SOLID MILK OBTAINED BY COMPACTING POWDERED MILK
20200345025 ยท 2020-11-05
Assignee
Inventors
Cpc classification
A23C9/16
HUMAN NECESSITIES
International classification
Abstract
A solid milk may include 0.5 wt % to 4 wt % of free fat, wherein a total fat content, including the free fat, is 5 wt % or higher. The solid milk may have a porosity of 30% to 50% and a solubility of 5 seconds to 180 seconds, where the solubility is defined as a time required to dissolve the solid milk completely when the solid milk is placed in 100 mL of water at 50 C. and shaken at a rate of 1.5 cycles/sec and an amplitude of 30 cm. The solid milk may have a hardness of 30 N to 300 N, where the hardness is defined as a force causing fracture when a load is applied in a direction in which a surface area of a fracture surface of a sample becomes minimal.
Claims
1-17. (canceled)
18. A solid milk, comprising: 5 wt % to 4 wt % of free fat, wherein a total fat content, including the free fat, is 5 wt % or higher, wherein the solid milk has a porosity of 30% to 50%, wherein the solid milk has a solubility of 5 seconds to 180 seconds, where the solubility is defined as a time required to dissolve the solid milk completely when the solid milk is placed in 100 mL of water at 50 C. and shaken at a rate of 1.5 cycles/sec and an amplitude of 30 cm, wherein the solid milk has a hardness of 30 N to 300 N, where the hardness is defined as a force causing fracture when a load is applied in a direction in which a surface area of a fracture surface of a sample becomes minimal, and wherein powdered milk particles on a surface of the solid milk are bridged together and form a shell and a hardness of the surface of the solid milk is greater than a hardness inside the solid milk.
19. The solid milk according to claim 1, wherein the solid milk has a moisture content of 1 to 4 wt %.
20. The solid milk according to claim 1, wherein the solid milk as a volume of 1 cm.sup.3 to 50 cm.sup.3.
21. The solid milk according to claim 1, wherein the solid milk comprises the free fat in an amount of 1 wt % to 2.5 wt %.
22. The solid milk according to claim 1, wherein the solid milk has a volume of 4 cm.sup.3 to 20 cm.sup.3.
23. The solid milk according to claim 1, wherein the solid milk has a tetragonal rod shape with rounded corner portions.
24. The solid milk according to claim 1, wherein the solid milk is manufactured by a method comprising, in the following order: a compacting process of compacting powdered milk and obtaining a solid compacted body of powdered milk; a humidifying process of wetting the compacted body of powdered milk obtained in the compacting process; and a drying process of drying the compacted body of powdered milk humidified in the humidification process,
25. The solid milk according to claim 24, wherein an amount of moisture added to the compacted body of powdered milk in the humidifying process is 0.5% to 3%.
26. The solid milk according to claim 24, wherein the content of free fat in the compacted body of powdered milk in the drying process is 0.5 wt % to 4 wt %, and
27. The solid milk according to claim 24, wherein the powdered milk used in the compacting process has a total fat content of 5 wt % or higher.
28. The solid milk according to claim 24, wherein substantially no additives are added to the ingredient in the compacting process.
29. The solid milk according to claim 24, wherein the compacting force is controlled in the compacting process so that the porosity of the compacted body of powdered milk becomes 30% to 50%.
30. The solid milk according to claim 24, wherein the compacting force for compacting the powdered milk in the compacting process is 1 MPa to 15 MPa.
31. The solid milk according to claim 24, wherein in the drying process, the moisture content of the solid milk is controlled to be no more than 1% higher or lower than the moisture content of the powdered milk used as the ingredient.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0047]
[0048]
[0049]
[0050]
DESCRIPTION OF THE PREFERRED EMBODIMENTS
1. Solid Milk
[0051] The solid milk in accordance with the present invention is solid milk with a porosity of 30% to 50%. The higher the porosity becomes, the higher the solubility becomes, but the lower the strength becomes. Furthermore, if the porosity is small, solubility decreases. The porosity is mainly controlled by the compacting force in the compacting process. Furthermore, in accordance with the present invention, the preferred porosity is 35% to 50%, but the porosity may be adjusted according to the application of the solid milk and may be 30% to 35%, 30% to 45%, 40% to 45%, or 40% to 50%. As described below, if the porosity is within those ranges, good solid milk free from problems of oil-off or the like can he obtained.
[0052] It is preferred that a plurality of individual pores be present in the solid milk. The pores are preferably dispersed uniformly in the solid milk. Because the pores are almost uniformly distributed in the solid milk, a higher solubility can be obtained. The larger are the pores, the easier water penetrates therein and a high solubility can be obtained. On the other hand, if the pore size is too large, strength decreases or the surface of solid milk becomes rough. Accordingly, the pore size is, for example, 10 m to 500 m, preferably 50 m to 300 m. Such pore size can be measured by well-known means, for example, by observing the surface and cross section of solid milk with a scanning electron microscope.
