Method for dispersing plant sterol in aqueous phase and plant sterol-dispersed beverages

Abstract

Disclosed are a method for dispersing plant sterol in aqueous substrates and a plant sterol-dispersed beverage. The dispersion of plant sterols starts with the admixing of plant sterol to an emulsifier, followed by melting the admixture by heating at 60 to 200° C. Afterwards, the molten substance is mixed with an aqueous beverage alone or an emulsifier-containing aqueous beverage. This resulting mixture is stirred at a high speed to give a dispersion of plant sterols in an aqueous beverage. Optionally, the dispersion may be homogenized. In the beverage thus obtained, there are contained nano-sized micelles which are superior in bioavailability, having no influence on the characteristic taste and flavor of the beverages. Also, the improvement in the dispersion stability of the plant sterol micelles has the effect of prolonging the life span of the beverage, guaranteeing the stability of the products for a long period of time.

Description

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a method for dispersing plant sterol in aqueous substrates and plant sterol-dispersed beverages. More particularly, the present invention relates to a method for preparing a dispersion of plant sterol in which plant sterol micelles are formed with a size of several hundreds of nanometers and to a beverage containing the dispersion.

[0003] 2. Description of the Prior Art

[0004] Recently, people have increasingly been subjected to over-ingesting cholesterol. As a result, diseases associated with cholesterol are increasingly becoming a big social problem. In particular, the eastern people, who have experienced westernization in their lifestyles, including diet, have far more opportunities to consume high cholesterol foods than before on account of the deluge of instant or fast foods. When being ingested, the cholesterol of such foods increases the cholesterol level in blood and may act as a main cause of cardiovascular diseases, including hyperlipidemia, arteriosclerosis, arrhythmia, cardiac infarction, and so on.

[0005] Through studies of the metabolism of cholesterol, it has been shown that both endogenic and dietary cholesterol move into the small intestine and about 50% thereof is absorbed from the intestines (Bosner, M. S., Ostlund, R. E., Jr., Osofisan, O., Grosklos, J., Fritschle, C., Lange, L. G. 1993). Based on this fact, a mechanism of preventing cholesterol from being absorbed from intestines is of special concern to those who have made efforts to discover clues for the prophylaxis and treatment of cholesterol-associated diseases.

[0006] Plant sterol or phytosterol can be divided into sitosterol, campesterol, and stigmasterol while plant stanol or phytostanol belongs to either sitostanol or campestanol. For purposes of convenience, they are all called plant sterol herein.

[0007] With structures very similar to that of cholesterol, plant sterol is known to inhibit intestinal cholesterol absorption, thereby reducing the serum cholesterol level, as disclosed in U.S. Pat. No. 5,578,334. Being a naturally occurring material, plant sterol is non-toxic and can be found in a broad spectrum of plants such as bean, corn, wood, tall oil, etc. By taking advantage of the inhibitory function of plant sterol against intestinal cholesterol absorption, clinical trials have been conducted of plant sterol as a therapeutic agent for treatment of cardiovascular diseases, coronary artery diseases and hyperlipidemia (Atherosclerosis 28:325-338).

[0008] Despite this useful function, plant sterol is difficult to apply to foods on account of its physical properties, that is, very poor solubility in both water and oil. Accordingly, the general public can only limitedly ingest plant sterol.

[0009] With the aim of increasing the solubility of plant sterol, some researchers have synthesized various derivatives of plant sterol. For example, ester forms of plant sterol were developed, which have excellent solubility in oil phases (Mattson F. H., R. A. Volpenhein, and B. A. Erickson, 1997). In U.S. Pat. No. 5,502,045, sitostanol fatty acid ester is disclosed which is prepared by the interesterification of sitostanol with a fatty acid ester. According to this patent, the sitostanol fatty acid ester is reported to reduce the LDL-C level by as much as 16% when being used in an applied form in an oil phase (margarine).

[0010] PCT Patent International Publication No. WO 99/15546 and WO 99/15547 describe water- and oil-soluble plant sterol derivatives which are synthesized by linking a water- or oil-soluble molecule to plant sterol or plant stanol via an ester linkage.

[0011] However, a research result is reported, disclosing that synthetic plant sterol derivatives with improved solubility have lower inhibitory effect on intestinal cholesterol absorption than does natural plant sterol (Mattson et al., The American Journal of Clinical Nutrition 35: Apr. 1982 pp 697-700). Particularly, oil-soluble derivatives are disadvantageous in that a lot of edible oil must also be ingested at the same time.

