Low moisture extrusion method

Abstract

To provide a production method for a dried food using a less amount of drying energy.SOLUTION: A production method includes the steps of: providing raw materials for a dried food to a preconditioning vessel at a first flow rate; preconditioning the raw materials in the preconditioning vessel and forming dough; and moving dough having a moisture content from about 4% to about 10% through an inlet of an extruder. The method further includes a step of extruding the dough through a die plate of the extruder and forming kibbles by applying thermal energy to the dough and applying mechanical energy to the dough, where the ratio of the thermal energy to the mechanical energy can range from at least about 2.0 to about 4.0.SELECTED DRAWING: Figure 1

Description

Description of Related Applications

[0001] This application claims priority to U.S. Provisional Patent Application No. 62 / 972,501, filed February 10, 2020, which is incorporated herein by reference in its entirety. This application is also a divisional application of Japanese Patent Application No. 2022-536574, filed February 10, 2021. [Technical field]

[0002] The present disclosure relates to a low moisture extrusion process. [Background technology]

[0003] Many foods, including dry pet food products and treats, are prepared by extrusion cooking, which involves forming a composition from ingredients and passing it sequentially through a pre-processing unit, an extruder, and a dryer. The extruded product can be cut or separated into pieces, such as puffs or kibbles.

[0004] In conventional systems, pet food ingredients are hydrated, heated and mixed during a pretreatment step to form a dough. Additional liquids such as oils, fats and colorants may also be added during this pretreatment step. The pretreatment equipment may utilize steam and water at levels sufficient to initiate starch gelatinization while hydrating and mixing the ingredients.

[0005] In such conventional systems, the dough enters the extruder through the pretreatment device outlet and is forced through the extruder and into a die plate. Additional moisture can be added during this process to further hydrate the dough and control the texture of the final product. Steam can also be added during this process to further cook the dough and / or for density control. As the dough is forced through the die plate to form the extrudate, the extrudate typically has a large amount of moisture and must be further dried by a separate dryer to obtain a stable kibble that is safe for consumption. The drying process is an energy intensive unit operation and accounts for the majority of production costs and carbon emissions. Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, there is a need in the art for a method that uses less drying energy to reduce or eliminate the need for dryers. [Means for solving the problem]

[0007] The objectives and advantages of the disclosed subject matter will be set forth in and will be obvious from the following description, as well as will be learned by practice of the disclosed subject matter. Additional advantages of the disclosed subject matter will be realized and attained by the apparatus particularly pointed out in the written description and claims hereof, as well as the appended drawings.

[0008] To achieve these and other advantages, and in accordance with the objects of the disclosed subject matter as embodied and broadly described, the disclosed subject matter is a method of producing a dry food, comprising the steps of: supplying dry food ingredients to a pre-treatment vessel at a first flow rate; pre-treating the ingredients in the vessel to form a dough; passing the dough, having a moisture content of about 4% to about 10%, through an inlet of an extruder at a second flow rate; extruding the dough through a die plate of the extruder by applying thermal energy to the dough and applying mechanical energy to the dough to form a kibble, wherein the ratio of thermal energy to mechanical energy can range from at least about 2.0 to about 4.0.

[0009] According to another aspect of the disclosed subject matter, a method for producing a dry food product produces kibbles having a moisture content of about 8% to about 13.5% upon exiting the extruder.

[0010] In certain embodiments, the method includes the step of drying the kibble.

[0011] In certain embodiments, the kibble is dried to have a water activity of about 0.63.

[0012] In certain embodiments, the moisture flash-off after the dough passes through the die is from about 4.0% to about 7.0%.

[0013] In certain embodiments, applying thermal energy to the fabric includes using steam.

[0014] In certain embodiments, the steam flow rate is about 6.0% to about 10.0% of the second flow rate.

[0015] In certain embodiments, the steam pressure in the extruder is from about 80 psi to about 150 psi (about 552 kPa to about 1.03 MPa).

[0016] In certain embodiments, the thermal and mechanical energy heats the dough above its melting point, thereby reducing the viscosity of the dough.

[0017] In certain embodiments, the first flow rate is from about 0.8 to about 12 tons per hour.

[0018] In certain embodiments, the pre-treatment step includes adding steam at a flow rate of up to 3% of the steam based on the first flow rate.

[0019] In certain embodiments, the steam flow rate to the pretreatment device is 0 tons per hour.

[0020] In certain embodiments, the pretreatment step further comprises adding water at a flow rate up to 4% of the first flow rate.

[0021] In certain particular embodiments, the water flow rate is 0% of the first flow rate.

[0022] In certain embodiments, extruding the dough includes increasing the temperature in the extruder from 30-36° C. to 144-160° C. and increasing the moisture content from 10-12% moisture to 16-18% moisture.

[0023] In certain embodiments, the moisture content of the dough in the extruder is from about 16% to about 18%.

[0024] In certain embodiments, the extruder is one of a single screw extruder or a twin screw extruder.

[0025] In certain embodiments, after the dough extrusion step, the kibbles are not dried in a dryer.

[0026] In certain embodiments, after the dough extrusion step, the kibbles are air dried.

[0027] In certain embodiments, the dough comprises about 10% to about 80% carbohydrate, about 5% to about 35% fat, and about 5% to about 60% protein.

[0028] In certain embodiments, the protein comprises an animal protein.

[0029] In certain embodiments, the disclosure relates to a method of producing a dry food, comprising the steps of providing a dough having a moisture content of about 4% to about 10%, placing the dough into an extruder at a first flow rate, processing the dough in the extruder, comprising applying thermal energy to the dough and applying mechanical energy to the dough, wherein a ratio of thermal energy to mechanical energy is at least about 4, and extruding the dough from the extruder through a die plate to form a kibble.

[0030] In certain embodiments, the kibbles have a moisture content of about 8% to about 13.5% upon exiting the extruder.

[0031] In certain embodiments, the dough is heated above its melting point by thermal and mechanical energy, thereby reducing the viscosity of the dough.

[0032] In certain embodiments, after the dough extrusion step, the kibbles are not dried in a dryer.

