Patent Description:
Vitamin D is a nutrient that plays an important role of promoting absorption of calcium and phosphoric acid in the small intestine, maintaining calcium functions, preventing osteoporosis, serving as a hormone, and helping in preventing and treating various diseases such as Alzheimer's and the like. The types of vitamin D discovered so far are from D2 to D7, and among these types, D2 and D3 have biologically high activity.

The recommended daily allowance intake of this vitamin D is <NUM>µg (<NUM> IU) for children aged <NUM> or under and women aged <NUM> or over, and <NUM>µg (<NUM> IU) for adults aged <NUM> or under, but recently, vitamin D biosynthesis in the skin has been disturbed because the time of exposure to UV rays is limited due to increased indoor life, wearing of masks due to fine dust and the like, and the use of sunscreen. In particular, vitamin D deficiency may lead to rickets in growing children and osteomalacia in perimenopausal women and the elderly, and cause hypocalcemia, hypothyroidism, and bone loss.

Vitamin D, which may be taken through the diet, is contained in trace amounts in mushrooms, fish, meat, and milk.

Particularly, mushrooms contain a lot of ergosterol, a precursor of vitamin D2; hence, when vitamin D2 synthesized from ergosterol is taken as a health functional food, the vitamin D2 is converted to <NUM>, <NUM>-hydroxyvitamin D2, an active form of vitamin D2 through both in the liver and kidneys, to performs various physiological functions as vitamin D2.

Most vitamin D3 distributed in the market is chemically synthesized from cholesterol obtained from wool. In other words, since vitamin D3 is synthesized through processes of extracting and purifying Lanolin of the wool with an organic solvent → separating and purifying cholesterol → chemically synthesizing <NUM>-dehydrocholesterol → performing UV irradiation, it is highly likely that organic solvents, cholesterol, impurities and the like will remain in final vitamin D3 products. In addition, there is "yeast vitamin D3" distributed in the market, but the yeast vitamin D3 is not a vitamin actually derived from yeast, but is prepared by mixing synthetic vitamin D3 synthesized from lanolin of wool with yeast.

Vitamin D produced from button mushrooms has a problem in that since the structure of fruiting bodies is soft, and the moisture content is high, and thus the initial number of bacteria is <NUM> /g or more; and hence, it is not suitable for a standard when producing a final product.

In addition, there are few types of foods that can supply vitamin D through the diet, and the vitamin D content in the foods is very low, so intake through food is very limited. Therefore, there is an urgent need to develop foods fortified with vitamin D.

Meanwhile, Patent Documents <NUM> to <NUM> disclose methods for synthesizing vitamin D2 from ergosterol contained in mushrooms by irradiating the mushrooms with UV-B (<CIT>, <CIT>, and <CIT>). However, in the case of Patent Documents <NUM> to <NUM>, there is an advantage that vitamin D2 has been increased by irradiating the mushrooms with UV-B, but as a result, since the content of vitamin D2 is less than <NUM>µg/g in oyster mushrooms and <NUM>µg/g in shiitake mushrooms, which are very low, and there is a problem of low marketability and economic feasibility, such as an increase in manufacturing cost due to a long irradiation time.

Accordingly, the present inventors studied not only conditions for irradiating mushrooms with UV light in the related art but also pretreatment conditions that may affect the content of vitamin D, and established an optimal condition for preparing mushrooms with a significantly increased vitamin D content, by analyzing a difference in content of vitamin D, thereby completing the present invention. Non-patent document <NUM> concerns the provision of Shiitake mushrooms with increased vitamin D2 content. Non-patent document <NUM> discloses a method for preparing shiitake mushrooms with an increased vitamin D2 content comprising: (i) aging shiitake mushrooms; (ii) chopping the aged shiitake mushrooms; (iii) irradiating the chopped shiitake mushrooms with UV-B; <NUM> (iv) freeze drying the shiitake mushroom pieces irradiated with UV-B; and (<NUM>) crushing the thermally treated shiitake mushroom pieces.

It is an object of the present invention to provide a method for preparing shiitake mushrooms with an increased vitamin D2 content and shiitake mushrooms with an increased vitamin D2 by the method.