[0012] Along with the effort to increase the solubility of plant sterol through the synthesis of derivatives, intensive research has been and continues to be directed to improving the bioavailability of plant sterol.

[0013] In regard to this research, a pharmaceutical dispersible powder of sitosterols for oral administration was developed which can be prepared from a mixture of sitosterol, starch hydrolysate, silicon dioxide, and polyoxylene sorbitan monostearate in a certain proportion by homogenization, deaeration, pasteurization, and evaporation, as disclosed in U.S. Pat. No. 3,881,005.

[0014] Disclosed in U.S. Pat. No. 5,932,562 is an aqueous homogeneous micellar mix of a plant sterol and lecithin and lysolecithin mix which has been dried to a finely divided water soluble powder. This was obtained by mixing plant sterol, lecithin and lysolecithin together in chloroform at a fixed mole ratio and removing the chloroform therefrom. In this patent, the total amount of the emulsifiers used in the patent, however, is greater than that of the plant sterol. Lysolecitin is a very expensive emulsifier. What is worse, the organic solvent used to form the micelles makes the water-soluble powder unsuitable for ingestion.

[0015] Other water-soluble plant sterols can be found in U.S. Pat. Nos. 6,054,144 and 6,110,502. According to these patents, aqueous-dispersible plant sterol is produced by admixing oryzanol or plant sterol, monofunctional surfactant and polyfunctional surfactant in water at a fixed ratio and drying the admixture. This production method is evaluated to be superior in terms of being free from homogenization and deaeration steps. Polyoxylene sorbitan monopalmitate and sorbitan monooleate are adopted as a monofunctional surfactant and a polyfunctional surfactant, respectively.

[0016] In European Pat. Publication No. 289,636 is described a method of producing emulsified or solubilized sterol in a stable form by admixing plant sterol at a fixed ratio with a liquid polyhydroxy compound containing sucrose fatty ester and/or polyglycerol fatty ester and diluting the admixture with water. When being applied to drinks, micelle particles of the plant sterol produced amount, in size, to as large as tens of micrometers, being bristly to the feel of the mouth. Furthermore, the micelle particles have the disadvantage of making the drinks opaque.

SUMMARY OF THE INVENTION

[0017] With the above problems in mind, the intensive and thorough research on the soluble form of plant sterol, conducted by the present inventors, resulted in the finding that, when plant sterol and an emulsifier are heated together in the absence of other components, they are brought into homogeneous contact with each other while being fused, to form fine micelles which are as small as nanometers in size, leading to the present invention.

[0018] Therefore, the object of the present invention is to provide a method of dispersing plant sterol in aqueous substrates into a convenient form which is suitable for use in drinks and improved in the bioavailability of the plant sterol in addition to having no influence on the characteristic taste and flavor of the applied beverage.

[0019] It is another object of the present invention to provide a beverage containing a dispersion of plant sterol, which is not bristly to the feel of the mouth.

[0020] It is a further object of the present invention to provide an additive suitable for use in beverages, which can be prepared by the method.

[0021] In one embodiment of the present invention, there is provided a method for dispersing plant sterol, comprising the steps of: thermally melting an admixture of plant sterol and an emulsifier at 60 to 200° C.; admixing the molten mixture to an aqueous beverage or an emulsifier-containing aqueous beverage; and stirring the admixture at a high speed to give a dispersion of plant sterol in the beverage.

[0022] In another embodiment of the present invention, there is provided a method for dispersing plant sterol, comprising the steps of: thermally melting an admixture of plant sterol and an emulsifier at 60 to 200° C.; admixing the molten mixture to an aqueous beverage or an emulsifier-containing aqueous beverage; and stirring the admixture at a high speed and homogenizing to give a plant sterol-dispersed beverage.

[0023] In accordance with a further embodiment, there is provided a plant sterol-dispersed beverage.

[0024] In accordance with still a further embodiment, there is provided an additive suitable for use in beverages, prepared by thermally melting an admixture of plant sterol and an emulsifier at 60 to 200° C.

DETAILED DESCRIPTION OF THE INVENTION

[0025] Plant sterols are naturally occurring materials which are similar in structure to cholesterol. In the natural world, there are found a variety of plant sterols, of which sitosterol, campesterol, stigmasterol and sitostanol predominate over other sterols. At an ordinary level of intake, plant sterols have little influence on the level of cholesterol in blood, but a large quantity of plant sterols inhibits the absorption of intestinal cholesterol and bile cholesterol on account of their structures being similar to that of cholesterol, thereby lowering the serum cholesterol level.