[0053] The components of solid milk are basically identical to those of powdered milk serving as an ingredient therefor, with the exception of the amount of water. Examples of solid milk components include fats, sugars, proteins, minerals, and water.
[0054] The content ratio of fat in the solid milk is, for example, 5 wt % to 70 wt %, preferably 5 wt % to 50 wt %, even more preferably 10 wt % to 45 wt %.
[0055] The solid milk in accordance with the present invention may contain emulsified fat or free fat as fat. Thus, in the conventional powdered milk or solid milk, problems were associated with the free fat spoiling the taste and floating on the water (oil-off) when the milk was dissolved in warm water and, therefore, the free fat was actively removed. It is preferred that the solid milk in accordance with the present invention proactively contain the free fat. This free fat is effectively employed in place of a lubricant and the like. As a result, the present invention makes it possible to manufacture good solid milk, without using additives. However, if the amount of free fat is too high, it raises the oil-off problem. Accordingly, the content ratio of free fat in the solid milk in accordance with the present invention is, for example, 0.5 wt % to 4 wt %, preferably 0.7 wt % to 3 wt %, more preferably 1 wt % to 2.5 wt %. This is because if the content ratio of free fat is within those ranges, good hardness and solubility are obtained and excess oil-off is inhibited, as will be shown in the below-described embodiments. Furthermore, the amount of free fat at which oil-off becomes a problem differs depending on the fat composition and physical properties such as fat globule diameter in the powdered milk used as an ingredient. Therefore, the amount of free fat contained in the solid milk may be appropriately corrected within the above-described ranges.
[0056] If the moisture content in solid milk is high, stability in storage is degraded, and if the moisture content is low, the solid milk becomes brittle. Therefore, the content ratio of moisture in the solid milk is, for example, 1 wt % to 4 wt %, preferably 2 wt % to 3 wt %.
[0057] The shape of the solid milk in accordance with the present invention is not limited, provided it has a certain size. Thus, the solid milk may have the: shape of round rods, elliptical rods, rectangular parallelepipeds, cubes, plate, balls, polygonal rods, polygonal cones, polygonal pyramids, and polyhedrons. From the standpoint of convenience of handling, the shape of round rods or tetragonal rods is preferred. Furthermore, in order to prevent the solid milk from fracturing, it is preferred that the corner portions be rounded.
[0058] It is preferred that one piece or several pieces (preferably, one piece) of the solid milk in accordance with the present invention produce one serving for drinking when dissolved in warm water. Therefore, the volume of the solid milk is, for example, 1 cm.sup.3 to 50 cm.sup.3, preferably 2 cm.sup.3 to 30 cm.sup.3, more preferably 4 cm.sup.3 to 20 cm.sup.3.
[0059] The solid milk in accordance with the present invention has to have certain solubility. The solid milk in accordance with the present invention, for example, has solubility of 180 sec or less, preferably 120 sec or less, more preferably 60 see or less under the below-described solubility measurement conditions. However, if the time is too short homogeneous liquid cannot be obtained. Therefore, it is preferred that the solubility be 5 sec or more.
[0060] The solid milk in accordance with the present invention has to have a certain strength to prevent it from fracturing during transportation. The solid milk in accordance with the present invention preferably has a hardness of 30 N or higher under the below-described tablet hardness measurement conditions. On the other hand, from the standpoint of solubility, the solid milk with hardness of 300 N or less is preferred.
2. Manufacturing Process
[0061] A method for manufacturing the solid milk in accordance with the present invention comprises a compacting process for compacting powdered milk and obtaining a solid compacted body of the powdered milk, a humidification process for humidifying the compacted body of powdered milk obtained in the compacting process, and a drying process for drying the compacted body of powdered milk obtained in the humidification process.
2.1. Compacting Process
[0062] The compacting process is the process for compacting powdered milk and obtaining a solid compacted body of the powdered milk. In the compacting process, a compacted body of the powdered milk maintaining pores for permeation is obtained by tableting the powdered milk under a comparatively low pressure sufficient for transferring the powdered milk to the next process. In the compacting process, the powdered milk is compacted so as to satisfy the condition of manufacturing a compacted body of powdered milk that is provided with adequate pores and has a shape retaining ability. Thus, the porosity in the compacting process is directly related to the porosity of solid milk. Furthermore, poor lubricating ability of the compacted body of powdered milk can cause troubles in making tablets, such as the adhesion of part of the compacted body of powdered milk to the equipment such as a tablet machine. Moreover, a problem associated with poor shape retaining ability of the compacted body of powdered milk is that it will not retain its shape in the process of manufacturing the solid milk.