[0033] In certain embodiments, after the dough extrusion step, the kibbles are air dried.

[0034] In certain embodiments, the dough comprises about 10% to about 80% carbohydrate, about 5% to about 35% fat, and about 5% to about 60% protein.

[0035] In certain embodiments, the protein comprises an animal protein. [Brief description of the drawings]

[0036] The subject matter of the present application will be more readily understood from the following detailed description when read in conjunction with the accompanying drawings. [Figure 1] Schematic diagram of the equipment system used in the conventional process [Diagram 2] Single screw extruder for use in low moisture extrusion processes according to the disclosed subject matter [Diagram 3] Moisture circulation in conventional extrusion processes [Figure 4] Moisture circulation in low moisture extrusion processes according to the disclosed subject matter [Diagram 5] 1 is a graph comparing temperature and moisture of kibbles made from dough processed by a low moisture extrusion process in accordance with the disclosed subject matter and kibbles made from dough processed by a conventional extrusion process; [Figure 6A] Tomographic image of a kibble made by a low moisture extrusion process according to the disclosed subject matter. [Figure 6B] Tomographic image of a kibble made by a low moisture extrusion process according to the disclosed subject matter. [Figure 6C] Tomographic image of a kibble made by a low moisture extrusion process according to the disclosed subject matter. [Figure 6D] Tomographic image of a kibble made by a conventional extrusion process [Figure 6E] Tomographic image of a kibble made by a conventional extrusion process [Figure 6F]Tomographic image of a kibble made by a conventional extrusion process [Figure 7A] Images from a microscopic study of the composition of kibbles made by a low moisture extrusion process according to the disclosed subject matter. [Figure 7B] Images from a microscopic study of the composition of kibbles made by the extrusion process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] The present disclosure particularly relates to low moisture extrusion (LME) processes that use less water than conventional extrusion processes.

[0038] definition The terms used herein generally have their ordinary meanings in the art, within the context of this disclosure and in the specific context in which each term is used. Certain terms are explained below or elsewhere herein to provide additional guidance in describing the compositions and methods of the present disclosure and how they are made and used.

[0039] As used in this specification and the appended claims, nouns include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a "compound" includes a mixture of compounds.

[0040] The term "about" or "approximately" means within an acceptable error range of a particular value as determined by one of ordinary skill in the art, which will depend in part on the limitations of the method by which the value is measured or determined, i.e., the measurement system. For example, "about" can mean within 3 standard deviations or more than 3 standard deviations, as is customary in the art. Alternatively, "about" can mean a range of up to 20%, preferably up to 10%, more preferably up to 5%, and even more preferably up to 1% of a given value. Alternatively, particularly with respect to a system or process, the term can mean within an order of magnitude, preferably within 5-fold, and more preferably within 2-fold, of a value. The term "about" in the context of moisture content (wt%) means ±1 wt%. The term "about" in the context of water activity (Aw) means ±0.05. The term "about" in the context of final moisture means ±3%. The term "about" in the context of viscosity means ±3%.

[0041] The term "animal" or "pet" as used in accordance with the present disclosure means domestic animals, including, but not limited to, domestic dogs, domestic cats, horses, cows, ferrets, rabbits, pigs, rats, mice, gerbils, hamsters, goats, and the like. Domestic dogs and domestic cats are specific non-limiting examples of pets. The term "animal" or "pet" as used in accordance with the present disclosure may further refer to wild animals, including, but not limited to, bison, elk, deer, venison, ducks, poultry, fish, and the like.

[0042] The terms "animal feed", "animal feed composition", "pet food", "pet food article", or "pet food composition" are used interchangeably herein and refer to compositions intended for consumption by an animal or pet. Pet food can include, without limitation, nutritionally balanced compositions suitable for daily feeding, such as kibble, as well as supplements and / or treats, which may be nutritionally balanced. A nutritionally balanced complete pet food composition will generally include ingredients such as proteinaceous materials and / or starchy materials. In alternative embodiments, the supplements and / or treats are not nutritionally balanced.

[0043] As used herein, "comprises," "comprising," or any other variation thereof is intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements does not include only those elements, but may include other elements not expressly listed or that are inherent to such process, method, article, or apparatus.

[0044] In the detailed description herein, references to "an embodiment," "an embodiment," "one embodiment," "in various embodiments," and the like indicate that the described embodiment may include a particular feature, structure, or characteristic, but not all embodiments may necessarily include that particular feature, structure, or characteristic. Moreover, such phrases do not necessarily refer to the same embodiment. Moreover, when a particular feature, structure, or characteristic is described in relation to one embodiment, it is believed to be within the knowledge of one of ordinary skill in the art to affect such feature, structure, or characteristic in relation to other embodiments, whether or not explicitly described. After reading this description, it will be apparent to one of ordinary skill in the relevant art how to implement the present disclosure in alternative embodiments.

[0045] The term "extrusion" with respect to a composition or animal feed refers to a composition or animal feed that has been processed, for example, by passing through one or more extruders. Any type of extruder can be used, non-limiting examples of which include single screw extruders and twin screw extruders, such as, but not limited to, extruder models Wenger X-115, Wenger X-185, and Wenger X-235.

[0046] The term "non-extruded" as used herein refers to food products prepared by any method other than extrusion cooking, such as frying, baking, broiling, grilling, pressure cooking, boiling, ohmic cooking, steaming, etc.

[0047] The term "pet treat" refers to a composition that is intended to be consumed periodically by an animal or pet. Pet treats can be nutritionally balanced. In alternative embodiments, pet treats are not nutritionally balanced.

[0048] As used herein, "kibble" or "dry kibble" refers to an extruded food product having a moisture level of 15% or less, by weight of the food product. Kibble can be nutritionally balanced and complete.

[0049] The term "semi-moist" as used herein refers to foods having a moisture level between 15% and 50%, by weight of the food. The term "wet" as used herein refers to foods having a moisture content of 50% or more, by weight of the food. Semi-moist or wet foods can be prepared, at least in part, using extrusion cooking, or can be prepared entirely by other methods.

