WO2010027117A1

WO2010027117A1 - Preparation method of gaba by fermentation of seaweed

Info

Publication number: WO2010027117A1
Application number: PCT/KR2008/005321
Authority: WO
Inventors: Bae Jin Lee; Young Mog Kim; Myung Suk Lee; Jin Soo Kim; Dong Uk Jang; Ji Hyun Lim
Original assignee: Marine Bioprocess Co., Ltd.
Priority date: 2008-09-04
Filing date: 2008-09-10
Publication date: 2010-03-11
Also published as: JP5281101B2; JP2011512836A; KR101059482B1; KR20100028265A

Abstract

The present invention relates to a method for preparing a fermented seaweed product, comprising the steps of: (1) autoclaving seaweed at 120-125°C for 15-30 minutes to prepare a medium; (2) inoculating the medium with at least one microorganism of lactic acid bacteria or yeasts, and fermenting the medium in aerobic or anaerobic conditions depending on the inoculated microorganism to induce the conversion of glutamate into gamma- aminobutyric acid (GABA) and the degradation of seaweed polysaccharides into monosacchariodes and oligosaccharides; and (3) autoclaving the fermentation product at 120-125°C for 15-30 minutes. Also, the invention relates to a fermented seaweed product obtained by the preparation method, a method for preparing a seasoning from the fermentation broth of the fermented seaweed product, a fermented seaweed seasoning obtained by the preparation method, a method for preparing fermented seaweed powder from the fermentation residue of the fermented seaweed product, and fermented seaweed powder obtained by the preparation method. According to the invention, GABA can be produced using natural glutamate as a main material, and thus it is possible to overcome problems associated with monosodium glutamate (MSG) that remains without being converted into GABA when GABA is produced using MSG as a main raw material according to the prior art. In addition, unlike the prior art utilizing only an extract of seaweed, whole seaweed is used, and glutamate is continuously extracted in the processes of autoclaving and fermenting the seaweed, whereby GABA can be obtained in high yield.

Description

PREPARATION METHOD OF GABA BY FERMENTATION OF

SEAWEED

Technical Field

[1] The present invention relates to a method of preparing gamma- aminobutyric acid

(GABA) by the fermentation of seaweed, and more particularly to a method for preparing a fermented seaweed product, comprising the steps of: (1) autoclaving seaweed at 120-125 ⁰C for 15-30 minutes to prepare a medium; (2) inoculating the medium with at least one microorganism of lactic acid bacteria or yeasts, and fermenting the medium in aerobic or anaerobic conditions depending on the inoculated microorganism to induce the conversion of glutamate into gamma- aminobutyric acid (GABA) and the degradation of seaweed polysaccharides into monosacchariodes and oligosaccharides; and (3) autoclaving the fermentation product at 120-125 ⁰C for 15-30 minutes. Also, the present invention relates to a fermented seaweed product obtained by said preparation method, a method for preparing a seasoning from the fermentation broth of the fermented seaweed product, a fermented seaweed seasoning obtained by said preparation method, a method for preparing fermented seaweed powder from the fermentation residue of the fermented seaweed product, and fermented seaweed powder obtained by said preparation method. Background Art

[2] It is known that the major causes of death in Korea are traffic accidents in the 20-3Os age group, liver diseases in the 40s age group, and vascular diseases (i.e., hypertension and palsy) in the 50 or older age group. Particularly, as life expectancy rises, the number of people suffering from adult diseases such as hypertension, diabetes and palsy increases, and the age of onset of adult diseases also gradually decreases, such that the number of 30-40-year-old people suffering from adult diseases increases.

[3] Generally, gamma-aminobutyric acid (GABA) is a kind of non-protein amino acid which is widely distributed in nature. It is an inhibitory neurotransmitter which is present in the mammalian brain or spinal cord. It is known that GABA is involved in the regulation of many physiological mechanisms in the human body, such that it acts to activate cerebral blood flow and to increase the supply of oxygen to the brain, thus promoting the metabolic function of brain cells. Also, it is known that GABA is involved in the secretion and regulation of growth hormones and has the effects of lowering blood pressure, alleviating pain, tranquilizing mind, improving liver and kidney functions and inhibiting colorectal cancer. Due to such pharmacological functions, GABA receives a great deal of attention. [4] It was recently reported that GABA significantly increases learning capacity, contributes to long-term memory formation, suppresses an increase in blood pressure and acts to regulate appetite and satiation, and thus it receives worldwide attention. As oral formulations, pills containing 5 mg or 10 mg of GABA are being marketed, but it is known that synthetic GABA formulations shows side effects in the digestive system, including appetite loss, constipation and diarrhea.

[5] Due to such functions, GABA is receiving attention not only as medical drugs, but also as functional food materials. Because GABA is frequently found in germinated crops such as germinated brown rice, green tea, and crops such as Chinese cabbage roots, it can be orally taken. However, the content of GABA in these crops is low, and thus GABA in the amount required to exhibit physiological action is not easy to take from food. To overcome this shortcoming, studies focused on finding food materials containing a large amount of GABA and applying the found food materials in industrial applications are being actively conducted.

[6] Moreover, L-glutamic acid that is a typical neurotransmitter of the central nervous system is known as a material inducing nerve cell activity. L-glutamic acid is decar- boxylated by the catalysis of glutamic acid decarboxylase (GAD, EC 4. 1. 1. 15), and thus converted to GABA. Since GABA was found for the first time in mammalian brain extracts by Florey and Robert in 1950, studies on GABA have been actively conducted. GABA has a molecular weight of 103.2 dalton, is called piperidinic acid, has a melting point of 202 ⁰C, is stable to heat, has a molecular formula of C₄H₉NO₂, and has high solubility in water.