[0026] Effects of plant sterols on the reduction of serum cholesterol level have long been under study. Such studies have shown that plant sterols can reduce the total serum cholesterol level by 0.5 to 26%, especially the LDL-C level by 2 to 33%, depending on dosage, severity of patient's symptoms, and prescribed diet. The cholesterol level-reducing effect is also affected by the gender, age, and state of health of the patient, and its administration form (suspension, crystal, capsule, etc.).

[0027] Now, there is generally accepted the hypothesis that plant sterols effectively segregate dietary cholesterol, which remains in an oily phase within intestines, and settles it, thereby inhibiting the absorption of the dietary cholesterol from the intestines. Accordingly, plant sterols are believed to be ineffective against the cholesterol which is in a micelle form. In fact, it is reported that dietary cholesterol is more resistant to absorption by plant sterols than is endogenic cholesterol (Mattson, F. H., Volpenhein, R. A., and Erickson, B. A., Effect of Plant Sterol Esters on the Absorption of Dietary Cholesterol., J. Nutr. 1977; 107:1139-1146). However, U.S. Pat. No. 5,932,562 performed an experiment with plant sterol, teaching that, when being administered even at a small amount, a micellar mix of plant sterol is very effective in reducing the serum cholesterol level. It is believed that a micelle phase of plant sterol well settles the cholesterol in a micelle phase to effectively inhibit its absorption by the intestine.

[0028] Products developed, thus far, which take advantage of plant sterols in reducing the level of cholesterol, especially LDL-cholesterol in blood, are commercially available in many countries such as Finland, England, United States of America, and Australia. They are mainly in forms of spreads or dressings in which plant sterols are bonded to fatty acids via ester linkages. These products are reported to be more effective when being used in combination with statin drugs for hypercholesterolemia patients. However, the products contain fat components in large quantities, so that these are also ingested at the same time.

[0029] Many attempts have been made to provide plant sterols in beverage forms. However, because plant sterols are sparingly soluble in water, most of the beverage forms developed thus far suffer from the disadvantages of being poor in the bioavailability of plant sterols, lacking dose proportionality and employing large amounts of emulsifiers. Additionally, it takes a significant period of time for conventional aqueous based forms of plant sterols to effect inhibition of cholesterol absorption on account of their slow utilization rate in vivo. Further, plant sterols show very poor dispersion stability, so that a drying process is required to remove the solubilizer used for dispersion of the plant sterols, such as water, to provide plant sterols in powder forms. To circumvent these problems, various solutions have been suggested, including pulverization of plant sterols into fine powders, addition of at least two different additives, and use of high-pressure homogenizers (5000 psig).

[0030] As mentioned above, a variety of solubilizers and emulsifiers are employed to solubilize plant sterols. According to U.S. Pat. No. 5,932,562, sitosterol can be easily dispersed through formation of micelles from an organic solution of sitosterol. This process and the micellar mix thus obtained are unsuitable for application to beverages, which generally attach great importance to taste and flavor. For instance, large quantities of solubilizers or emulsifiers have unfavorable influence on the taste of the final edible product. In addition, organic solvents, which are generally unsuitable for use in foods, may remain in the micelles.

[0031] Therefore, the present invention pertains to a method of dispersing plant sterols into micelles with a size of hundreds of nanometers, which improves the bioavailability of sparingly soluble plant sterols, has proper dose proportionality and shows a maximum of dispersion stability.

[0032] In accordance with the present invention, a great improvement is brought about in the bioavailability of plant sterols, giving rise to a decrease in their effective dosage. Further, a clear dispersion of plant sterols is obtained without affecting the characteristic taste and flavor that beverages of interest retain. When being applied, the micelles of the present invention are so small in particle size as not to be bristly to the feel of the mouth.

[0033] In one embodiment of the present invention, the dispersion of plant sterols starts with the admixing of plant sterol with an emulsifier, followed by melting the admixture by heating at 60 to 200° C. Afterwards, the molten substance is mixed with an aqueous beverage alone or an emulsifier-containing aqueous beverage. This resulting mixture is stirred at a high speed to give a dispersion of plant sterols in an aqueous beverage.

[0034] In an alternative embodiment of the present invention, the stirred solution is further homogenized. That is, a plant sterol and an emulsifier are mixed and melted at 60 to 200° C., followed by adding the molten mixture to an aqueous beverage alone or an emulsifier-containing aqueous beverage. The resulting mixture is stirred at a high speed and then homogenized to give a dispersion of plant sterol in an aqueous beverage.