[0063] It is preferred that only powdered milk be used as an ingredient in the compacting process and substantially no additives are added. A commercial powdered milk can be purchased or it may be manufactured by well-known manufacturing methods (for example, manufacturing methods described in Japanese Patent Laid-open Publication Nos. H10-262553, H11-178506, 2000-41576, 2001-128615, 2003-180244, and 2003-245039). Examples of powdered milk compositions are the same as those of the above-described solid milk. A fat may be added to the ingredient of the compacting process. However, if a fat is added, this fat. becomes an oil-off base. Furthermore, because the fat added to the milk adheres to the powdered milk surface, the die filling accuracy is decreased. Therefore, powdered milk manufactured so as to contain the target quantity of free fat is preferably used in the compacting process.
[0064] When the content ratio of fat in the powdered milk is high, a small compacting force can be used. On the other hand, when the content ratio of fat in the powdered milk is small, the compacting force has to be increased. Therefore, using powdered milk with a high content of fat makes it possible to satisfy the condition of manufacturing a compacted body of powdered milk that is provided with adequate pores and has a shape retaining ability. From this standpoint, the content ratio of fat in the powdered milk can be, for example, 5 wt % to 70 wt %, preferably 5 wt % to 50 wt %, more preferably 10 wt % to 45 wt %.
[0065] As mentioned above, the powdered milk preferably contains free fat. In accordance with the present invention, this free fat is effectively employed in place of a lubricant and so on. As a result, good solid milk can be manufactured without adding any additive. In the solid milk in accordance with the present invention, the content ratio f free fat is, for example, 0.5 wt % to 3 wt %, preferably 0.7 wt % to 2.4 wt %, more preferably 1 wt % to 2 wt %.
[0066] If the moisture content of the powdered milk is high, shape-retaining ability is degraded, and if the moisture content is low, the powdered milk becomes brittle (shape retaining ability is degraded). Accordingly, the moisture content ratio in the powdered milk is, for example, 1 wt % to 4 wt %, preferably 2 wt % to 3.5 wt %.
[0067] In the compacting process, the compacted body of powdered milk is manufactured with compacting means for compacting the powdered milk and obtaining a solid compacted body of powdered milk. The compacting means is not limited, provided that it can compact powdered milk and produce a solid compacted body of the powdered milk. Well-known pressure molding machines such as a tablet machine and a compacting testing machine can be used as the compacting means, and among them the tablet machine is preferred. Examples of suitable tablet machines are described in Japanese Examined Patent Publication No. S33-9237, Japanese Patent Laid-open Publication Nos. S53-59066, H6-218028, and 2000-95674, and Japanese Patent No. 2650493.
[0068] When a powdered material is compacted by using a tablet machine, the powdered, material is introduced into a die, a compacting force is applied to the powdered material with a punch, and a solid shape is obtained. If the powdered material has poor lubricating ability, the powdered material sometimes sticks to the punch surface. This not only degrades the product quality, but also makes it necessary to clean the punch surface, thereby decreasing the yield. For this reason, a lubricant is usually added, in particular in drug manufacture. However, the lubricant is a wax with poor solubility in water. Therefore, the addition of a lubricant is undesirable when a product is consumed after dissolving in warm water, as in the case of solid milk. This is one of the reasons why solid milk is difficult to manufacture. As described above, in accordance with the present invention, an appropriate amount of free fat, which has heretofore been considered as an undesirable component, is used as a lubricant, thereby preventing the powdered milk from sticking to the punch. Furthermore, as described above, producing a compacted body of powdered milk having the adequate porosity makes it possible to obtain readily soluble solid milk that excels in shape retaining ability. Furthermore, the addition of a disintegrating agent causes the formation of sediment, but in the method for manufacturing solid milk in accordance with the present invention, the disintegrating agent is unnecessary. Therefore, this problem can be effectively resolved.
[0069] Ambient temperature in the compacting process is not limited, and the process can be carried out at room temperature. More specifically, the ambient temperature in the compacting process is, for example, 10 C. to 30 C. Humidity in the compacting process can be, for example, 30% RH, to 50% RH. It is preferred that the powdered milk compaction operation be conducted continuously in the compacting process.
2.2. Humidification Process.
[0070] The humidification process is conducted to wet the compacted body of powdered milk obtained in the compacting process. Wetting the compacted body of powdered milk partially dissolves and bridges together the particles located close to the surface of the compacted body of powdered milk. As a result, the strength close the surface of the compacted body of powdered milk is increased.
