Dry pet food

Abstract

To provide a palatable dry pet food that does not differ greatly in a composition and constitution from general pet foods and has improved palatability.SOLUTION: A dry pet food comprises puffed pellets having a moisture content of 3-12 mass%, where a content of oil and fat is 10 mass% or more based on a total amount of the dry pet food, and a rate of oil and fat exudation on a surface of the dry pet food is 0.06% or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to dry pet food. [Background technology]

[0002] Dry pet food is in high demand as a pet food to be fed daily from the viewpoints of ease of handling, good storage stability, etc. However, dry pet food often has a higher proportion of powder ingredients than pet foods with a high moisture content, such as soft dry food, semi-moist food, and wet food, and may be less palatable.

[0003] Various efforts have been made to develop pet foods that are palatable to pets, that is, to improve palatability. For example, Patent Document 1 describes an animal food product that has improved palatability by containing a grain-based shell component and a soft inner component containing a lipid component, and by providing the animal food product with a double structure in which the soft inner component is completely surrounded by the shell component. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4689932 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the composition and structure of the modified pet food may be significantly different from that of the pet food that is normally fed to the pet, and pet owners have concerns that artificially modified pet food with improved palatability may affect the health of their pets.

[0006] The present invention has been made in consideration of the above circumstances, and its object is to provide a dry pet food that is not significantly different in composition and structure from general pet foods, and has improved palatability and good palatability. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention has the following aspects. [1] A dry pet food containing puffed pellets having a moisture content of 3 to 12% by mass, The content of oils and fats is 10% by mass or more based on the total amount of the dry pet food, A dry pet food, wherein the oil and fat seepage rate on the surface of the dry pet food is 0.06% or more under the following measurement conditions: (Measurement conditions) (1)Filter paper area 420×600cm 2 The mass of the filter paper is measured. (2) The filter paper is spread and placed on a plastic tray with external dimensions of width W705 mm, depth D462 mm, and height H57 mm. (3) 500 g of the dry pet food is spread evenly on the filter paper spread on the tray. (4) The tray on which the dry pet food is placed is left standing in an electric oven heated to 37°C for 30 minutes. (5) The tray is removed from the electric oven, and the mass of the filter paper is measured. (6) Calculate the oil / fat seepage rate on the surface of the dry pet food using the following formula. Oil and fat seepage rate (%) of the surface of dry pet food = [(mass of filter paper measured in (5) above) / (mass of filter paper measured in (1) above)] × 100 [2] The dry pet food according to [1], wherein the expanded pellets include pellets having a surface with an arithmetic mean surface roughness Sa of 14 μm or more as measured using an L filter with a nesting index of 0.25 mm. [3] The dry pet food according to [1] or [2], wherein the melting point of the oil or fat is 30 to 40°C. [4] The dry pet food according to any one of [1] to [3] above, wherein the substance that seeps onto the surface of the dry pet food contains at least one selected from the group consisting of triglycerides and proteins. [5] The dry pet food according to any one of [1] to [4] above, which contains a powdered palatability enhancer in an amount of 3.0% by mass or more relative to the total amount of the dry pet food. [6]L * a * b * L in color space * The dry pet food according to any one of [1] to [5] above, wherein the value is 21 to 33. [7] The dry pet food according to [2], which contains wheat flour in an amount of 30% by mass or more based on the total amount of the dry pet food. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide dry pet food that is not significantly different in composition and structure from general pet foods and has improved palatability. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a cross-sectional view showing an example of a dry pet food manufacturing apparatus according to the present embodiment. [Figure 2] FIG. 2 is a cross-sectional view illustrating a method for producing pet food granules using the apparatus of FIG. [Figure 3] 1 is an infrared absorption spectrum of an ethyl acetate extract of a substance that has seeped out onto the surface of the dry pet food according to this embodiment. [Figure 4] 1 is an example of an infrared absorption spectrum of a triglyceride. [Figure 5] 1 is an infrared absorption spectrum of an ethyl acetate extract of a substance that has seeped out onto the surface of the dry pet food according to this embodiment. [Figure 6] This is an example of an infrared absorption spectrum of a protein. DETAILED DESCRIPTION OF THE INVENTION

[0010] In this specification, the term "pet" refers to an animal kept by a human. In a narrower sense, a pet is an animal kept as a pet by its owner. Furthermore, the term "pet food" refers to feed for pets. The pet food of the present invention can be sold as "animal feed" or "animal food."

[0011] In this specification, "palatability" is an index of whether a food is enjoyed by pets and is determined by texture, taste, smell, and the like.