[0035] Useful in the present invention is a plant sterol selected from the group consisting of sitosterol, campesterol, stigmasterol, sitostanol, campestanol and mixtures thereof. Additionally, other plants sterols can be used in the present invention.

[0036] To be useful in the present invention, the emulsifiers are required to not be denatured at 60° C. or higher. Examples of the emulsifiers include sucrose fatty acid ester, sorbitan fatty acid ester, polysorbate, polyglycerol fatty acid, propylene glycerol fatty acid, and polyglycerine fatty acid ester.

[0037] In the dispersion of the present invention, the weight ratio of plant sterols to total emulsifiers are in the range of 1:0.01 to 1:10 and preferably in the range of 1:0.2 to 1:2.0 (w/w). For example, if the weight ratio of the emulsifier to plant sterol is below 0.01, sufficient emulsification is not achieved while precipitation occurs, and the emulsified particles, if formed, amount to as large as tens of micrometers in size. On the other hand, if the weight ratio exceeds 10, the resulting beverage acquires the taste of the emulsifier, being poor to the feel of the mouth. As for the emulsifier admixed with an aqueous beverage, it is used at a weight ratio of 0.8 or less compared with the emulsifier admixed with plant sterols (i.e., 80% by weight or less based on the weight of the emulsifier admixed with plant sterols) and preferably at a weight ratio of 0.5 or less (i. e., 80% by weight or less). A weight ratio of greater than 0.8 (w/w) (80% by weight) makes it difficult to form nanoparticles because the amount of the emulsifier admixed with plant sterol is relatively low.

[0038] Almost all aqueous beverages can be used in the present invention, as exemplified by water, juice beverages, carbonated drinks, milk, soya milk, drinks made of grains, and favorite drinks such as coffee, tea, and so on.

[0039] The admixing of plant sterol and an emulsifier is conducted through heating at 60 to 200° C. Preferable heating temperatures of the admixture fall within the range of 120 to 150° C. When the admixing is conducted at less than 60° C., the micelle particles have a size of from tens to hundreds of micrometers, being poor to the feel of the mouth as well as in bioavailability. On the other hand, an admixing temperature higher than 200° C. denatures the emulsifier and when the temperature exceeds 250° C., the plant sterol undergoes thermal denaturation.

[0040] On the whole, when plant sterol, a sparingly water-soluble substance, is emulsified in water in the presence of an emulsifier, only poor emulsification occurs, resulting in settling the plant sterol into particles with a size ranging from tens to hundreds of micrometers. In the present invention, intensive research was directed to maximizing the emulsification of plant sterol, thereby producing micelle particles with a size of hundreds of nanometers or less. As a result of the intensive research, it was found that emulsification could be maximized under the condition of a homogenous mixture of plant sterol and an emulsifier. In order to homogeneously mix plant sterol with an emulsifier, the plant sterol is heated at near its melting point (sitosterol: about 140° C.; campesterol: about 157° C., stigmasterol: about 170° C.) to bring the two components into liquid phases before mixing.

[0041] Together with an aqueous beverage or an emulsifier-containing aqueous beverage, the heated admixture of plant sterol and emulsifier is stirred at a high speed. The emulsifier added to the aqueous beverage is preferably identical to that admixed with the plant sterol. However, a different one may be used if they are compatible with each other.

[0042] The weight ratio of the plant sterol to the aqueous beverage falls within the range of 1:10 to 1:10,000 (w/w) and preferably within the range of 1:10 to 1:100 (w/w).

[0043] Examples of aqueous beverages usable in the present invention include water, juice beverages, carbonated drinks, milk, soya milk, drinks made of grains, and favorite drinks such as coffee, tea, and so on with a preference for water. In the case that water is employed, the dispersion of plant sterol obtained by subsequent high-speed stirring and homogenizing processes may be diluted with other aqueous beverages such as juice beverages, carbonated drinks, milk, soya milk, drinks made of grains, and favorite drinks, to afford desired plant sterol-containing beverages.

[0044] Alternatively, plant sterol may admixed with an emulsifier before being heated at near the melting point thereof. Then, the liquefied admixture is added to an aqueous beverage to give a plant sterol-containing beverage. In this case, however, the beverage obtained is poor in terms of transparency and feel to the mouth.

[0045] When water is employed as an aqueous substrate, plant sterol can be provided in a convenient form which can applied to aqueous beverages. The dispersion obtained after the admixture of plant sterol and emulsifier is dispersed in water, is evaporated and freeze-dried or spray-dried to produce an aqueous plant sterol powder which can be provided to food or drinks or incorporated into solid and suspension dosage forms.