More specifically, an object of the present invention is to provide shiitake mushrooms with an increased vitamin D2 content including: (<NUM>) a first step of pre-aging shiitake mushrooms, wherein the first step is to store the shiitake mushrooms at <NUM> for <NUM> day; (<NUM>) a second step of aging the aged shiitake mushrooms, wherein the second step is to store the aged shiitake mushrooms at <NUM> for <NUM> days; (<NUM>) a third step of chopping the aged shiitake mushrooms; (<NUM>) a fourth step of irradiating the chopped shiitake mushrooms with UV-B; (<NUM>) a fifth step of thermally treating the shiitakemushroom pieces irradiated with UV-B; and (<NUM>) a sixth step of crushing the thermally treated shiitake mushroom pieces, wherein the chopped shiitake mushrooms have lengths of <NUM> or less in width, length and height, respectively, and the thermally treatment is performed at <NUM> for 24hours.

In order to solve the above object, the present invention provides a method for preparing shiitake mushrooms with an increased vitamin D2 content. The present invention provides a method for preparing shiitake mushrooms with an increased vitamin D2 content including: (<NUM>) a first step of pre-aging shiitake mushrooms, wherein the first step is to store the shiitake mushrooms at <NUM> for <NUM> day; (<NUM>) a second step of aging the aged shiitake mushrooms, wherein the second step is to store the aged shiitake mushrooms at <NUM> for <NUM> days; (<NUM>) a third step of chopping the aged shiitake mushrooms; (<NUM>) a fourth step of irradiating the chopped shiitake mushrooms with UV-B; (<NUM>) a fifth step of thermally treating the shiitakemushroom pieces irradiated with UV-B; and (<NUM>) a sixth step of crushing the thermally treated shiitake mushroom pieces, wherein the chopped shiitake mushrooms have lengths of <NUM> or less in width, length and height, respectively, and the thermally treatment is performed at <NUM> for <NUM> hours.

In addition, the present invention may be characterized in that the chopped shiitake mushrooms have lengths of <NUM> to <NUM> or less in width, length and height, respectively.

In addition, the present invention may be characterized in that the chopped shiitake mushrooms have the moisture content of <NUM> to <NUM> wt%.

In addition, the UV-B irradiation of the present invention is characterized by inverting the shiitake mushrooms at a predetermined time interval once every <NUM> minutes, while irradiating the shiitake mushroom sample with the UV-B for <NUM> minutes at an intensity of <NUM>,<NUM> to <NUM>,<NUM>µW/cm<NUM> and a relative humidity of <NUM> to <NUM>% in a state that the shiitake mushroom sample is placed on a stainless steel plate of a stainless steel chamber equipped with a UV light lamp.

In addition, the present invention may be characterized in that the shiitake mushrooms prepared by the method produce vitamin D2 of <NUM>µg (<NUM>,<NUM> IU)/g or more.

In addition, the present invention may be characterized in that the shiitake mushrooms prepared by the method may have a bacterial count of <NUM> or less per g, and E. coli is negative.

In addition, the present invention may be characterized in that the shiitake mushrooms prepared by the method contain beta-glucan, polyphenol, copper (Cu), zinc (Zn), selenium (Se), ergosterol, eritadenine, a sulfur compound, an antiinflammatory material, an immune enhancing material, an anticancer material, an antiviral material, an antibacterial material, an antifungal material, and a blood sugar regulator.

As described above, the present invention provides shiitake mushrooms with the increased vitamin D2 content, thereby significantly increasing the vitamin D2 content <NUM> times to <NUM> times or more relative to conventional methods, and manufacturing a final product with a low bacterial count and secured safety without using any organic solvent.

Accordingly, the definitions of these terms should be made based on the contents throughout the present specification. Throughout the specification, when a part "comprises" a component, this means that other components may be further included, rather than excluding the other component unless otherwise described.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

However, the following Examples and Preparation Examples are just illustrative of the present invention, and the contents of the present invention are not limited to the following Examples and Preparation Examples.

The materials and methods used in the Examples below are as follows.

For sample shiitake mushroom fruiting bodies, a medium grade product grown in Geumgok-myeon, Jinju-si, Gyeongsangnamdo was used.