[0012] In this specification, the moisture content (wt%) of pet food is determined by the normal pressure heat drying method, and the moisture content determined by this method includes the moisture in the ingredients. (Normal pressure heating drying method) The weight of the aluminum weighing can (W1 gram) is measured in advance as a constant value. Put the sample in and measure its weight (W2 grams). Then, use a forced-circulation hot air dryer. The sample is dried at 135°C for 2 hours in a dry atmosphere (silica gel desiccator). After cooling, the weight (W 3 grams) is measured. Calculate the moisture content. Moisture content (unit: weight%) = (W2 - W3) ÷ (W2 - W1) × 100

[0013] [Hardness measurement method] In this specification, the hardness (breaking hardness) of food granules is a value obtained by the following measurement method. Using a compression tester (Texture Analyzer, Model No. EZ-SX, manufactured by Shimadzu Corporation), the pet food granules are compressed at a constant compression speed and the breaking stress is measured under the following conditions. Plunger: conical plunger with a diameter of 10 mm, platform: flat plate, compression speed: 60 mm / min, lowest point of plunger: 2.25 mm (compression distance), measurement temperature: 25°C. Specifically, one pet food pellet to be measured is placed on a flat plate, and the plunger is pressed vertically from directly above the pellet at a constant speed to measure the stress. The peak (maximum) value of the stress is read as the breaking stress. The measurement is repeated for 10 pellets to obtain the average value. The breaking stress (unit: kgw) measured by the compression tester is multiplied by 9.8 to convert the breaking hardness into Newtons (N). The hardness of pet food granules shall be the value measured immediately after opening the pet food product within 30 days from the date of manufacture, or the value measured under equivalent conditions.

[0014] [Arithmetic mean surface roughness Sa] In this specification, as an example of calculation, the arithmetic mean surface roughness Sa is calculated by observing the surface of food grains (magnification: 40 times, observation field area: 19 to 20 mm) using a non-contact three-dimensional shape measuring instrument VR-3200 (manufactured by Keyence Corporation, using an L filter with a nesting index of 0.25 mm). 2 ) is performed, and the arithmetic mean roughness Sa of the surface of the food granules is calculated.

[0015] As used herein, L * , a * and b * is the L standardized by the CIE (International Commission on Illumination). * a * b * This is the value expressed by the color space measurement system (JISZ8729). * a * b * In L * represents the brightness of the color, with a value of 0 being the diffuse color toward black and a value of 100 being the diffuse color toward white. * b * represents chromaticity, and a * is a hue between red and green, and negative values ​​indicate a hue toward green, and positive values ​​indicate a hue toward red. * is a hue between yellow and blue, with negative values ​​indicating a hue toward blue and positive values ​​indicating a hue toward yellow. * a * b *is expressed as a three-dimensional coordinate.

[0016] A "complete nutritional food" is a pet food product that is intended to be fed to dogs or cats as their main daily meal and is nutritionally balanced so that the pet food and water alone will maintain the health of the animal at a specified stage of growth. Standards for complete nutritional food include those established by the Association of American Feed Control Officials (AAFCO). In this specification, a "complete nutritional food" may be a food that meets the criteria for any of the following stages, regardless of the growth stage: "puppy / kitten / growth stage or growth," "adult dog / adult cat / maintenance stage or maintenance," or "pregnancy / lactation stage," or it may be a food that meets all three of these criteria: "for all growth stages" or "for all stages."

[0017] In this specification, "palatability" is an index of whether a food is enjoyed by pets and is determined by texture, taste, smell, and the like.

[0018] <Dry pet food> The dry pet food according to this embodiment contains puffed pellets having a moisture content of 3 to 12% by mass. The moisture content of the puffed pellets is preferably 3.0 to 10.0% by mass, more preferably 5.0 to 8.0% by mass.

[0019] The dry pet food according to this embodiment has an oil and fat content of 10% by mass or more, preferably 10 to 15% by mass, and more preferably 10.5 to 14% by mass, based on the total mass of the dry pet food. When the fat and oil content is 10% by mass or more, the palatability is likely to be good even if the dry pet food has a common composition and structure.

[0020] The dry pet food according to this embodiment has an oil and fat seepage rate on the surface of the dry pet food (hereinafter also referred to as "oil and fat seepage rate at 37°C") of 0.06% or more, preferably 0.07% or more, and more preferably 0.08% or more under the following measurement conditions: If the fat / oil seepage rate at 37°C is 0.06% or more, the palatability is likely to be good even if the dry pet food has a common composition and structure.