[7] GABA that is a non-protein amino acid is a neurotransmitter present in the brain or spinal cord. It is known that GABA is a brain nutritional supplement which improves blood flow and increases the supply of oxygen to the brain, thus promoting brain metabolism and increasing brain memory. GABA is known to inhibit nervous activity, unlike glutamic acid that activates nerve, and this function has an important effect on the function and information processing of nerve cells. Particularly, GABA is known to determine direction-sensitive and angle-sensitive responses in the brain and control delicate motor functions. In addition, it is known that GABA is involved in suitably controlling the excitation of the brain to control abnormal excessive activity. It was reported that neurons transmitting GABA are present in vertebrates and invertebrates and that, when GABA is sufficiently supplied to the neurons, epileptic seizures are inhibited. The cerebral blood flow-promoting effect and oxygen supply-increasing effect of GABA promote the metabolism of brain cells to alleviate squelae of stroke and cerebralarteriosclerosis, and due to such effects, GABA is used as medical drugs. It is known that low GABA and GAD concentrations in cerebral blood are closely associated with the occurrence of diseases such as epilepsy, Parkinson's disease and schizophrenia, and persons with alcohol problems have relatively low GABA concentrations compared to normal persons. In addition, GABA is physiologically very useful, because it has the effects of regulating the secretion of growth hormones, alleviating pain, tranquilizing mind and nerve, lowering blood pressure and inhibiting ACE activity.

[8] GABA having such functions is widely distributed in animal and plant systems, is abundantly present in shellfish neuromuscular junctions and mammalian cerebellums and acts as a major inhibitory neurotransmitter in the central nervous system. The content of GABA in plants has been reported to be low, but it is known that, if plants are stressed by external environmental factors, including hypoxia, low and high temperatures, darkness and mechanical stimulation, the production of GABA will rapidly increase. Particularly, it is known that the content of GABA in brown rice is increased by more than three times, when the brown rice is germinated.

[9] With respect to the general effects of GABA, GABA acts not only as amino acid, but also as a neurotransmitter, and is effective in controlling seizures or depression. Also, it is known that GABA is effective in removing hangover by promoting alcohol metabolism and has the effects of lowering blood pressure this blood pressure controlling effect alleviates diabetic complications, improves liver and kidney functions, prevents obesity, and alleviates menopausal disorders, asthenia universalis, headaches, etc.), promoting brain cell metabolism (improving learning capacity), increasing memory, relieving stress, alleviating women's premenstrual tension, enhancing immunity, and restoring eyesight.

[10] In the view that hypertension can be prevented by improving dietary lifestyles, teas, brown rice and solid materials, which contain GABA, have been developed, but the content of GABA in the developed products is low and the range of application of the products is limited. Also, since the recognition level of GABA increases and the appearance of high-concentration GABA-containing goods in markets is anticipated, the selection of new materials and the development of new products utilizing them are required. Accordingly, the selection of high-concentration GABA materials usable in a wide range of processed foods is a very important issue, and another important issue is the development and supply of technology which converts glutamic acid present in seaweed in a large amount of GABA such that GABA which is taken into a limited amount in a natural state can be taken in an amount capable of exhibiting physiological activity.

[11] With respect to the prior art, Korean Patent Registration No. 10-0558760-0000 discloses a method for preparing germinated brown rice having increased GABA content and a method for preparing germinated brown rice tea having increased GABA content, and Korean Patent Registration No. 10-0452050-0000 discloses a method of preparing Takju and Yakju using non-steamed brown rice. The two patents shows the method for increasing GABA content and the development of alcoholic drinks using germinated brown rice, respectively, but there are no examples about the use of seaweed to prepare a extracted fermentation broth and fermented powder which contain GABA together with a large amount of functional oligosaccharides and about a preparation method thereof.

[12] In addition, as the level of living rapidly increases, life expectancy increases, leading an increase in aged population, and as interest in individual health increases, interest in physiological activity -regulating function which is the third function of food is being maximized. Koreans commonly think that health can be maintained by daily taken foods, and Korean traditional drugs are mostly in the form of foods. For this reason, functional foods have been deeply connected with Korean life for a long period of time. According to industrialization, urbanization and family nuclearization, the intake of processed food is increasing, and the incidence of adult diseases, including hypertension, diabetes and cancer, is increasing, leading to a continuous increase in medical expenditures. Accordingly, the functionality and effectiveness of food are the most important concerns for consumers. Particularly, hypertension is one of typical adult diseases, and methods for managing hypertension are required not only in Korea, but also in the world. Among these methods, diet therapy can be used as an important method for managing hypertension, and thus it is needed to develop blood pressure- lowering functional foods and either treat mild hypertension patients with the developed functional foods or prevent the onset of hypertension with the functional foods.

[13] Meanwhile, Korea is surrounded by the sea on three sides and is relatively rich in the marine organism resources, and the amount of seaweed produced in the Korean coast reaches 777000 tons. Such marine organisms are exposed to high salt concentrations, water pressures and seawater, and thus are likely to be attacked by pathogenic microorganisms. Also, these marine organisms live in environments very different from those for terrestrial organisms, and thus it can be presumed that the marine organisms have developed their metabolic systems or body defense systems having evolutionary processes completely different from those of terrestrial organisms. Accordingly, metabolites from marine natural products show new types of chemical structures and various physiological activities.

[14] Seaweed is a food that can be very abundantly eaten and has a fresh sea taste.

