AU769958B2

AU769958B2 - Manufacturing procedure of powdered milk

Info

Publication number: AU769958B2
Application number: AU42412/99A
Authority: AU
Inventors: Masayuki Eto; Tomoyuki Fujii; Tadashi Idota; Hiroshi Morita; Norifumi Sato; Masaharu Shimatani
Original assignee: Snow Brand Milk Products Co Ltd
Current assignee: Megmilk Snow Brand Co Ltd
Priority date: 1998-07-31
Filing date: 1999-07-30
Publication date: 2004-02-12
Anticipated expiration: 2019-07-30
Also published as: AU4241299A

Description

1

AUSTRALIA

Patents Act 1990 Snow Brand Milk Products Co., Ltd.

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: Manufacturing procedure of powdered milk The following statement is a full description of this invention including the best method of performing it known to us:- Background of the Invention Field of the Invention This invention relates to a process of producing powdered milk by a multinozzle spray system, which sprays multiple ingredients individually with different spray nozzles, or by a fluidized-bed manufacturing system. In particular, the present invention relates to a process of producing powdered milk by mixing metal components S. 10 and fat components containing polyunsaturated fatty acids, without a process of liquidto-liquid mixing or powder-to-powder mixing.

og o. Description of the Related Art •go° Polyunsaturated fatty acids, which are composed of no less than eighteen 15 carbons and no less than three double-bonds, such as c-linolenic acid, y-linolenic acid, dihomo-y-linolenic acid, arachidonic acid, eicosapentaenoic acid, and docosahexanoic acid, act physiologically in vivo, by themselves or when metabolized to prostaglandin, to adjust blood pressure, hormone secretion, or cholesterol concentration. Thus, polyunsaturated fatty acid-containing fats such as soy bean oil, evening primrose oil, perilla oil, and fish oil have been tentatively added to nutritious supplements, functional foods, pharmaceutical products, cosmetics, and feeds.

However, such polyunsaturated fatty acids can be oxidized easily by heat, light and oxygen, and can produce distinctive odors and harmful substances when oxidized.

Thus, it has been extremely difficult to produce nutritional supplements, functional foods, pharmaceutical products, cosmetics or feeds with polyunsaturated fatty acidcontaining fats.

There are several suggestions to prevent foods or polyunsaturated fatty acidcontaining fats from being oxidized. For example, a method of adding a mixture of an antioxidant and an oxidation-synergistic agent into polyunsaturated fatty acidcontaining fats (Japanese Patent Application Laid-open No. 60-192547, Japanese Patent Application Laid-open No. 61-212243, Japanese Patent Application Laid-open No. 2- 166194), and a method of reforming polyunsaturated fatty acid-containing fats, -11.

especially fish oil apt to be highly deteriorated by oxidation, by transesterification with saturated fatty acids (Japanese Patent Application Laid-open No. 8-269477).

When polyunsaturated fatty acid-containing fats contact metals such as iron, copper, and zinc in solution, not only a distinctive metallic taste but also an offensive odor will develop as polyunsaturated fatty acids can be easily oxidized. As to foods wherein polyunsaturated fatty acids and metals such as iron, copper, and zinc co-exist, the use of conventional antioxidants or methods of stabilizing the oil itself could not long suppress deterioration in quality such as a distinctive smell of oxidized oil.

As a method of suppressing this particular smell, a technique of adding masking 10 agents, such as lecithin, having an effect of preventing oxidation, is reported (Japanese Patent Application Laid-open No. 3-130042), but there is a problem in that the foods which can adopt this technique are limited because the masking agent itself frequently contains a distinctive odor. In addition, another method is reported to prevent oxidation in the manufacture of oil contained in powdered milk, by separately condensing and 15 spray-drying an O/W (oil-in-water) emulsion comprising fats containing unsaturated fatty acids and a solution containing metals such as iron, copper and zinc which can *°oooo promote oxidization of the unsaturated fatty acids, followed by mixing the respective go•• thus-obtained powders, power-to-power mixing (Japanese Patent Application Laidopen No. 6-245698). However, mixing powders produced by spray-drying requires S 20 extensive labor and well equipped facilities.

In view of nutrition, it is very useful to provide foods in which polyunsaturated fatty acids exhibiting several physiological actions, coexist with metals such as iron, copper and zinc, which exist as trace elements in living organisms and are necessary substances for normal growth and maintaining life. However, there is a problem in that polyunsaturated fatty acids are oxidized and deteriorate easily by contact with metals such as iron, copper and zinc. For example, when divalent metal ions that are reported to be highly absorbed in the human body (3A Infant Dietetics of New Pediatric Medical University, Nakayama Book Store, 1998) are used, there is a problem in that oxidation of polyunsaturated fatty acids cannot be suppressed simply by adding antioxidants; or rather, the polyunsaturated fatty acids in the solution are easily oxidized due to the strong oxidation catalytic ability of the divalent metal ions.

Summary of the Invention For the above reasons, although powdered milk, to which metal components and polyunsaturated fatty acid-containing fats are added, is known, the powdered milk has been produced conventionally by power-to-power mixing powered milk containing polyunsaturated fatty acid-containing fats and (ii) trace metals such as iron, copper, and zinc which can promote oxidation of polyunsaturated fatty acids, in order to long prevent deterioration in quality such as a reverted oil flavor. However, mixing powders requires extensive labor, facilities, and quality control. The present inventors have 10 conducted intensive research on a technique that could produce powdered milk easily :1 and effectively by adding both metal elements and polyunsaturated fatty acid-containing o fats, without mixing powders. As a result, the present inventors have discovered that it is possible to produce powdered milk having as good quality, flavor, and/or shelf stability as those produced by mixing powders: At least either a first component, which 15 comprises a first active ingredient, or a second component, which comprises a second active ingredient, comprises raw materials for powdered milk; and agglomeration of a mixture of the first and second components is conducted by mixing the components while at least either the first component or the second component is being spray-dried from a liquid state while spray-drying of at least one of the components is in 20 progress or before the spray-drying is complete). Accordingly, the present invention has been completed.

According to an embodiment of the present invention (Embodiment A), powdered milk is manufactured by mixing a first component and a second component while separately spray-drying a solution of the first component and a solution of the second component by using different spray nozzles. According to another embodiment (Embodiment agglomeration is performed while a first component, used as a binding solution, is sprayed onto a second component, used as a raw material powder.

