FIELD OF THE INVENTION

The present invention relates to a method of producing a food product. More particularly, the invention relates to a method of producing a food product by extrusion and colloid milling from four-legged livestock including undervalued parts of the livestock.

BACKGROUND OF THE INVENTION

Extrusion is widely used in the manufacture of various food products. Broadly, extrusion is a continuous process which uses an extruder having one or two screws. The extruder provides transport, compression, mixing, cooking, shearing, heating, cooling and shaping of raw material to final products.

Sustainable food production necessitates use of methods in which food raw materials can be effectively used in their entirely. In the production of a meat product, it means that undervalued parts of an animal, such as bones and tendons, are used in the food production. There is literature available which discusses use of undervalued parts of poultry in various food products.

US 5853790 discloses a method for commercial preparation of poultry meat for human consumption by using extrusion. The method effectively maximizes the use of poultry meat from an entire poultry carcass, and enhances the value of all of the meat from a bird carcass. The meat portions of whole birds are deboned in the method.

BRIEF DESCRIPTION OF THE INVENTION

It has now been found that a food product for human consumption with satisfactory organoleptic properties, such appealing taste and good mouthfeel, comprising a four-legged livestock meat material and a plant-based food material, may be produced from undervalued parts of four-legged livestock meat material containing bones, and optionally additionally, e.g., hard tissues, tendons, skin, blood, plasma and/or cartilages. Four-legged livestock meat from an entire fourlegged livestock carcass may be effectively used and converted to a valuable food product with consumer acceptable organoleptic properties. The satisfactory organoleptic properties of the food product are provided by grinding an extruded food mass containing four-legged livestock meat material and a plant-based food material using a colloid mill. In an aspect, the present invention provides a method for producing a food product from a four-legged livestock meat material and a plant-based food material. The method effectively utilizes all meat from livestock carcass including bones, and optionally hard tissues, tendons, skin, blood, plasma and/or cartilages.

The term "four-legged livestock" is used interchangeable with "livestock". In the present invention, "four-legged livestock" includes pig, cattle, sheep, goat and horse, without limiting thereto. In an embodiment, the livestock is a pig.

The invention thus provides a sustainable method in which livestock may be effectively used in the production of a ready-to-consume food product for human consumption providing environmental benefits. Additionally, the food product can be used as an ingredient or extender and combined with other food materials to produce a wide variety of food compositions.

The food product produced by the method of the invention is also suitable as an animal feed.

The invention also provides a method in which undervalued parts of a livestock or of low hygienic quality may be used providing economic benefits in that the product can be offered at a lower cost.

The invention further provides a method of producing a food product with an increased nutritional value.

Further, the invention provides a method of producing a food product which enables reduction of global meat production providing environmental benefits.

The invention also provides a method of producing a food product with high microbiological quality and substantially eliminated Salmonella bacteria.

In another aspect, the invention provide a food composition comprising a food product produced by the method of the invention.

In an aspect, the invention provides use of a food product produced by the method of the invention in the food composition.

In further aspect, the invention provides an apparatus comprising means for implementing the method of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 generally illustrates a process flow diagram of an embodiment of the method of the invention.

Figure 2 illustrates an embodiment of an apparatus of the invention. DETAILED DESCRIPTION OF THE INVENTION

In an aspect, the present invention provides a method of producing a food product comprising a four-legged livestock meat material and a plant-based food material, comprising the steps of:

- providing a gutted four-legged livestock meat material comprising bones,

- providing a plant-based food material,

- grinding the gutted four-legged livestock meat material with a meat grinder having a particle size of at most 5 mm to provide a ground four-legged livestock mass,

- adding the plant-based food material to the ground four-legged livestock mass to provide a mixture of the ground four-legged livestock mass and the plant-based food material,

- subjecting the mixture of the ground four-legged livestock mass and the plant-based food material to a wet extrusion to provide an extruded mass,

- mincing the extruded mass with a colloid mill to provide a minced extruded mass as a food product.