[0021] (Measurement conditions for oil seepage rate at 37°C) (1)Filter paper area 420×600cm 2 The mass of the filter paper is measured. (2) The filter paper is spread and placed on a plastic tray with external dimensions of width W705 mm, depth D462 mm, and height H57 mm. (3) 500 g of the dry pet food is spread evenly on the filter paper spread on the tray. (4) The tray on which the dry pet food is placed is left standing in an electric oven heated to 37°C for 30 minutes. (5) The tray is removed from the electric oven, and the mass of the filter paper is measured. (6) Calculate the oil / fat seepage rate on the surface of the dry pet food using the following formula. Oil and fat seepage rate (%) of the surface of dry pet food = [(mass of filter paper measured in (5) above) / (mass of filter paper measured in (1) above)] × 100

[0022] The dry pet food according to this embodiment has an oil / fat seepage rate on the surface of the dry pet food (hereinafter also referred to as "oil / fat seepage rate at 25°C") under the following measurement conditions of preferably 0.02% or more, more preferably 0.03% or more, and even more preferably 0.04% or more. If the oil and fat seepage rate at 25°C is 0.02% or more, the palatability is likely to be good even if the dry pet food has a common composition and structure.

[0023] (Measurement conditions for oil seepage rate at 25°C) (1)Filter paper area 420×600cm 2 The mass of the filter paper is measured. (2) The filter paper is spread and placed on a plastic tray with external dimensions of width W705 mm, depth D462 mm, and height H57 mm. (3) 500 g of the dry pet food is spread evenly on the filter paper spread on the tray. (4) The tray on which the dry pet food is placed is left to stand at room temperature (25°C) for 30 minutes. (5) The mass of the filter paper is measured. (6) Calculate the oil / fat seepage rate on the surface of the dry pet food using the following formula. Oil and fat seepage rate (%) of the surface of dry pet food = [(mass of filter paper measured in (5) above) / (mass of filter paper measured in (1) above)] × 100

[0024] The dry pet food according to this embodiment has improved palatability by increasing the amount of oil and fat contained in the food granules. A large amount of oil and fat remains on the surface of the food granules, creating a synergistic effect with the umami components derived from the proteins that adhere to the surface. This makes a big impact on pets when they first start eating, making them more likely to eat. Meanwhile, for pet owners, the appearance of the pet food gives the impression that the flavor has permeated the surface of the food granules more than conventional dry pet foods, and the increased palatability of pets makes it feel special.

[0025] In the dry pet food according to this embodiment, the puffed pellets preferably include pellets having surfaces with an arithmetic mean surface roughness Sa of 14 μm or more as measured using an L filter with a nesting index of 0.25 mm. When the expanded granules include granules with surfaces having an arithmetic mean surface roughness Sa of 14 μm or greater, not only do they facilitate drawing oil and fat into the interior of the food granules, but they also facilitate increasing the amount of oil and fat absorbed while leaving a sufficient amount of oil on the surface of the food granules.

[0026] Expanded pellets containing pellets having a surface with an arithmetic mean surface roughness Sa of 14 μm or more can be obtained, for example, by cutting pet food material discharged from an extruder (extrusion molding machine) after the material has expanded, to have a soft center with an exposed cross section and a peripheral portion that is harder than the center.

[0027] There is no particular upper limit to the arithmetic mean surface roughness Sa, but when coating food granules with oil or fat, if the arithmetic mean surface roughness Sa is too large, it becomes difficult to achieve a uniform coating. For example, Sa is preferably 30 μm or less, and more preferably 25 μm or less.

[0028] In the dry pet food according to this embodiment, the melting point of the oil or fat is preferably 30 to 40°C, more preferably 35 to 40°C, and even more preferably 38 to 39°C. When the melting point of the oil or fat is within the above-mentioned preferred range, it melts easily on the tongue of a pet (especially a cat), which tends to increase palatability. In addition, since it does not melt easily at room temperature, it tends to increase palatability and have good storage stability.

[0029] In the dry pet food according to this embodiment, the substance that exudes onto the surfaces of the food granules preferably contains at least one substance selected from the group consisting of triglycerides and proteins, and more preferably contains triglycerides and proteins. If the substance that exudes onto the surface of the food granules contains triglycerides and / or proteins, the palatability of the dry pet food is more likely to increase.

[0030] The dry pet food according to this embodiment preferably contains 3.0% by mass or more of a powdered palatability enhancer relative to the total amount of the dry pet food, more preferably 4.0% by mass or more, and even more preferably 5.0% by mass or more. When the content of the powdered palatability improver is within the above preferred range, a large amount of powdered palatability improver is likely to be present on the surface of the food granules, which makes it easier to inhibit the penetration of oil and fat into the interior of the food granules and makes it easier for the oil and fat to remain on the surface of the food granules, thereby making it easier to increase palatability.

[0031] The dry pet food according to this embodiment is L * a * b * L in color space * The value is preferably 21-33, more preferably 22-32, and even more preferably 23-31. L * a * b * L in color space * When the value is within the above preferred range, pet owners are more likely to get the impression from the appearance of the pet food that the flavor has permeated the surface of the food granules than conventional dry pet foods, and pets are more likely to eat it, making it feel special.