The sample shiitake mushroom fruiting bodies were stored in a temperature-controlled storage room (<NUM> to <NUM>).

A sealed stainless steel chamber is equipped with three UV light lamps (<NUM> to <NUM>: <NUM> W) on the top thereof, and a stainless steel plate capable of holding the sample is equipped at a distance of <NUM> to <NUM> from the UV light lamps (distance adjustable).

A temperature-controlled (room temperature to <NUM>) dryer was used.

The sample for the analysis of vitamin D2 was prepared by a standard preparation method of the vitamin D2 of the Ministry of Food and Drug Safety, and the vitamin D2 analysis of the prepared sample was analyzed by standard a HPLC system and method of the Ministry of Food and Drug Safety. Statistics on the analyzed value were verified by a Tukey's multiple comparison test. Mean values with different English small letters within the same treatment mean that there is significance at p < <NUM>.

The shiitake mushroom fruiting bodies were pre-aged in the combination of various temperatures (<NUM>, <NUM>, <NUM>, and <NUM>) and various aging periods (<NUM>, <NUM>, <NUM>, and <NUM> days) in a temperature-controlled storage room immediately after harvest. The pre-aged shiitake mushroom fruiting bodies were washed with water and water on the surface of fruiting bodies was removed to select fruiting bodies having a moisture content of <NUM> to <NUM> wt%. The selected shiitake mushroom fruiting bodies were chopped to prepare a sample in the same state as sawdust (width × length × height of <NUM> or less). The sample was laid with a thickness of <NUM> to <NUM> on a stainless steel plate (at a distance of <NUM> from the light lamp) of a stainless steel chamber equipped with UV light lamps, and then inverted the sample once every <NUM> minutes while irradiating with UV for <NUM> minutes at an intensity of <NUM>,<NUM> to <NUM>,<NUM>µW/cm<NUM> and a relative humidity of <NUM> to <NUM>%. The UV-irradiated sample was thermally treated at <NUM> for <NUM> hours, crushed, and used as a vitamin D2 analysis sample to measure the vitamin D2 content.

As a result, as shown in Table <NUM>, the sample pre-aged at <NUM> for <NUM> day had the highest vitamin D2 content. However, the tissue was too softened, and thus chopping was difficult, agglomeration phenomenon occurred during drying, and a slight decay phenomenon occurred, and thus the number of mold and bacteria was high, making it unsuitable for use as a sample.

Shiitake mushroom fruiting bodies were pre-aged for <NUM> day in a <NUM> storage room immediately after harvest, and aged again in the combination of temperatures (<NUM>, <NUM>, <NUM>, and <NUM>) and periods (<NUM>, <NUM>, <NUM>, and <NUM> days). The aged shiitake mushroom fruiting bodies were washed with water and water on the surface of fruiting bodies was removed to select fruiting bodies having a moisture content of <NUM> to <NUM> wt%. The aged shiitake mushroom fruiting bodies were chopped to prepare a sample in the same state as sawdust (width × length × height of <NUM> or less). The sample was laid with a thickness of <NUM> to <NUM> on a stainless steel plate (at a distance of <NUM> from the light lamp) of a stainless steel chamber equipped with UV light lamps, and then inverted the sample once every <NUM> minutes while irradiating with UV for <NUM> minutes at an intensity of <NUM>,<NUM> to <NUM>,<NUM>µW/cm<NUM> and a relative humidity of <NUM> to <NUM>%. The UV-irradiated sample was thermally treated at <NUM> for <NUM> hours, crushed, and used as a vitamin D2 analysis sample to measure the vitamin D2 content.

As a result, as shown in Table <NUM>, the sample aged at <NUM> for <NUM> days had the highest vitamin D2 content, but the most suitable storage period was <NUM> to <NUM> days.