[0071] In the humidification process, the compacted body of powdered milk can be wetted with humidification means for wetting the compacted body of powdered milk. Examples of humidification means include well known humidification means such as a high-humidity chamber, a sprayer, and steam. Furthermore, a method of placing in a high-humidity environment, a method of spraying water with a sprayer, and a method of blowing steam can be employed as the humidification means. Humidity of the high-humidity environment is, for example, 60% RH to 100% RH, preferably 80% RH to 100% RH, more preferably 90% RH to 100% RH. The duration of treatment under the high-humidity environment is, for example, 5 sec to 1 h, preferably 10 sec to 20 min, more preferably 15 sec to 15 min. The temperature in the method of placing under high-humidity environment is, for example, 30 C. to 100 C., preferably 40 C. to 80 C.
[0072] The amount of moisture (also referred to below as humidification amount) added to the compacted body of powdered milk may be appropriately adjusted. However, in accordance with the present invention, because substantially only powdered milk is used as an ingredient, the humidification amount is desirably within the following range, as indicated in the below-described embodiments (Embodiment 5) and shown in
2.3. Drying Process
[0073] The drying process is conducted to dry the compacted body of powdered milk that was humidified in the humidification process. Because the compacted body of powdered milk that was humidified in the humidification process is dried in the drying process, surface tackiness is eliminated and the solid milk can he handled as a product. Well-known methods capable of drying the compacted body of powdered milk that was humidified in the humidification process can be employed as drying methods in the drying process. Examples of suitable methods include a method of placing under a low-humidity and high-temperature atmosphere and a method of bringing into contact with dry air or high-temperature dry air.
[0074] Humidity in the method involving placing under a low-humidity and high-temperature atmosphere is, for example, 0% RH to 30% RH, preferably 0% RH to 25% RH, more preferably 0% RH to 20% RH. It is thus preferred that humidity be set to as low a level as possible. Temperature in the method involving placing under a low-humidity and high-temperature atmosphere is, for example, 20 C. to 150 C., preferably 30 C. to 100 C., more preferably 40 C. to 80 C. Drying time in the method involving placing under a low-humidity and high-temperature atmosphere is, for example, 0.2 min to 2 h, preferably 0.5 min to 1 h, more preferably 1 min to 30 min.
[0075] As described above, if the moisture content of solid milk is increased, shape retaining ability thereof is degraded, and if the moisture content is low, the solid milk become brittle. For this reason, in the drying process, the moisture content ratio of the solid milk is controlled to be no more than 1%(more preferably 0.5%) higher or lower than the moisture content ratio of the powdered milk used as the ingredient,
3. Method for Manufacturing Powdered Milk and Solid Milk
[0076] The method for manufacturing powdered milk and solid milk in accordance with the present invention comprises a process of manufacturing the powdered milk and a process of manufacturing the solid milk by using the powdered milk as an ingredient. Part of the powdered milk manufactured in the process for manufacturing the powdered milk can be placed as is in a container and used as a product. In this way, powdered milk and solid milk can be obtained.
3.1. Method for Manufacturing Powdered Milk
[0077] Specific features of methods for the manufacture of powdered milk differ depending on the type of product such as modified milk represented by whole powdered milk, defatted powdered milk, and powdered milk for infants. However, basically, powdered milk can he manufactured by a process comprising the following steps: ingredient (adjustment).fwdarw.clearing.fwdarw.sterilization.fwdarw.concentration.fwdarw.(homogenization).fwdarw.spray drying.fwdarw.sieving.fwdarw.filling. The size of powdered milk after spray drying is about 5 m to 150 m, and the size of the granulated powdered milk is about 100 m to 500 m. Furthermore, after the powdered milk is mixed with granules thereof, the pores obtained have a size of about 5 m to 150 m.
[0078] Milk is used as an ingredient for powdered milk. Fresh milk can be used as the milk. More specifically, milk of cows (Holstein cows, Jersey cows, and the like), goats, sheep, and buffalos can be used. The content ratio of fat in the milk can be adjusted by removing part of the fat by centrifugal separation or the like. Furthermore, the below-described nutritional components can be added. On the other hand, when a modified powdered milk is manufactured, the below-described nutritional components are used upon adding to water and mixing.
[0079] Powdered milk can be manufactured by treating the aforementioned liquid ingredient, starting material, by processes of clearing, sterilization, homogenization, concentration, spray drying, sieving, and filling.
[0080] Milk proteins and milk protein fractions such as casein, whey proteins (a-lactoalbumin, -lactoalbumin, and the like), whey protein concentrate (WPC), and whey protein isolate (WPI); animal proteins such as egg protein; vegetable proteins such as soybean protein and wheat protein; peptides of various chain length obtained by decomposing those proteins with enzymes or the like; and amino acids such taurine, cystine, cysteine, alginine, and glutamine can be used individually or in mixtures as proteins serving as ingredients for powdered milk.
