Technical Field

[0001] The present disclosure relates to a system for, and a method of manufacturing pet food.

Background

[0002] Pet food is progressively becoming humanised. The term "pet parents" is replacing the term "pet owners". In addition to demanding high quality nutrients, pet parents are also demanding that their pet foods be visually appealing to them. Therefore presentation of pet food is becoming a factor when purchasing pet food.

[0003] The wet pet food sector (cans, pouches, chilled, frozen, etc.) has responded to the presentation demand by designing gourmet style offerings. Casserole style pet foods can be manufactured by adding meat chunks, vegetable pieces, or the like, to a base recipe. The finished product's presentation almost resembles that of a human meal.

[0004] Due to manufacturing constraints, the dry pet food sector lags behind the wet pet food sector in this respect. Extrusion cooking is the dominant manufacturing process in the dry pet food sector. This is due to low operational costs and high volume throughputs that extrusion processing offers. The resulting product is a homogeneous and a partially expanded kibble. To add variety and in order to make an extruded kibble look more appealing, some dry pet food manufacturers employ colour and shape variation techniques. For example, a green coloured kibble may represent vegetables or a fish shaped kibble may denote a fish product. These differentiation attempts by the manufacturers are sometimes seen as a gimmick and can be negatively perceived by the customer.

[0005] The inability of dry pet food manufacturers to showcase certain components of a recipe in a form that closely resembles the component's original form remains a challenge.

[0006] Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each claim of this application.

Summary

[0007] Displaying a piece of, say, carrot is visual evidence of its presence in the product and is more appealing to the customer. However, dehydrated foods such as vegetables, where most of the nutrients are almost intact, can undergo partial degradation during the

manufacturing process, in particular during the milling process. Most extruded pet foods are milled at between 0.5mm and 2mm prior to extrusion. The mechanical and thermal energies generated during the milling process reduce the efficacy of micronutrients such as vitamins. As described herein, if on the other hand a dehydrated ingredient is made to by-pass the milling process, and an appropriate design for the extrusion system is used, then the sensitive components of the ingredients may be preserved.

[0008] Accordingly, in one embodiment there is provided a method of manufacturing a dry pet food, the method comprising: providing a meal mix; preconditioning the meal mix with a liquid to create a wet mix; introducing the wet mix into an extruder; introducing dried food particles to the extruder such that the dried food particles retain their integrity within a subsequently formed extrudate; extruding contents of the extruder as the extrudate; and cutting the extrudate to create kibble, wherein the kibble contains discrete dried food particles which are discernible.

[0009] As used herein, the dried food particles retaining their integrity broadly means that the kibble does not disintegrate or crumble, and that the dried food particles generally remain in the kibble, for example when the kibble is cut at a cutting assembly, or thereafter.

[0010] Introducing the dried food particles may occur during the preconditioning so that the dried food particles retain their integrity within the extrudate.

[0011] Introducing the dried food particles may occur during the extruding, and then introducing the dried food particles may further comprise soaking the dried food particles prior to the adding so that the dried food particles retain their integrity within the extrudate. The soaking may be in an aqueous solution for between about 2 and 12 minutes. [0012] The dried food particles may be hydrophilic. Each kibble may comprise up to about 60% discernible dried food particles. The dried food particles may be larger than particles of the meal mix.

[0013] A residence time in in a preconditioner used for preconditioning may be between about 10 and 60 seconds. The extruding may occur within a temperature range of about 90 - 200°C. A moisture content of the dried food particles when introduced to the extruder is between about 10 and 80%.

[0014] The method may further comprise drying and coating the kibble.

[0015] In another embodiment there is provided a dry pet food manufactured using the method as described above.

[0016] In another embodiment there is provided a system for manufacturing a dry pet food, the system comprising: an extruding system that receives a meal mix and dried food particles, the extruding system comprising: a preconditioner that preconditions the meal mix; and an extruding unit that extrudes an extrudate, wherein the extrudate is formed from the meal mix and the dried food particles; a dried food particle providing unit that provides dried food particles to the extruding system such that the dried food particles retain their integrity within the extrudate; and a cutting assembly that receives and cuts the extrudate from the extruding unit into kibble, wherein the kibble contains discrete dried food particles which are discernible.

[0017] The dried food particle providing unit may comprise a conveying assembly for conveying the dried food particles to the preconditioner, and wherein the preconditioner is configured to receive and precondition the dried food particles together with the meal mix so that the dried food particles retain their integrity within the extrudate.