According to another embodiment of Embodiment A of the present invention, a powdered milk having the components well dispersed and having a good classification characteristic can be produced by spray-drying plural solutions containing different ingredients wherein the spraying zone of each spray nozzle overlaps another spraying zone by adjusting the angle of each spray nozzle and the distance between the adjacent spray nozzles. Thus, according to Embodiment A, a method is provided to produce a powdered milk; which comprises mixing ingredients while separately spray-drying multiple solutions containing different ingredients by using respective spray nozzles. In particular, a method is provided to produce a powdered milk; which method comprises mixing ingredients while spray-drying the ingredients in such a way that the spraying zone of each spray nozzle overlaps another spraying zone by adjusting the angle of each spray nozzle and the distance between the adjacent spray nozzles.

Further, particularly in Embodiment B of the present invention, a problem, 10 which resides in a manufacturing process of a one-solution spraying system that is conventionally conducted, is resolved. That is, in the conventional process, a Sconcentrated liquid such as milk is sent to a drying machine by using a high-pressure 555.

pump, wherein minute droplets produced by pressure or centrifugal force are atomized into the interior of the drying machine and mixed with heated air. The moisture of the 15 droplets continuously evaporates, and moist powder having a relatively high water content deposits inside an internal fluidized bed and is subjected to fluidized-bed drying. In the internal fluidized bed, because the density of moist powder increases, oooo 0 agglomerate is produced as a result of repeatedly binding and drying moist particles.

Further, for the purpose of surface modification of powder, another method is also 20 conducted wherein a lecitin solution, for example, is sprayed onto powder through a spray nozzle in the internal fluidized bed or in an external fluidized bed disposed outside the drying machine, thereby forming agglomerate via twice moistening.

However, it is extremely difficult to maintain good quality, flavor and shelf stability of powdered milk containing active ingredients such as trace metals and polyunsaturated fatty acid-containing fats that are not milk ingredients, when the powdered milk is produced by the above agglomeration method when using a solution containing all ingredients.

For the above reasons, as in Embodiment A, Embodiment B of the present invention also develop a technique that can more easily and efficiently manufacture a powdered milk which contains active ingredients that are not milk components, such as trace metals and polyunsaturated fatty acid-containing fats, which powdered milk is conventionally manufactured by mixing powders. That is, according to an embodiment of Embodiment B, the powdered milk containing active ingredients, which are not milk components, and having the same quality, flavor and shelf stability as those manufactured by the conventional process, can be manufactured by fluidizing a raw material powder obtained by spray-drying a milk comprising polyunsaturated fatty acidcontaining fats, in an internal fluidized bed disposed at the bottom of a drying machine or in an external fluidized bed disposed outside the drying machine, and by spraying a solution containing trace metals, for example, supplied as a binding solution from a spray nozzle, directly onto the fluidizing material powder.

In addition, according to another embodiment of the present invention, by reducing the quantity of free fats in the powder, deterioration in the quality of the product, such as an unpleasant smell caused by fat oxidation can be prevented.

Detailed Description of the Preferred Embodiment Basic Aspect of First Embodiment In one embodiment of the present invention (Embodiment a multi-nozzle system (J.

of the Society of Dairy Technology, vol. 43, 1990), which is a method allowing efficient spray-drying of a single solution of uniform components by using multiple spray nozzles, is basically adopted to manufacture a powdered milk by mixing components while individually spray-drying multiple solutions containing different ingredients 20 through different spray nozzles. In particular, in this embodiment, the method is for mixing ingredients while spray-drying multiple solutions containing different components using high-pressure pumps disposed in respective lines. With this method, a powdered milk having components uniformly dispersed can be manufactured because components easily influenced when contacting each other in a liquid state can be spraydried separately.

In addition, when spray-drying the multiple solutions containing different ingredients separately under conditions where the spraying zone of each spray nozzle overlaps another spraying zone by adjusting the angle of each spray nozzle and the distance between the adjacent spray nozzles, a powdered milk having components well dispersed and having a good classification characteristic can be manufactured.

By using above embodiment of the present invention, a powdered milk, which has good quality and flavor and has long shelf life, can be manufactured by mixing components while spray-drying the multiple solutions containing different ingredients through different nozzles by using respective high-pressure pumps disposed on different lines. For example, when manufacturing a powdered milk comprising polyunsaturated fatty acid-containing fats as well as metals, the following embodiments may be included: First, a solution comprising polyunsaturated fatty acids-containing fats is in the form of an O/W emulsion concentrated-solution. A solution comprising trace metals such as iron, copper and zinc, which promote oxidization of polyunsaturated fatty acids, is then prepared separately from the O/W emulsion solution. The components are mixed while spray-drying the respective solutions sprayed through different spray nozzles by using high-pressure pumps disposed on different lines to produce a powdered milk which comprises polyunsaturated fatty acid-containing fats as well as trace metals and which maintains good quality, flavor, and shelf stability.

Basic Aspect of Second Embodiment Another embodiment (Embodiment B) of the present invention is a process of manufacturing agglomerate of powdered milk comprising non-milk active ingredients such as trace metals and polyunsaturated fatty acid-containing fats, based on the principle of conventional agglomeration methods. In this embodiment, first, a solution 20 which is composed mainly of milk components and further comprises polyunsaturated fatty acid-containing fats is concentrated and spray-dried to obtain a raw material powder. Another solution, which comprises a component, such as metal, causing undesired effects when coexisting with active ingredients such as polyunsaturated fatty acid-containing fats in a liquid state, is used as a binding solution. By spraying the binding solution directly onto the raw material powder in the internal fluidized bed disposed at the bottom of the drying machine and in the extemrnal fluidized bed disposed outside of the drying machine, through spray nozzles arranged inside the fluidized bed, C*agglomerate of powdered milk, which comprises active ingredients other than milk and which has good quality, flavor, and shelf stability, can be produced. For example, a process of manufacturing agglomerate of powdered milk comprising trace metals and polyunsaturated fatty acid-containing fats may be as follows: First, the quantity of free fats is reduced by homogenizing the solution composed mainly of milk components and further of polyunsaturated fatty acid-containing fats under high pressure to obtain an O/W emulsion concentrated-solution. The solution comprising trace metals such as iron, copper, and zinc which can promote oxidation of polyunsaturated fatty acids is prepared as a binding solution. The first solution and the second solution are prepared separately. The O/W emulsion concentrated-solution comprising polyunsaturated fatty acid-containing fats is then spray-dried in the drying machine to obtain a raw material powder. The raw material powder is then fluidized in the internal fluidized bed at the bottom of the drying machine or in the external fluidized bed located outside the drying machine. While the raw material powder is fluidizing, the binding solution containing trace metals such as iron, copper, and zinc is sprayed onto the powder through spray nozzles disposed inside the fluidized bed, while mixing the components to obtain agglomerate. Accordingly, through the above processes, the agglomerate of powdered milk, which contains polyunsaturated fatty acid-containing fats and trace metals and which has good quality, flavor, and shelf stability, can be produced.