Generally, seaweed has a protein content of about 10% and a starch content of about 30-40%, but it is not expressed in calories, because it is a fibrous cellulosic material. Seaweed contains large amounts of various inorganic salts essential for health and at the same time, contains body composition nutrients such as proteins. Seaweeds such as laver, sea mustard or sea tangle are alkaline health foods which are rich in potassium ions and have excellent chemical properties. Among them, laver is a health food which has a very high nutrient content and contains proteins and carbohydrates in amounts significantly larger than those of other foods. Also, seaweed is effective as a health food for preventing adult diseases, because it is a fibrous cellulosic material. Ions generated from seaweed are excreted after being bonded with acidic waste products in the body, and thus are absolutely necessary for metabolism. Accordingly, the nature of seaweed greatly contributes not only to the direct excretion of waste products, but also to the removal of toxicity which can secondarily occur. The reason why seaweed has an excellent function as health food is that it contains a large amount of alginic acid that is a good-quality fibrous cellulosic material. Particularly, seaweed is effective in relieving constipation by stimulating the peristaltic movement of the colon. Seaweed is rich in calcium ions (Ca++), and thus is effective in preventing osteoporosis or osteomalacia and preventing aging. Also, an iodine component that is abundantly contained in seaweed promotes appetite, prevents thyroid eczema and softens hair. Raw laver has a faint fragrant sea odor, and it abundantly contains dietary fiber in amounts similar to those of sea mustard, sea tangle or other seaweeds, and thus stimulates the peristaltic movement of the colon to induce the smooth excretion of waste products.

[15] Specifically, seaweeds contain large amounts of amino acids (glutamic acid, aspartic acid, etc.) and are rich in seaweed oligosaccharides (fucoidan, etc.) which receive attention as highly functional natural materials, and thus, seaweeds are recognized as ideal natural foods. In addition, seaweeds abundantly contain various minerals and vitamins, and the results of studies on the physiological effects of seaweeds, actively conducted by domestic and foreign experts, revealed that seaweeds are deeply involved in weight loss, the treatment of constipation by intestinal regulation, and the elimination of heavy metals and radioactive materials from the body. In addition, it was reported that a sulfur-containing polysaccharide known as Fucoidan has antimicrobial, antioxidant, antiviral and anticancer activities and is effective in preventing adult diseases, including arteriosclerosis, myocadial infarction, hypertension, angina and stroke.

[16] However, in the prior art, in the case of brown algae among seaweeds, highly viscous alginic acid or the like is dissolved out during extraction and processing to deteriorate processability in separation and purification processes, thus increasing production costs. Particularly, fucoidan known to be abundant in brown algae such as sea tangle or sea mustard among seaweeds is a highly viscous, sulfur-containing polysaccharide, and in order to extract, separate and purify fucoidan, a technology for effectively separating and purifying fucoidan from highly viscous materials such as alginic acid is necessarily required. Microfiltration methods used to separate and purify such functional materials with high purity include hollow-fiber membrane ultrafiltration which is carried out using a flat sheet membrane or hollow-fiber membrane filter and the pores of the membrane. However, for the application of a smooth ultrafiltration process, pre- filtration must be carried out before microfiltration. In addition, due to the fouling phenomena of the membrane filter during the filtration process, separation efficiency is rapidly decreased, and particularly, due to poor separation efficiency and excessive operating expenses, it is impossible to introduce highly viscous materials such as seaweed extracts into mass production processes. In addition, seaweeds are taken in the form of powders or pills, but are not consumed in large amounts due to poor taste and preference. To overcome this limitation, seaweeds are added to prepare seaweed noodles (sea tangle noodles and fusiforme noodles), but due to poor mouth feel, flavor and processing suitability, it is difficult to increase the amount of seaweeds added, so as to exhibit the substantial effects of seaweeds.

[17] Meanwhile, seaweed (sea tangle) as a natural well-being food has dietary effects and highly functional, physiologically active materials such as fucoidan, contains large amounts of monosodium glutamate known as MSG, and has been widely used as a traditional natural seasoning. It was recently demonstrated through worldwide clinical trials that GABA has excellent physiological activities, including blood pressure lowering, brain cell metabolism promotion, and hangover relief. It was proven that GABA is produced from the precursor glutamate through decarboxylation by GAD. Technology for increasing the content of GABA is being developed in worldwide countries including Japan, and the development of this technology consists mainly of the development of fermenting lactic acid bacteria that ferment the artificially added chemical MSG to convert the MSG to GABA. Disclosure of Invention Technical Problem

[18] The present inventors have found that, when whole seaweed containing a large amount of natural glutamate is autoclaved and fermented, glutamate can be continuously extracted from the seaweed during the autoclaving and fermentation processes, and the extracted glutamate can be converted into GABA, thus obtaining GABA in high yield. Specifically, the present inventors have found that GABA can be produced using natural glutamate as a main raw material, and the yield of GABA can further be increased by using whole seaweed, thereby completing the present invention.

[19] Specifically, the present invention is to provide a method for preparing a fermented seaweed product, the method comprising the steps of: (1) autoclaving seaweed at 120-125 ⁰C for 15-30 minutes to prepare a medium; (2) inoculating the medium with at least one microorganism of lactic acid bacteria or yeasts, and fermenting the medium in aerobic or anaerobic conditions depending on the inoculated microorganism to induce the conversion of glutamate into gamma-aminobutyric acid (GABA) and the degradation of seaweed polysaccharides into monosacchariodes and oligosaccharides; and (3) autoclaving the fermentation product at 120-125 ⁰C for 15-30 minutes.

[20] Also, the present invention is to provide a fermented seaweed product obtained by said preparation method and containing GABA and seaweed polysaccharide-derived monosaccharides and oligosaccharides.

[21] Also, the present invention is to provide a fermented seaweed seasoning, comprising the steps of: (1) filtering said fermented seaweed product to separate it into a fermentation broth and a fermentation residue and collecting the fermentation broth; (2) microfiltering the fermentation broth; and (3) concentrating and drying the micro- filtered fermentation broth.

[22] Also, the present invention is to provide a fermented seaweed seasoning obtained by said preparation method.

