Relation to Co-Pending Applications

This application is a continuation-in-part of Applicant's co-Dending Application No. 07/948,155.

Field of the Invention

The present invention relates generally to methods of preserving baked goods, and more particularly to a natural, low-cost method of preserving baked goods for a time period in excess of thirty days.

Background of the Invention

A variety of methods for preserving baked goods are known to the art. For example, it is known to preserve baked goods by adding a preserving agent such as ampylopectin to flour dough prior to baking. In addition, it is known to preserve a baked product by partially baking the dough at the usual temperature, packing it in a hermetic package under partial vacuum, and sterilizing it while in the hermetic package. Methods in which the baked good is preproofed, partially baked and maintained in a frozen condition until the date of use are also known, as are continuous processes for sterilizing a hygroscopic product by positioning individual units in a plastic tube of thermosealable plastic by means of a transverse seal that furnishes a communicating passage between the units.

A variety of problems are associated with known methods of preserving baked goods. For example, all methods using artificial preservatives are disfavored due to the large and growing segment of the food industry which is dedicated to natural foods. Methods of preserving baked goods by packaging them in evacuated and hermetically sealed packages have the disadvantage of requiring

additional and expensive equipment. Methods in which the baked goods are frozen require not only freezing equipment at the bakery, but also require refrigerated delivery systems from the bakery to the end user.

A need therefore exists for a method of preserving baked goods that does not require extensive equipment or temperature-sensitive handling techniques. The present invention addresses this need.

SUMMARY OF THE INVENTION

In one aspect of the present invention there is provided a method of preserving a baked good by inserting the baked good into a special plastic bag, closing the bag with the flexible tie, heating the bag and baked good for a time and at a temperature effective to kill molds and bacillus species, and cooling the bag and baked good for a time and at a temperature effective to arrest bacillus spores. Most commonly the heating is with a time/temperature combination effective to raise the internal core temperature of the baked good to about 165°F, while the cooling is with a time/temperature combination effective to lower the core temperature to about 40°F. Further, in certain embodiments the heating step not only kills the bacillus bacteria, it also seals the bag.

In another aspect of the invention the bag and baked good are heated until the baked good has a temperature of about 165°F about one-half inch below the surface of the good. In this aspect the cooling step cools the baked good to a temperature of about 40°F at that same one-half inch depth.

One object of the present invention is to provide a method of preserving baked goods that does not require additional and expensive equipment.

A further object of the present invention is to provide a method of preserving baked goods that does not require freezing or refrigerated handling systems.

A further object of the present invention is to provide a method of preserving baked goods without the use of artificial preservatives.

Further objects of the present invention will be apparent in the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of the process of the present invention, according to one preferred embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT

For the purposes of promoting an understanding of the principles of the invention, reference will now be made to preferred embodiments and specific language will be used to describe the same. It will nevertheless be understood, that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated processes, and such further applications of the principles of the invention as illustrated herein being contemplated as would normally occur to one skilled in the art to which the invention relates.

The process of the present invention is a natural, low-cost process which requires only the oven the product was baked in and a cooler/freezer to remove the hea ^" t from the product after sterilization is complete. As briefly described above, in one aspect of the present invention a baked good is first placed in a plastic bag and heated to an internal temperature of about 165°F to kill molds and bacillus species in the product. Then, the development of harmful bacilli spores is arrested by cooling the bagged baked good to a temperature of less than about 40°F.

In the present invention the baked good is fully baked before placing it in the plastic bag. If desired, the baked good may be finished with crumbs and/or other toppings except wet processed icings. Additionally, the finished goods may be sliced or portioned as needed.

After the baked goods are fully prepared they are placed in special plastic bags. The baked goods may be placed in the bags either individually, as with loaves of bread, or with several goods in each bag, as with rolls or doughnuts. The baked goods may be placed in the bags while the goods are still warm, or they may be fully cooled prior to bagging.

The bags used in the process are an important aspect of the invention. Because the bags are to be used throughout the process,

the preferred bags are able to withstand temperatures of about 400°F or more without splitting or melting, and cooling temperatures as low as about -20°F without cracking or otherwise compromising their structural integrity. In addition, the closed and sealed bags must be able to withstand the steam pressure generated by the baked good during the sterilization process. Pressures of between about 5 and 10 psi may be generated, and preferred bags are capable of withstanding such pressures.

Of course, the bags must be appropriate for use with food products, and are preferably made of a material specifically approved for such use. Most preferably, the bags are made of a material approved by the U.S. Food & Drug Administration for use in commercially packaging food items.

The bags must be heat sealable, preferably at sterilization temperatures, and must be capable of assuring the integrity of the sterilized environment for a period of one or more months. Moisture migration through the bag should be minimal, with the moisture migration associated with polyethylene bags being generally inappropriate for the present invention. Preferred bags have a thickness of less than about 0.005", with a thickness of less than about 0.003" being most preferred with materials used to date.

It has been found that the cellophane content of the bag should not be too high to assure the desired characteristics. If the cellophane content is too high, the bag may not seal properly or may split or break when heated to kill bacilli species.

Bags made of Extrel-11 copolymer made by Exxon Chemical Company have been particularly preferred. Extrel-11 is an extrusion cast film with improved low temperature performance. The film is coπurionly used in sterilization pouches and is particularly well fitted for side weld bag use. Other polymers or co-polymers, particularly polyester films such as DuPont Mylar--, may be used to

make the bags of the present invention so long as the bags are heat sealable, are capable of maintaining their structural integrity at temperatures effective to kill molds and bacilli species (typically heating at temperatures of between about 240°F and about 400°F), and do not crack or break at temperatures effective to cool the baked good to a temperature of less than about 40°F (typically cooling temperatures of between about -20°F and 35°F) .