[0081] Milk fat, lard, animal oils and fats such as beef tallow and fish oil, vegetable oils such as soybean oil, rapeseed oil, corn oil, coconut oil, palm oil, palm kernel oil, safflower oil, cotton seed oil, linseed oil, and MCT, fractionated oils, hydrogenated oils, and transesterified oils thereof can be used individually or in mixtures as oils and fats serving as ingredients for powdered milk.
[0082] Milk sugar, cane sugar, grape sugar, malt sugar, oligosaccharides such as galacto-oligosaccharides, fructo-oligosaccharides, and lactulose, polysaccharides such as starch, soluble polysaccharides, and dextrin, and artificial sweeteners can be used individually or in mixtures as sugars serving as ingredients for powdered milk.
[0083] Furthermore, water-soluble and fat-soluble vitamins, minerals, spices, and flavors can be added as ingredients for powdered milk.
3.1.1. Clearing Process
[0084] The clearing process serves to remove fine foreign matter contained, e.g., in the cow milk by well-known means such as a centrifugal separator or a filter.
3.1.2. Sterilization Process
[0085] The sterilization process serves to kill microorganisms such as bacteria that are contained, e.g., in the milk. Sterilization temperature and holding time of the sterilization process differ depending on the type of powdered milk, and conditions relating to well-known sterilization treatment can be employed.
3.1.3. Concentration Process
[0086] The concentration process is any process for concentrating, e.g., the cow milk in advance prior to the below-described spray drying process; well-known means such as vacuum evaporation tank and conditions can be employed for the concentration process.
3.1.4. Homogenization Process
[0087] The homogenization process is any process for homogenizing the solid components such as fat globules dispersed in the cow milk. Well-known means such as causing a liquid, which is to be treated, to pass through a narrow gap under a high applied pressure and conditions can be used in the homogenization process.
3.1.5. Spray Drying Process
[0088] The spray drying process serves to obtain a powder by evaporating water present in the condensed milk. Well known means such as a spray drier and well-known conditions can be employed in the spray drying process.
3.1.6. Sieving Process
[0089] The sieving process serves to remove particles with a large diameter such as powder aggregates by passing the powder obtained in the spray drying process through a sieve, thereby adjusting the particle-size of the powder.
3.1.7. Filling Process
[0090] The filling process serves to fill a bag or can with the powdered milk.
[0091] In the method for manufacturing powdered milk and solid milk in accordance with the present invention, after the powdered milk has been manufactured in the above-described manner, the above-described method for manufacturing solid milk can be employed. Thus, the above-described compacting process may be carried out by using as an ingredient the powdered milk that passed through the above-described sieving process.
4. Method for Using the Solid Milk
[0092] The solid milk in accordance with the present invention is generally dissolved in warm water and drunk. More specifically, warm water is poured into a container provided with a lid and then the necessary number of pieces of the solid milk in accordance with the present invention is placed therein. It is preferred that the solid milk be rapidly dissolved by lightly shaking the container and drunk in a state with an appropriate temperature.
[0093] The embodiments are described below and specific features of the present invention are explained. However, the present invention is not limited to those embodiments. First, methods for evaluating each evaluation item in the embodiments will be explained below and then reference examples and embodiments will be described.
Test 1. (Measurement of Solid Milk Porosity)
[0094] The porosity of solid milk was found by the following formula.
Porosity(%)=(1W/PV)100
[0095] W: weight of solids (g);
[0096] P: density of solids measured by using a Beckman air-type density meter (g/cm.sup.3);
[0097] V: volume calculated by measuring the diameter and thickness of solids with a micrometer (cm.sup.3).
Test 2 (Measurement of Free Fat Content Ratio)
[0098] The free fat content ratio was measured in the following manner. First, the solid milk was finely ground with a cutter, this was done so as not to grind it down entirely (grinding process). Then, the ground solid milk was passed through a 32 mesh sieve (sieving) process. The milk that passed through the sieve and the sieving process was used as a sample, and the content ratio of free fat was measured by the method described in Determination of Free Fat on the Surface of Milk Powder Particles, Analytical Method for Dry Milk Products, A/S NIRO ATOMIZER (1978). The content ratio of free fat determined by this method was represented by wt % of the fat extracted with carbon tetrachloride under shaking at constant rate within the prescribed time.
Test 3 (Measurement of Tablet Hardness)
[0099] The tablet hardness of solid milk was measured with a hardness tester manufactured by Fujiwara Seisakusho Co. Thus, a load was applied in the direction in which the surface area of the fracture surface of the sample became minimal and the load at the time of fracture was measured.
