improvement on the process described by ~ur~ess et al, is disclosed in U.S. Patent 4,21~,894 by Franzen et al. According to that procedure, the proteina-ceous meaty materials are processed to prepare a pumpable slurry ~f fresh, uncooked meaty material in a solution containing sufficient pre~ervative to maintain the meat free from microbial spoilage for a period of at least 5 days, holding the slurry at a temperature effective to maintain homogeneity of the slurry including dispersed fat until needed for processing and then pasteurizing the meaty mater-ials, shaping it with any additional ingredients, and packaging the resulting product.
The process of this invention is particularly well adapted to use with slurries of -the type dis-cussed in the above-identified Franzen et al patent because the meaty materials can be stabilized in slurries which contain sufficient liquid material to maintain them flowable and pumpable over extended periods with a minimum of dry solids needed for preservation.

., ~6807a The preferred solutions for adding to the slur-ries of meaty materials according to this embodiment of the present invention will contain monopropionin, monobutyrin or a combination of these, a polyhydric 05 alcohol, such as propylene glycol, and an adjunct antimicrobial such as potassium sorbate. The slurry will thus have sufficient flowability for processing as well as have suitable stab.ility for holding in the tank for extended periods. The most preferred systems will also contain other water bin~ers in the form of salts and sugars and contain an acid to modify the pH from near neutral to a value less conducive to microbiological growth.
To prepare the slurry, the meaty materials requiring it must be comminuted as by grinding in one or a series of stages. Useful as "meaty mate-rials" are "meat", "meat by-products" and "meat meal". Of these the "meat" and "meat by-products"
will usually be ground. The term "meat" is under-stood to apply no-t only to the flesh of cattle, swine, sheep and goats, but also horses, and other mammals, poultry and fish. The term "meat by-product" is intended to refer to those non-rendered parts of the carcass of slaughtered animals includ-ing, but not restricted to, mammals, poultry and thelike. Both the terms "meat" and "meat by-products"
include such ingredients as are embraced by the terms as defined in the official publication of the Association of American Feed Con~rol Officials, Incorporated. The term `'meat meal" refers to the finely ground, dry, rendered residue from animal tissues, including those dried residues embraced by the term "meat meal" as defined by the aforesaid Association.

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The meaty material will preferably constitute a portion of pet food products; typically, it will be greater than about 10% by weight and preferably greater than 20%. A usual range for such ingre-05 dients in intermediate-moisture dog foods is about 20% to 40%, preferably 25% to 35%, by weight. It is whithin the scope of this invention that the preser-vatives disclosed would be applicable to non-meat containing pet food products.
Typically, the meaty materials, usually stored frozen, are first fed to a coarse grinder, such as a Rietz Extructor, which chops the material into pieces ranging in size up to as long as 2 -to 4 inches in major dimension, and starts thawing the meaty materials. The coarsely chopped material is then fed into a secondary grinder, such as a Hobart grinder, which continues the thawing process and grinds the meaty material, where the majority of the meat pieces have a maximum diameter of from about 1/8 to about 1/2 inch. This type of grinding is conventional and can be successfully employed ac-cording to this invention. However, the best re-sults according to this invention are achieved when the meaty material is yet further ground, i.e., finely ground, to an extent that the majority of the meaty particles are no larger -than 0.050 to 0.100 inch in diameter. This fine grinding procedure can be pexformed in Urschel Comitrol or Seydelmann bowl chopper. To aid the grinding and establish the limited preservation system, the liquid materials in the composition are preferably mixed ~ith the meaty material.
Typical of the liquid materials which can be employed are the monopropionin and monobutyrin, polyhydric alcohols and corn syrups. Typically, the liquids added will be present at a level of at least 10% of the weight of the meaty material.
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After grinding, the meaty material is mixed with the other materials required for storage there-with until needed for production. When so re~uired, the slurry is mixed with the additional pet food 05 ingredients.
Non-meat pxoteinaceous materials, i.e., protein sources other than meaty materials, are preferably employed to achieve a fully-balanced, nutritional feed ration. Typically, the protein will be derived from a vegetable protein source such as soybean, cottonseed, peanuts and the like. The protein may be present in the form of grits, meal, flour, con-centrate, isolate or the like. Additional protein and flavor may be derived ~rom the meat meal and milk products such as dried buttermilk, dried skim-med milk, whey, casein and other like protein sour-ces, such as eggs or cheese.
After admixing all the remaining ingredients, the complete formulation is preferably pasteurized.
The pasteurization can be pertormed either continu-ously or batchwise, and heating can be either direct by injection of steam or indirect by employing a heated jacket on the cooker. Continuous operation with direct steam injection in an extruder-cooker is preferred. Typical of the continuous cooking devic-es which can be employed are an Anderson extruder-cooker and a Wenger mixer-conditioner.
For batchwise pasteurization, a simple kettle fitted with a stirring device ade~uate to keep the matrix material under constant agitation, can be employed. Heat can be supplied by steam supplied to a jacket around the kettle.
Upon discharge from the cooker, the food matrix is preferably cooked prior to shaping into the desired final product form. It is possible with the 807~

continuous pasteurization to employ a cooling jacket around the final stage of the extruder-cooker to enable shaping to the desired final size directly upon exiting the extruder. Typically, however, the 05 matrix material is discharged into a separate cool-ing device which may be of any conventional con-struction, for example, a wire mesh belt, a per-forated deck, or a jet zone cooler, wherein cooled air at a temperature of about 20 C is directed across the matrix material. To enable optimum shaping and handling characteristics, the matrix material is preferably cooled to a temperature of below 30 C, and preferably to about 25 C. The final shaping and packaging of the product from this point on can be done in conventional manner, for example, using the teachings of the Burgess et al patent, U.S. 3,202,514, mentioned above.