In the above, in order to effectively conduct agglomeration, the addition of gelatin, dextrin, starch, alginic acid soda, or lecithin as a binding agent is known (Edited "by Japanese powder industry group "granule manufacturing guide" Ohmusha published i 1975 J of the society of Dairy Technology, vol. 43, 1990). In contrast, this invention 20 suppresses deterioration of powdered milk caused by oxidation, by adding trace metals, which can have negative effects when coexisting with the other components in a liquid state, to the binding solution. Thus, the present invention is a completely different method from the above conventional method which uses a binding solution to which a binding agent is solely added.

In addition, according to this embodiment, by reducing the quantity of free fats in the raw material powder when producing a powdered milk containing active ingredients other than non-milk components, agglomerate of powdered milk having good quality, flavor, and shelf stability can be produced. In the above, the quantity of free fats can be reduced by homogenizing the solution to be spray-dried under high pressure.

Material for Powdered milk In the present invention, proteins which can be used as a raw material for powdered milk include lactic protein and fractionated milk protein such as casein, whey protein concentrate (WPC), whey protein isolate (WPI), a-casein, 3-casein, calactalbumin, and 3-lactoglobulin; animal protein such as egg protein; vegetable protein such as soy protein; glutenin; peptides having various lengths decomposed by enzymes; and amino acid such as taurine, cystine, cysteine, arginine and glutamine. These ingredients can be used singly or by any combination.

In the present invention, fats and oils which can be used a raw material for powdered milk include animal fats such as milk fat, lard, beef tallow, and fish oils; or vegetable oils such as soy oil, rapeseed oil, corn oil, coconut oil, palm oil, palm kernel oil, safflower oil, perilla oil, linseed oil, evening primrose oil, MCT and cottonseed oil; and fractionated oils; hydrogenated oils, and ester interchanged oils derived from the foregoing. These ingredients can be used singly or in any combination.

In the present invention, saccharides which can be used as a raw material for powdered milk include starch, soluble polysaccharide, dextrin, sucrose, lactose, maltose, glucose, and oligosaccharides such as galacto oligosaccharide, fructo oligosaccharide, and lactulose, and artificial sweeteners. These ingredients can be used singly or in any combination.

i In the above, it can be determined whether polyunsaturated fatty acid-containing 20 fats are added as an active ingredient to obtain an O/W emulsion solution or whether °trace metals such as iron, copper, and zinc are added as other active ingredients to obtain a solution, how the above components are divided in different solutions, .depends on or considers potential undesired effects on the other components. In brief, S: active ingredients that can undesirably or adversely interact with other ingredients in a liquid state should be separated into a first component and a second component (or can oeee be separated into a higher number of solutions such as a three-component system or a four-component system), and a raw material(s) for powdered milk can be added to any :::solution in view of ease of agglomeration or can be allocated into the solutions.

"Active Ingredients In the present invention, several components can be used as active ingredients, and can be added without deterioration of quality of powdered milk even if they are ingredients that can react with other ingredients in a liquid state. For example, polyunsaturated fatty acid-containing fats that can be added into a powdered milk may be any fats composed of no less than eighteen carbons and no less than three doublebonds, such as a-linolenic acid, y-linolenic acid, dihomo-y-linolenic acid, arachidonic acid, eicosapentaenoic acid, and docosahexanoic acid. Examples of such fats include soybean oil, evening primrose oil, borage oil, black currant oil, perilla oil, fish oil, egg yolk phospholipid extract, and fermented microorganism products.

In the present invention, other ingredients, which can be added into the powdered milk as other active ingredients, may be metals including copper salts such as copper sulfate, cupric carbonate, cupric citrate, cupric sulfate, and copper gluconate, iron salts such as ferrous carbonate, ferrous fumarate, ferrous succinate, ferric chloride, ferrous citrate, ferric citrate, sodium ferric citrate, ferric ammonium citrate, ferrous gluconate, ferric gluconate, ferrous lactate, hydrogen reduced iron, carbonyl iron, ferrous pyrophosphate, ferric pyrophosphate, sodium ferric pyrophosphate, and ferrous sulfate; and zinc salt such as zinc acetate, zinc chloride, zinc oxide, zinc gluconate, and zinc sulfate.

Various Aspects of Production Process In the present invention, an important point when conducting spray-drying through separate spray nozzles in order to mix ingredients evenly, is that the ratio of 20 respective solutions to be sprayed must be constant, and the starting time and the ending .time of the respective solutions' spraying must be synchronized. In this regards, it is suggested that orifices and cores attached to the spray nozzles be chosen properly by calculating the spraying ratio per time unit from the gross weight of each solution. In particular, in Embodiment A, it is preferable that the angle of the spray nozzles and the distance between the adjacent nozzles be adjusted so that adjacent spraying zones i'"'"overlap by 1% to 90%, more preferably 1% to In Embodiment B, if the content of free fats is high in a raw material powder, trace metals present in a binding solution to be sprayed in the fluidized bed tends to easily contact the free fats included in the raw material powder. Therefore, it is suggested for extending shelf stability that the content of free fats of the raw material powder be reduced. In addition, a decrease in the ratio of free fats to the fats of the raw material powder indicates that the protective coating on the powder surface is formed sufficiently, thereby preventing deterioration caused by fat oxidation. For the above reasons, it is preferable to reduce free fats in the product as much as is practical. For example, by reducing free fats to no more than the peroxide value can be as low as no more than 1.5 meq/kg after an accelerated storage test, indicating that a powder having excellent oxidation stability can be produced. In addition, in order to reduce free fats, it is preferred that a fat-containing solution is subjected to homogenization under high pressure in advance.

For example, when a solution has a ratio of fat to protein of 1.0 to 2.5, under a homogeneous pressure between 150 and 450 kg/c m2, the relationship simulated by a formula Y=-0.0039X 1.8274 can be established, wherein X is homogeneous pressure, and Y is free fat content. In the present invention, free fats are defined as neutral fats that can be extracted from powder containing fats with tetracarbon that is a nonpolar solvent (Noda M and Shiinoki J. Texture Studies, vol. 17, p. 189, 1986). The quantity of free fats can be calculated by the formula; Free fat Content {(Quantity of Extracted Fat)/(Gross Weight of Powder)) x 100.

As described above, powdered milk containing trace metals and polyunsaturated fatty acid-containing fats is a desirable product in terms of quality, flavor, and shelf S.stability, and the product can maintain good quality for a long period of time.