[23] Also, the present invention is to provide a method for preparing fermented seaweed powder, comprising the steps of: (1) filtering said fermented seaweed product to separate it into a fermentation broth and a fermentation residue, and collecting the fermentation residue; (2) microfiltering the fermentation broth to collect a fermentation residue remaining in the fermentation broth; and (3) drying and powdering the fermentation residues of steps (1) and (2).

[24] Also, the present invention is to provide fermented seaweed powder obtained by said preparation method. Technical Solution

[25] The present invention relates to a method for preparing a fermented seaweed product, comprising the steps of:

[26] (1) autoclaving seaweed at 120-125 ⁰C for 15-30 minutes to prepare a medium;

[27] (2) inoculating the medium with at least one microorganism of lactic acid bacteria or yeasts, and fermenting the medium in aerobic or anaerobic conditions depending on the inoculated microorganism to induce the conversion of glutamate into gamma- aminobutyric acid (GABA) and the degradation of seaweed polysaccharides into monosacchariodes and oligosaccharides; and

[28] (3) autoclaving the fermentation product at 120-125 ⁰C for 15-30 minutes.

[29] Hereinafter, each step of the method for preparation of the fermented seaweed product will be described in further detail.

[30] 1. Step of preparing medium by autoclaving seaweed [31] Examples of seaweed which can be used in the present invention include, but are not limited to, sea tangle, sea mustard, Hizikiafusiforme, Sargassum fulvellum, laver, agar- agar (Gelidium amansiϊ), Seaweed tenax, green laver, Codium fragile, Porphyra tenera , Seaweed fulvescen, Ecklonia cava, sea oak, and carrageenin. In the present invention, seaweed is preferably sea tangle. Sea tangle is known to contain glutamate in an amount of about 5 wt% based on the dry weight thereof.

[32] Seaweed is desalted by washing several times with water. In a preferred embodiment, the washed seaweed and water are mixed at a ratio of 1 : 5-15, and then autoclaved at 120-125 ⁰C for 15-30 minutes. Herein, water can also be substituted with a natural material extract (e.g., sea tangle extract, oyster extract, or a mixture thereof) or concentrate. The autoclaving process can be carried out using an autoclave which is widely used in the art. By the autoclaving process, microorganisms can be killed, while glutamate and various nutrient components including seaweed polysaccharides can be extracted from seaweed.

[33] Meanwhile, the prior art adopted a liquid-state fermentation process comprising extracting seaweed, separating the extract, sterilizing the separated extract, and then performing fermentation using the extract as a medium. However, in the present invention, a medium is prepared by autoclaving seaweed intact without extraction fermenting the autoclaved seaweed. Namely, the medium of the present invention is characterized in that it is prepared using whole seaweed. Also, by autoclaving whole seaweed without a separate extraction process, microorganisms can be killed, while glutamate and various nutrient components including seaweed polysaccharides can be extracted from the seaweed.

[34] In the present invention, rice bran is preferably added to the medium. Namely, the medium is preferably prepared by autoclaving seaweed together with rice bran. As used herein, the term "rice bran" is a by-product of rice milling. Rice bran is preferably in the form of powder, and the rice bran powder preferably has a thickness of 50-100 mesh. Rice bran is preferably added in an amount of 1-3 wt% based on the total weight of the medium. Rice bran is an important medium component which can promote the proliferation of microorganisms to promote fermentation, and GABA contained in rice brain is extracted to further increase the amount of GABA in the fermented amount. In addition, rice bran has a nutty taste to improve flavor.

[35] Moreover, in the present invention, a glutamate-containing natural material is preferably added to the medium in order to further increase the yield of GABA in the final fermentation product. Examples of the glutamate-containing natural material which can be used in the present invention include, but are not limited to, an oyster, an oyster extract, a sea tangle extract, mixtures thereof, and a concentrate of one or a mixture of oyster and sea tangle. The oyster, the oyster extract or the like is par- ticularly preferable, because it enhances the amount of functional materials (such as taurine) and taste compounds in the fermented seaweed product of the present invention. The natural material is preferably added in an amount of 1-10 wt% based on the total weight of the medium. The extract is preferably a hot- water extract of a glutamate-containing natural material. In the present invention, it is more preferable to use a filtrate fraction having a molecular weight of less than 60 KDa, obtained by fractioning the hot- water extract using an "external-circulation-loop vacuum membrane" in order to effectively remove viscous polysaccharides such as alginic acid, and thus to improve flavor.

[36] Furthermore, in the present invention, a glutamate-containing synthetic material may also be added to the medium in order to further increase the yield of GABA in the final fermentation product. The synthetic material is typically, but not limited to, monosodium glutamate (MSG). The synthetic material is added in a small amount, preferably about 1-10 wt%, and more preferably about 1-2 wt%, based on the total weight of the medium.

[37] 2. Inoculation and culture of microorganisms

[38] As a fermenting microorganism in the present invention, at least one of lactic acid bacteria or yeast may be used.

[39] Examples of lactic acid bacteria which can be used in the present invention include

Lactobacillus sp., Streptococcus sp., Bifidobacterium sp., Leuconostoc sp., Pe- diococcus sp. , and Lactococcus sp. Preferably, Lactobacillus brevis is used as lactic acid bacteria. More preferably, Lactobacillus brevis B J- 20 (KCTCl 1377BP) is used.

[40] Examples of yeast which can be used in the present invention include Saccharomyces sp., Schizosaccharomyces sp., Kluyveromyces sp., Hansenula sp., Candida sp., and Pichia sp. Preferably, Saccharomyces cerevisiae is used. Particularly, yeast can remove an acid taste (sour taste) inevitably produced in lactic acid bacteria fermentation, remove a seaweed odor, and improve the flavor of the fermentation product by exhibiting savory flavor and producing a sweet taste.