Best_Mode For Carrying Out The Invention The following Examples are for the purpose of further illustrating the present invention and are not to be taken as limiting in any regard. Unless otherwise indicated, all parts and percentages are by weight.

Exam~le 1 According to this example, an intermediate-moisture do~ food according to the present invention having an aW of about 0.86-0.87 was prepared from the following formulation:

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Meat Slurry Formula Beef Trims 10.0 parts Beef Tripe 24.0 parts Corn Syrup 3.0 parts 05 Emulsifier 0.5 parts 37.5 parts Dry Ingredients Soy Flakes 33.0 parts Sucrose 16.5 parts Soy Hulls 2.0 parts Dicalcium Phosphate 3.1 parts Whey 1.5 parts Salt 1.2 parts Vitamins 0.14 parts Color 0.02 parts 57.46 To prepare the dog food, the beef trims and tripe were chopped in frozen condition and extruded through a one-eighth inch die using a Hobart grinder This ground material was then placed in a jacketed sigma blade mixer and the corn syrup and emulsifier were added. The resulting slurry was thoroughly mixed as it was heated to about 200 F. The listed dry ingredients were then bat:ched and pre-mixed in a Hobart mixer. The resulting uniform dry mix was then added to the heated slurry and the total mix heated to about 180 F under constant agitation.
This total mix was then transferred to a flat tray for cooling to room temperature, packed in seal polymer film bags, and placed in 0 F storage for at least 24 hours. The samples remained frozen until use, at which time they were thawed and admixed with the indicated additional preservatives and inoculat-* Trade Mark ~3 ~807a ed with Staphylococcus sp. (9 x 104 organisms/gram).
The test results were as follows:

Count after 7 days Preservative Added (Organisms per gram) 05 Nothing (Control) ~lo8 5.5% 1,2-propanediol 1 x 103

2.0% monopropionin + 3.5% 1,2-propanediol <100 The systems containing monopropionin showed no mold growth after three months.

ExamPle 2 This example repeats the procedure of Example 1 except that the dog food had an aW of 0.83 and only a mold (spore suspension) inoculum was employed, and the monopropionin was employed as the sole anti-microbial. The inoculum was Asper~illus niger(spore suspension) plus Penicillium ~e~ (spore suspension) and A. ~laucus (spore suspension). The results were as follows:

Preservative AddedTime for Visible Mold Growth .. .. ~
20 Nothing (Control)3 days 2% monopropionin5 months 4% monopropionin>8 months Example 3 This example repeats the procedure of Example 1 except that: the dog food had an aW of 0.89-0.90, and lacked coloring, a different inoculum was em-ployed to determine resistence to lackic bateria which can cause souring of inadequately stabilized pet foods. Monoacetin and l-monobutyrin were com-pared in effectiveness to 1,2-propanediol. The , ~ ~6807~

inoculum was Lactobacillus sp. strain Q (7 x 10 organisms/gram) which grows at a relatively low aw.
The results were as follows:
Count-(Organisms Per Gram) 05 Preservative Added 7 days 22 days 35 days 3 months 6 months None (Control)2 x 106 5 x 106 4 x 106 4 ~ 105 2 x 103 4% 1,2-propanediol 2 x 105 4 x 104 1 x 104 2 x 106 4% ~onoacetin3 x 106 7 ~ 105 1 x 106 1 x 104 <103 4/O l-monobutyrin 2 x 103 1 x 104 <105 <105 <104 or less Example 4 This example repeats the procedure of Example 2 except that the dog food had an aW of 0.83-0.84 and 1-monobutyrin and monoacetin were compared to 1,2-propanediol for their effectiveness against mold growth. The xesults were as follows:

Preservative Added Time for Visible Mold Growth -Nothing ~Control) 12 days 2% 1,2-propanediol >6 months 20 2% 1-monobutyrin 53 days 2% monoacetin 18 days.