EXAMPLE

The present invention will be explained in detail with reference to examples and tests as follows: Example 1 To a solution obtained by adding 8.8 kg of whey protein concentrate (WPC) and 52 kg of lactose to 200 kg of water, added were 75 kg of milk, 3.9 kg of casein dissolved with alkali, 1.45 kg of water-soluble vitamins (vitamin B 1, vitamin B2, niacin, vitamin B6, biotin, folic acid, pantothenic acid, vitamin B12, vitamin C, choline, and inositol) and minerals (calcium, phosphorus, chlorine, magnesium, potassium, iodine, manganese, and selenium), and 25 kg of fats containing polyunsaturated fatty acids (soy bean oil, evening primrose oil, and fish oil) containing oil-soluble vitamins (vitamin A, -carotene, vitamin D, vitamin E, and vitamin K) and antioxidants (vitamin C palmitate, lecithin, and tocopherol). The mixture was homogenized and sterilized by heating to obtain 247 kg of an O/W concentrated emulsion including polyunsaturated fatty acid-containing fats with a solid matter of 40 On the other hand, a concentrated casein solution containing 1 kg of casein dissolved with alkali was prepared, and 0.05 kg of copper, iron and zinc dissolved in water was added to the casein solution to obtain 25 kg of a metal-combined casein solution having a concentration of 4%.

The O/W emulsion concentrated-solution comprising fats having polyunsaturated fatty acids and the metal-coupled casein solution were sprayed at a liquid ratio of 91:9 from respective spray nozzles (Type SX SPRAYDRY NOZZLE SPRAYING SYSTEM'S CO) disposed at an upper part of the drying machine using high-pressure pumps provided on different lines. In the above, the spray nozzles were arranged to overlap their spraying zones by 60% by adjusting their angles and the distance between the spray nozzles. In the spray nozzle for the O/W emulsion concentrated-solution including polyunsaturated fatty acids, orifice No. 54 and core No.

21 were used, and in the spray nozzle for the casein solution comprising metals, orifice No. 71 and core No. 16 were used. Spraying pressure under normal conditions was 140 kg/cm2. Accordingly, 100 kg of powdered milk, which contained trace metals such as copper, iron, and zinc, as well as polyunsaturated fatty acid-containing fats, were produced.

Example 2 To a solution obtained by adding 9.4 kg of whey protein concentrate (WPC) and 55 kg of lactose to 300 kg of water, added were 6.1 kg of casein dissolved with alkali, 1.95 kg of water-soluble vitamins (vitamin B 1, vitamin B2, niacin, vitamin B6, biotin, e •folic acid, pantothenic acid, vitamin B12, vitamin C, choline, and inositol) and minerals (calcium, phosphorus, chlorine, magnesium, potassium, iodine, manganese, and -"'""selenium), and 27.8 kg of fats containing polyunsaturated fatty acids (soy bean oil, evening primrose oil, fish oil, and a fermented microorganism product) containing oilsoluble vitamins (vitamin A, 3-carotene, vitamin D, vitamin E, and vitamin K) and antioxidants (vitamin C palmitate, lecithin, and tocopherol). The mixture was homogenized and sterilized by heating to obtain 247 kg of an O/W concentrated emulsion including polyunsaturated fatty acid-containing fats with a solid matter of On the other hand, a concentrated 5% casein solution containing 1 kg of casein dissolved with alkali was prepared, and 0.05 kg of copper, iron and zinc dissolved in water was added to the casein solution to obtain 25 kg of a metal-combined casein solution having a concentration of 4%.

The O/W emulsion concentrated-solution comprising fats having polyunsaturated fatty acids and the metal-coupled casein solution were sprayed at a liquid ratio of 91:9 from respective spray nozzles (Type SX SPRAYDRY NOZZLE SPRAYING SYSTEM'S CO) disposed at an upper part of the drying machine using high-pressure pumps provided on different lines. In the above, the spray nozzles were arranged to overlap their spraying zones by 90% by adjusting their angles and the distance between the spray nozzles. In the spray nozzle for the O/W emulsion concentrated-solution including polyunsaturated fatty acids, orifice No. 54 and core No.

S. •Example 3 S.To a solution obtained by adding 9.4 kg of whey protein concentrate (WVPC) and 55 kg of lactose to 300 kg of water, added were 6.1 kg of casein dissolved with alkali, 1.95 kg of water-soluble vitamins (vitamin B 1, vitamin B2, niacin, vitamin B6, biotin, folic acid, pantothenic acid, vitamin B12, vitamin C, choline, and inositol) and minerals (calcium, phosphorus, chlorine, magnesium, potassium, iodine, manganese, and S selenium), and 27.6 kg of fats containing polyunsaturated fatty acids (soy bean oil, evening primrose oil, fish oil, and an egg yolk phospholipid extract) containing oilsoluble vitamins (vitamin A, -carotene, vitamin D, vitamin E, and vitamin The mixture was homogenized and sterilized by heating to obtain 247 kg of an O/W concentrated emulsion including polyunsaturated fatty acid-containing fats with a solid matter of 40 On the other hand, a concentrated 5% casein solution containing 1 kg of casein dissolved with alkali was prepared, and 0.05 kg of copper, iron and zinc -12dissolved in water was added to the casein solution to obtain 25 kg of a metal-combined casein solution having a concentration of 4%.

Example 4 To a solution obtained by adding 7.5 kg of whey protein concentrate (WPC) and ii 40.3 kg of lactose to 240 kg of skimmed milk, added were 70 g of casein dissolved with alkali, 0.65 kg of water-soluble vitamins (vitamin B1, vitamin B2, niacin, vitamin B6, biotin, folic acid, pantothenic acid, vitamin B12, vitamin C, choline, and inositol) and minerals (calcium, phosphorus, chlorine, magnesium, potassium, iodine, manganese, and selenium), and 28.1 kg of fats containing polyunsaturated fatty acids (soy bean oil, evening primrose oil, fish oil, a fermented microorganism product, and an egg yolk phospholipid extract) containing oil-soluble vitamins (vitamin A, -carotene, vitamin D, vitamin E, and vitamin K) and antioxidants (vitamin C palmitate, lecithin, and tocopherol). The mixture was homogenized and sterilized by heating to obtain 247 kg of an O/W concentrated emulsion including polyunsaturated fatty acid-containing fats with a solid matter of 40 On the other hand, a concentrated 16% casein solution containing 3.75 kg of lactose was prepared, and 0.05 kg of copper, iron and zinc dissolved in water was added to the casein solution to obtain 25 kg of a metal-combined casein solution having a concentration of -13- The O/W emulsion concentrated-solution comprising fats having polyunsaturated fatty acids and the metal-coupled casein solution were sprayed at a liquid ratio of 91:9 from respective spray nozzles (Type SX SPRAYDRY NOZZLE SPRAYING SYSTEM'S CO) disposed at an upper part of the drying machine using high-pressure pumps provided on different lines. In the above, the spray nozzles were arranged to overlap their spraying zones by 90% by adjusting their angles and the distance between the spray nozzles. In the spray nozzle for the O/W emulsion concentrated-solution including polyunsaturated fatty acids, orifice No. 54 and core No.