[41] At least one microorganism of lactic acid bacteria and yeasts is inoculated into the medium prepared in the previous step and is cultured. The microorganism is preferably inoculated in an amount of 0.1-5 vol% based on the total volume of the medium. When both lactic acid bacteria and yeasts are used, lactic acid bacteria and yeasts are preferably inoculated at a ratio of 1-3 : 3-1. Fermentation by the microorganism is carried out at 25-40 ⁰C for 2-4 days.

[42] Fermentation in the present invention is carried out in aerobic or anaerobic conditions depending on the inoculated microorganism. When lactic acid bacteria are used, they may be cultured in both aerobic and anaerobic conditions, and but are preferably cultured in anaerobic conditions. When yeasts are used, they are particularly preferably cultured in anaerobic conditions. As used herein, the term "anaerobic conditions" is meant to include quasi-anaerobic conditions. The term "quasi- anaerobic conditions" refers to conditions in which the introduction of oxygen during culture is blocked and microorganisms employ oxygen present in an incubator.

[43] In the fermentation step, glutamate extracted from seaweed in the above-described autoclaving step is converted into gamma- aminobutyric acid (GABA) or 4-aminobutyric acid, and glutamate is extracted continuously from seaweed in the fermentation step and converted into GABA. If the medium contains a glutamate- containing natural or synthetic material, glutamate derived from the natural or synthetic material is also converted into GABA. In addition, seaweed polysaccharides (e.g., fucoidan) derived from seaweed and the glutamate-containing natural material can be degraded into monosaccharides (e.g., fucose) and oligosaccharides, thus obtaining a fermented seaweed product containing GABA and seaweed polys accharide-derived monosaccharides and oligosaccharides.

[44] In the prior art, because a sterilized seaweed extract is autoclaved and fermentation is carried out using the autoclaved extract as a medium, limited amounts of glutamate and seaweed polysaccharides in the extract can be used. On the contrary, in the present invention, whole seaweed is autoclaved and fermented, and thus natural glutamate is continuously extracted from the seaweed. For this reason, glutamate can be used in an amount larger than that in the prior art, and thus a fermented seaweed product containing a high concentration of GABA and seaweed polysaccharide-derived monosaccharides and oligosaccharides can be obtained.

[45] 3. Autoclaving of fermentation product

[46] After fermentation, the fermentation product is additionally autoclaved at 120-125 ⁰C for 15-30 minutes. The autoclaving process can be carried out using an autoclave which is widely used in the art. By the autoclaving process, microorganisms present in the fermentation product can be killed.

[47] The present invention relates to a fermented seaweed product obtained by the above- described preparation method. The fermented seaweed product contains a high concentration of GABA and seaweed polysaccharide-derived monosaccharides and oligosaccharides, because natural glutamate and seaweed polysacchariodes are continuously extracted during the processes of autoclaving and fermenting whole seaweed, the glutamate is converted into GABA, and the seaweed polysaccharides are degraded into monosaccharides and oligosaccharides.

[48] Moreover, the present invention is characterized by fermenting whole seaweed, and thus the fermentation product of the present invention consists of a fermentation broth (the liquid-phase portion of the fermentation product) and a fermentation residue (the solid-phase portion of the fermentation product). The seaweed fermentation broth (or dried powder of the seaweed fermentation broth) can be used as a raw material for producing functional beverages, functional health foods, and seasonings, while the seaweed fermentation residue (or dried powder of the seaweed fermentation residue) can be used as a dietary fiber material, a dietary material, a food bulking agent and the like, but the scope of the present invention is not limited thereto.

[49] Accordingly, the present invention relates to a method for preparing a fermented seaweed seasoning, the method comprising the steps of: (1) filtering said fermented seaweed product to separate it into a fermentation broth and a fermentation residue, and collecting the fermentation broth; (2) microfiltering the fermentation broth; and (3) concentrating and drying the microfiltered fermentation broth. The fermented seaweed seasoning obtained by this preparation method constitutes one aspect of the present invention.

[50] The process of separating the fermented seaweed product into the fermentation broth and the fermentation residue can be achieved, but is not limited by, centrifugation or filtration. When the filtration process is carried out, a 20-200-meshfilter is preferably used.

[51] After that, the fermentation broth obtained in the previous step is microfiltered. In the microfiltration process, it is preferable to use an "external-circulation-loop vacuum membrane" through which only a material having a molecular weight of less than 60 kDa passes. The microfiltration process employing "the external-circulation-loop vacuum membrane" makes it possible to completely block the exposure of the fermentation broth to an external environment so as to prevent the fermentation broth from being contaminated by external sources, such that the taste and flavor of the fermentation broth can be maintained intact without loss. Also, the microfiltration process enables an offensive taste and odor occurring in seaweed to be removed so as to improve the taste and flavor of the fermentation broth. In addition, the bodies of microorganisms killed by autoclaving of step (3) can be removed such that only a pure fermentation broth can be obtained.

[52] Thereafter, the microfiltered seaweed fermentation broth is concentrated, and if necessary, a vehicle (e.g., maltodextrin, skimmed milk powder, lactose, casein, etc.) is added thereto. The concentrated fermentation broth is freeze-dried, spray-dried or vacuum-dried, and the dried fermentation broth is powdered, thus preparing a fermented seaweed seasoning.

[53] In another aspect, the present invention relates to a method for preparing fermented seaweed powder, the method comprising the steps of: (1) filtering said fermented seaweed product to separate it into a fermentation broth and a fermentation residue and collecting the fermentation residue; (2) microfiltering the fermentation broth to collect a fermentation residue remaining in the fermentation broth; and (3) drying and powdering the fermentation residues of steps (1) and (2). The fermented seaweed powder obtained by this preparation method constitutes one aspect of the present invention.