Shiitake mushroom fruiting bodies were pre-aged for <NUM> day in a storage room of <NUM> immediately after harvest, and then aged at <NUM> for <NUM> days again. The aged shiitake mushroom fruiting bodies were washed with water and water on the surface of fruiting bodies was removed to select fruiting bodies having a moisture content of <NUM> to <NUM> wt%. The selected shiitake mushroom fruiting bodies were chopped to prepare a sample in the same state as sawdust (width × length × height of <NUM> or less). The sample was laid with a thickness of <NUM> to <NUM> on a stainless steel plate (at a distance of <NUM> from the light lamp) of a stainless steel chamber equipped with UV light lamps, and then inverted the sample once every <NUM> minutes while irradiating with the amounts of UV (<NUM>, <NUM>, <NUM>,<NUM>, <NUM>,<NUM>, <NUM>,<NUM>, <NUM>,<NUM>, and <NUM>µW/cm<NUM>) for <NUM> minutes at a relative humidity of <NUM> to <NUM>%. The UV-irradiated sample was thermally treated at <NUM> for <NUM> hours, crushed, and used as a vitamin D2 analysis sample to measure the vitamin D2 content.

As a result, as shown in Table <NUM>, the sample irradiated with UV at <NUM>,<NUM>µW/cm<NUM> for <NUM> minutes had the highest vitamin D2 content, but there was no difference in vitamin D2 production at <NUM>,<NUM> to <NUM>,<NUM>µW/cm<NUM>.

Shiitake mushroom fruiting bodies were pre-aged for <NUM> day at a storage room of <NUM> immediately after harvest, and then aged at <NUM> for <NUM> days again. The aged shiitake mushroom fruiting bodies were washed with water and water on the surface of fruiting bodies was removed to select fruiting bodies having a moisture content of <NUM> to <NUM> wt%. The selected shiitake mushroom fruiting bodies were chopped to prepare a sample in the same state as sawdust (width × length × height of <NUM> or less). The sample was laid with a thickness of <NUM> to <NUM> on a stainless steel plate (at a distance of <NUM> from the light lamp) of a stainless steel chamber equipped with UV light lamps, and then inverted at a predetermined number of times (<NUM>, <NUM>, <NUM>, and <NUM>) while irradiating with UV for a predetermined time (<NUM>, <NUM>, <NUM>, and <NUM> minutes) at an intensity of <NUM>,<NUM> to <NUM>,<NUM>µW/cm<NUM> and a relative humidity of <NUM> to <NUM>%. The UV-irradiated sample was thermally treated at <NUM> for <NUM> hours, crushed, and used as a vitamin D2 analysis sample to measure the vitamin D2 content.

As a result, as shown in Table <NUM>, the sample inverted once at UV of <NUM>,<NUM> to <NUM>,<NUM>µW/cm<NUM> for <NUM> minutes had the highest vitamin D2 content, but similar vitamin D2 content was obtained even in the sample inverted twice. In addition, in the case of the sample irradiated for <NUM> minutes, similar vitamin D2 content was obtained even in the sample inverted twice.

Shiitake mushroom fruiting bodies were pre-aged for <NUM> day at a storage room of <NUM> immediately after harvest, and then aged at <NUM> for <NUM> days again. The aged shiitake mushroom fruiting bodies were washed with water and water on the surface of fruiting bodies was removed to select fruiting bodies having a moisture content of <NUM> to <NUM> wt%. The selected shiitake mushroom fruiting bodies were chopped to prepare a sample in the same state as sawdust (width × length × height of <NUM> or less). The sample was laid with a thickness of <NUM> to <NUM> on a stainless steel plate (at a distance of <NUM> from the light lamp) of a stainless steel chamber equipped with UV light lamps, and then inverted once every <NUM> minutes while irradiating with UV for <NUM> minutes at an intensity of <NUM>,<NUM> to <NUM>,<NUM>µµW/cm<NUM> and a relative humidity of <NUM> to <NUM>%. The sample irradiated with UV was thermally treated for <NUM> hours at a predetermined temperature (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>) and thermally treated at <NUM> for a predetermined time (<NUM>, <NUM>, <NUM>, <NUM>, and <NUM> hours) and then crushed to be used as a vitamin D2 analysis sample to measure the vitamin D2 content.

As a result, as shown in Table <NUM>, the sample thermally treated at the temperature of <NUM> to <NUM> for <NUM> hours had the highest vitamin D2 content. In addition, at the temperature of <NUM>, the sample treated for <NUM> to <NUM> hours had the high vitamin D2 content.