Example The O/W emulsion concentrated-solution comprising fats having polyunsaturated fatty acids and the metal-coupled casein solution, which were obtained as in Example 2, were sprayed as in Example 2 except that the spray nozzles were arranged to overlap their spraying zones by 95% by adjusting their angles and the distance between the spray nozzles. Accordingly, 100 kg of powdered milk, which S 20 contained trace metals such as copper, iron, and zinc, as well as polyunsaturated fatty acid-containing fats, were produced.

Comparative Example 1 *The O/W emulsion concentrated-solution comprising fats having polyunsaturated fatty acids and the metal-coupled casein solution, which were obtained as in Example 1, were mixed and sprayed to obtain 100 kg of powdered milk, which contained trace metals such as copper, iron, and zinc, as well as polyunsaturated fatty acid-containing fats.

*Comparative Example 2 To a solution obtained by adding 8.8 kg of whey protein concentrate (WPC) and 45 kg of lactose to 200 kg of water, added were 75 kg of milk, 4.9 kg of casein dissolved with alkali, 1.45 kg of water-soluble vitamins (vitamin B 1, vitamin B2, niacin, vitamin B6, biotin, folic acid, pantothenic acid, vitamin B12, vitamin C, choline, and inositol) and minerals (calcium, phosphorus, chlorine, magnesium, potassium, iodine, manganese, and selenium), and 25.2 kg of fats containing polyunsaturated fatty acids (soy bean oil, evening primrose oil, and fish oil) containing oil-soluble vitamins (vitamin A, 3-carotene, vitamin D, vitamin E, and vitamin K) and antioxidants (vitamin C palmitate, lecithin, and tocopherol). The mixture was homogenized, sterilized by heating, and concentrated to obtain an O/W concentrated emulsion including polyunsaturated fatty acid-containing fats with a solid matter of 40 The concentrated emulsion was spray-dried to obtain 93 kg of powdered milk. On the other hand, 7 kg of lactose and 0.05 kg of copper, iron, and zinc were mixed and uniformly dispersed, followed by pulverizing the dispersion with a grinder to obtain 7.05 kg of lactose including iron, copper, and zinc. The thus-obtained powdered milk having polyunsaturated fatty acid-containing fats and the thus-obtained powdered lactose having iron, copper, and zinc were mixed by power-to-powder mixing. Accordingly, 100 kg of powdered milk, which included metals such as copper, iron, and zinc, and fats with polyunsaturated fatty acids, were produced.

Test Example 1 The powdered milk in Comparative Example 1 was obtained by spray-drying the single solution. Thus, no problem in dispersibility of iron, copper, and zinc, which are 20 trace components, is at issue. However, each powdered milk obtained in Examples and Comparative Example 2 need to be analyzed to confirm distribution of the trace components, iron, copper and zinc. Thus, each powdered milk obtained by Example 1, Example 2, and Comparative example 2 was sampled by randomly collecting samples at three points, A, B, and C, and the samples were analyzed to measure the quantity of each iron, copper and zinc. The results are shown in Table 1.

a Table I Iron Content Copper Content Zinc Content Point A Point B Point C Point A Point B Point C Point A PointB PointC Example 1 5.98 6.01 6.10 0.37 0.35 0.35 2.70 2.65 2.74 Example 2 6.23 6.22 6.30 0.32 0.38 0.38 2.61 2.51 2.50 Comparative Example 2 6.13 6.13 6.02 0.35 0.36 0.36 2.54 2.59 2.51 (unit:mg%) In addition, each powdered milk obtained by Example 1 and Example 2 was analyzed to measure the quantity of each iron and copper upon sieving the powders with a 150pm-mesh sieve to obtain two types of powder, one remaining on the mesh (UP) and the other passing through the mesh (UNDER). The results are shown in Table 2.

Table 2 Iron Content Copper Content UP UNDER UP UNDER Example 1 5.81 5.98 0.37 0.35 Example 2 6.22 6.13 0.35 0.39 (unit:mg%) According to the results of analysis, distribution of trace components, iron, copper, and zinc, included in each powdered milk obtained in Example 1, Example 2, and Comparative Example 2, was good. In addition, classification characteristics of the trace components, iron and copper, included in each powdered milk obtained by Example 1, Example 2, and Comparative 2 were also good. Therefore, it is understood that there is no problem of dispersion and classification when spray-drying solutions containing different ingredients from different spray nozzles using high-pressure pumps 15 disposed on different lines, based on the conventional multi-nozzle spray system.

:"Test Example 2 Each powdered milk obtained by Examples 1-5 and Comparative Examples 1 and 2 was packed into a 350 ml white plain steel can, and stored in an open-air dark place at 37C for accelerated oxidation. Samples were collected at pre-set intervals, and 20 a sensual evaluation value of odors and a peroxide value (POV) were measured for each sample. The sensual evaluation was conducted by 10 panelists. 5 points were given to powdered milk with no indication of deterioration by oxidation, and 1 point was given to powdered milk with obvious indication of deterioration by oxidation. The average of evaluation values by 10 panelists was calculated to one decimal place. The POV was 25 measured according to the JOCS method (Japan Oil Chemistry Association, Standard Oil Test Analysis 2.4.12-71, Maruzen, 1971). The results are shown in Table 3.

-16- Table 3 1 1 1 1 Storing Period (weeks) 0 1 2 3 4 Example 1 Flavor 5.0 5.0 4.9 4.8 4.7 4.6 POV 0.4 0.5 0.6 0.8 0.9 Example 2 Flavor 5.0 4.9 4.9 4.6 4.4 4.3 POV 0.5 0.6 0.7 0.9 1.0 1.1 Example 3 Flavor 5.0 4.9 4.7 4.7 4.5 4.4 POV 0.5 0.5 0.7 0.9 1.1 1.2 Example 4 Flavor 5.0 4.9 4.6 4.4 4.3 4.1 POV 0.6 0.8 0.9 1.0 1.2 1.3 Example 5 Flavor 4.9 4.4 4.2 3.9 3.7 4.3 POV 0.7 1.5 2.0 2.7 3.5 4.3 Comparative Example 1 Flavor 4.8 4.2 3.9 3.6 3.1 2.6 POV 0.8 1.8 2.2 3.5 4.6 5.1 Comparative Example 2 Flavor 5.0 5.0 4.8 4.7 4.6 POV 0.4 0.4 0.6 0.9 1.1 1.1 (unit of POV:meq/kg) 6 0 9 0* s o.