[54] Steps (1) and (2) of the method for preparing the fermented seaweed powder are substantially the same as steps (1) and (2) of the method for preparing the fermented seaweed seasoning, except that the fermentation residue is collected in step (1), and the non-microfiltered fermentation residue remaining in the fermentation broth is collected in step (2). If the microfiltration process is carried out using an "external-circulation-loop vacuum membrane" through which only a material having a molecular weight of less than 60 kDa passes, the fermentation residue remaining in the fermentation broth will be a material of more than 60 kDa which does not pass through the membrane.

[55] In step (3), the fermentation residue of step (1) is mixed with the fermentation residue of step (2), and the residue mixture is dried using a hot-air dryer or a vacuum dryer at 50-70 ⁰C for 6-12 hours. After completion of the drying process, the dried residue is powdered with a dry grinder, thus preparing fermented seaweed powder.

[56] Hereinafter, a preferred embodiment of the present invention will be described in further detail with reference to the accompanying drawing.

[57] FIG. 1 is a general process flowchart showing methods for preparing a fermented seaweed product, a fermented seaweed seasoning and fermented seaweed powder according to the present invention.

[58] Referring to FIG. 1, in step (a) of preparing a raw material, seaweed is washed and desalted with a sufficient amount of water, and then wet- or dry-ground, such that taste compounds, such as glutamate, and components useful for the human body, such as seaweed polysaccharides, are efficiently extracted in the subsequent autoclaving step.

[59] In step (b) of autoclaving the raw material, the seaweed ground to a suitable size is mixed with water at a ratio of 1:5-15 depending on the state of the raw material, and then, if necessary, rice bran, a glutamate-containing natural material and the like are added thereto. Then, in order to effectively extract glutamate and components useful for the human body, such as seaweed polysaccharides (fucoidan, etc.), and to perform fermentation by microorganisms, the raw material is autoclaved at 120-125 ⁰C for 15-30 minutes, whereby various bacteria present in the raw materials including seaweed are killed. After completion of the autoclaving process, the raw material is cooled to the optimal growth temperature of microorganisms. Herein, the glutamate- containing natural material which is added if necessary is a component which is used to overcome a problem of reduced taste resulting from the microbial conversion of the taste component glutamate into GABA. The glutamate-containing natural material can be substituted with a raw oyster, an oyster extract or a mixture thereof and may be a natural material containing a large amount of glutamate. Rice bran is a component for increasing the GABA content of the fermentation product by the extraction of GABA therefrom.

[60] In step (c) of inoculating a microorganism, the above-prepared autoclaved medium is inoculated with at least one microorganism of lactic acid bacteria and yeasts. Step (c) is carried out while maintaining an aseptic environment to prevent the medium from being contaminated by various bacteria such as airborne bacteria. Herein, the microorganism is inoculated in an amount of 0.1-5 vol% based on the volume of the medium.

[61] In step (d) of fermenting seaweed by microorganisms, the microorganisms grow exponentially using the medium while inducing the production of physiologically active materials and the degradation of polysaccharides. Particularly, glutamate is converted into GABA, and seaweed polysaccharides (Fucoidan, etc.) are degraded into monosac- chartides (Fucose, etc.) and oligosaccharides. By the microbial fermentation, an offensive taste and odor such as a seaweed odor can be completely removed. The microbial fermentation is carried out in aerobic or anaerobic conditions depending on the inoculated microorganism.

[62] In step (e) of autoclaving the fermentation product, the microbial fermentation product is autoclaved at 120-125 ⁰C for 15-30 minutes. By doing so, the microorganisms can be killed, and when yeasts are used as the microorganisms in the previous step (d), the taste of the fermentation can be enhanced by extracting the taste compound nucleic acid contained in the yeasts which increased exponentially in the previous step (d).

[63] In step (f) of separating the fermentation product into a seaweed fermentation broth and a fermentation residue, the fermentation product is separated into parts using a 20-200-mesh filter.

[64] Step (g) of microfiltering the seawed fermentation broth is a first step of the method for preparing a fermented natural seaweed seasoning using the above-separated fermentation broth. In step (g), the seaweed fermentation broth is filtered using an external-circulation-loop vacuum membrane through only a material having a molecular weight of less than 60 kDa passes, so that fine residues including killed microbial bodies remaining after the autoclaving of step (e) are completely removed, thereby producing a purified seaweed fermentation broth.

[65] In step (10 of concentrating and drying the seaweed fermentation broth, the seaweed fermentation broth obtained as described above is concentrated under reduced pressure, and then a vehicle (e.g., maltodextrin, skimmed milk powder, lactose, casein, etc.) is added thereto. Then, the concentrated fermentation broth is freeze-dried, spray- dried or vacuum-dried, and the dried fermentation broth is powdered, thus preparing a fermented seaweed seasoning containing a large amount of GABA.

[66] If necessary, the fermented seaweed seasoning thus prepared is subjected to step (i) of packaging the fermented seaweed seasoning according to volume.

[67] Step (j) of drying the seaweed fermentation residue is a first step of the method for preparing fermented seaweed powder. In step (j), the fermentation residue which was not passed through the mesh filter in step (f) is mixed with the fermentation residue which was not microfiltered in step (g), that is, the fermentation residue having a molecular weight of more than 60 kDa. The residue mixture is dried using a hot-air drier or a vacuum drier at 50-70 ⁰C for 6-12 hours.

[68] Step (k) of grinding the seaweed fermentation residue is a step of powdering the fermentation residue. In step (k), the fermentation residue is powdered with a dry grinder, thus preparing fermented seaweed powder.

[69] If necessary, the fermented seaweed powder thus prepared is subjected to step (1) of packaging the seaweed powder according to volume in the same manner as the case of the fermented seaweed seasoning.

Advantageous Effects

[70] According to the present invention, GABA can be produced at a yield higher than that in the prior art by using natural glutamate-containing seaweed as a main raw material.