[0046] An admixture of plant sterol and sucrose fatty acid ester, which is obtained by heating before mixing, is added to water, after which a stirring process and a high-pressure homogenizing process are conducted in due order to give a clear plant sterol dispersion. When plant sterol is used an amount of 1%, conventional emulsification processes cannot guarantee the dispersion stability of the resulting solution, giving rise to an increase in settling of plant sterol. While conventional emulsification processes produce dispersions which show a transmittance at 700 nm of as low as 0.16%, the method according to the present invention promises a transmittance at 700 nm of 80.0% or higher.

[0047] With regard to the mixing of the admixture of plant sterol and emulsifier with the aqueous beverage, the admixture of plant sterol and emulsifier may be added to the aqueous beverage in the form of a hot liquid phase or a solid phase cooled to room temperature. Better emulsification can be obtained in terms of emulsification rate and capacity when the admixture of plant sterol and emulsifier is added as a liquid phase than as a solid phase. In the former case, the aqueous beverage is preferably heated to the temperature of 60 to 140 ° C. in order to enhance the emulsification efficiency. Particularly, the heating temperature of the aqueous beverage is preferably set to be similar to that of the admixture of plant sterol and emulsifier in order to make the micelle particles small. Upon emulsification in water, pressure is needed to raise the temperature to higher than 100° C. For example, about five atm is required to emulsify the plant sterol admixture in water.

[0048] After stirring the mixture, nanoparticles are formed. In this regard, the stirring is preferably conducted at 6,800-7,000 rpm for about 10 min. 90% or more of the micelles obtained after the stirring process were measured to be 300 nm or less in size. In contrast, the micelles obtained under the same conditions, except that the admixture of plant sterol and emulsifier is not heated, were measured to range, in particle size, from tens to hundreds of micrometers. Therefore, these comparative measurements demonstrate that the process of melting plant sterol and an emulsifier and mixing them is very important in forming nanoparticles.

[0049] Upon heating in the absence of other components, the plant sterol and an emulsifier can be brought into homogeneous contact with each other while being melted, so that the micelles are obtained with a size of hundreds of nanometers after the emulsification. Contrary to conventional techniques, the present invention is, therefore, capable of producing nanoparticles suitable for use in beverages without using any organic solvents in which plant sterol is fairly soluble.

[0050] After the stirring process, a homogenizing process is needed to pulverize aggregated micelles. This homogenizing process may be conducted with the aid of a high-pressure homogenizer, a colloid mill or a sonicator with a preference for a high-pressure homogenizer. After this process, 95% or more of the micelles thus obtained were measured to be 300 nm or less.

[0051] The dispersion, which is obtained by thermally melting plant sterol and an emulsifier, admixing them, stirring the admixture in water and treating under high pressure in accordance with the present invention, is diluted with juice beverages, carbonated drinks, milk, soya milk, drinks made of grains, or favorite drinks to afford desired plant sterol-containing beverages. In these beverages, the micelles with a particle size as small as nanometers have large surface areas and particle curvatures and are superior in bioavailability, having no influence on the characteristic taste and flavor of the beverage.

[0052] Additionally, the beverages according to the present invention do not undergo layer separation even after being stored in a refrigerator because the plant sterol micelles are improved in dispersion stability. Further, the plant sterol micelles maintain the excellent dispersion stability at 90° C., guaranteeing the stability of the products for a long period of time.

[0053] A better understanding of the present invention may be obtained in light of the following examples which are set forth to illustrate, but are not to be construed to limit the present invention.

Comparative Example 1

[0054] To a 1 liter vessel, 500 g of water was added and heated at about 80° C. To the heated water were added 5 g of plant 5 sterol (sitosterol 75%, campesterol 10%, stigmasterol sitostanol 15%) and 4.25 g of sucrose stearate ester, after which the mixture was stirred at a speed of 6,800 to 7,000 rpm for 10 min. The particles thus obtained were analyzed for size and the results are given in Table 1, below. 1 TABLE 1 Particle Size (&mgr;m) Cumulative % 0.985 0.07 1.89 12.41 2.50 32.52 3.31 53.23 4.38 66.82 5.27 77.28 6.35 85.32 11.11 95.69 21.32 98.96 78.56 100.00