'00:0,

S

SO

S.

S

*500 @000 0* @0 5 0@ 0 According to Table 3, clearly more panelists sensed an oil odor or a reverted flavor in the powdered milk of Comparative Example 1, which was obtained by spray- 5 drying the single solution, as compared with that of Comparative Example 2 which was obtained by powder-to-powder mixing. The POV values also increased in Comparative Example 1. That is, deterioration by oxidation of polyunsaturated fatty acids in the powdered milk occurred in Comparative Example 1. On the other hand, regarding each powdered milk of Examples 1-4, less panelists sensed a deterioration odor by oxidation of fats as in Comparative Example 2, as compared with the powdered milk obtained by spray-drying the single solution in Comparative Example 1, indicating that polyunsaturated fatty acids of the powdered milk of Examples 1-4 and Comparative Example 2 were not subject to deterioration by oxidation. However, an oil odor or a reverted flavor was slightly sensed in the powdered milk of Example 5, indicating that deterioration by oxidation of polyunsaturated fatty acids in the powdered milk occurred 0 0 in Example 5. Thus, by utilizing the multi-nozzle spray-drying method, if the overlapping of spraying zones is within the ranges shown in Examples 2-4, there is no problem of undesired flavors and deterioration by oxidation of polyunsaturated fatty acids when spray-drying solutions containing different ingredients through different spray nozzles using high-pressure pumps disposed on different lines.

Example 6 To a solution obtained by adding 8.8 kg of whey protein concentrate (WPC) and 52 kg of lactose to 200 kg of water, added were 75 kg of milk, 3.9 kg of casein dissolved with alkali, 1.45 kg of water-soluble vitamins (vitamin B1, vitamin B2, niacin, vitamin B6, biotin, folic acid, pantothenic acid, vitamin B12, vitamin C, choline, and inositol) and minerals (calcium, phosphorus, chlorine, magnesium, potassium, iodine, manganese, and selenium), and 25 kg of fats containing polyunsaturated fatty acids (soy bean oil, evening primrose oil, and fish oil) containing oil-soluble vitamins (vitamin A, -carotene, vitamin D, vitamin E, and vitamin K) and antioxidants (vitamin C palmitate, lecithin, and tocopherol). The mixture was homogenized until the free fat content was reduced to approximately 0.3% under a pressure of 400 kgf/cm2, and was .then sterilized by heating to obtain 247 kg of an O/W concentrated emulsion including polyunsaturated fatty acid-containing fats with a solid matter of40 On the other .o1- hand, a concentrated 5% casein solution containing 1 kg ofcasein dissolved with alkali 'i 20 was prepared, and 0.05 kg of copper, iron and zinc dissolved in water was added to the casein solution to obtain 25 kg of a metal-combined casein solution having a concentration of 4%.

The O/W emulsion concentrated-solution comprising fats having polyunsaturated fatty acids was sprayed from a spray nozzle (Type SX SPRAYDRY :oo 25 NOZZLE SPRAYING SYSTEM'S CO) disposed at an upper part of the drying machine, and the metal-coupled casein solution was sprayed from a spray nozzle disposed in an internal fluidized bed at the bottom of the drying machine. They were sprayed at a liquid ratio of91:9 using respective high-pressure pumps provided on different lines. In the spray nozzle for the O/W emulsion concentrated-solution including polyunsaturated fatty acids, orifice No. 54 and core No. 21 were used, and in the spray nozzle for the casein solution comprising metals, orifice No. 71 and core No.

16 were used. Spraying pressure under normal conditions was 140 kg/cm2.

Accordingly, 100 kg of powdered milk agglomerate, which contained trace metals such as copper, iron, and zinc, as well as polyunsaturated fatty acid-containing fats, were produced.

Example 7 To a solution obtained by adding 9.4 kg of whey protein concentrate (WPC) and kg of lactose to 300 kg of water, added were 6.1 kg of casein dissolved with alkali, 1.95 kg of water-soluble vitamins (vitamin B1, vitamin B2, niacin, vitamin B6, biotin, folic acid, pantothenic acid, vitamin B12, vitamin C, choline, and inositol) and minerals (calcium, phosphorus, chlorine, magnesium, potassium, iodine, manganese, and selenium), and 27.8 kg of fats containing polyunsaturated fatty acids (soy bean oil, evening primrose oil, fish oil, and a fermented microorganism product) containing oilsoluble vitamins (vitamin A, 1-carotene, vitamin D, vitamin E, and vitamin K) and antioxidants (vitamin C palmitate, lecithin, and tocopherol). The mixture was homogenized until the free fat content was reduced to approximately 0.65% under a pressure of 300 kgf/cm2, and was then sterilized by heating to obtain 247 kg of an O/W concentrated emulsion including polyunsaturated fatty acid-containing fats with a solid matter of 40 On the other hand, a concentrated 5% casein solution containing 1 kg of casein dissolved with alkali was prepared, and 0.05 kg of copper, iron and zinc 20 dissolved in water was added to the casein solution to obtain 25 kg of a metal-combined •casein solution having a concentration of 4%.

The O/W emulsion concentrated-solution comprising fats having •polyunsaturated fatty acids was sprayed from a spray nozzle (Type SX SPRAYDRY NOZZLE SPRAYING SYSTEM'S CO) disposed at an upper part of the drying 25 machine, and the metal-coupled casein solution was sprayed from a spray nozzle *disposed in an internal fluidized bed at the bottom of the drying machine. They were sprayed at a liquid ratio of 91:9 using respective high-pressure pumps provided on V different lines. In the spray nozzle for the O/W emulsion concentrated-solution including polyunsaturated fatty acids, orifice No. 54 and core No. 21 were used, and in the spray nozzle for the casein solution comprising metals, orifice No. 71 and core No.

16 were used. Spraying pressure under normal conditions was 140 kg/cm2.

-19- Accordingly, 100 kg of powdered milk agglomerate, which contained trace metals such as copper, iron, and zinc, as well as polyunsaturated fatty acid-containing fats, were produced.