[0050] As used herein, the term "meal" refers to dry starting materials. Starting materials include, but are not limited to, proteinaceous materials, starchy materials, and carbohydrates and other materials not necessarily falling into either category, including legumes such as alfalfa and soybeans. In certain embodiments, the meal includes ground materials. In certain embodiments, the terms "meal" and dry feed can be used interchangeably.

[0051] As used herein, the term "proteinaceous materials" includes, but is not limited to, vegetable protein meals such as soybean, cottonseed, or peanut meal, animal proteins such as casein, albumin, whey, including dried whey, and meat tissues, including raw meat and rendered or dried meat "meals" such as fish meal, poultry meal, meat meal, meat and bone meal, enzyme-treated protein hydrolysates, etc. Proteinaceous materials can further include microbial proteins such as yeast, and other types of proteins, including materials such as wheat gluten, corn gluten, and feather meal.

[0052] As used herein, the term "farmaceous materials" includes, but is not limited to, enzyme farmaceous materials, grains such as corn, maize, wheat, sorghum, barley, and various other grains that are relatively low in protein.

[0053] As used herein, the term "dough" refers to hydrated meal or dry feed.

[0054] As used herein, the term "meal flow rate" refers to the rate at which the meal is fed to the pretreatment vessel. In certain embodiments, the term "meal flow rate" can refer to the rate at which the meal is fed to the extruder.

[0055] As used herein, specific mechanical energy (SME) refers to the energy applied to the dough as it is forced through the die plate. SME can be adjusted subtly or indirectly to manage process speed and throughput. In certain embodiments, SME can be increased by increasing the screw speed or by modifying the screw itself, such as by increasing the screw periodicity. In a single screw extruder, useful screw speeds can range from 350 or 375 rpm to 600 rpm. Manipulating the SME can contribute to improved texture in at least two ways. First, a higher SME helps to break up the starch granules, allowing amylose to leach out of the starch and amylopectin or other molecules from the starch granules to expand more or more quickly. Second, a higher SME can thoroughly mix the dough and hydrate it in the final moments before it is forced through the die plate, promoting starch gelatinization and preparing the dough to expand during extrusion.

[0056] As used herein, specific heat energy (STE) refers to the energy that any stream that enters a pretreatment unit or extruder and contacts the meal or dough transfers to the meal or dough based on its temperature. If steam is injected into the pretreatment unit or extruder, this heat energy is a function of the steam pressure (enthalpy) and flow rate. In certain embodiments, the STE can be increased by increasing the steam flow rate, or by increasing the steam pressure, or by changing the temperature of the streams entering the pretreatment unit or extruder. Manipulating the STE can contribute to improving texture. A higher STE can help increase the cooking of the starch, allowing amylose to leach out of the starch and amylopectin or other molecules from the starch granules to expand more or more quickly, promoting starch gelatinization and helping prepare the dough for expansion during extrusion.

[0057] Traditional Extrusion Process Many foods, including dry pet food products and treats, are prepared by extrusion cooking, which includes pretreatment, extrusion, and drying steps. A conventional extrusion process flow is shown in FIG. 1. Raw materials are fed into a pretreatment vessel 103 through a pretreatment inlet 101. During the pretreatment step, the raw materials are mixed with at least one of water and steam in the pretreatment vessel 103 to form a dough composition. Upon completion of the pretreatment step, the composition is transferred through an outlet 105 of the pretreatment vessel to an extruder 107. An exemplary extruder is shown in FIG. 2. The extruder has an extruder inlet, seven barrels, and an extruder outlet. Steam can be added throughout the extrusion process. During the extrusion process, the dough composition is extruded through a pressure sealed extruder, in which the material is exposed to high temperatures and pressures. The dough composition is then extruded from an extruder outlet 109 through a die 111 to form an extrudate, which is formed into a kibble and then sent to a dryer 113.

[0058] The moisture cycle in a conventional extrusion process is shown in FIG. 3. During step 1, ground grains and meals are placed in a pretreatment vessel. The composition begins with a moisture content of about 4-10%. During the pretreatment process, water is added to provide a composition with a moisture content of about 22%. Conventional wisdom in the art suggests that a moderate moisture level, such as about 17% to about 35%, is necessary to provide a product with the desired palatability and texture characteristics. In certain embodiments, as shown in FIG. 5 and further discussed herein, the pretreatment process for this conventional extrusion process adds about 15% moisture during the pretreatment process, resulting in a composition with a moisture content of about 24%. In certain embodiments of the process for this conventional extrusion process, the moisture level at the end of the pretreatment process is about 19% to about 35%.

[0059] During step 2 of Figure 3, the composition is passed through a pressure sealed extruder where the material is exposed to high temperature and low steam flow rate but high steam pressure. In certain embodiments, the material is exposed to steam pressures of about 80 psi (about 552 kPa) to about 150 psi (about 1.03 MPa) with a steam flow rate of up to 4% of the meal flow rate. In certain embodiments, the temperature of the dough is raised in the extruder from about 54-98°C to about 119-139°C.

[0060] In certain embodiments, the specific mechanical energy of conventional extrusion processes is from about 17.8 to about 36.0 kWh / metric ton. In certain embodiments, the specific mechanical energy of conventional extrusion processes is from about 64.2 to about 129.5 kJ / kg.

[0061] In certain embodiments, the ratio of specific heat energy to specific mechanical energy in an extruder during a conventional extrusion process is less than about 0.7. In certain embodiments, the ratio of specific heat energy to specific mechanical energy in an extruder during a conventional extrusion process is 0.

[0062] After passing through the extruder, the extrudate is cut into pieces to form kibbles. In the extruder, the pressure and temperature are higher than ambient pressure and temperature, so some of the moisture evaporates by flashing off, and the resulting kibbles have a moisture content of about 16% to about 28%. As shown in FIG. 3, the material must then be dried in a dryer (step 3) to a food-safe moisture level, which depends on the water activity of the product. Depending on the product, the final dry pet food product must contain less than about 15% moisture, less than about 12% moisture, less than about 10% moisture, less than about 8% moisture, or less than about 6% moisture. Thus, at least about 10% to 25% of the water must be removed during the drying process. The kibbles can then be treated with additional coatings, and the final product will have about the same moisture content as the starting material, about 4% to 10% moisture.