Comparative Example 2

[0055] The dispersion prepared in Comparative Example 1 was treated at 7,000 psi in a high-pressure homogenizer, such as manufactured by Microfluidics, identified as “Microfluidizer M110EHI”. The particles thus obtained were analyzed for size and the results are given in Table 2, below. The resulting dispersion was measured to have a transmittance at 700 nm of 0.16%. 2 TABLE 2 Particle Size (&mgr;m) Cumulative % 0.985 0.03 1.89 11.25 2.50 30.43 3.31 54.47 4.38 66.55 5.27 79.74 6.35 88.45 11.11 96.21 21.32 99.46 94.65 100.00

EXAMPLE 1

[0056] In a vessel, plant sterol (sitosterol 75%, campesterol 10%, stigmasterol sitostanol 15%) and sucrose stearyl ester and/or sorbitan lauryl ester were melted at 130 to 140° C. with stirring. After completion of the melting, the solution was stirred for 1 min and added to water maintained at about 80 ° C., followed by stirring at 6,800 to 7,000 rpm for about 10 min. The resulting solution was treated at 7,000 psi in a high-pressure homogenizer, such as manufactured by Microfluidics, identified as “Microfluidizer M110EHI”. Table 3 lists the amounts of plant sterol, sucrose stearyl ester, and sorbitan lauryl ester used, specifying whether a high-pressure homogenizing process was carried out or not. 3 TABLE 3 Plant Sucrose stearyl Sorbitan lauryl High pressure No. Sterol ester Ester H2O Homogenization 1  5 g 4.25 g — 500 g Not done 2  5 g 4.25 g — 500 g Done 3  5 g 3.036 g 1.214 g 500 g Not done 4  5 g 3.036 g 1.214 g 500 g Done 5 25 g 2.5 g 1.75 g 500 g Not done 6 25 g 2.5 g 1.75 g 500 g Done 7 25 g 2.126 g 2.124 g 500 g Not done 8 25 g 2.126 g 2.124 g 500 g Done

[0057] The solution of No. 1 in Table 3 was analyzed for particle size and the results are given in Table 4, below. 4 TABLE 4 Particle Size (&mgr;m) Cumulative % 0.096 20.35 0.127 52.19 0.153 68.49 0.184 75.29 0.222 85.33 0.294 91.52 0.985 99.21 5.27 100.0

[0058] For purposes of reference, analysis results of the particles of Nos. 3, 5 and 7 in Table 3 were similar to those shown in Table 4 for the particle of No. 1.

[0059] In the case of No. 2 in Table 3, the analysis results of the particle are given in Table 5, below. 5 TABLE 5 Particle Size (&mgr;m) Cumulative % 0.096 13.67 0.127 49.40 0.153 69.39 0.184 77.61 0.222 89.07 0.294 95.22 0.985 99.89 2.08 100.0

[0060] For purposes of reference, analysis results of the particles of Nos. 4, 6 and 8 in Table 3 were similar to those shown in Table 5 for the particle of No. 2.

[0061] The plant sterol dispersions prepared in Example 1 (Nos. 2, 4, 6, and 8) were measured to range, in transmittance at 700 nm, from 80.0 to 80.5%.

EXAMPLE 2

[0062] In a vessel, plant sterol (sitosterol 75%, campesterol 10%, stigmasterol sitostanol 15%) and sucrose stearyl ester and/or sorbitan lauryl ester were melted at 130 to 140° C. with stirring. After completion of the melting, the solution was stirred for 1 min and added to water (80 to 90° C) containing 1 g of sucrose stearyl ester, followed by stirring at 6,800 to 7,000 rpm for about 10 min. The resulting solution was treated at 7,000 psi in a high-pressure homogenizer, such as manufactured by Microfluidics, identified as “Microfluidizer M110EHI”. Table 6 lists the amounts of plant sterol, sucrose stearl ester, and sorbitan lauryl ester used, specifying whether a high-pressure homogenizing process was fulfilled or not. 6 TABLE 6 Plant Sucrose Sorbitan High-pressure No. Sterol stearyl ester lauryl ester H2O Homogenization  9  5 g 4.25 g — 500 g Not done 10  5 g 4.25 g — 500 g Done 11  5 g 3.036 g 1.214 g 500 g Not done 12  5 g 3.036 g 1.214 g 500 g Done 13 25 g 2.5 g 1.75 g 500 g Not done 14 25 g 2.5 g 1.75 g 500 g Done 15 25 g 2.126 g 2.124 g 500 g Not done 16 25 g 2.126 g 2.124 g 500 g Done

[0063] The solution of No. 9 in Table 6 was analyzed for particle size and the results are given in Table 7, below. 7 TABLE 7 Particle Size (&mgr;m) Cumulative % 0.096 19.21 0.127 52.30 0.153 68.72 0.184 76.41 0.222 85.95 0.294 92.05 0.985 99.35 4.80 100.0

[0064] For purposes of reference, analysis results of the particles of Nos. 11, 13 and 15 in Table 6 were similar to those shown in Table 7 for the particle of No. 9.