Test Example 4 (Solubility Measurement)
[0100] The solubility of the solid milk was measured in the following manner. First, 100 mL of water was placed into a glass container having a capacity of 200 mL and equipped with a lid and the temperature was set to 50 C. One piece of solid milk was placed into the water, immediately followed by shaking, and the time required for the complete dissolution of solid milk was measured. Shaking conditions were as follows: 1.5 reciprocal movements per 1 sec with an amplitude of 30 cm.
Test Example 5 (Floating Oil Measurement)
[0101] The floating oil (oil-off) was measured in the following manner. First, 50 mL of water at a temperature of 50 C. was prepared in a beaker with a capacity of 100 mL. One piece of solid milk was placed into the water and completely dissolved. The solution was allowed to stay for 2 h and the presence of oil drops was then visually evaluated.
Test Example 6 (Peroxide Value Measurement)
[0102] The peroxide value was measured in the following manner. Hot water at a temperature of 60 C. to 70 C. was added to a sample and an emulsion was obtained by thorough mixing and dissolution. An aqueous solution of a ionic surfactant (polyoxyoetylpheriol ether) and sodium tripolyphosphate was added to the emulsion and emulsification was terminated, followed by the separation into an oil layer and a water layer by centrifugal separation. The oil layer was taken out and measurements were conducted by an iodine titration method (Japan Oil Chemists' Society, Standard method for Oil and Fat Analysis and Testing, Peroxide Value (Chloroform Method). The value measured by this method was represented by a miliequivalent value of iodine separated when potassium iodide was added to the sample, this value corresponding to 1 kg of the sample, and was used as an indicator of oxidation and deterioration of lipids.
Test Example 7 (Taste Test)
[0103] In the taste test, a sample was dissolved in water at a temperature of 50 C. so as to obtain a concentration of 14 wt % and the solution was drunk by a panel of 10 people. Each sample was evaluated based on a 7-grade scale and assigned with numbers from 1 to 7 based on tastefulness thereof (4 being the central value representing the usual taste) and the evaluation was conducted by the average value.
Reference Example 1 (Manufacture of Powdered Milk)
[0104] Liquids obtained by adding sugars, proteins, milk, and minerals to water and mixing were treated in a sequence of processes including homogenization, concentration, and spray drying to manufacture powdered milk of various compositions.
Embodiment 1
(Relationship Between Compacting Force and Porosity, Solubility, Hardness)
[0105] The powdered milk obtained by the manufacturing method of the reference example (fats 25 wt %, sugars 58.3 wt %, proteins 11.7%, balance minerals and water) was compaction molded with a universal test autograph (manufactured by Shimazu Sedsakusho Co.) under a compacting force of 0.5 MPa to 30 MPa and a punch lowering speed of 10 mm/min. The compacted milk was then allowed to stay for 5 min under conditions of 40 C. and 95% RH in a thermostat with a constant humidity level (manufactured by TABAI ESPEC Co.). Then, it was dried for 30 min at 40 C. with an air oven (manufactured by Yamato Kagako Co.). A piece of solid with a diameter of 25 mm and a weight of about 5 g was thus obtained. The powdered milk used as an ingredient and the solid milk obtained herein were evaluated according to Test Examples 1 to 5. The results are shown in Table 1. Of the data shown in Table 1, the relationship between the porosity and dissolution time is shown in
TABLE-US-00001 TABLE 1 Compacting force and state of solid milk Compacting force (MPa) 0 0.5 1 2 5 7.5 10 15 20 30 Porosity (%) 62.7 54.8 51.9 48.6 39.5 35.4 31.8 30.1 25.7 19.3 Free fat (%) 0.46 0.69 0.77 0.69 1.29 1.80 2.39 2.66 3.57 5.75 Hardness prior prior to 0 1.5 5.1 8.2 32.9 53.3 68.6 83.8 116.5 181.7 humidification (N) Hardness (N) 18.3 30.2 40.3 81.8 106.0 140.3 154.4 185.3 291.0 Rapid solubility (sec) 10 10 10 10 20 40 50 110 278 490 Oil off () + +
TABLE-US-00002 Oil off evaluation No floating substance Fine floating substance with a size (0.5 mm or less) creating no problems in practical use were observed + Floating substance in the form of oil drops was observed (0.5 mm or more)
[0106]
[0107] Table 1 shows that if the compacting force exceeds 20 MPa, oil droplets are observed on the water surface, raising the oil-off problem. Oil-off was found to cause no practical problems when the compacting force was 15 MPa or less. Thus, from the standpoint of it is preferred that the porosity be 30% or higher and the compacting force be 15 MPa or less. Furthermore,
[0108] The tablet hardness of the compaction molded body is also increased by humidification and drying processes. The tablet hardness necessary for distribution and handling by the user is about 30 N and it can be attained by molding with a compacting force of 1 MPa, humidification, and drying.