[0063] Low Moisture Extrusion Process The moisture cycle of the disclosed LME process is shown in FIG. 4. During step 1, ground grains and meals are placed in a pretreatment vessel. The composition initially has a moisture content of about 4-10%. During the pretreatment process, a small amount of water is added, resulting in a composition with a moisture content of about 4% to about 15%. During step 2, the composition is passed through an extruder at high temperature, pressure, and high steam flow rate. After passing through the extruder and through the die, flashing off evaporates some of the moisture, leaving the composition with a moisture level of about 8% to about 14%. In the LME process, a higher percentage of moisture is lost during flashing off due to the higher temperature and pressure in the extruder compared to the extrusion process, resulting in a kibble that requires little or no drying. The excess moisture is then removed during optional step 3 (drying), resulting in a dried kibble with a moisture level of about 5-10%. The kibble can then be treated with additional coatings, resulting in a final product with a moisture content of about 4-10%. This moisture level is approximately the same as that present in the starting material.

[0064] LME-produced kibbles, like conventionally produced kibbles, can be nutritionally complete and balanced animal feeds that provide all essential nutrients (except water) required for life support. Nutritionally complete and balanced pet food products can meet consensus nutritional profiles, such as AAFCO standards for dog or cat food, and can achieve such nutritional profiles with formulations that include proteinaceous materials, starchy materials, and other materials. In some embodiments, the presently disclosed extruded kibbles are produced from a dough that includes about 10% to about 80% carbohydrate, about 5% to about 35% lipid, and about 5% to about 60% protein. In some embodiments, the dough includes about 5% to about 60% animal protein. In some embodiments, the dough, and the resulting kibbles, can include additional ingredients, including, without limitation, vitamins, minerals, colors, flavors, and the like.

[0065] The LME process according to the disclosed subject matter overcomes the problems outlined above in conventional systems and is described in more detail below.

[0066] Pretreatment Food ingredients can be pretreated in a pretreatment step prior to processing the pet food material in the LME process. The pretreatment unit initiates the cooking process of the raw materials before they enter the extruder. The dough or ingredients for the dough can be mixed with steam and / or water in the pretreatment unit under controlled conditions to precook or preheat the dough, mix all the ingredients into the dough, and / or prepare (such as by hydration) the dough to the desired condition during extrusion cooking. Additional liquids including oils / fats and colorants can be added here. The pretreatment unit can utilize high steam flow rates and high water flow rates to initiate the gelation process while hydrating and mixing the ingredients. However, the process is fairly energy inefficient because the pretreatment unit, unlike the extruder, is not pressure sealed and can release steam and heat (i.e., energy) to the atmosphere.

[0067] The moisture level in this pretreatment step is set at a low level to minimize the amount of water used during the manufacturing process as well as the amount of drying required after extrusion cooking. In certain embodiments, the composition exiting the pretreatment device has a moisture content of about 10% to about 14% by weight. In conventional processes, gelation typically begins during the pretreatment step, but it has been surprisingly found that initial gelation can be delayed until the extrusion step. In some embodiments, it has been surprisingly found that the moisture level and gelation in the pretreatment step can be reduced while still achieving a final kibble with texture characteristics comparable to those of kibbles produced by conventional processes. In certain embodiments according to the disclosed subject matter, when an LME process is used, less than 5%, less than 4%, less than 3%, less than 2%, or less than 1% moisture is added during pretreatment based on the meal flow rate. In certain embodiments according to the disclosed subject matter, unlike conventional processes, no steam is added during the pretreatment step. However, in certain embodiments according to the disclosed subject matter, when using the LME process, a low steam pressure is used during the pretreatment step, for example, about 15 psi (about 103 kPa) to about 60 psi (about 414 kPa). Furthermore, in certain non-limiting embodiments, as shown in FIG. 5, when using the LME process, less than 1% moisture is added and no steam is used during the pretreatment step. Importantly, this LME-based process provides more efficient heat transfer and thermal energy input because the pretreatment equipment, unlike an extruder, is not pressure sealed and can vent steam and heat (i.e., energy) to the atmosphere. Additionally, when using the LME process, a lower water flow rate can be used because only a small amount of moisture is added during this pretreatment step. The operational differences in the pretreatment step in the disclosed LME process versus the conventional extrusion process are shown in Table 1.1.

[0068] [Table 1-1]

[0069] In certain embodiments, conventional extrusion processes use high water flow rates, e.g., about 10% to about 22% based on the meal flow rate during pretreatment. In certain embodiments, conventional extrusion processes use high steam flow rates, e.g., about 5% to about 13% based on the meal flow rate during pretreatment. In certain embodiments, conventional extrusion processes use low steam pressures, e.g., about 15 psi (about 103 kPa) to about 60 psi (about 414 kPa).

[0070] In certain embodiments, the LME process uses a low water flow rate, for example, up to 4%, based on the meal flow rate during pretreatment. In certain embodiments, no water is added during pretreatment. In certain embodiments, the LME process uses a low steam flow rate, for example, up to 3%, or up to 4%, based on the meal flow rate during pretreatment. In certain embodiments, no steam is added during pretreatment. In certain embodiments, the LME process uses a low steam pressure, for example, a steam pressure of about 15 psi (about 103 kPa) to about 60 psi (about 414 kPa).

[0071] The dough from the pretreatment step exits the pretreatment unit and enters an extruder. Here, the dough is forced out of the extruder towards a die to form an extrudate, which is further shaped into kibbles. At this stage, dyes, oil, water, and steam can be added to the extruder. The extruder, such as but not limited to a single screw extruder or a twin screw extruder, applies high temperature, pressure, and high shear to induce gelatinization of the starch molecules. An exemplary extruder that can be used for the LME process is provided in FIG. 2.