[0065] In the case of No. 10 in Table 6, the analysis results of the particle are given in Table 8, below. 8 TABLE 8 Particle Size (&mgr;m) Cumulative % 0.096 14.50 0.127 48.24 0.153 70.68 0.184 77.92 0.222 90.61 0.294 96.74 0.985 99.85 1.89 100.0

[0066] For purposes of reference, analysis results of the particles of Nos. 12, 14 and 16 in Table 6 were similar to those shown in Table 8 for the particle of No. 10.

[0067] The plant sterol dispersions prepared in Example 2 (Nos. 10, 12, 14, and 16) were measured to range, in transmittance at 700 nm, from 80.5 to 82.5%.

EXAMPLE 3

[0068] The dispersion prepared in Example 1 or 2 was spray-dried to give aqueous plant sterol powder.

EXAMPLE 4

[0069] 100 g of the dispersion prepared in Example 1 or 2 was diluted with 400 g of an aqueous beverage selected from water, juice beverages, carbonated drinks, milk, soya milk, drinks made of grains, and favorite drinks. 9.25 g of the powder prepared in Example 3 was added to 490.75 g of an aqueous beverage selected from water, juice beverages, carbonated drinks, milk, soya milk, drinks made of grains, and favorite drinks. The resulting diluted beverage was allowed to be taken by 50 skilled subjects (20 males in thirties and forties, 20 females in thirties and forties, 10 females in twenties) for property test by sense perception. As a test beverage, a juice beverage (orange juice) was used. The results are given in Tables 9 and 10, below. 9 TABLE 9 Overall Test Better than As good as Poorer than Original Original original No. of persons  9 40 1 Percentage 18% 80% 2%

[0070] 10 TABLE 10 Taste Test Strongly Strongly Perception agree Agree Neutral Disagree disagree Sour 2 6 30  11  1 Sweet 1 3 43  2 1 Bitter 0 1 2 5 42  Particle-sensed 0 0 0 3 47 

[0071] From other beverages, results similar to those of Tables 9 and 10 were obtained.

EXAMPLE 5

[0072] The beverage prepared in Example 4 was stored for 6 months in a refrigerator (4° C.). Separately, the same beverage was treated at 90° C. for 4 hours. Not only were the beverages observed to maintain a normal dispersion state, but also no other abnormality was detected.

EXAMPLE 6

[0073] In a vessel, 5 g of plant sterol and 4.25 g of sucrose stearyl ester were placed and then melted at 130 to 140° C. with stirring. After completion of the melting, the solution thus obtained was further stirred for 1-2 min. To the solution was added 490.75 g of an aqueous beverage selected from water, juice beverages, carbonated drinks, milk, soya milk, drinks made of grains, and favorite drinks. The diluted beverage was allowed to be taken by 50 skilled subjects (20 males in thirties and forties, 20 females in thirties and forties, 10 females in twenties) for property test by sense perception. As a test beverage, a juice beverage (orange juice) was used. The results are given in Tables 11 and 12, below. 11 TABLE 11 Overall Test Better than As good as Poorer than Original original original No.of persons  6 42 2 Percentage 12% 84% 4%

[0074] 12 TABLE 12 Taste Test Strongly Strongly Perception agree Agree Neutral Disagree Disagree Sour 3 5 31  10  1 Sweet 1 3 43  2 1 Bitter 0 1 3 4 42  Particle-sensed 0 0 1 4 45 

[0075] From other beverages, results similar to those of Tables 11 and 12 were obtained.

[0076] As described hereinbefore, plant sterol nanoparticles are formed by thermally melting plant sterol and an emulsifier and dispersing the molten mixture in an aqueous substrate, in accordance with the present invention. The plant sterol-containing beverage of the present invention inhibits the absorption of intestinal cholesterol and bile cholesterol on account of their structures being similar to that of cholesterol, to lower the serum cholesterol level. Upon heating in the absence of other components, the plant sterol and an emulsifier come into homogeneous contact with each other while being melted, thereby producing micelles with a size of hundreds of nanometers after the emulsification. The nanoparticles are suitable for use in beverages because they contain no organic solvents. In these beverages, the micelles are superior in bioavailability, having no influence on the characteristic taste and flavor of the beverages. Additionally, the improvement in the dispersion stability of the plant sterol micelles has the effect of prolonging the life span of the beverage, guaranteeing the stability of the products for a long period of time.