[0032] The dry pet food according to this embodiment is L * a * b * The b* value in the color system is preferably 12-23, more preferably 13-22, and even more preferably 14-21. L * a * b * b in color space * When the value is within the above preferred range, pet owners are more likely to get the impression from the appearance of the pet food that the flavor has permeated the surface of the food granules than conventional dry pet foods, and pets are more likely to eat it, making it feel special.

[0033] The dry pet food of this embodiment preferably contains expanded granules having a surface with an arithmetic mean surface roughness Sa of 14 μm or more as measured using an L filter with a nesting index of 0.25 mm, and contains wheat flour in an amount of 30% by mass or more, more preferably 35% by mass or more, and even more preferably 40% by mass or more, based on the total amount of the dry pet food. When the expanded granules include granules having surfaces with an arithmetic mean surface roughness Sa of 14 μm or more, and the wheat flour content is within the above-mentioned preferred range, the oil and fat are more likely to seep onto the surface of the food granules, which tends to improve palatability.

[0034] In the dry pet food according to this embodiment, the hardness of the food granules (granular raw material mixture) is preferably from 10 to 90N, more preferably from 15 to 70N, and even more preferably from 20 to 50N. When the hardness of the food granules is within the above preferred range, palatability is likely to be improved.

[0035] The shape of the complete nutritional pet food according to this embodiment is not particularly limited as long as it is a shape suitable for consumption by pets. For example, any shape such as a sphere, an ellipsoid (go stone shape), a pellet, a cylinder, a polygonal prism, a hexahedron (plate shape), a clover shape, a heart shape, a star shape, a cross shape, etc. can be applied.

[0036] The size of the food granules may be small enough for a pet to eat in one bite, or large enough for a pet to chew multiple times. For example, the food granules are preferably in the form of pellets (granular or chunky) with a minor diameter and major axis of 3 to 25 mm when placed on a horizontal table and viewed from above, and a thickness of 2.5 to 20 mm from the bottom (bottom edge) to the top (top edge) of the food granules on the horizontal table, more preferably pellets with a minor diameter and major axis of 3 to 13 mm and a thickness of 2.5 to 9 mm, and even more preferably pellets with a minor diameter and major axis of 6 to 12 mm and a thickness of 2.5 to 8 mm. This shape makes it easy to adjust the hardness within a preferred range when adjusting to a specified moisture content during the heating and drying processes in the pet food granule manufacturing process.

[0037] Pet foods can be classified into complete nutritional foods given as regular meals, snacks given as treats, therapeutic foods containing specific ingredients used for pets with illnesses, and other specialized foods, but the pet food of the present invention is suitably a complete nutritional food.

[0038] ≪Raw materials≫ As ingredients for the complete nutritional pet food according to this embodiment, powder ingredients and liquid ingredients known in the manufacture of pet food can be used. Specific examples of powder raw materials include grains (corn, wheat, flour, wheat bran, rice, breadcrumbs, barley, oats, rye, etc.), potatoes (sweet potatoes, potatoes, etc.), beans (whole soybeans, etc.), starches (wheat starch, corn starch, rice starch, potato starch, tapioca starch, sweet potato starch, sago starch, modified starch, etc.), vegetable proteins (corn gluten meal, wheat protein, bean protein, rice protein, potato protein, etc.), meat (livestock meat and animal meat such as beef, pork, lamb, deer, rabbit, chicken, turkey, Examples of ingredients include poultry meat such as quail and poultry; meals (chicken meal, pork meal, beef meal, mixed meals of these), seafood (fish such as tuna, bonito, and horse mackerel; crustaceans such as shrimp and crab; mollusks such as octopus and squid; shellfish such as scallops and turban shells; fish extracts; dried bonito flakes, meal (fish meal), etc.), vegetables, nuts and seeds, mushrooms, eggs, sugars, milk, and additives (vitamins, minerals, amino acids, flavor ingredients, powdered palatability enhancers, fiber, colorants, phosphates, pH adjusters, seasonings, antioxidants, trehalose, etc.).

[0039] Meal refers to meat or seafood that has been compressed and crushed into fine powder. More specifically, powdered palatability improvers include extracts of animal raw materials, extracts of plant raw materials, yeast extracts, dried yeast, and enzyme decomposition products of proteins derived from animals and plants. Specific examples of liquid ingredients (including semi-solid ingredients) include water, oils and fats (animal oils and fats such as chicken oil, lard, beef tallow, dairy fat, and fish oil; vegetable oils and fats such as olive oil, cacao oil, palm oil, palm kernel oil, coconut oil, coconut oil, and camellia oil), liquid palatability enhancers, liquid sugar, moisturizers, preservatives, emulsifiers, flavorings, and coloring agents.

[0040] Examples of the composition of the dry pet food according to this embodiment include 30 to 50% by mass of wheat flour, 0 to 20% by mass of grains other than wheat flour, 10 to 30% by mass of meat, 5 to 20% by mass of animal fats and oils, 5 to 15% by mass of yeast, 2 to 10% by mass of seafood, and 2 to 10% by mass of additives such as vitamins, minerals, and amino acids.