Shiitake mushroom fruiting bodies were pre-aged for <NUM> day at a storage room of <NUM> immediately after harvest, and then aged at <NUM> for <NUM> days again. The aged shiitake mushroom fruiting bodies were washed with water and water on the surface of fruiting bodies was removed to select fruiting bodies having a moisture content of <NUM> to <NUM> wt%. The selected shiitake mushroom fruiting bodies were chopped to prepare a sample in the same state as sawdust (width × length × height of <NUM> or less). The sample was laid with various thicknesses <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, and <NUM> to <NUM>) on a stainless steel plate (at a distance of <NUM> from the light lamp) of a stainless steel chamber equipped with UV light lamps, and then inverted once every <NUM> minutes while irradiating with UV for various times (<NUM>, <NUM>, <NUM>, <NUM>, and <NUM> minutes) at an intensity of <NUM>,<NUM> to <NUM>,<NUM>µW/cm<NUM> and a relative humidity of <NUM> to <NUM>%. The UV-irradiated sample was thermally treated at <NUM> for <NUM> hours, crushed, and used as a vitamin D2 analysis sample to measure a vitamin D2 content.

As a result, as shown in Table <NUM>, the sample laid with a thickness of <NUM> to <NUM> and irradiated with UV for <NUM> to <NUM> minutes had the highest vitamin D2 content. There was no difference in the vitamin D2 content between the sample laid with a thickness of <NUM> to <NUM> and irradiated with UV for <NUM> minutes and the sample laid with a thickness of <NUM> to <NUM> and irradiated with UV for <NUM> to <NUM> minutes.

Shiitake mushroom fruiting bodies were pre-aged for <NUM> day at a storage room of <NUM> immediately after harvest, and then aged at <NUM> for <NUM> days again. The aged shiitake mushroom fruiting bodies were washed with water and water on the surface of fruiting bodies was removed to prepare fruiting bodies having a moisture content (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>%) as a sample. The selected shiitake mushroom fruiting bodies were chopped to prepare a sample in the same state as sawdust (width × length × height of <NUM> or less). The sample was laid with a thickness of <NUM> to <NUM> on a stainless steel plate (at a distance of <NUM> from the light lamp) of a stainless steel chamber equipped with UV light lamps, and then inverted once every <NUM> minutes while irradiating with UV for <NUM> minutes at an intensity of <NUM>,<NUM> to <NUM>,<NUM>µW/cm<NUM> and a relative humidity of <NUM> to <NUM>%. The UV-irradiated sample was thermally treated at <NUM> for <NUM> hours, crushed, and used as a vitamin D2 analysis sample to measure a vitamin D2 content.

As a result, as shown in Table <NUM>, the sample having the moisture content of <NUM>% had the highest vitamin D2 content, but the samples having the moisture content of <NUM> to <NUM>% had no difference in the vitamin D2 content.

Shiitake mushroom fruiting bodies were pre-aged for <NUM> day at a storage room of <NUM> immediately after harvest, and then aged at <NUM> for <NUM> days again. The aged shiitake mushroom fruiting bodies were washed with water and water on the surface of fruiting bodies was removed to select fruiting bodies having a moisture content of <NUM> to <NUM> wt%. The selected shiitake mushroom fruiting bodies were chopped to prepare a sample in the same state as sawdust (width × length × height of <NUM> or less). The sample was laid with a thickness of <NUM> to <NUM> on a stainless steel plate (at a distance of <NUM> from the light lamp) of a stainless steel chamber equipped with UV light lamps, and then inverted once every <NUM> minutes while irradiating with UV for <NUM> minutes at an intensity of <NUM>,<NUM> to <NUM>,<NUM>µW/cm<NUM> and various relative humidity (<NUM>, <NUM>, <NUM>, <NUM>, and <NUM>%). The UV-irradiated sample was thermally treated at <NUM> for <NUM> hours, crushed, and used as a vitamin D2 analysis sample to measure a vitamin D2 content.

As a result, as shown in Table <NUM>, the sample having the relative humidity in the chamber of <NUM>% had the highest vitamin D2 content, but the samples having the relative humidity of <NUM> to <NUM>% had no difference in the vitamin D2 content.