Figure 1 illustrates an embodiment of the method of the invention. The dotted line illustrates optional method steps. The method may include further optional method steps not shown in the figure.

The gutted livestock meat material comprises bones. The content of the bones in the gutted livestock meat material may vary in the range of about 10 wt- % to about 60 wt-%. Use of increased amount of bones in the gutted livestock meat material beneficially results in an increased amount of calcium in the final food product.

In an embodiment, the gutted livestock meat material further contains hard tissues, tendons, skin, blood, plasma and/or cartilages, and can be provided by legs, necks, skin and/or heads of livestock.

The gutted livestock meat material is ground to crush bones and other hard tissues and to provide a ground livestock mass which is in a suitable form to be fed to a wet extrusion. The grinding is carried out with a meat grinder having a hole size of at most 5 mm. In an embodiment, the meat grinder has a hole size in the range of about 2 mm up to 5 mm. If the gutted livestock meat material contains large pieces of bones, the large pieces need to be crushed with a bone crusher to smaller pieces before grinding.

In an embodiment, the ground livestock mass is subjected to a colloid mill to further crush bone particles to smaller pieces. Generally, "colloid mill" is a machine which has a high-speed rotor and a stator providing superfine grinding results along with simultaneous emulsifying, homogenizing, and dispersing. The rotor pushes the material into small gaps between the rotor and stator causing intense mechanical shear. In the present invention, colloid milling provides a homogenous, ultra-fine bone particles of bone-containing livestock mass and beneficially enhances softening of bone particles in the subsequent wet extrusion. In an embodiment, colloid milling of the ground livestock mass provides bone particles having an average particle size of at most 500 gm.

In an embodiment, the method of the invention involves two colloid milling steps, i.e., colloid milling of the ground four-legged livestock mass and colloid milling of the extruded mass.

After grinding with a meat grinder, and optional further grinding with a colloid mill, the obtained ground livestock mass is mixed with a plant-based food material. Any food-grade plant-based food material is suitable to be added to the ground livestock mass. The plant-based food material includes, but is not limited to, a food material which is rich in protein, carbohydrate and/or fibre. In an embodiment, the plant-based food material comprises soy protein, pea protein, cereal proteins, broad bean protein, maize protein, potato starch, maize starch, or any mixture thereof. In an embodiment, the plant-based food material is provided as finely ground powder. In an embodiment, the plant-based food material is thoroughly mixed with the ground livestock mass to provide a uniform mixture of the ground four-legged livestock mass and the plant-based food material.

The plant-based food material is added to the ground livestock mass in an amount so as to provide a food product containing about 5 wt-% to about 50 wt- % of the plant-based food material. In an embodiment, the food product contains about 10 wt-% to about 30 wt-% of the plant-based food material.

In an embodiment, the food product contains about 50 wt-% to about 95 wt-% of the gutted livestock meat material. In another embodiment, the food product contains about 70 wt-% to about 90 wt-% of the gutted livestock meat material.

In an embodiment, the mixture of the ground four-legged livestock mass and the plant-based food material is cooled to a temperature of about -25°C to about 6°C. Cooling of the mixture improves microbiological quality of the mixture before feeding it to the extrusion process.

The mixture of the ground four-legged livestock mass and the plant- based food material is subjected to a wet extrusion to provide an extruded mass. In context of the present invention, the term "wet extrusion" means that the mixture of the ground four-legged livestock mass and the plant-based food material to be extruded has a moisture content of at least 30%. In an embodiment, the moisture content of the mixture of the ground four-legged livestock mass and the plantbased food material is in the range of 30% to about 70%. If the moisture content is lower than 30%, it may be difficult to carry out the extrusion process, since the mixture in the extruder is dry. On the other hand, if the moisture content is higher than 70%, liquid is undesirably separated from the dry matter of the mixture.

The wet extrusion may be carried out with a single-screw or twin-screw extruder. Shearing and tearing combined with moisture in the extrusion step causes softening of the hard tissues of livestock and provides a unique structure to the final food product.