[71] Specifically, in the prior art, only an extract of seaweed was used as a medium, and thus only a limited amount of glutamate contained in the extract could be converted into GABA. On the contrary, in the present invention, because whole seaweed is au- toclaved and fermented, glutamate is continuously extracted from the whole seaweed during the autoclaving and fermentation processes, so that a larger amount of glutamate can be converted into GABA, thus obtaining GABA in high yield.

[72] Also, in the prior art, GABA was produced using MSG as a main raw material. On the other hand, in the present invention, MSG is not used or is used in a very small amount, and thus the problems associated with MSG remaining in the final product can be overcome.

[73] The fermented seaweed product of the present invention is obtained by fermenting whole seaweed, and thus consists of a fermentation broth (a liquid-phase portion) and a fermentation residue (a solid-phase portion). Because the fermentation broth can be used as a seasoning, and the fermentation residue can be used as a dietary fiber material, a dietary carrier and the like, the whole fermented seaweed product is useful. Namely, because a yield of 100% relative to the sea tangle introduced can be achieved, the efficiency and cost effectiveness of the preparation process can be realized. The seaweed fermentation broth (or dried powder of the seaweed fermentation broth) can be used as, or to produce, functional beverages, functional health foods, seasonings and the like, and the seaweed fermentation residue (or powder of seaweed fermentation residue) can be used as a dietary fiber material, a dietary material, a food bulking agent and the like, but the scope of the present invention is not limited thereto.

[74] Because seasonings containing the fermentation product of the present invention contain no artificial MSG, they can overcome various problems caused by artificial MSG and contribute to healthy dietary life.

[75] Because the fermentation product of the present invention contains a high concentration of GABA and seaweed polysaccharide-monosaccharides and oligosaccharides, it is expected that the fermentation product will have advantageous effects of enhancing antioxidant activity and immunity, preventing obesity, removing hangover, lowering blood pressure, promoting blood flow, relieving stress by blood flow promotion and brain cell metabolism promotion, and enhancing concentration. Brief Description of Drawings

[76] FIG. 1 is a general process flowchart showing methods for preparing a fermented seaweed product, a fermented seaweed seasoning and fermented seaweed powder according to the present invention. Best Mode for Carrying out the Invention

[77] Example 1: Fermentation of sea tangle

[78] 1-1: Fermentation of sea tangle by lactic acid bacteria

[79] Dry sea tangle pieces (1-3 cm²) were desalted by washing twice with cold water and mixed with water at a ratio of 1:5-1:15. Then, rice bran powder (50-100 mesh) was added thereto in an amount of 1-3 wt% based on the weight of water added. The mixture was stirred, and then autoclaved at 121 ⁰C for 20 minutes and cooled to 30 ⁰C, thus preparing a medium. Then, lactic acid bacteria (Lactobacillus brevis BJ -20, KCTCl 1377BP) previously cultured in MRS medium for 18 hours were inoculated into the prepared medium in an amount of 1-4 vol% based on the total volume of the medium, and the inoculated medium was fermented at 25-35 ⁰C for 2-4 days. After completion of the fermentation process, the fermented medium was autoclaved at 121 0C for 20 minutes to kill the lactic acid bacteria and cooled, whereby a large amount of natural glutamate contained in the sea tangle was converted into GABA, and a large amount of highly functional seaweed polysaccharides present in the sea tangle were degraded into low-molecular- weight saccharides, thus preparing a sea tangle fermentation broth containing a high concentration of sea tangle-derived natural GABA and functional low-molecular- weight oligosaccharides.

[80] Table 1 [Table 1] [Table ]

Free amino acid contents of sea tangle fermentation broth obtained by yeast fermentation

[81]

Mode for the Invention

[82] 1-2: Fermentation of sea tangle by yeast [83] Dry sea tangle pieces (1-3 cm²) were desalted by washing twice with cold water, and water was added thereto in an amount 15 times the weight of the sea tangle. Then, rice bran powder (50-100 mesh) was added thereto in an amount of 2 wt% based on the weight of water added. The mixture was stirred, and then autoclaved at 121 ⁰C for 20 minutes and cooled to 30 ⁰C, thus preparing a medium. Then, yeasts (Saccharomyces cerevisiae) previously cultured in YM medium for 18 hours were inoculated into the prepared medium in an amount of 2-5 vol% based on the total volume of the medium, the inoculated medium was fermented at 37 ⁰C for 3 days to ferment the medium. After completion of the fermentation process, the fermented medium was autoclaved at 121 0C for 20 minutes to kill the lactic acid bacteria and extract the cultured yeasts and was cooled, whereby a large amount of natural glutamate contained in the sea tangle was converted into GABA, and a large amount of highly functional seaweed polysaccharides present in the sea tangle were degraded into low-molecular-weight saccharides, thus preparing a sea tangle fermentation broth containing a high concentration of sea tangle-derived natural GABA and functional low-molecular- weight oligos accharides .

[84] Table 2 [Table 2]

[Table ]

[85] The contents of GABA and glutamic acid according to fermentation time in the aerobic/anaerobic fermentation carried out in Examples 1-1 and 1-2 are shown in Table 3 below.