Example 8 To a solution obtained by adding 9.4 kg of whey protein concentrate (WPC) and kg of lactose to 300 kg of water, added were 6.1 kg of casein dissolved with alkali, 1.95 kg of water-soluble vitamins (vitamin B 1, vitamin B2, niacin, vitamin B6, biotin, folic acid, pantothenic acid, vitamin B12, vitamin C, choline, and inositol) and minerals (calcium, phosphorus, chlorine, magnesium, potassium, iodine, manganese, and selenium), and 27.6 kg of fats containing polyunsaturated fatty acids (soy bean oil, evening primrose oil, fish oil, and a egg yolk phospholipid extract) containing oilsoluble vitamins (vitamin A, 3-carotene, vitamin D, vitamin E, and vitamin The mixture was homogenized until the free fat content was reduced to approximately 0.65% under a pressure of 300 kgf/cm2, and was then sterilized by heating to obtain 247 kg of an O/W concentrated emulsion including polyunsaturated fatty acid-containing fats with a solid matter of 40 On the other hand, a concentrated 5% casein solution containing 1 kg of casein dissolved with alkali was prepared, and 0.05 kg of copper, i iron and zinc dissolved in water was added to the casein solution to obtain 25 kg of a metal-combined casein solution having a concentration of 4%.

20 The O/W emulsion concentrated-solution comprising fats having polyunsaturated fatty acids was sprayed from a spray nozzle (Type SX SPRAYDRY "NOZZLE SPRAYING SYSTEM'S CO) disposed at an upper part of the drying S•machine, and the metal-coupled casein solution was sprayed from a spray nozzle disposed in an internal fluidized bed at the bottom of the drying machine. They were sprayed at a liquid ratio of91:9 using respective high-pressure pumps provided on different lines. In the spray nozzle for the O/W emulsion concentrated-solution including polyunsaturated fatty acids, orifice No. 54 and core No. 21 were used, and in the spray nozzle for the casein solution comprising metals, orifice No. 71 and core No.

16 were used. Spraying pressure under normal conditions was 140 kg/cm2.

Example 9 To a solution obtained by adding 7.5 kg of whey protein concentrate (WPC) and 40.3 kg of lactose to 240 kg of skimmed milk, added were 70 g of casein dissolved with alkali, 0.65 kg of water-soluble vitamins (vitamin B 1, vitamin B2, niacin, vitamin B6, biotin, folic acid, pantothenic acid, vitamin B 12, vitamin C, choline, and inositol) and minerals (calcium, phosphorus, chlorine, magnesium, potassium, iodine, manganese, and selenium), and 28.1 kg of fats containing polyunsaturated fatty acids (soy bean oil, evening primrose oil, fish oil, a fermented microorganism product, and a fermented microorganism product) containing oil-soluble vitamins (vitamin A, 3-carotene, vitamin D, vitamin E, and vitamin K) and antioxidants (vitamin C palmitate, lecithin, and tocopherol). The mixture was homogenized until the free fat content was reduced to approximately 0.65% under a pressure of 300 kgf/cm2, and was then sterilized by heating to obtain 247 kg of an O/W concentrated emulsion including polyunsaturated fatty acid-containing fats with a solid matter of 40 On the other hand, a 16% lactose solution containing 3.75 kg of lactose was prepared, and 0.05 kg of copper, iron and i zinc dissolved in water was added to the lactose solution to obtain 25 kg of a metalcombined casein solution having a concentration of S 20 The O/W emulsion concentrated-solution comprising fats having polyunsaturated fatty acids was sprayed from a spray nozzle (Type SX SPRAYDRY NOZZLE SPRAYING SYSTEM'S CO) disposed at an upper part of the drying machine, and the metal-coupled casein solution was sprayed from a spray nozzle disposed in an internal fluidized bed at the bottom of the drying machine. They were sprayed at a liquid ratio of 91:9 using respective high-pressure pumps provided on different lines. In the spray nozzle for the O/W emulsion concentrated-solution including polyunsaturated fatty acids, orifice No. 54 and core No. 21 were used, and in the spray nozzle for the casein solution comprising metals, orifice No. 71 and core No.

16 were used. Spraying pressure under normal conditions was 140 kg/cm2.

Example An O/W emulsion concentrated-solution comprising fats having polyunsaturated fatty acids was prepared by homogenization under a pressure of 150 kgf/cm2 in such a way as to have a free fat content of 1.30% and to exhibit no separation of fats. The other conditions including the preparation of the metal-coupled casein solution were the same as in Example 7. Accordingly, 100 kg of powdered milk agglomerate, which contained copper, iron, and zinc, as well as polyunsaturated fatty acid-containing fats, were produced.

Comparative Example 3 The O/W emulsion concentrated-solution comprising fats having polyunsaturated fatty acids and the metal-coupled casein solution, which were obtained as in Example 6, were mixed and sprayed to obtain 100 kg of powdered milk agglomerate, which contained trace metals such as copper, iron, and zinc, as well as polyunsaturated fatty acid-containing fats.

Comparative Example 4 .To a solution obtained by adding 8.8 kg of whey protein concentrate (WPC) and 45 kg of lactose to 200 kg of water, added were 75 kg of milk, 4.9 kg of casein 20 dissolved with alkali, 1.45 kg of water-soluble vitamins (vitamin B1, vitamin B2, niacin, vitamin B6, biotin, folic acid, pantothenic acid, vitamin B 12, vitamin C, choline, and inositol) and minerals (calcium, phosphorus, chlorine, magnesium, potassium, 0 iodine, manganese, and selenium), and 25.2 kg of fats containing polyunsaturated fatty acids (soy bean oil, evening primrose oil, and fish oil) containing oil-soluble vitamins *ooo 25 (vitamin A, -carotene, vitamin D, vitamin E, and vitamin K) and antioxidants (vitamin C palmitate, lecithin, and tocopherol). The mixture was homogenized until the free fat content was reduced to approximately 0.3% under a pressure of 400 kgf/cm2, and was then sterilized by heating to obtain an O/W concentrated emulsion including polyunsaturated fatty acid-containing fats with a solid matter of 40 The concentrated emulsion was spray-dried to obtain 93 kg of powdered milk. On the other hand, 7 kg of lactose and 0.05 kg of copper, iron, and zinc were mixed and uniformly dispersed, followed by pulverizing the dispersion with a grinder to obtain 7.05 kg of lactose including iron, copper, and zinc. The thus-obtained powdered milk having polyunsaturated fatty acid-containing fats and the thus-obtained powdered lactose having iron, copper, and zinc were mixed by power-to-powder mixing. Accordingly, 100 kg of powdered milk agglomerate, which included metals such as copper, iron, and zinc, and fats with polyunsaturated fatty acids, were produced.

Test Example 3 The powdered milk in Comparative Example 3 was obtained by spray-drying the single solution. Thus, no problem in dispersibility of iron, copper, and zinc, which are trace components, is at issue. However, each powdered milk obtained in Examples 6-10 and Comparative Example 4 need to be analyzed to confirm distribution of the trace components, iron, copper and zinc. Thus, each powdered milk obtained by Example 6, Example 7, and Comparative example 4 was sampled by randomly collecting samples at three points, A, B, and C, and the samples were analyzed to measure the quantity of each iron, copper and zinc. The results are shown in Table 4.