[0077] The present invention has been described in an illustrative manner, and it is to be understood that the terminology used is intended to be in the nature of description rather than of limitation. Many modifications and variations of the present invention are possible in light of the above teachings. Therefore, it is to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

Claims

1. A method for dispersing plant sterol, comprising the steps of:

thermally melting an admixture of plant sterol and an emulsifier at 60 to 200° C.;

admixing the molten mixture to an aqueous beverage or an emulsifier-containing aqueous beverage; and

stirring the admixture at a high speed to give a dispersion of plant sterol in the beverage.

2. A method for dispersing plant sterol, comprising the steps of:

thermally melting an admixture of plant sterol and an emulsifier at 60 to 200° C.;

admixing the molten mixture to an aqueous beverage or an emulsifier-containing aqueous beverage; and

stirring the admixture at a high speed and homogenizing to give a plant sterol-dispersed beverage.

3. The method as set forth in claim 1 or 2, further comprising the step of drying the dispersion to produce aqueous plant sterol powder.

4. The method as set forth in claim 3, wherein the drying step comprises evaporating or freeze-drying or spray-drying.

5. The method as set forth in claim 1 or 2, wherein the plant sterol is selected from the group consisting of sitosterol, campesterol, stigmasterol, sitostanol, campestanol and mixtures thereof.

6. The method as set forth in claim 5, wherein the plant sterol is sitosterol.

7. The method as set forth in claim 1 or 2, wherein the emulsifier is selected from the group consisting of sucrose fatty acid ester, sorbitan fatty acid ester, polysorbate, polyglycerol fatty acid, propylene glycerol fatty acid, polyglycerine fatty acid ester and mixtures thereof.

8. The method as set forth in claim 7, wherein the emulsifier is sucrose fatty acid ester.

9. The method as set forth in claim 1 or 2, wherein the aqueous beverage is water, a juice beverage, a carbonated drink, milk, soya milk, a drink made of grains, and a favorite drink.

10. The method as set forth in claim 1 or 2, wherein the melting step is carried out at 120 to 150° C.

11. The method as set forth in claim 1 or 2, wherein the plant sterol is mixed at a weight ratio of 1:0.01 to 1:10 with the emulsifier in total.

12. The method as set forth in claim 1 or 2, wherein the plant sterol is mixed at a weight ratio of 1:0.2 to 1:2.0 with the emulsifier in total.

13. The method as set forth in claim 1 or 2, wherein the emulsifier admixed with the aqueous beverage is used at an amount of 80% by weight or less based on the weight of the emulsifier admixed with the plant sterol.

14. The method as set forth in claim 1 or 2, wherein the plant sterol is mixed at a weight ratio of 1:10 to 1:10,000 (w/w) with the aqueous beverage.

15. The method as set forth in claim 14, wherein the plant sterol is mixed at a weight ratio of 1:10 to 1:100 with the aqueous beverage.

16. The method as set forth in claim 1 or 2, wherein the admixture of the aqueous beverage and the plant sterol after the admixing step is maintained at 60 to 140° C.

17. The method as set forth in claim 9, wherein the aqueous beverage is water.

18. The method as set forth in claim 1 or 2, wherein the dispersion has a transmittance at 700 nm of 80.0% or greater.

19. The method as set forth in claim 2, wherein the homogenizing step is carried out by use of a high-pressure homogenizer, a colloid mill or a sonicator.

20. A plant sterol-dispersed beverage prepared by the method of claim 1 or 2.

21. The plant-sterol-dispersed beverage as set forth in claim 20, wherein the beverage is based on water, a juice beverage, a carbonated drink, milk, soya milk, a drink made of grains, or a favorite drink.

22. An additive suitable for use in beverages, prepared by thermally melting an admixture of plant sterol and an emulsifier at 60 to 200° C.

23. The additive as set forth in claim 22, wherein the admixture is heated at 130 to 140° C.

24. The additive as set forth in claim 22, wherein the plant sterol is selected from the group consisting of sitosterol, campesterol, stigmasterol, sitostanol, campestanol and mixtures thereof.

25. The additive as set forth in claim 22, wherein the emulsifier is selected from the group consisting of sucrose fatty acid ester, sorbitan fatty acid ester, polysorbate, polyglycerol fatty acid, propylene glycerol fatty acid, polyglycerine fatty acid ester, and mixtures thereof.