[0041] The dry pet food according to this embodiment is preferably coated with a coating agent, and more preferably coated multiple times. Examples of coating agents include oils and fats, powdered palatability enhancers, and the like.

[0042] The oil or fat of the coating agent may be vegetable oil or animal oil. One type of oil or fat may be used, or two or more types may be used in combination. The oil or fat may be liquid at room temperature or solid at room temperature. To make the oil or fat liquid, it may be heated as needed before use. The fats and oils preferably contain animal fats and oils, as this makes it easier to obtain high palatability. Examples of animal fats and oils include chicken oil, lard, beef tallow, and dairy fat. Only one type of animal fat and oil may be used alone, or multiple types may be used in combination.

[0043] As the powdered palatability improver, at least one selected from the group consisting of enzymatic decomposition products of animal raw materials, enzymatic decomposition products of plant raw materials, extracts of animal and plant raw materials, and yeast extracts can be used. Examples of enzymatic hydrolysates of animal raw materials include enzymatic hydrolysates of chicken meat, enzymatic hydrolysates of chicken liver (hereinafter also referred to as chicken liver), enzymatic hydrolysates of pork meat, enzymatic hydrolysates of pork liver, enzymatic hydrolysates of beef, enzymatic hydrolysates of beef liver, and enzymatic hydrolysates of seafood. Examples of enzymatic hydrolysates of plant raw materials include enzymatic hydrolysates of beans (soybeans, etc.) and enzymatic hydrolysates of tubers (potatoes, etc.). Examples of yeast extracts include brewer's yeast extract, baker's yeast extract, and torula yeast extract. One or more types of palatability enhancers may be used.

[0044] <Dry pet food manufacturing method> The method for producing the pet food according to this embodiment can be a known method, and is not particularly limited as long as it satisfies the requirements of this embodiment. Known methods include a method for producing pet food in the following order: a granulation step, a drying step, and a coating step.

[0045] [Granulation process] In the granulation step, the raw material mixture is granulated to obtain food granules. Known methods can be used for mixing the raw materials to form a raw material mixture and for shaping (granulating) the raw material mixture into granules. For example, a method of producing expanded pellets using an extruder can be suitably used. Examples of methods for producing expanded granules using an extruder include the methods described in "Small Animal Clinical Nutrition, 5th Edition" (Michael S. Hand, Craig D. Thatcher, Rebecca L. Remillard, Philip Roudebusg, Bruce J. Novotny, eds., Mark Morris Associates, 2014; pp. 209-215).

[0046] An example of a method for producing puffed pellets using an extruder will be described. First, the raw materials for the puffed pellets, excluding external additives, are crushed as necessary and then mixed. They may be mixed while crushed using a grinder or the like. Water (not included in the raw material composition) is also added as necessary to obtain a raw material mixture. The resulting raw material mixture is placed in an extruder, heated and pressurized, and then extruded from an outlet. The outlet is equipped with a plate with holes of a predetermined shape and a cutter that cuts the raw material mixture extruded from the plate to a predetermined length (thickness). The raw material mixture is extruded through the holes in the plate and cut by the cutter to form it into a predetermined shape. At the same time, the pressurized state is released to normal pressure, causing the water vapor in the raw material mixture to expand, which causes the raw material mixture to expand and produce porous particles.

[0047] When producing expanded granules containing granules having surfaces with an arithmetic mean surface roughness Sa of 14 μm or more as measured using an L filter with a nesting index of 0.25 mm, for example, the apparatus shown in Fig. 1 can be used. Fig. 1 is a cross-sectional view schematically showing the main parts of the apparatus. Fig. 2 is a cross-sectional view illustrating a method for producing pet food granules using the apparatus shown in Fig. 1. In the figure, reference numeral 1 denotes food granules, 2 denotes a kneaded material, and 11 denotes an extruder. Extruder 11 heats and kneads the raw material mixture and discharges kneaded material 2. A die plate 12 is provided at the discharge port of extruder 11, which discharges kneaded material 2 in a rod shape. Although not shown, a cutter for cutting the kneaded material 2 to a predetermined length is provided near the discharge port of the die plate 12. Reference numeral 13 in Fig. 2 indicates the cutting position by the cutter. For example, a rotary blade is used as the cutter. The die plate 12 has a first opening 12a formed on the extruder 11 side and a second opening 12b on the cutter side. In the flow path connecting the first opening 12a and the second opening 12b, the diameter of the first opening 12a gradually decreases in the direction toward the second opening 12b and is connected to the second opening 12b via a minimum inner diameter portion 12c. The inner diameter of the second opening 12b is constant. The minimum inner diameter of the flow path is denoted by r, and the inner diameter of the second opening 12b is denoted by R.