[0072] As shown in Figures 7A and 7B, when the initial gelatinization of starch molecules is delayed until the extrusion process, and this extrusion process is performed on a dough having a reduced moisture level compared to the conventional process, it has been found that the amount of uncooked starch in the final kibble product is approximately the same as for kibbles produced by the conventional process. In addition, although it is commonly believed that adding moisture and initiating the starch gelatinization process during the pretreatment step reduces the specific mechanical energy (SME) required for the extruder, in some embodiments, it has been found that the SME of the extruder remains substantially the same as that of the conventional process. Without being bound by theory or mechanism, the SME was substantially the same in the LME process as in the conventional process because the temperature of the LME extruder exceeds the melting point of the dough in the extruder, which may reduce the viscosity of the dough material.

[0073] Additional studies were conducted to compare the starch gelation range between the conventional and LME processes. The studies showed that the differences were not statistically significant. For example, both processes produce a gel ratio in the final product ranging from 77-100% using the NIR method and between 81-100% using the wet chemical method. Therefore, the SME of the processes disclosed herein can still be comparable to or even lower than the conventional process. Certain embodiments according to the disclosed embodiments do not need to use an extruder with a higher horsepower motor to produce the same kibble as the conventional system. In certain embodiments, the extruder has a power output of about 300 to about 500 horsepower.

[0074] The specific mechanical energy can be varied during the extrusion process by varying the screw speed, hi certain embodiments, the screw speed of the extrusion process can be from about 283 rpm to about 450 rpm, from about 320 rpm to about 420 rpm, or from about 240 rpm to about 263 rpm.

[0075] Table 1.2 provides a further comparison of products made by conventional extrusion and LME processes. In certain embodiments, for LME processing, the dough is extruded with an SME of at least about 56.3 kJ / kg. This SME can range from about 50 kJ / kg to about 100 kJ / kg, which is generally lower than the SME of dough extruded in a conventional extrusion process, as shown in Table 1.2 below.

[0076] [Table 1-2]

[0077] The moisture percentage change after flash off is calculated as follows:

[0078]

number

[0079] Heat energy is provided during the extrusion process, for example, by direct steam injection during processing, and can be quantified by specific heat energy (STE). Steam added during the extrusion process adds moisture to the dough. In certain embodiments, the composition has a moisture content of about 16% to about 18% before proceeding through the die. In certain embodiments, as shown in Figure 5, the extrudate has a moisture content of about 18% before entering the die when produced by the LME process, compared to about 25% when produced by the extrusion process.

[0080] The ratio of STE to SME during the LME process (excluding the pretreatment step) can range from about 2.0 to about 4.0, as given in Table 1.2. This is the opposite of the ratio of STE to SME during a conventional extrusion process, where the ratio can range from about 0 to about 0.7, as given in Table 1.2.

[0081] The cooked dough is forced through a forming die and cut as an extrudate. During this process, the extrudate expands due to the temperature and pressure difference between the extruder and the intermediate external environment. Importantly, the temperature of the extrudate before entering the die is much higher than its melt temperature Tm. This promotes more flash-off, i.e., moisture loss in the form of steam caused by the difference between the ambient temperature of the external environment and the temperature inside the extruder, as further explained herein with respect to FIG. 5. As shown in the examples of Table 1.2, moisture flash-off is shown for the conventional process and the LME process examples. This moisture flash-off percentage represents less moisture in the extruder than the moisture after flash-off. In the conventional extrusion process, the moisture flash-off can range up to 4.0%. In contrast, in the LME process, the moisture flash-off can range from about 4.0% to about 7.0%, which is a much higher flash-off than the conventional process. Thus, the corresponding moisture percentage change after flash-off for the conventional extrusion process, the flash-off percentage, can range from about 10.3% to about 19.7%. In contrast, the moisture percentage change after flash-off for the LME process can range from about 25.2% to 31.2%, which is much larger than the flash-off percentage for the conventional extrusion process.

[0082] FIG. 5 provides a graph comparing temperature and moisture of kibbles made from dough processed by the LME process according to the disclosed subject matter (shown as a solid line) and kibbles from dough processed by a conventional extrusion process (shown as a dashed line). For the LME process, as is evident from FIG. 5, the temperature of the raw materials is about 20° C. when they enter the pre-treatment vessel, and the temperature of the dough is about 30-36° C. when the dough exits the pre-treatment vessel. As shown in FIG. 5 for the LME process and described herein, high pressure steam and mechanical energy are added to the dough in the extruder, and the temperature of the dough increases from about 30-35° C. to about 150° C. just before the dough exits the extruder. In certain embodiments, the temperature of the dough just before the dough exits the extruder is about 144° C. to about 160° C. With reference to FIG. 5, the increasing temperature of the dough for the LME process causes the dough to reach various stages in the extruder beginning with the onset of protein denaturation (about 55° C.), through the onset of starch gelatinization (about 60° C.), and the death of certain bacteria such as Salmonella (about 70-80° C.). Additionally, the increasing temperature of the dough for the LME process causes the dough to reach a glass transition temperature (represented by line Tg) and melting point (represented by line Tm) in the extruder during the LME process (not in a pre-treatment vessel as shown in the conventional example of FIG. 5). Interestingly, for the LME process, in this example, the moisture content of the dough entering the extruder is about 10-11%, and the moisture content of the dough before exiting is about 18%. This moisture content drops to about 12% after exiting the extruder through flash-off.

[0083] As can further be seen from FIG. 5, in this example, the LME process according to the disclosed subject matter reduced the moisture content of the kibble by 10% compared to the conventional process prior to drying. Because the resulting kibble has a lower moisture content than the kibble from the conventional process, the resulting kibble requires less drying, thus significantly reducing the energy requirements of the overall process. In certain embodiments, the LME process uses at least about 30% less energy than the conventional process. In certain embodiments, the kibble can be dried to have a water activity of up to about 0.63 after drying. In some embodiments, the kibble produced by the LME process has a moisture level low enough to achieve a water activity of about 0.63 or less after flash-off without the need for an active drying step (e.g., running the kibble through a dryer).