Table 4 Iron Content Copper Content Zinc Content Point A Point B Point C Point A Point B Point C Point A Point B Point C Comparative Example 4 6.25 6.01 6.30 0.33 0.35 0.33 2.70 2.27 2.65 Example 6 6.1 6.22 6.23 0.37 0.35 0.33 2.62 2.58 2.74 Example 7 6.13 6.1 6.3 0.35 0.38 0.38 2.65 2.7 2.66 •(unit:mg%) According to the results, distribution of trace components, iron, copper, and zinc, included in each powdered milk obtained in Example 6, Example 7, and Comparative Example 4, was good. Therefore, it is understood that there is no problem 20 of dispersion of components when agglomeration is carried out by mixing while spraydrying solutions containing different ingredients using high-pressure pumps disposed on different lines, based on the fluidized bed agglomeration system.

Test Example 4 Each powdered milk obtained by Examples 6-10 and Comparative Examples 3 and 4 was packed into a 350 ml white plain steel can, and stored in an open-air dark place at 37C for accelerated oxidation. Samples were collected at pre-set intervals, and a sensual evaluation value of odors and a peroxide value (POV) were measured for each sample. The sensual evaluation was conducted by 10 panelists. 5 points were given to powdered milk with no indication of deterioration by oxidation, and 1 point was given to powdered milk with obvious indication of deterioration by oxidation. The average of evaluation values by 10 panelists was calculated to one decimal place. The POV was measured according to the JOCS method (Japan Oil Chemistry Association, Standard Oil Test Analysis 2.4.12-71, Maruzen, 1971). The results are shown in Table Table Storing Period (weeks) 0 1 2 3 4 Example 6 Flavor 5.0 5.0 4.9 4.8 4.7 POV 0.4 0.5 0.6 0.8 0.9 1.1 Example 7 Flavor 5.0 4.9 4.7 4.5 4.3 4.2 POV 0.5 0.6 0.8 1.0 1.1 1.2 Example 8 Flavor 5.0 4.9 4.7 4.7 4.5 4.4 POV 0.5 0.5 0.7 0.9 1.1 1.2 Example 9 Flavor 5.0 4.9 4.6 4.4 4.3 4.1 POV 0.6 0.8 0.9 1.0 1.2 1.3 Example 10 Flavor 4.9 4.4 4.2 3.9 3.7 POV 0.7 1.5 2.0 2.7 3.5 4.3 Comparative Example 3 Flavor 4.8 4.2 3.9 3.6 3.1 2.6 POV 0.8 1.8 2.2 3.5 4.6 5.1 Comparative Example 4 Flavor 5.0 5.0 4.8 4.7 4.6 POV 0.4 0.4 0.6 0.9 1.1 1.1 (unit of POV:meq/kg)

S.

0-0 ft* According to the above, clearly more panelists sensed an oil odor or a reverted flavor in the powdered milk of Comparative Example 3, which was obtained by spraydrying the single solution, as compared with that of Comparative Example 4 which was obtained by powder-to-powder mixing. The POV values also increased in Comparative Example 3. That is, deterioration by oxidation of polyunsaturated fatty acids in the powdered milk occurred in Comparative Example 3. On the other hand, regarding each -24powdered milk of Examples 6-9, less panelists sensed a deterioration odor by oxidation of fats as in Comparative Example 4, as compared with the powdered milk obtained by spray-drying the single solution in Comparative Example 3, indicating that polyunsaturated fatty acids of the powdered milk of Examples 6-9 and Comparative Example 4 were not subject to deterioration by oxidation. However, an oil odor or a reverted flavor was slightly sensed in the powdered milk of Example 10, indicating that deterioration by oxidation of polyunsaturated fatty acids in the powdered milk occurred in Example 10. Thus, by utilizing the fluidized bed agglomeration method, if the free fat content is lower than those illustrated in Examples 6-9, there is no problem of undesired flavors and deterioration by oxidation of polyunsaturated fatty acids when mixing while spray-drying solutions containing different ingredients using highpressure pumps disposed on different lines encounters.

As explained above, according to an embodiment of the present invention, it is possible to produce powdered milk containing trace metals such as iron, copper, and zinc, and polyunsaturated fatty acid-containing fats. As with powdered milk obtained by powder-to-powder mixing, the powdered milk does not virtually exhibit degradation of flavor and quality even after being stored for a long period of time, despite the fact that the powdered milk comprises polyunsaturated fatty acid-containing fats having a nutritional value and exhibiting physiological effects, coexisting with iron, copper, 20 and zinc highly promoting oxidation. Further, according to another embodiment of the present invention, advantageously, the manufacturing process comprises less steps than in conventional powder-to-powder mixing, and can efficiently produce a powdered milk containing trace metals, copper, iron, and zinc and fats with polyunsaturated fatty acids.

It will be understood by those of skill in the art that numerous and various modifications can be made without departing from the spirit of the present invention.

Therefore, it should be clearly understood that the forms of the present invention are S .illustrative only and are not intended to the scope of the present invention.

Claims

1. A method of producing a powdered milk, characterised by agglomeration carried out by mixing a first component and a second component while spray-drying at least either the first component or the second component in a liquid state, wherein the first component comprises a first active ingredient including a metal component supplement, the second component comprises a second active ingredient including polyunsaturated fatty acid-containing fats, and at least either the first component or the second component further comprises a raw material for powdered milk.

2. The method according to claim 1, wherein the first and second components are mixed while spray-drying the first component in a liquid state.

3. The method according to claim 1 or 2, wherein the first and second components are mixed while separately spray-drying the first and second components in a liquid state through different spray nozzles.

4. The method according to claim 3, wherein the spray nozzles have spraying zones overlapping each other by adjusting the angles of the spray nozzles and the distance between the nozzles, The method according to claim 4, wherein the spraying zones overlap by 1% to 9%.

6. The method according to claim 1, wherein the first component is used as a 25 binding solution, and sprayed onto the second component which is in the form of a raw material powder, thereby agglomerating the powdered milk.

7. The method according to claim 6, wherein the raw material powder has a free fat content of no more than 0.7%.

8. The method according to claim 1, wherein the second component is an O/W •.type emulsion.

9. The method according to any one of claims 1 to 8, wherein the agglomeration is carried out in a fluidised bed. m:\speci\080000\86-8 7 \861 The method according to any one of claims 1 to 9, wherein the first component is composed mainly of non-milk components, and the second component is composed mainly of milk components. Dated this second day of December 2003 Snow Brand Milk Products Co., Ltd. Patent Attorneys for the Applicant: F B RICE CO *ee• *f m:\speci\080000\86-87\86140clmrlo.doc