[0109] It is clear that compaction conditions of a porosity of 30% to 50% and a compacting force of 1 MPa to 15 MPa are suitable for evaluating flowability, tablet hardness before and after humidification and drying, and oil-off.
Embodiment 2
[0110] (Using Milk in the Form of Powder and Granules with Different Fat Content)
[0111] Solid milk pieces with a diameter of 25 min and a weight of about 5 g were obtained by the processes and under conditions identical to those of Embodiment 1, except that the powdered milk with a fat content of 5% to 40% was molded with a compacting force of 5 MPa. The pieces were evaluated according to Test Examples 1 to 5. The results are shown in Table 2. The oil-off evaluation item was the same as in Embodiment 1.
TABLE-US-00003 TABLE 2 Content of fat and state of solid milk Fat content ratio (%) 5 10 18 25 30 40 Powdered Shape Granules Granules Granules Granules Powder Powder milk as Free fat (%) 0.03 0.28 0.46 0.46 1.33 1.48 ingredient Molded Porosity (%) 45.0 42.2 41.5 39.5 36.3 31.0 product Free fat (%) 0.11 0.51 0.84 1.29 3.02 3.93 Hardness prior to 0 4.2 12.5 32.9 17.4 30.0 humidification (N) Hardness (N) 18.1 17.6 46.0 81.8 25.9 83.0 Rapid solubility 30 20 30 20 40 50 (sec) Oil off ()
[0112] When the powdered milk with a fat content of 5% was used, the compaction molded body (free fat 0.11%) before humidification and drying treatment had a very low hardness and was difficult to transfer to the next process. When the powdered milk with a fat content of 10% or higher was used, compaction molded bodies with good properties were obtained, regardless of the presence of the granulation stage.
[0113] Thus, the powdered milk containing a certain amount of fat makes it possible to obtain compaction molded bodies combining hardness with solubility, which are reciprocal properties, without the addition of special additives, by adjusting the compacting force, porosity, and free fat amount to the ranges limited by the present invention.
Embodiment 3
(Effect of Free Fat)
[0114] The results obtained in Embodiment 2 showed that when the powdered milk with a fat content of 5% was used, the compaction molded body before humidification and drying treatment had a very low hardness The augmenting effect of free fat on hardness was studied by adding (i) 0.5 wt (ii) 1.0 wt %, and (iii) 2.0 wt % butter oil (manufactured by Corman Co.) to the powdered milk comprising 5% fat and conducting the compaction molding under the conditions described in Embodiment 2. The results are shown in Table 3.
TABLE-US-00004 TABLE 3 Amount of fat added and state of solid milk Amount of butter oil added (%) 0 0.5 1 2 Porosity (%) 45.9 45.6 45.6 44.7 Hardness prior to 0 0 0 0 humidification {circle around (1)} (N) Hardness prior to 0 7.2 7.3 7.3 humidification {circle around (2)} (N) {circle around (1)} Compaction molding immediately after the addition of butter oil {circle around (2)} Butter oil is added, and compaction molding is conducted for 2 days in a sealed container
[0115] When compaction molding was conducted immediately after adding the butter oil, hardness was very low in all the cases, but when compaction molding was conducted after 2 days, a hardness of about 7 N was obtained. When no butter oil was added, a very low hardness was obtained regardless of the stay interval. Because no significant difference in porosity of the compaction molded bodies was observed, it is clear that the addition of oil acted to augment the shape retention ability.
[0116] The above-described results suggest that if fat is added, it does not merely contribute to the increase in hardness, but the fat that penetrated from the surface of powdered milk particles into inner zones thereof with the passage of time and is present therein acts to augment the hardness. When a solid fat that in a wax-like form at room temperature (palm hardened oil, melting point 58 C., manufactured by Oya Yushi K. K.) was added instead of the butter oil, which is a liquid at room temperature, the hardness increase effect was not obtained.
[0117] Solid fat (wax) is generally known to demonstrate a lubricating action reducing friction during compaction molding and has been widely used for this purpose. However, when compaction molding under a low pressure is required to ensure cavities, as in accordance with the present invention, the fat effectively acts both to impart lubricating properties and augment the shape retention ability. Adding a fat that is liquid at room temperature is effective for this purpose, but because an additional process is required and the flow-ability of the powder having a liquid fat added thereto decreases and die filling accuracy also decreases, a very effective approach is to free the fat that has originally been present in powdered milk from the emulsified product in an amount necessary for compaction molding.