After the baked goods have been placed in the plastic bags, the bags are closed and "sealed, " preferably with standard flexible ties. Any flexible tie such as those made of plastic or paper or plastic-covered wire may be used. Twist ties are preferred. The tie is used to close the end of the bag in the conventional manner. Although the tie need not seal the bag merely upon application, the tie must be effective to hold the bag in a substantially closed condition during the heating process. Alternatively, the bag may be sealed with a heat sealer designed for that purpose, such as those having jaws heated by electric resistance heat. Heat sealers appropriate for use in the present invention are commercially available, and may be selected by one skilled in the art without undue experimentation.

Once the baked good has been placed in the bag and closed with a tie, the bag and baked good are heated to kill molds and bacilli species in the baked good. Preferably, this step is accomplished by heating the baked good until the internal temperature is approximately 165°F. Most preferably, the heating step comprises placing the baked good in a 240° to 400°F oven for a time sufficient to kill the aforementioned species. Because the bag is made of a material which is heat sealable at a temperature effective to kill bacilli bacterial, the heating step simultaneously may be used to seal the bag; i.e., the sterilization and sealing processes may be accomplished in a single step.

The heating time required to effectively sterilize the product is a function of both the temperature used and the weight of the product to be sterilized. For many products, it has been

found that a time equal to the square root of the product of the weight (in ounces) and 480 minus the processing temperature (in degrees F) is effective. For example, when using a temperature of approximately 240°F, a time of approximately one hour is required to adequately sterilize a one pound bread loaf.

One formula for computing the heating time appropriate to kill molds and bacillus species is:

= (W x (480 - T ) ) wherein

T is the time (in minutes) required for effective sterilization;

W is the weight of the baked good in ounces; and

T _p is the processing temperature in °F.

Note, though, that specific heating times appropriate for killing desired molds and bacillus species depend on the moisture in the baked good, the atmospheric pressure in the oven, and other parameters specific to the product being treated and the facilities available for treatment.

The heating step may be accomplished in any oven currently in commercial use. For example, deck ovens, reel ovens, rack ovens and conveyor-type ovens may be used at normal operating temperatures. Convection and other types of forced air ovens may be used, although a downward temperature adjustment may be required for that particular type of oven. The appropriate temperature may be selected by one skilled in the art without undue experimentation. Preferably sufficient clearance is provided around the bagged product to allow for expansion in the oven.

After heating the baked good to kill molds and bacillus species, the bag and baked good are cooled to a temperature effective to arrest bacilli spores which are not killed in the

heating step. These spores, particularly Ba cill us mesenteri cus , are responsible for the "ropiness" which results in untreated products. Most preferably, the baked good is cooled until the internal temperature is less than about 40°F. Flash freezing is not required, nor is it recommended in order to practice the present invention. Preferably a cooler/freezer effective to bring the internal temperature of the processed product down to a temperature of below about 40°F within a 6 hour period is used.

The cooling of the baked good "arrests" Baci ll us mesen teri cus spores by inducing the spores to a state of dormancy. Although the cooling step may not kill or arrest the development of rope bacteria spores altogether, the cooling slows their growth to a rate such that the shelf life of the baked good is extended from approximately 3 to 4 days to approximately 30 to 40 days.

The method described above is particularly effective for preserving sliced baked goods in which bacteria may reside deep within the interior of the bread. In another aspect of the invention an unsliced baked good is placed in a plastic bag and heated at a time/temperature combination effective to kill molds and bacillus species near the surface of the good. Then, the baked good is then cooled at a time/temperature combination effective to arrest bacillus spores near the surface of the good. Preferably, the heating and cooling steps are effective for killing and/or arresting bacteria up to about one-half inch below the surface of the product.

EXAMPLE ONE

An 18 ounce loaf of sliced rye bread is preserved by the process of the present invention. The 18 ounce loaf is initially baked at a temperature of between about 380° F and 425°F and is allowed to partially cool. The baked bread is placed in a plastic bag made of unoriented polypropylene and is closed with a paper-covered twist tie. The bread is brought to an internal

temperature of about 165°F by heating in a 240°F oven for approximately 66 minutes ((18 x (480 - 240) ¹² ) . After sterilization is complete the baked good is allowed to cool to a temperature of about 40° .

Forty days after processing the bag is opened and the loaf is inspected. No deterioration of the baked good is observed.

EXAMPLE TWO

An 18 ounce loaf of unsliced bread is processed at a temperature of approximately 290°F. The loaf is baked, allowed to partially cool, and sliced before being placed in a plastic bag made of polyester film such as DuPont's Mylar-i*. The bag is heat sealed with an electric heat sealer before being placed in an oven for sterilization. The product is heated until the temperature is about 165°F one-half inch below the surface by heating for approximately 59 minutes. Then, the product is cooled until the temperature of the bread is about 35°F at the same one-half inch depth.

After a forty day shelf life, the bag is opened and the loaf is inspected. No deterioration of the baked good is observed.

While the invention has been illustrated and described in detail in the foregoing examples and description, the same are to be considered as illustrative and not restrictive in character. It is understood that only preferred embodiments have been shown and described, and that all changes and modifications that come within the spirit of the invention are desired to be protected.