[0048] 2, kneaded material 2, which has been under high heat and pressure inside extruder 11, passes from first opening 12a of die plate 12 through a flow path inside die plate 12, is extruded under normal pressure from smallest inner diameter section 12c, and expands inside second opening 12b. The material then expands sufficiently as it travels toward the exit of second opening 12b (the discharge port of die plate 12), and after beginning to shrink inside second opening 12b, is discharged from the discharge port of die plate 12 and cut by a cutter (cutting position 13), thereby forming (granulating) food granules 1. As the kneaded material 2 expands, bubbles are formed inside it, and it is cut with a cutter after the expansion is complete and it begins to shrink, so holes formed by the cutting of the bubbles exist on the cut surface. The food granules 1 formed in this way have a columnar shape obtained by cutting a rod-shaped kneaded material 2 along a plane perpendicular to the length direction. The cut surfaces perpendicular to the length direction (the upper and lower surfaces perpendicular to the thickness direction of the column) have a greater arithmetic mean surface roughness Sa than the side surfaces parallel to the length direction. For example, when viewed from a direction perpendicular to the length direction, the minor diameter and major axis of food granule 1 are preferably 3 to 25 mm, and the thickness from the bottom surface (bottom end in the thickness direction) to the top surface (top end in the thickness direction) of the food granule when placed on a horizontal table is preferably 2.5 to 20 mm, the minor diameter and major axis are more preferably 3 to 13 mm, the thickness is more preferably 2.5 to 9 mm, and the minor diameter and major axis are even more preferably 6 to 12 mm, and the thickness is 2.5 to 8 mm.

[0049] In die plate 12, inner diameter R of second opening 12b is 3.5 times or more (R / r≧3.5) the smallest inner diameter r of the flow passages within die plate 12. From the standpoint of moldability of the food granules, the upper limit of R / r, which represents the ratio of the inner diameters, is preferably 7 or less, and more preferably 6.5 or less. When the ratio R / r is 3.5 or greater, kneaded material 2 can expand sufficiently, resulting in larger air bubbles formed inside the kneaded material and larger holes formed on the cut surface. In other words, the surface roughness of the cut surface of food granules 1 increases, resulting in food granules with surfaces having an Sa of 14 μm or greater. The size of the minimum inner diameter r is designed according to the size of the food granules to be obtained. The shape of the outlet of minimum inner diameter section 12c is designed according to the shape of the food granules that are to be obtained.

[0050] The distance D from when the kneaded material 2 leaves the minimum inner diameter portion 12c to when it leaves the second opening 12b is set to a length required for the kneaded material 2 traveling through the second opening 12b to begin to shrink after being sufficiently expanded. For example, it is preferable that the minimum inner diameter r of the flow path is 3 to 10 mm, the inner diameter R of the second opening 12b is 9 to 40 mm, and the distance D is 10 to 22 mm. More preferably, r is 3 to 6 mm, R is 12 to 26 mm, and D is 15 to 20 mm.

[0051] [Drying process] The granules obtained in this manner are dried, if necessary, until they reach a predetermined moisture content to obtain expanded granules (food granules). When producing dry-type food granules, a drying step is essential. For example, the moisture content of the granules discharged from the extruder is 10 to 30% by mass. When the granules contain moisture at this level, good moldability is likely to be obtained. The temperature of the granules discharged from the extruder depends on the heating temperature inside the extruder, and is, for example, 90 to 150°C. The granules discharged from the extruder can be dried by any known method. Examples include hot air drying, which involves blowing hot air onto the granules to dry them, vacuum drying, and frying in oil. For example, hot air drying using a conveyor-type hot air dryer is preferred. The drying conditions (temperature, time) may be any conditions that allow the temperature of the grains to be raised to 100°C or higher to evaporate the moisture in the grains and adjust the moisture content to the desired level without causing thermal denaturation of the grain components. For example, when drying is performed using a hot air dryer, the temperature of the hot air brought into contact with the granules is preferably 100 to 140° C., more preferably 100 to 110° C. The drying time is not particularly limited, and is carried out for, for example, about 5 to 20 minutes.

[0052] After drying, the pet food may be further coated with a coating agent such as oils, fats, powder palatability enhancers, etc. The coating method is not particularly limited, and can be performed by, for example, a vacuum coating method. The vacuum coating method involves reducing the pressure while the heated food granules are in contact with or attached to the coating agent, and then slowly opening the granules to the atmosphere. The coating agent may be in liquid or powder form. The coating can improve palatability (eating habits) for pets. In this embodiment, it is preferable to coat the granules multiple times. [Example]