[0084] In contrast, the conventional process example in FIG. 5 (shown in dashed lines) utilizes water and low pressure steam in the pretreatment vessel for protein denaturation, starch gelation, and bacterial kill. This differs from the LME process, which achieves these thresholds in the extruder. The dough in the conventional process also reaches a glass transition temperature in the pretreatment vessel, as shown in FIG. 5. For the conventional process, at the exit of the pretreatment vessel, the dough has a moisture content of about 24% and reaches a temperature of about 80° C. as it enters the extruder. The dough in the extruder of the conventional process is exposed to high pressure steam and high mechanical energy as shown above, and the dough has a moisture content of about 25% and a temperature of about 125° C. before exiting the extruder. Flash-off of the dough after exiting the extruder reduces the dough to a moisture content of about 22%. As shown in FIG. 5, the LME process offers energy savings compared to the conventional process.

[0085] The operational differences in the extrusion step in the disclosed LME process versus the conventional extrusion process are shown in Table 2 below.

[0086] [Table 2]

[0087] In certain embodiments, conventional extrusion processes use low water flow rates, e.g., up to about 2% water flow rate based on meal flow rate. In certain embodiments, conventional extrusion processes use low steam flow rates, e.g., up to about 4% steam flow rate based on meal flow rate. In certain embodiments, conventional extrusion processes use high steam pressures, e.g., steam pressures of about 80 psi to about 150 psi (about 552 kPa to about 1.03 MPa).

[0088] In certain embodiments, the LME process uses a low water flow rate, e.g., a water flow rate of up to about 2% based on the meal flow rate. In certain embodiments, the LME process uses a high steam flow rate, e.g., a steam flow rate of about 6% to about 10% based on the meal flow rate. In certain embodiments, the LME process uses a high steam pressure, e.g., a steam pressure of about 80 psi to about 150 psi (about 552 kPa to about 1.03 MPa). EXAMPLES

[0089] The following examples are merely illustrative of the presently disclosed subject matter, and they should not be construed as limiting the scope of that subject matter in any way.

[0090] Example 1: LME process Example 1 provides a process for preparing pet food kibbles by the LME process.

[0091] The kibble raw material powders / meals are mixed in a pre-treatment vessel. The composition has an initial moisture content of about 10%. A low flow rate of steam is added, such as about 3% to about 14% of the meal flow rate, at a pressure of about 30 psi (about 207 kPa). A low water flow rate is applied to the mixture, such as about 1% to about 14% of the meal flow rate. This pre-treatment step adds about 3% moisture to the starting materials and, based on the meal flow rate, a dough is formed. The process parameters for the pre-treatment step are shown in Table 3.

[0092] [Table 3]

[0093] The dough enters the extruder through the discharge of the pretreatment device. In an alternative embodiment, where the pretreatment device is located remotely from the extruder, the dough could be fed into the extruder by an intermediate hopper or the like. In this example, the extruder is a 7-head device, with barrel 1 being the inlet barrel, as shown in FIG. 2. The single screw extruder applies high temperature, pressure and high shear to cause gelation of the starch molecules. Steam adds approximately 6.5% moisture to the mixture, based on the meal flow rate. This process heats the ground dough above its melting point, which in turn reduces the viscosity of the material. The material is forced through a forming die, cut into kibbles, and expands due to the temperature and pressure difference between the extruder and the environment. The process parameters for the pretreatment process are shown in Table 4.

[0094] [Table 4]

[0095] The kibbles are then dried to remove moisture from the surface and core of the kibbles. This process can be beneficial for storage stability at ambient conditions and to prevent mold. The process parameters for this drying process are shown in Table 5.

[0096] [Table 5]

[0097] Example 2: Comparative Example Example 2 provides a process for preparing pet food kibbles by a conventional extrusion process.

[0098] The kibble raw material powders / meals are mixed in a pre-treatment vessel. The composition has an initial moisture of about 10%. A high flow rate of steam, e.g., up to about 13% of the meal flow rate, is added at a pressure of about 30 psi (about 207 kPa). A high water flow rate, e.g., up to 22% based on the meal flow rate, is applied to the mixture. This pre-treatment step adds about 10% moisture from the water and an additional 10% moisture from the steam, based on the meal flow rate, to the starting materials to form a dough.

[0099] The dough enters the extruder from the discharge of the pretreatment unit. The extruder is a seven head unit with barrel 1 being the inlet barrel as shown in Figure 2. The single screw extruder applies high temperature, pressure and high shear to continue the gelatinization of the starch molecules. The material is forced through a shaping die, cut into kibbles and expands due to the temperature and pressure difference between the extruder and the environment.

[0100] The kibbles are then dried in a dryer to remove moisture from the surface and core of the kibbles.

[0101] Example 3: Comparison of kibbles produced by LME and conventional processes Example 3 provides various comparative tests that were conducted to compare kibbles produced by the LME process and the conventional process.

[0102] Extrusion mass and energy balance The extrusion mass and energy balance for the processes described in Examples 1 and 2 are shown in Table 6. Example 1 was made by an LME process in accordance with the disclosed subject matter, and Example 2 was made by a conventional process.

[0103] Table 6 provides an illustrative comparison of extrusion mass and energy balance for the disclosed LME process and a conventional extrusion process.

[0104] [Table 6]

[0105] As shown in Table 6, the STE is similar between the conventional extrusion process and the disclosed LME process because the steam system is shifted from the pretreatment step to the extrusion step in the LME process. In addition, the SME is similar (even lower) for the LME process due to the extrusion process as disclosed. This can be explained by the composition having a lower viscosity at higher temperatures in the LME process.

[0106] X-ray computed tomography Pet food kibbles from Example 1 and Example 2 were examined by X-ray tomography as shown in Figures 6A-F, as further described herein. Example 1 was formed by an LME process according to the disclosed subject matter and Example 2 was formed by a conventional process. Each sample was examined using an NSI ImagiX X-Ray Tomography system. The samples were prepared for analysis by fixing the center to a paper thimble using a piece of Styrofoam. The thimble containing the sample was then placed into a 50 ml polypropylene tube. Tomographic slices of the samples were taken in the X, Y, and Z planes as shown in Figures 6A-F, as further described herein. The polypropylene tube was taped to an X-ray tomography holder. ImageJ software was used to measure air entrapment. The results of the air entrapment analysis are summarized in Table 7.