[0018] The dried food particle providing unit may comprise: a vessel for soaking the dried food particles so that the dried food particles retain their integrity within the extrudate; and a pump for delivering the soaked food particles to the extruding unit. The dried food particle providing unit may further comprise an agitator for agitating the soaking food particles in the vessel. [0019] Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

Brief Description of Drawings

[0020] Embodiments of the disclosure are now described by way of example with reference to the accompanying drawings in which: -

[0021] Fig. 1 schematically illustrates an embodiment of a system for manufacturing a dry pet food;

[0022] Fig. 2 is a flow chart of an embodiment of a method of manufacturing a dry pet food; and

[0023] Figure 3 is a flow chart of another embodiment of a method of manufacturing a dry pet food.

[0024] In the drawings, like reference numerals designate similar parts. Description of Embodiments

[0025] Fig. 1 of the drawings shows a schematic representation of a system 100 for manufacturing a dry pet food. The system 100 provides a meal mix from a milling assembly 110, and has a preconditioner 132 that preconditions the meal mix with a liquid to create a wet mix. The wet mix is introduced to an extruding unit 134 (which may be a conventional extruder). Dried food particles are introduced to the extruder such that the dried food particles retain their integrity within a subsequently formed extrudate . The extruding unit 134 extrudes contents of the extruder as the extrudate, and a cutter assembly 140 that cuts the extrudate to create kibble. The kibble contains discrete dried food particles which are discernible.

[0026] Generally, three types of dry ingredients are processed in the milling assembly 110: wholegrain cereals 114, animal meals 116, and minor ingredients 118 such as vitamins and minerals and other minor inclusions. Once the mill ingredients are combined the whole mixture undergoes a grinding process in a hammer mill 112 resulting in the formation of a homogeneous mix, i.e. the meal mix. The finer the mill screen size, the better quality finished product is expected. However as the screen size is reduced, the mechanical shear strength and temperature of the system are increased, and this may negatively affect sensitive ingredients so that, for example, vitamins may lose some of their efficacy.

[0027] A conveying assembly 120 that has a feed hopper 122 (for example a screw feeder) and a conveyor 124 conveys the meal mix to an extrusion assembly 130. The extrusion assembly 130 includes the preconditioner 132 and the extruding unit 134, as well as one or more liquid containers 136 that provide liquids and/or slurries directly into the extruding unit 134.

[0028] The meal mix is continuously metered into the preconditioner 132, that typically is located above the extruding unit 134. The preconditioner 132 may be a conventional preconditioner that preconditions the meal mix before the meal mix enters the extruding unit 134. Preconditioning typically includes soaking the meal mix in liquids such as water, colour solutions, oils/fats, animal digests, and/or steam, thereby creating a wet mix.

[0029] The extruding unit 134 may be a conventional extruder (e.g. a single screw extruder such as a Wenger 185 model) that includes a heated barrel in which the wet mix is cooked under pressure and at a temperature that ranges between about 90 and 200°C, for example between about 130 andl80°C. The wet mix from the preconditioner 132 enters the extruding unit 134 where a screw inside the barrel conveys the mix along the barrel to a discharge end 138. Residence time in the extruder may be up to about a minute. The discharge end 138 of the extruding unit 134 has a die face with one or more apertures that determine the shape of the extrudate that leaves the extruding unit 134.

[0030] The extrudate leaving the extruding unit 134 expands due to the release of steam and forms a shape as determined by the die design. A cutting motor 146 equipped with one or more blades 142 slices the extrudate into individual kibbles that are sucked up from a cutter 144 by a pneumatic assembly 150. The moisture content of these cut kibbles may range between 10 and 30% moisture, and is typically around 20 to 25% moisture (measured by weight). The pneumatic assembly 150 provides the kibble to a drying unit 160. The drying unit includes a conventional dryer 162 as typically used in the production of dry pet food. The dried kibble exiting the drying unit 160 is typically at a temperature between about 65 and 75°C , and typically has a moisture content below about 15%, for example below 10%.

[0031] In some embodiments the extruder 130 and cutting assembly 140 are provided in the same machine, for example a Wenger extruder with a rotary blade cutter.

[0032] In some embodiments, the dried kibble may then pass through a coating assembly 170. The dried kibbles are metered into a coating chamber 172 to which dry and/or liquid palatants 174 are added. The coated kibbles drop through a bottom opening of the coating chamber 172 into a cooling chamber 180. This combination kibble, a combination of conventional kibble and dried food particles, is then the finished product ready for packaging.

[0033] To manufacture kibble that includes dried food particles, the system 100 includes a dried food particle providing unit. The structure of the dried food particle providing unit depends on the manufacturing process used to add the dried food particles, as described below. In one embodiment, the dried food particle providing unit includes a conveying assembly 190 as shown in Fig. 1 of the drawings. In another embodiment, the dried food particle providing unit includes a vessel 131 for soaking the dried food particles, and a pump 135 for pumping the soaked particles to the extruding unit 134. In some embodiments, a combination of the two methods may be used, and the system 100 may include both types of dried food particle providing units. In still further embodiments, a combination of these two methods together with any other additional method known to those in the art having the benefit of this disclosure may be used.