[0053] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0054] Example 1: Production of dry pet food Pet food granules were produced using the apparatus shown in Figures 1 and 2. The minimum inner diameter r of the flow path in the die plate 12 was 4.5 mm, the inner diameter R of the second opening was 18 mm, and the distance D was 18 mm. The ratio of R / r was 4. The outlet of the minimum inner diameter portion 12c and the outlet of the second opening 12b were both circular. First, using a preconditioner, the raw materials, excluding animal fats and some palatability enhancers, were mixed according to the formulation shown in Table 1, and water and steam were added and the mixture was heated at 90 to 100°C for 3 minutes to obtain a raw material mixture. The resulting raw material mixture was then supplied to an extruder and heated at 120-135°C for 30 seconds while being kneaded, and the kneaded mixture was then ejected from the die plate and cut to form cylindrical food granules with a diameter of 10 mm and a thickness of 4.5 mm. The resulting food granules were then dried in a dryer at approximately 100 to 110°C for approximately 15 minutes, and the moisture content was adjusted to 6% by mass. After drying, the pellets were coated twice with animal fats and oils and a palatability enhancer to obtain pet food granules (1).

[0055] [Comparative Example 1: Production of dry pet food] Pet food granules (2) were obtained in the same manner as in Example 1, except that the raw materials were changed to the composition shown in Table 1 and the animal fats and oils and some of the palatability enhancers were coated only once.

[0056] [Table 1]

[0057] [Evaluation of oil seepage rate] The oil / fat exudation rate from the surface of the dry pet food granules (1) and (2) was measured under the following measurement conditions. The results are shown in Table 2. (Measurement conditions) (1)Filter paper area 420×600cm 2The mass of the filter paper (product name: ADVANTEC Qualitative Filter Paper No. 1 600 x 600; manufactured by Toyo Roshi Kaisha, Ltd.) was measured using an electronic balance (product name: METTLER AE200; manufactured by Nippon SiberHegner Co., Ltd.). (2) The filter paper was spread and placed on a plastic tray (product name: tray container; manufactured by Gifu Plastic Industry Co., Ltd.) with external dimensions of width W705 mm, depth D462 mm, and height H57 mm. (3) The amount of pet food granules (1) or (2) shown in Table 2 was placed on the filter paper spread on the tray, spreading it evenly. (4) The tray on which the dry pet food was placed was left standing in an electric oven heated to 37°C for 30 minutes, or at room temperature (25°C) for 30 minutes. (5) The tray is removed from the electric oven, or the tray is left standing at room temperature (25°C) for 30 minutes, and the mass of the filter paper is measured. (6) Calculate the oil / fat seepage rate on the surface of the dry pet food using the following formula. Oil and fat seepage rate (%) of the surface of dry pet food = [(mass of filter paper measured in (5) above) / (mass of filter paper measured in (1) above)] × 100

[0058] [Preference evaluation] Pet food granules (1) or (2) were used as pet food P, and commercially available pet food (a granular pet food consisting of pet food granules with cream filled inside a grain-based shell; Sheba (registered trademark) Duo (registered trademark)) was used as pet food Q. The palatability of pet food P and pet food Q was evaluated by comparing the amount of food consumed. The test was conducted over two days using 20 cats as monitors. On the first day, one of pet foods P and Q was given to each cat at the same time, one from the left and the other from the right, in the prescribed feeding amounts, and the amount of pet food eaten by the cat was measured when the cat had finished eating either one or 30 minutes later. The ratio of the amount of pet food Q consumed to the amount of pet food P consumed (P:Q, P+Q=100%) was calculated as a percentage relative to the total mass of pet food consumed by each cat on Day 1. The percentages obtained based on the number of cats monitored were averaged to obtain the result for Day 1. On the second day, pet foods P and Q were given to each cat, one from the right and the other from the left, in the opposite order to that given on the first day. Each cat was given the same amount of food as on the first day, and the amount of pet food eaten by the cat was measured when the cat had finished eating one of the foods or one hour later. The results for the second day were obtained using the same calculation method as on the first day. Finally, the results from the first and second days were averaged to determine the final result, the ratio of pet food P to pet food Q (P:Q). A higher P or Q value indicates that the test cat preferred the food. A P value of 50% or higher indicates improved palatability over pet food Q. The results are shown in Table 2 as "palatability evaluation results."

[0059] [Table 2]

[0060] From the results shown in Table 2, comparing Test Example 1 and Comparative Test Example 1, it was confirmed that pet food granules (1) had a higher exudation rate than pet food granules (2) at 25°C (room temperature). A comparison of Test Example 2 and Comparative Test Example 2 confirmed that pet food granules (1) had a higher exudation rate than pet food granules (2) at 37° C. Therefore, it is presumed that pet food granules (1) exude oils and fats more easily on the cat's tongue (approximately 38 to 39° C.), increasing its palatability.

[0061] Furthermore, the results shown in Table 2 confirmed that pet food granules (1) were relatively more palatable than pet food granules (2).

[0062] [Production of pet food granules (3)] Pet food granules (3) were obtained in the same manner as in Example 1, except that the raw materials were changed to the composition shown in Table 3.