[0107] [Table 7]

[0108] The results from Table 7 show that the kibbles from Example 1 had an air inclusion of about 32% while the kibbles from Example 2 had an air inclusion of about 40%.

[0109] Figures 6A-F further illustrate the difference in air inclusion between the two kibbles by showing cross-sectional slices. Air inclusion is indicated by the white areas. The slices shown in Figures 6A-C, which correspond to the kibble of Example 1, have fewer white areas and therefore are shown to have less air inclusion than the comparative kibble shown in Figures 6D-F. However, the air bubbles in the kibble of Example 1 are smaller than those of Example 2. In addition, the air bubbles of the kibble of Example 1 are elongated in shape, whereas the air bubbles of Example 2 are spherical.

[0110] In addition to the various embodiments depicted and claimed, the disclosed subject matter is directed to other embodiments having other combinations of the features disclosed and claimed herein. Thus, the specific features presented herein can be combined with each other in other manners within the scope of the disclosed subject matter such that the disclosed subject matter includes any suitable combination of the features disclosed herein. The foregoing description of specific embodiments of the disclosed subject matter has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosed subject matter to those disclosed embodiments.

[0111] It will be apparent to those skilled in the art that various modifications and variations can be made in the systems and methods of the disclosed subject matter without departing from the spirit or scope of the disclosed subject matter. Thus, it is intended that the disclosed subject matter cover modifications and variations that come within the scope of the appended claims and their equivalents.

[0112] Various patents and patent applications are cited herein, the contents of which are incorporated herein by reference in their entireties.

[0113] Preferred embodiments of the present invention will be described below in detail.

[0114] EMBODIMENT 1 1. A method for producing a dry food, comprising: (a) supplying a dry food ingredient to a pretreatment vessel at a first flow rate; (b) pre-treating the ingredients in the pre-treatment vessel to form a dough; (c) passing the dough, having a moisture content of about 4% to about 10%, through an inlet of an extruder; and (d)(i) applying thermal energy to the substrate; (ii) applying mechanical energy to the fabric; extruding the dough through a die plate of the extruder to form a kibble; and The method, wherein the ratio of said thermal energy to said mechanical energy can range from at least about 2.0 to about 4.0.

[0115] EMBODIMENT 2 2. The method of claim 1, wherein the kibble has a moisture content of about 8% to about 13.5% upon exiting the extruder.

[0116] EMBODIMENT 3 (e) drying the kibble; 2. The method of embodiment 1, further comprising:

[0117] EMBODIMENT 4 4. The method of embodiment 3, wherein the kibble is dried to have a water activity of up to about 0.63.

[0118] EMBODIMENT 5 2. The method of embodiment 1, wherein the moisture flash-off after the dough passes through the die is from about 4.0% to about 7.0%.

[0119] EMBODIMENT 6 2. The method of claim 1, wherein applying thermal energy to the dough comprises using steam.

[0120] EMBODIMENT 7 7. The method of embodiment 6, wherein the flow rate of the steam is about 6.0% to about 10.0% of the first flow rate.

[0121] EMBODIMENT 8 7. The method of embodiment 6, wherein the pressure of the steam is from about 80 psi to about 150 psi (about 552 kPa to about 1.03 MPa).

[0122] EMBODIMENT 9 2. The method of embodiment 1, wherein the thermal energy and the mechanical energy heat the dough above its melting point, thereby reducing the viscosity of the dough.

[0123] EMBODIMENT 10 2. The method of embodiment 1, wherein the first flow rate is from about 0.8 to about 12 tons per hour.

[0124] EMBODIMENT 11 2. The method of embodiment 1, wherein the pre-treating step comprises adding steam at a flow rate of up to 3% of the steam based on the first flow rate.

[0125] EMBODIMENT 12 12. The method of embodiment 11, wherein the flow rate of the steam is 0 tons per hour.

[0126] EMBODIMENT 13 2. The method of embodiment 1, wherein the pretreatment step further comprises adding water at a flow rate up to 4% of the first flow rate.

[0127] EMBODIMENT 14 14. The method of embodiment 13, wherein the water flow rate is 0% of the first flow rate.

[0128] EMBODIMENT 15 2. The method of claim 1, wherein extruding the dough comprises increasing the temperature in the extruder from 30-36° C. to 144-160° C. and increasing the moisture content from 10-12% moisture to 16-18% moisture.

[0129] EMBODIMENT 16 2. The method of claim 1, wherein the moisture content of the dough in the extruder is from about 16% to about 18%.

[0130] EMBODIMENT 17 2. The method of embodiment 1, wherein the extruder is one of a single screw extruder or a twin screw extruder.

[0131] EMBODIMENT 18 2. The method of embodiment 1, wherein the kibble is not dried in a dryer after the dough extruding step.

[0132] EMBODIMENT 19 2. The method of embodiment 1, wherein the dough comprises about 10% to about 80% carbohydrate, about 5% to about 35% lipid, and about 5% to about 60% protein.

[0133] EMBODIMENT 20 20. The method of embodiment 19, wherein the protein comprises an animal protein.

[0134] EMBODIMENT 21 A method for producing a dry food, comprising: (a) providing a dough having a moisture content of about 4% to about 10%; (b) placing the dough into an extruder at a first flow rate; (c) processing the dough in the extruder, (i) applying thermal energy to the fabric; (ii) applying mechanical energy to the fabric; Including, a ratio of said thermal energy to said mechanical energy is at least about 4; and (d) extruding the dough from the extruder through a die plate to form a kibble; The method comprising:

[0135] EMBODIMENT 22 22. The method of claim 21, wherein the kibble has a moisture content of about 8% to about 13.5% upon exiting the extruder.

[0136] EMBODIMENT 23 22. The method of embodiment 21, wherein the thermal energy and the mechanical energy heat the dough above the melting point of the dough, thereby reducing the viscosity of the dough.