Direct dry feeding process 200

[0034] In one embodiment, as illustrated diagrammatically in Fig. 2 of the drawings, after the meal mix is provided at 202, at 204 dried food particles are added directly to the premix stream fed to the preconditioner 132 so that both the meal mix and the dried food particles are subjected to a combined preconditioning process 206. Depending on the process and the hydrophilic properties of the particles, addition of water and steam to the preconditioner 132, as is the common process in pet food extrusion, may provide adequate hydration and softening of the particles resulting in infusion into the extrudate matrix without adversely affecting the clean cutting of the extrudate. For carrots, for example, the following example levels will achieve an appropriate softening of the dried food particles:

Steam levels: steam injection between about 5 and 12%, for example about 8%;

Water levels: water levels between about 5 and 20%, for example about 11%.

[0035] In an example implementation using carrots for the dried food particles, dry carrots containing 10% moisture were brought up to between about 60% and 70% moisture to cause infusion and be soft enough to cut yet not too soft to break up. As different types of food will have different hydrophilic properties, the moisture would be controlled based on the reduction in particle size of the particles following extrusion (i.e. comparing the average particle size of the conditioned ingredient prior to injection into the extruder to the average particle size of particles in the extrudate). Should the reduction in particle size of the ingredient in the extrudate exceed a selected threshold, for example about 10%, then this would be an indication that the dried food particles are over-conditioned. To control loss of particle size in the extrudate (i.e. to reduce degradation), parameters such as water and steam are adjusted.

[0036] A preconditioned mix that includes both the meal mix and the dried food particles (which would now have a moisture content of between 10 and 80%) is then extruded and cut at 208, after which drying and, optionally, coating occur at 210. This process 200 is referred to as direct dry feeding, as the dried food particles are fed directly into the preconditioner. In one embodiment this method uses a dried food conveying assembly 190 that includes a screw feeder 192 that conveys the dried food particles from a dried food particle container 194 via a hopper 196, delivering the ingredients to the preconditioner 132. In another embodiment, the dried food particles are held in a holding tank, and pumped to the preconditioner 132 using, for example, a 1,5 inch mono pump with a capacity of 1,5 tonnes/hour.

[0037] In the preconditioner 132, steam, water and other liquids, through process adjustments, can be made to condition the dry nutrients prior to entering the extruder barrel. The preconditioner residence time, steam levels, and/or water levels may be adjusted in order to control the particle hydration rate, thereby helping to ensure that the particles have sufficient structural flexibility to permit proper mixing and infusion within the extrudate matrix. [0038] The direct dry feeding method may be suitable when the system 100 includes a preconditioner 132 with operational flexibility so that the residence time can be adjusted to accommodate the addition of the dried food particles. The residence time of the dried food particles in the preconditioner may vary between about 10 to 60 seconds, for example between 10 and 20 seconds, between 20 and 30 seconds, between 30 and 40 seconds, between 40 and 50 seconds, or between 50 and 60 seconds. The direct dry feeding process may also be appropriate for dried food particles that are of a type and size that can achieve the required structural flexibility during the preconditioning step.

Pre-soaked process 300

[0039] In another embodiment, as illustrated diagrammatically in Fig. 3 of the drawings, the process 300 is referred to as the pre-soaked process. Adding the meal mix at 202 is the same as in process 200 illustrated in Fig. 2. Similarly, the extruding and cutting at 208, and the drying and optional coating at 210, are comparable to the same steps as in process 200.

However, in process 300, preconditioning at 306 only includes the meal mix and not the dried food particles. Instead, the dried food particles are added at 302, and at 304, the dried food particles are soaked in the vessel 131 to ensure that the particles have sufficient structural flexibility to permit proper mixing and infusion within the extrudate matrix. Typically, the dried food particles are soaked in a medium that is already part of the extrusion process, for example, liquid animal digest (a palatant). In some embodiments, the dried food particles may be soaked in a different liquid, for example in water.

[0040] In this embodiment, some of the objectives of the soaking step 302 include

(1) soaking the particles to improve infusion and cutting, as well as (2) delivery of the particles to the extruder.