Example 5 This example repeats the procedure o Example 1 e~cept that: the dog food had an aW o 0.89, a p~
of 6.4, and contained 0.1% potassium sorbate; the inoculum was different; and 1-monobutyrin was com-pared to 1,2-propanediol in effectiveness against bacterial growth. The inoculum was Staphy~ococcus sap~phytlcus, strain W (2 x 105 organisms/gram3.
The results were as follows~

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Count (Organisms Per Gram) Presexvative Added 8 days 15 days 1 month Nothing (Control) 3 x 108 4% 1,2-Propanediol 2 x 103 1 x 103 6 x 102 05 4% l-Monobutyrin1 x 10 3 x 10 1 x 10 Example 6 This example repeats the procedure of Example 5, except that the dog food had an aW of 0.91 and a pH of 4.9. The results were as follows:

10Count (Organisms Per Gram) Preservative Added 8 days 15 days 1 month 2 month~
Nothing (Control) 2 x 10 3 x 10 2 x 108 4% 1,2-Propanediol 800 100 <100 100 4% l-Monobutyrin 100 100 200 <100 Example 7 This example repeats the procedure of Example 5 at varying pH and aW values with an inoculum of Aspergillus niger (Spore Suspension) plus A. glaucus (Spore Suspension) and Penicillium sp. to determine effectiveness at lower pH values. The results are summarized as follows:

Preservative AddedTime for Visible Mold Growth (days) pH 6.4 (Control) 11 aW .89 (4% 1,2-Propanediol) ~90 (4% l-Monobutyrin) >90 pH 4.9 (Control) 19 aW .89 (4% 1,2-Propanediol) >90 (4% l-Monobutyrin) >90 11~80~ ~

Preservative AddedTime for Visible Mold Growth (days) _ pH 4.9 (Control 11 aW .91 (4% 1,2-propanediol) >90 (4% l-Monobutyrin) >90 05 Exam~le 8 This example repeats the procedure of ~xample 6 at pH 4.9 and various aW values. The results are summarized as follows:

Count (Organisms Per Gram) 10Preservative Added 7 days 16 days 44 days 3 months (Control 1 x 105 1 x 10 aW .88 (3/0 Monobutyrin) <100 <100 ~100 <100 (2~ Monobutyrin) <100 <100 <100 <100 (Control) 2 x 106 3 x 108 aW .89 (3~ Monobutyrin) <100 <100 <100 <100 (2% Monobutyrin) <100 ~100 <100 <100 (Control) 7 x 107 aW ~90 (3/0 Monobutyrin) <100 <100 <100 <100 (2% Monobutyrin) <100 <100 <100 <100 Example 9 This example repeats the procedure of Example 7 at pH 4.9 and varying aW levels with lower concen-trations of the l-Monobutyrin. The results are summarized as follows:

Preservative Added Time for Visible Mold Growth ~days) (Control) 4 aW .88 (3% Monobutyrin) >50 (2% Monobutyrin) >50 1 16807~

Preservative AddedTime for Visible Mold G~owth (days) (Control) 4 aW .89 (3% Monobutyrin) >50 (2% Monobutyrin) 17 05 (Control) 4 aW 90 (3% Monobutyrin) >50 (2% Monobutyrin) >50 The above description is for the purpose of : teaching those skilled in the art how to practice the present invention and is not intended to recite all the possible modifications and variations there-of which will become apparent to the skilled worker upon reading. It is intended, however, that all such modifications and variations be included within the scope of the invention which is defined by the following claims.

Claims (12)

1. An improved intermediate-moisture nutritionally balanced pet food comprising, protein, carbohydrates, vitamins and minerals having an aW within the range of from 0.80 to 0.90 and having moisture content between 15% to 50% of the weight of the food composition which wherein the improvement consists essentially of incorporating an amount of monopropionin, monobutyrin, or a combination of these, which is effective to protect the food against bacterial and mold growth.

2. An improved intermediate-moisture food composition according to claim 1 wherein the mono-propionin, monobutyrin, or combination of these, is present at a concentration within the range of from 1 to 5% based on the total weight of the composition.

3. An improved intermediate-moisture food composition according to claim 2 wherein the mono-propionin, monobutyrin, or combination of these is present at a concentration within the range of from 2 to 4%, based on the total weight of the composition.

4. An improved intermediate-moisture food composition according to claim 2 having a pH within the range of from 4.0 to 8Ø

S. An improved intermediate-moisture food composition according to claim 4 having a pH within the range of from 4.5 to 6.5.

6. An improved intermediate-moisture food composition according to claim 4 comprising from 2 to 4% of monopropionin, based on the weight of the composition.

7. An improved intermediate-moisture food com-position according to claim 4 comprising 2 to 4% of monobutyrin, based on the weight of the composition.

8. An improved process for preparing an intermediate-moisture pet food comprising protein, carbohydrates, vitamins and minerals having an aW
within the range of from 0.80 to 0.90 and having a moisture content between 15% to 50% of the weight of food composition incorporating into said food a preservation system effective to control bacterial and mold growth, wherein the improvement consists essentially of adding monopropionin, monobutyrin, or a combination of these, in an amount which is effec-tive to protect the food against bacterial and mold growth.

9. An improved process according to claim 8 wherein the food has a pH within the range of from 4.0 to 8Ø

10. An improved process according to claim 9 wherein the monopropionin, monobutyrin, or combina-tion of these is present at a concentration within the range of from 1 to 5% based on the total weight of the composition.

11. An improved process according to claim 10 wherein monopropionin is added to the composition.

12. An improved process according to claim 10 wherein monobutyrin is added to the composition.