Shiitake mushroom fruiting bodies were pre-aged for <NUM> day at a storage room of <NUM> immediately after harvest, and then aged at <NUM> for <NUM> days again. The aged shiitake mushroom fruiting bodies were washed with water and water on the surface of fruiting bodies was removed to select fruiting bodies having a moisture content of <NUM> to <NUM> wt%. The selected shiitake mushroom fruiting bodies were sliced with various sizes (<NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, and <NUM> to <NUM>) or chopped with various sizes (<NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, and <NUM> to <NUM>) to prepare a sample. Placed <NUM> of sample on a stainless steel plate (at a distance of <NUM> from the light lamp) of a stainless steel chamber equipped with UV light lamps, and then inverted once every <NUM> minutes while irradiating with UV for <NUM> minutes at an intensity of <NUM>,<NUM> to <NUM>,<NUM>µW/cm<NUM> and a relative humidity of <NUM> to <NUM>%. The UV-irradiated sample was thermally treated at <NUM> for <NUM> hours, crushed, and used as a vitamin D2 analysis sample to measure a vitamin D2 content.

As a result, as shown in Table <NUM>, very low vitamin D2 was produced in a non-chopped or non-sliced sample. However, the vitamin D2 content was the highest in a sample chopped to <NUM> to <NUM> or less, and had no difference from a sample chopped to <NUM> to <NUM> or less. Also, in the case of slicing, the vitamin D2 content was the highest in a sample sliced to <NUM> to <NUM> or less, but the content thereof was relatively lower than the chopped sample.

Shiitake mushroom fruiting bodies were pre-aged for <NUM> day at a storage room of <NUM> immediately after harvest, and then aged at <NUM> for various periods (<NUM>, <NUM>, <NUM>, <NUM>, and <NUM> days) again. The aged shiitake mushroom fruiting bodies were washed with water and water on the surface of fruiting bodies was removed to select fruiting bodies having a moisture content of <NUM> to <NUM> wt%. The selected shiitake mushroom fruiting bodies were sliced at about <NUM> to prepare a sample. The sample was laid with a thickness of <NUM> to <NUM> on a stainless steel plate (at a distance of <NUM> from the light lamp) of a stainless steel chamber equipped with UV light lamps, and then inverted once every <NUM> minutes while irradiating with UV for <NUM> minutes at an intensity of <NUM>,<NUM> to <NUM>,<NUM>µW/cm<NUM> and a relative humidity of <NUM> to <NUM>%. The UV-irradiated sample was thermally treated at <NUM> for <NUM> hours, crushed, and used as a vitamin D2 analysis sample to measure a vitamin D2 content.

As a result, as shown in Table <NUM>, the sample aged for <NUM> to <NUM> days had the highest vitamin D2 content.

Shiitake mushroom fruiting bodies were pre-aged for <NUM> day at a storage room of <NUM> immediately after harvest, and then aged at <NUM> for <NUM> days again. The aged shiitake mushroom fruiting bodies were washed with water and water on the surface of fruiting bodies was removed to select fruiting bodies having a moisture content of <NUM> to <NUM> wt%. The selected shiitake mushroom fruiting bodies were sliced at about <NUM> to prepare a sample. The sample was laid one by one on a stainless steel plate (at a distance of <NUM> from the light lamp) of a stainless steel chamber equipped with UV light lamps, and then inverted at various intervals while irradiating with UV for various times (<NUM>, <NUM>, and <NUM> hours) at an intensity of <NUM>,<NUM> to <NUM>,<NUM>µW/cm<NUM> and a relative humidity of <NUM> to <NUM>%. The UV-irradiated sample was thermally treated at <NUM> for <NUM> hours, crushed, and used as a vitamin D2 analysis sample to measure a vitamin D2 content.

As a result, as shown in Table <NUM>, the sample irradiated with UV for <NUM> hour and inverted <NUM> to <NUM> times had the highest vitamin D2 content.