[0137] EMBODIMENT 24 22. The method of embodiment 21, wherein the kibble is not dried in a dryer after the dough extruding step.

[0138] EMBODIMENT 25 22. The method of embodiment 21, wherein the dough comprises about 10% to about 80% carbohydrate, about 5% to about 35% lipid, and about 5% to about 60% protein.

[0139] EMBODIMENT 26 26. The method of embodiment 25, wherein the protein comprises an animal protein.

[0140] EMBODIMENT 27 1. A method for producing a dry food, comprising: (a) supplying a dry food ingredient to a pretreatment vessel at a first flow rate; (b) pre-treating the ingredients in the pre-treatment vessel to form a dough; (c) passing the dough, having a moisture content of about 4% to about 10%, through an inlet of an extruder; and (d)(i) applying thermal energy to the substrate; (ii) applying mechanical energy to the fabric; extruding the dough through a die plate of the extruder to form a kibble; and The method, wherein the ratio of said thermal energy to said mechanical energy can range from at least about 2.0 to about 4.0.

[0141] EMBODIMENT 28 28. The method of embodiment 27, wherein the kibble has a moisture content of about 8% to about 13.5% upon exiting the extruder.

[0142] EMBODIMENT 29 (e) drying the kibble; 28. The method of embodiment 27, further comprising:

[0143] EMBODIMENT 30 The method of embodiment 29, wherein the kibble is dried until it has a water activity of about 0.63.

[0144] EMBODIMENT 31 28. The method of embodiment 27, wherein the moisture flash-off after the dough passes through the die is from about 4.0% to about 7.0%.

[0145] EMBODIMENT 32 28. The method of embodiment 27, wherein applying thermal energy to the dough comprises using steam.

[0146] EMBODIMENT 33 33. The method of embodiment 32, wherein the flow rate of the steam is about 6.0% to about 10.0% of the first flow rate.

[0147] EMBODIMENT 34 33. The method of embodiment 32, wherein the steam has a pressure of about 80 psi to about 150 psi (about 552 kPa to about 1.03 MPa).

[0148] EMBODIMENT 35 28. The method of embodiment 27, wherein the thermal energy and the mechanical energy heat the dough above its melting point, thereby reducing the viscosity of the dough.

[0149] EMBODIMENT 36 28. The method of embodiment 27, wherein the first flow rate is from about 0.8 to about 12 tons per hour.

[0150] EMBODIMENT 37 28. The method of embodiment 27, wherein the pre-treating step comprises adding steam at a flow rate of up to 3% of the steam based on the first flow rate.

[0151] EMBODIMENT 38 38. The method of embodiment 37, wherein the flow rate of the steam is 0 tons per hour.

[0152] EMBODIMENT 39 28. The method of embodiment 27, wherein said pretreatment step further comprises adding water at a flow rate up to 4% of said first flow rate.

[0153] EMBODIMENT 40 40. The method of embodiment 39, wherein the water flow rate is 0% of the first flow rate.

[0154] EMBODIMENT 41 28. The method of embodiment 27, wherein extruding the dough comprises increasing the temperature in the extruder from 30-36°C to 144-160°C and increasing the moisture content from 10-12% moisture to 16-18% moisture.

[0155] EMBODIMENT 42 28. The method of embodiment 27, wherein the moisture content of the dough in the extruder is from about 16% to about 18%.

[0156] EMBODIMENT 43 28. The process of embodiment 27, wherein the extruder is one of a single screw extruder or a twin screw extruder.

[0157] EMBODIMENT 44 28. The method of embodiment 27, wherein after the dough extruding step, the kibble is air dried.

[0158] EMBODIMENT 45 28. The method of embodiment 27, wherein the kibble is not dried in a dryer after the dough extruding step.

[0159] EMBODIMENT 46 28. The method of embodiment 27, wherein the dough comprises about 10% to about 80% carbohydrate, about 5% to about 35% lipid, and about 5% to about 60% protein.

[0160] EMBODIMENT 47 47. The method of embodiment 46, wherein the protein comprises an animal protein.

[0161] EMBODIMENT 48 A method for producing a dry food, comprising: (a) providing a dough having a moisture content of about 4% to about 10%; (b) placing the dough into an extruder at a first flow rate; (c) processing the dough in the extruder, (i) applying thermal energy to the fabric; (ii) applying mechanical energy to the fabric; Including, a ratio of said thermal energy to said mechanical energy is at least about 4; and (d) extruding the dough from the extruder through a die plate to form a kibble; The method comprising:

[0162] EMBODIMENT 49 49. The method of embodiment 48, wherein the kibble has a moisture content of about 8% to about 13.5% upon exiting the extruder.

[0163] EMBODIMENT 50 49. The method of embodiment 48, wherein said thermal energy and said mechanical energy heat said dough above its melting point, thereby reducing the viscosity of said dough.

[0164] EMBODIMENT 51 49. The method of embodiment 48, wherein the kibble is not dried in a dryer after the dough extruding step.

[0165] EMBODIMENT 52 49. The method of embodiment 48, wherein the dough comprises about 10% to about 80% carbohydrate, about 5% to about 35% lipid, and about 5% to about 60% protein.

[0166] EMBODIMENT 53 53. The method of embodiment 52, wherein the protein comprises an animal protein. [Explanation of symbols]

[0167] 101 Pretreatment vessel inlet 103 Pretreatment Container 105 Pretreatment vessel outlet 107 Extruder 109 Extruder outlet 111 Die 113 Dryer

Claims

[Claim 1] 1. A method for producing a dry food, comprising: (a) supplying dry food ingredients to a pretreatment vessel at a first flow rate; (b) pre-treating the ingredients in the pre-treatment vessel to form a dough; (c) passing the dough, having a moisture content of about 4% to about 10%, through an extruder inlet; and (d)(i) applying thermal energy to the substrate; (ii) applying mechanical energy to the fabric; extruding the dough through a die plate of the extruder to form a kibble; and The method, wherein the ratio of the thermal energy to the mechanical energy may range from at least about 2.0 to about 4.0.

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