In an embodiment, the wet extrusion is performed at a temperature of about 100°C to about 400°C. Depending on the extruder used in the method, the extruder has to contain at least one heating segment where the temperature is at least 100°C. In addition, there may be further heating segments where the extrusion may be performed below 100°C, e.g., at 70°C. In an embodiment of the invention, an extruder is used which contains several heating segments each operated at a different temperature. In an embodiment, the temperature of the heating segments increases when the mass moves forward in the extruder.

The duration of the wet extrusion is dependent on the apparatus construction and settings.

In an embodiment, the wet extrusion is performed using about 100 rpm to about 1000 rpm speed. In another embodiment, the wet extrusion is performed using about 170 rpm to about 600 rpm speed. In an embodiment, about 170 rpm is employed in the wet extrusion.

In an embodiment, the wet extrusion of the ground livestock mass provides an extruded mass having a temperature of at least 100°C.

In an embodiment, the extruded mass is cooled to a temperature of about +60°C to about -30°C. In an embodiment, cooling of the extruded mass is performed in an extruder before the extruded mass is discharged from the extruder. Cooling in the extruder is conveniently carried out in the cooling die. When the extruded mass is cooled in the extruder, the temperature of the mass discharged from the extruder may range from about 1°C to about 80°C. In an embodiment, the temperature of the extruded mass is in the range from about 30°C to about 60°C. The extruded mass is then minced with a colloid mill to improve the sensory properties of the obtained food product. The colloid mill at this stage may be the same as or different from the colloid mill used for grinding the ground livestock mass. In an embodiment, water and/or oil is added to the extruded mass before colloid milling to enhance the performance of colloid milling. Grinding of the extruded mass with a colloid mill provides a food product containing bones with an average particle size of about 1 gm to about 200 gm. The colloid milled food product exhibits a smooth mouth feel without observable bone particles present.

The colloid milling of the extruded mass provides a food-grade product which is ready to be consumed as such.

Extrusion process decreases microbial load of livestock carcass enabling use of livestock of low hygienic quality. Microbial load is reduced by approximately 1000-10 ⁹ fold during the process.

The extruded food product produced by the method of the invention may imitate the texture, flavour, and mouthfeel of meat.

The method of the invention provides a food product which exhibits an increased nutritional value. By using calcium-containing parts of livestock, i.e., bones, and optionally hard tissues, tendons, and/or cartilages, the calcium content of the food product produced by the method is increased compared with typical livestock meat products. In an embodiment, the food product has a calcium content of about 0.2% w/w to about 0.7% w/w. In another embodiment, the calcium content of the food product is about 0.2% w/w to about 0.5% w/w, such as about 0.52% w/w. In a further embodiment, the calcium content of the food product is about 0.5% w/w to about 0.7% w/, such as about 0.52% w/w.

In an embodiment, the extruded and colloid milled food product is heat- treated at a temperature ranging from about 110°C to about 400°C to further improve sensory properties and mouthfeel of the product. The heat treatment may be carried out, e.g., by cooking in oil, e.g., at 150-300°C, grilling, pan frying, drying by heat, e.g., at 200-400°C, freeze drying below -70°C, microwaving or infrared radiating.

The sensory properties of the food product may be further improved by adding ingredients typically used in food manufacture to the food product produced by the method of the invention, e.g., flavouring agents, aromas, salt, stabilizers, emulsifiers, carbohydrates, fibres, oils and fats, etc.

The food product may be combined with other food materials to provide a wide variety of food compositions having different appearance, taste and structure. Thus, in an aspect, the invention provides use of a food product produced by the method of the invention as an ingredient or extender in the production of food compositions. The food product may be combined, for example, with a plantbased food raw material or livestock meat material without bones, hard tissues, tendons, skin, blood, plasma and/or cartilages. The food product produced by the method of the invention may be included in the food composition in an amount up to about 50% w/w without imparting any negative effect on the sensory properties of the food composition.