Shiitake mushroom fruiting bodies were pre-aged for <NUM> day at a storage room of <NUM> immediately after harvest, and then aged at <NUM> for <NUM> days again. The aged shiitake mushroom fruiting bodies were washed with water and water on the surface of fruiting bodies was removed to select fruiting bodies having a moisture content of <NUM> to <NUM> wt%. The selected shiitake mushroom fruiting bodies were sliced with various sizes (<NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, and <NUM> to <NUM>) to prepare a sample. The samples with various thicknesses were laid one by one on a stainless steel plate (at a distance of <NUM> from the light lamp of a stainless steel chamber equipped with UV light lamps, and then inverted every <NUM> minutes while irradiating with UV for various times (<NUM>, <NUM>, <NUM>, and <NUM> minutes) at an intensity of <NUM>,<NUM> to <NUM>,<NUM>µW/cm<NUM> and a relative humidity of <NUM> to <NUM>%. The UV-irradiated sample was thermally treated at <NUM> for <NUM> hours, crushed, and used as a vitamin D2 analysis sample to measure a vitamin D2 content.

As a result, as shown in Table <NUM>, the sample with a sliced thickness of <NUM> to <NUM> and irradiated with UV for <NUM> to <NUM> minutes had the highest vitamin D2 content. In addition, in the case of samples of <NUM> to <NUM>, a sample irradiated for <NUM> minutes had the highest vitamin D2 content, which had no difference in content from the sample of <NUM> to <NUM>, irradiated with UV for <NUM> to <NUM> minutes.

Shiitake mushroom fruiting bodies were aged for <NUM> day at a storage room of <NUM> immediately after harvest, and then aged at <NUM> for <NUM> days again. The aged shiitake mushroom fruiting bodies were washed with water and water on the surface of fruiting bodies was removed to select fruiting bodies having a moisture content of <NUM> to <NUM> wt%. The selected shiitake mushroom fruiting bodies were chopped to prepare a sample in the same state as sawdust (width × length × height of <NUM> or less). The sample was laid with a thickness of <NUM> to <NUM> on a stainless steel plate (at a distance of <NUM> from the light lamp) of a stainless steel chamber equipped with UV light lamps, and then inverted once every <NUM> minutes while irradiating with UV for <NUM> minutes at an intensity of <NUM>,<NUM> to <NUM>,<NUM>µW/cm<NUM> and a relative humidity of <NUM> to <NUM>%. The UV-irradiated sample was thermally treated at <NUM> for <NUM> hours, crushed, and used as a vitamin D2 analysis sample to measure a vitamin D2 content.

As a result, as shown in Table <NUM>, the vitamin D2 content produced under the optimal conditions was measured to be <NUM> ± <NUM>µg/g.

Shiitake mushroom fruiting bodies were pre-aged for <NUM> day at a storage room of <NUM> immediately after harvest, and then aged at <NUM> for <NUM> days again. The aged shiitake mushroom fruiting bodies were washed with water and water on the surface of fruiting bodies was removed to select fruiting bodies having a moisture content of <NUM> to <NUM> wt%. The UV-irradiated sample was thermally treated at <NUM> for <NUM> hours, crushed, and used as a vitamin D2 analysis sample to measure a vitamin D2 content.

In the method of the conventional patent (<CIT>), an irradiation region was irradiated with UV-B at <NUM> KJ/m<NUM> and at <NUM> and <NUM>% relative humidity on an inner wrinkle layer (<NUM>) of the sliced shiitake mushrooms.

Claim 1:
A method for preparing shiitake mushrooms with an increased vitamin D2 content comprising:
(<NUM>) a first step of aging shiitake mushrooms, wherein the first step is to store the shiitake mushrooms at <NUM> for <NUM> day;
(<NUM>) a second step of aging the aged shiitake mushrooms, wherein the second step is to store the aged shiitake mushrooms at <NUM> for <NUM> days;
(<NUM>) a third step of chopping the aged shiitake mushrooms;
(<NUM>) a fourth step of irradiating the chopped shiitake mushrooms with UV-B;
(<NUM>) a fifth step of thermally treating the shiitake mushroom pieces irradiated with UV-B; and
(<NUM>) a sixth step of crushing the thermally treated shiitake mushroom pieces,
wherein the chopped shiitake mushrooms have lengths of <NUM> or less in width, length and height, respectively, and
the thermally treatment is performed at <NUM> for <NUM> hours.