[0063] [Table 3]

[0064] [Evaluation of color difference analysis] The following samples were subjected to color difference analysis. Sample A: Commercially available dry food (product name: Physicalife; manufactured by Unicharm Corporation) Sample B: Pet food granules (1) Sample C: Pet food granules (3) The sample was placed in a glass cell, and measurements were carried out using a colorimeter (n=5) while changing the position of the glass cell to determine L*a*b*. The results are shown in Table 4. (Measurement conditions) Device: SE7700 (manufactured by Nippon Denshoku Industries Co., Ltd.). Light source: D65 Field of view: 2°

[0065] [Table 4]

[0066] [Analysis of the components of seeping substances] (External observation) In the "Evaluation of the oil / fat seepage rate" above, the filter paper of Test Example (2) obtained in (5) of (Measurement conditions) was used as a sample and visually observed. As a result, the sample was slightly yellowish in color compared to the filter paper before the dry pet food was placed on it, and minute light brown substances were observed in places.

[0067] (Measurement of infrared absorption spectrum (1)) The specimens in the above "appearance observation" were extracted with ethyl acetate to obtain an ethyl acetate extract. The infrared absorption spectrum of the obtained ethyl acetate extract was measured. Figure 3 is an infrared absorption spectrum of an ethyl acetate extract of the substance that has exuded onto the surface of the pet food granules 1. Figure 4 is an example of an infrared absorption spectrum of a triglyceride. The results shown in FIG. 3 confirmed that the infrared absorption spectrum of the ethyl acetate extract of the specimen was similar to the infrared absorption spectrum of triglycerides.

[0068] (Measurement of infrared absorption spectrum (2)) For the specimen in the above "appearance observation", the light brown substance was washed with water, air-dried and extracted with ethyl acetate to obtain an ethyl acetate extract. The infrared absorption spectrum of the obtained ethyl acetate extract was measured. Figure 5 is an infrared absorption spectrum of an ethyl acetate extract of a substance that has exuded onto the surface of pet food granules 1. Figure 6 is an example of an infrared absorption spectrum of a protein. The results shown in FIG. 5 confirmed that the infrared absorption spectrum of the ethyl acetate extract of the specimen was similar to the infrared absorption spectrum of protein.

[0069] The results of infrared absorption spectroscopy measurements (1) and (2) confirmed that the substances that exuded onto the surface of the pet food granules (1) mainly contained triglycerides and proteins. [Explanation of symbols]

[0070] 1 food pellet (pet food pellet) 2. Mixture 11 Extruder (extrusion molding machine) 12 Die Plate 12a First opening 12b Second opening 12c Minimum inner diameter 13 Cutting position

Claims

1. A dry pet food containing puffed granules having a moisture content of 3 to 12% by mass, The content of oils and fats is 10% by mass or more based on the total amount of the dry pet food, the L* value in the L*a*b* color system is 21 to 33; The b* value in the L*a*b* color system is 12 to 23, A dry pet food having an oil and fat seepage rate on the surface of the dry pet food of 0.06% or more under the following measurement conditions: (Measurement conditions) (1) Measure the mass of a filter paper with an area of ​​420 x 600 mm2 (product name: ADVANTEC Qualitative Filter Paper No. 1 600 x 600; manufactured by Toyo Roshi Kaisha, Ltd.). (2) The filter paper is spread and placed on a plastic tray having external dimensions of width W705 mm, depth D462 mm, and height H57 mm. (3) 500 g of the dry pet food is spread evenly on the filter paper spread on the tray. (4) The tray on which the dry pet food is placed is left standing in an electric oven heated to 37°C for 30 minutes. (5) The tray is removed from the electric oven, and the mass of the filter paper is measured. (6) The oil and fat seepage rate on the surface of the dry pet food is calculated using the following formula. Oil and fat seepage rate (%) on the surface of dry pet food = [(mass of filter paper measured in (5) above) - (mass of filter paper measured in (1) above)] / [mass of the dry pet food (500 g)] x 100

2. 2. The dry pet food according to claim 1, wherein the expanded granules include granules having a surface with an arithmetic mean surface roughness Sa of 14 μm or more as measured using an L filter with a nesting index of 0.25 mm.

3. The dry pet food according to claim 1, wherein the melting point of the oil or fat is 30 to 40°C.

4. The dry pet food according to claim 1 , wherein the substance that exudes onto the surface of the dry pet food contains at least one substance selected from the group consisting of triglycerides and proteins.

5. The dry pet food according to claim 1 , wherein the powdered palatability enhancer is contained in an amount of 3.0% by mass or more based on the total amount of the dry pet food.

6. The dry pet food according to claim 2 , wherein the dry pet food contains wheat flour in an amount of 30% by mass or more based on the total amount of the dry pet food.

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