Embodiment 4
(Ensuring Productivity)
[0118] The powdered milk obtained by the manufacturing method of the reference example (fats 25 wt %, sugars 58.3 wt %, proteins 11.7%, balance minerals and water) was continuously compaction molded for 1 h under the conditions of a compacting force of 5 MPa and a rate of 20 pieces/min. (1200 pieces/h) in a single-punch tablet machine (manufactured by Okada Seiko Co.), Then, the moldings were allowed to stay for 5 min under conditions of 40 C. and 95% RH in a thermostat with a constant humidity level (manufactured by TABAI ESPEC Co.) and dried for 30 rain at a temperature of 40 C. in an air oven (Yamato Kagaku K. K.) to obtain solid milk with a diameter of 25 mm and a weight of about 4.2 g.
[0119] In continuous making tablets for 1 h, damage for making tablets caused by the powder sticking to the die and punch was not observed and the operation was not interrupted. The results of continuous tablet test are shown in Table 4. The compacted molded body had a hardness of 10 N and no troubles, such as loss of shape, were encountered when it was transferred to the humidification process. The solubility of the solid milk body manufactured via the drying process was within 30 see and this body had a sufficient tablet hardness of 92.5 N. No oil-off was observed and the taste was not different from that of the powdered milk used as an ingredient. The porosity of the solid milk body was 36.3% and the content ratio of free fat was 0.54%.
TABLE-US-00005 TABLE 4 Continuous tablet test Powdered milk Solid of ingredient milk Porosity (%) 36.3 Hardness prior to 10.0 humidification (N) Hardness (N) 92.5 Rapid solubility (sec) 10 30 Free fat (%) 0.09 0.54 Oil off () Taste () 4.10 4.10
Embodiment 5
(Study of Humidification Conditions)
[0120] Humidification conditions were studied by using as a sample a compaction molded body (diameter 27 mm, weight about 7 g) obtained by compaction molding the powdered milk (fats 25 wt %, sugars 58.3 wt %, proteins 11.7%, balance minerals and water) with a universal test autograph (manufactured by Shicaazu Seisakusho Co.) under a compacting force of 5 MPa and a compaction rate of 10 mm/min.
[0121] The sample was then allowed to stay for a fixed time at 80 C. and 100% RH (combination oven, manufactured by Fujimach Co.) or 40 C. and 95% RH (thermostat with a constant humidity level, manufactured by TABAI ESPEC Co.) and the weight of moisture added by humidification was found by measuring the weight before and after the humidification. Then, drying was conducted for 30 min at a temperature of 40 C. in an air oven (manufactured by Yarnato Kagaku Co.) and the tablet hardness was measured. The relationship between the humidification time and tablet hardness found in Embodiment 5 is shown in
TABLE-US-00006 TABLE 5-1 Conditions: temperature 80-100% RH Humidifica- 0 5 10 15 30 60 90 120 180 tion time (sec) Humidifica- 0 0.5 0.5 0.8 1.1 1.5 2 2.5 2.8 tion weight (%) Hardness 12.7 22.5 23 31.3 56.5 96.7 103 119 114 after drying (N)
TABLE-US-00007 TABLE 5-2 Conditions: temperature 40-95% RH Humidification time 0 60 120 180 300 600 900 (sec) Weight of moisture 0 0.5 0.7 0.9 1.2 1.6 1.9 added by humidification (%) Hardness after 12.7 17.3 25 29.5 39.5 64.8 78.2 drying (N)
[0122]
Embodiment 6
(Long-Term Storage Ability)
[0123] The solid milk manufactured under a compacting force of 5 MPa of Embodiment 1 and the powdered milk used as an ingredient were placed in aluminum packages and stored for 3 months at a temperature of 30 C. and the dissolution time, tablet hardness, free fat, peroxide value, oil-off, and taste were examined following the test example. The results are shown in Table 6. From Table 6 it follows that the dissolution time, tablet hardness, free fat, oil-off, and taste after the storage were identical to the initial values at the time of manufacture. The peroxide value was about the same as that of the powdered milk used as an ingredient. The results described above demonstrate that the solid milk obtained by the manufacturing method in accordance with the present invention has excellent long-term storage ability.
TABLE-US-00008 TABLE 6 Long-term storage ability at a temperature of 30 C. Tablet Powdered milk (ingredient) Test item Initial After 3 months Initial After 3 months Free fat (%) 1.28 1.39 0.54 0.59 Peroxide value 0.08 0.95 0.12 0.78 (meq/kg) Oil off () Taste () 4.08 4.09 4.00 3.91 Dissolution 30 30 time (sec) Tablet 42 43 hardness (N)
[0124] Because it is clear that a marketable product can be produced when the solid milk in accordance with the present invention is actually manufactured, the solid milk and the method for the manufacture thereof in accordance with the present invention can be employed in food industry as a replacement for powdered milk and a method for the manufacture thereof.