[0041] (1) Soaking: The dried particles are allowed to soak in liquid animal digest. The digest can be from any animal and typically adjusted to a pH of between 2 and 3 and with a moisture content of about 60% to 80%. The mixture is mixed in the vessel 131 equipped with an agitator such as a mixing paddle 133. Water is added to adjust the viscosity to suit the delivery pump 135 which is positioned between the vessel 131 and the extruding unit 134. In an example embodiment, dried carrots (120kg) were mixed with animal digest (180kg) and water (250kg) to produce a viscous mixture with a bulk density of between 900g/l to 930g/l. [0042] Due to the hydrophilic nature of the particles adequate time is required for the particles to absorb moisture and reach equilibrium with the medium. The time will depend on the mixing efficiency of the vessel and the hydrophilic nature of the particles, and may be between about 5 and 15 minutes. In the abovementioned example, soaking lasted

approximately 10 minutes and the viscosity of the mixture appeared stabilised (i.e. not getting thicker). The moisture content of the particles following the soaking step 302 may be as high as around 80%.

[0043] (2) Delivery: The design of the delivery system and the pumping capability of the pump that provides the mixture to the extruding unit 134 dictate the viscosity of the mixture. Preferably, the mixture needs to possess adequate viscosity to ensure suspension of the particles, for example a viscosity between about 3000 and 3500cps. This will help to minimise separation during pumping. The abovementioned example mixture was shown to possess the correct consistency and viscosity to enable the pump to deliver the mixture while maintaining adequate distribution of particles within the mixture. An example of a pump that can be used to transfer the mixture to the extruding unit 134 is a 2 inch pneumatic diaphragm pump capable of delivering 300kg/hr.

[0044] The pre-soaked method may be suitable when the dried food particles are larger than required, and an optional mincing step is included in the soaking step (as is common with the addition of fresh meat during the manufacture of pet food). The mincing step may help to ensure mixture consistency through the creation of uniform particle sizes. In environments with elevated temperature and humidity, the pre-soaked method may provide some advantages over the direct dry feeding method, because handling hydrophilic particles in a hot and humid production environment may be problematic as the flow properties will be affected and the particles may become sticky. For carrot particles, for example, temperatures that exceed about 35°C and a humidity exceeding about 85% may result in the particles adhering together and adversely affecting the flow in the hopper 196, so that a pre-soaked process may be preferably under those circumstances.

[0045] For both these methods, the dried food particles are treated to ensure that the particles have sufficient structural flexibility. Over-conditioning or excessive mechanical input can cause particle size reduction. The optimum softening of the particles ensures not only a consistent extrudate, it also ensures that the extrudate is cut cleanly to achieve the desired final kibble shape. In addition, any structural damage to the dried food particles is minimised by avoiding chemical destructuring (e.g. caused by low pH animal digests), extended soaking times that weaken the structure, and/or mechanical damage (e.g. due to mechanical agitation, and/or as a result of the extrusion process). This means that the kibble with dried food inclusion is more likely to retain its integrity.

[0046] Typical ingredients used for the dried food particles are dried or partially dried hydrophilic ingredients with particle size greater than the mill screen size. Examples include but are not limited to dried vegetables such as carrots, dried meats, and dried cereals.

Hydrophobic ingredients such as oil seeds may resist infusion resulting in separation from the matrix. Particle sizes are selected to be compatible with kibble sizes, e.g. up to about 50% of the kibble size. Particles are random shapes, and may vary between about 0,5- 15mm in length/width, and about 0,3- lmm in thickness. A length and/or width between about 1 and 4mm, and a thickness of about lmm, may provide kibble with little loss of particles during the manufacturing process.

[0047] The methods described herein advantageously result in a dry pet food kibble that includes discrete and discernible dried food particles, for example visible pieces of carrot. Because the dried food particles are added after the milling process, the milling process does not affect the nutritional characteristics of the dried food particles. It is advantageous that the individual kibbles themselves include the dried food particles (as is the case when the integrity of the combination kibble is retained), as opposed to, for example, food particles that are mixed in with kibble when packaged. This is because animals that prefer either the kibble or the included dried food would not be able to eat around either as easily, but would instead be more likely to eat the kibble as a whole with the dried food particles included.

[0048] The methods described herein advantageously control the moisture content of the dried food particles so that the dried food particles retain their integrity within the extrudate. When the dried food particles that have been soaked or otherwise controlled to achieve the desired moisture content, the moisture content may be between 10 and 80%. The moisture content depends on the hydrophilic and structural strength of the ingredient for which the moisture content is adjusted. For example, for carrots the moisture content may be between 70 and 75%. Other inclusions (e.g. cranberries) are soft at a moisture content of 10% hence will not need soaking/preconditioning as much. [0049] Advantageously both methods described herein complement existing pet food extrusion processes with minimal disruption to extruder running conditions; once the mixture enters the extruder, it is possible to run the equipment in the same way as one would without the addition of dried food particles.

[0050] It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the above-described embodiments, without departing from the broad general scope of the present disclosure. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.