In another aspect, the invention provides a food composition comprising a food product produced by the method of the invention.

In a further aspect, the invention provides an apparatus for implementing the method of the invention, comprising means for implementing the method of the invention. An embodiment of the apparatus of the invention is illustrated in figure 2. The dotted line illustrates optional units. The apparatus may include further optional units not shown in the figure.

The following examples are presented for further illustration of the invention without limiting the invention thereto.

The calcium content of the food product was measured according to standard SFS-EN ISO 11885, 2009.

The level of aerobic microorganisms was measured according to standard NMKL 86:2013.

The amount of Salmonella was measured according to 1SO/D1S 20976- 2.

Example 1

70 kg of pork carcass (with bones, fat and muscle) was crushed to pieces of at most 0.5 cm diameter with a bone crushing machine. Then the obtained mass was minced with a meat grinder with a hole size of 2 mm. The ground pork mass was then colloid milled to a fine mass with bone particles with approximately diameter of 100 gm. The milled mass was properly mixed with 30 kg of a soy concentrate powder (protein content of 66 wt.%). The resultant mixture was kept at approximately 4°C. The mixture was then loaded to a silo connected to a conveyor screw that was connected to a hopper with approximately 30 liters of volume. The mixture was led from the hopper with an auger and a screw to an extruder in a controlled manner at approximately 30 kg/h.

The mixture of the ground pork mass and the soy concentrate powder was led to an extruder which had a cooling die integrated therewith. The moisture content of the mixture was about 55% w/w. The mixture was extruded at 170 rpm. Heating zones of the extruder were adjusted to a temperature of 60°C, 70°C, 80°C, 100°C, 120°C, 150°C and 170°C. First zone of the cooling die was set to 60°C and last zone to 40°C. The extrusion process took about 90 sec.

The extruded mass exited the cooling die at a temperature of less than 100°C. Only small amount of steam was released in the process. Solid mass and some amounts of separated oil exited the end of the cooling die.

The level of aerobic microorganisms of the solid mass obtained from the wet extrusion and that of the mixture of ground pork mass and a soy concentrate powder to be fed to the wet extrusion, i.e., "raw material") were measured at 30°C/72 h. The solid mass showed < 100 pmy/g, while the raw material showed more than 30 000 000 pmy/g. The measured level of aerobic microorganisms indicates that a food grade product for human consumption was obtained.

The food product, i.e., solid mass, had a calcium content of 0.52% w/w.

The solid mass exhibited 7-log reduction of Salmonella bacteria indicating that Salmonella was completely eliminated.

The solid mass was ground with a meat grinder having a hole size of 2 mm. Sunflower oil and water were both added to the ground mass each in a ratio of 2:10 (w/w) and were left to be absorbed by the mass at 4°C for 60 minutes. Batches of the mass were then milled with a colloid mill. The colloid milling provides a mass which is a ready-to-consume food product.

The mass may also be used as an ingredient of a food composition in an amount up to 50 wt-% of the total weight of the food composition.

Example 2

The extruded, colloid milled mass was produced as described in Example 1. The extruded mass was torn to particles having a particle size of about 1-5 mm. Fresh ground chicken meat was added to the particles in a ratio of 65:35 (w/w). Beef fat was added to the obtained mixture in a ratio of 1:10 (w/w) followed by grinding by a meat grinder with a 5 mm sieve to provide a dough.

2.0 wt-% of salt and spices including black pepper powder, hot pepper powder, cumin powder, garlic powder, onion powder and cayenne pepper were added to the dough. The dough was kneaded for about 20 minutes until a smooth mass was obtained. The mass was wrapped in an oil-coated aluminum foil, baked in an oven at 125°C until the internal temperature of the kebab-like mass was 80°C.

Product was cooled to +4°C and vacuum packaged. The resultant kebab-like food product exhibited an appealing taste and mouthfeel.

It will be obvious to a person skilled in the art that, as the technology advances, the inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.