[86] Table 3

[Table 3]

[Table ]

Contents of GABA and glutamic acid according to fermentation time in aerobic/ anaerobic fermentation

[87] 1-3: Fermentation of sea tangle by lactic acid bacteria and yeasts

[88] Dry sea tangle pieces (1-3 cm²) were desalted by washing twice with cold water and mixed with water at a ratio of 1:5-1:15. Then, rice bran powder (50-100 mesh) was added thereto in an amount of 2 wt% based on the weight of water added. The mixture was stirred, and then autoclaved at 121 ⁰C for 20 minutes and cooled to 30 ⁰C, thus preparing a medium. Then, lactic acid bacteria (Lactobacillus brevis BJ-20) and ( Sac- charomyces cerevisiae), previously cultured in MRS medium and YM medium, respectively, for 18 hours, were inoculated into the prepared medium in an amount of 3 vol% based on the total volume of the medium at varying ratios (lactic acid bacteria: yeasts) of 1:1, 2:1, 1:2, 1:3 and 3:1, and the inoculated medium was fermented at 37 ⁰C for 3 days. After completion of the fermentation process, the fermented medium was autoclaved at 121 ⁰C for 20 minutes to kill the lactic acid bacteria and cooled, whereby a large amount of natural glutamate contained in the sea tangle was converted into GABA, and a large amount of highly functional seaweed polysaccharides present in the sea tangle were degraded into low-molecular- weight saccharides, thus preparing a sea tangle fermentation broth containing a high concentration of sea tangle-derived natural GABA and functional low-molecular- weight oligosaccharides. [89] Table 4

[Table 4]

[Table ]

Amino acid contents of sea tangle fermentation broth obtained by lactic acid bacteria and yeast (1:1) fermentation

[90] Table 5

[Table 5]

[Table ]

Amino acid contents of sea tangle fermentation broth obtained by lactic acid bacteria and yeast (1:2) fermentation

[91] Table 6

[Table 6]

[Table ]

Amino acid contents of sea tangle fermentation broth obtained by lactic acid bacteria and yeast (1:3) fermentation

[92] Table 7

[Table 7]

[Table ]

Amino acid contents of sea tangle fermentation broth obtained by lactic acid bacteria and yeast (2:1) fermentation

[93] Table 8

[Table 8]

[Table ]

Amino acid contents of sea tangle fermentation broth obtained by lactic acid bacteria and yeast (3:1) fermentation

[94] Example 2: Fermentation of sea tangle to which oyster or oyster extract was added

[95] To increase the content of GABA produced in the preparation method of Example 1, it is required to increase the content of glutamate, because the content of glutamate as a GABA precursor in performing fermentation by lactic acid bacteria, yeasts or a mixture thereof is limited. For this reason, in this Example, in order to increase the content of glutamate using a natural material without adding artificial MSG, an oyster (raw oyster) and oyster extract containing a large amount of glutamate was added to sea tangle, and the resulting sea tangle was fermented using lactic acid bacteria, yeasts or a mixture thereof in anaerobic conditions in the same manner as in Example 1. As a result, a sea tangle fermentation broth containing a high concentration of GABA and functional low-molecular- weight oligosaccharides was prepared. This Example is characterized in that an oyster (raw oyster) is added during fermentation in an amount of 10 wt% based on the total weight of the medium, and an oyster extract (5 Brix) is substituted with water added.

[96] Table 9 [Table 9] [Table ]

Free amino acid contents of fermentation broth obtained by fermenting oyster- containing sea tangle using lactic acid bacteria

[97] Table 10

[Table 10] [Table ]

Free amino acid contents of fermentation broth obtained by fermenting oyster- containing sea tangle using yeasts

[98] Table 11

[Table 11] [Table ]

Free amino acid contents of fermentation broth obtained by fermenting oyster- containing sea tangle using lactic acid bacteria and yeasts

[99] Table 12

[Table 12] [Table ]

Free amino acid contents of fermentation broth obtained by fermenting oyster extract- containing sea tangle using lactic acid bacteria

Table 13

[Table 13] [Table ]

Free amino acid contents of fermentation broth obtained by fermenting oyster extract- containing sea tangle using yeasts

Table 14

[Table 14] [Table ]

Free amino acid contents of fermentation broth obtained by fermenting oyster extract- containing sea tangle using lactic acid bacteria and yeasts

[102] Example 3: Fermentation of sea tangle to which MSG was added

[103] To increase the content of GABA produced in the preparation method of Example 1, it is required to increase the content of glutamate, because the content of glutamate as a GABA precursor in performing fermentation by lactic acid bacteria, yeasts or a mixture thereof is limited. For this reason, in this Example, in order to increase the content of the GABA precursor glutamate, monosodium glutamate (MSG) was added to sea tangle, and the resulting sea tangle was fermented using lactic acid bacteria, yeasts or a mixture thereof in the same manner as in Example 1. As a result, a sea tangle fermentation broth containing a high concentration of natural GABA and functional low-molecular- weight oligosaccharides was prepared. This Example is characterized in that MSG as an additional GABA precursor is added in an amount of 1-10 wt% based on the total weight of the medium.

[104] Table 15

[Table 15]

[Table ]

Free amino acid contents of fermentation broth obtained by fermenting 1% MSG using lactic acid bacteria

Table 16

[Table 16]

[Table ]

Free amino acid contents of fermentation broth obtained by fermenting 1% MSG using yeasts

Table 17

[Table 17]

[Table ]

Free amino acid contents of fermentation broth obtained by fermenting 1% MSG- containing sea tangle using lactic acid bacteria and yeasts

[107] Example 4: Fermentation of sea tangle to which sea tangle extract was added

[108] In this Example, in order to increase the content of GABA produced in the preparation method of Example 1, it is required to increase the content of glutamate as a GABA glutamate in performing fermentation by lactic acid bacteria, yeasts or a mixture thereof. For this purpose, sea tangle was extracted with hot water and fractioned (microfiltered) using an external-circulation-loop membrane, thus obtaining a fraction having a molecular weight of less than 60 KDa. Then, the fraction was concentrated (solid content: 20 Brix), and the concentrate was added to the medium of Example 1 at a weight ratio of 1:1, and then fermented in anaerobic conditions in the same manner as in Example 1.

[109] Table 18

[Table 18]

[Table ]

Free amino acid contents of fermentation broth obtained by fermenting sea tangle extract-containing sea tangle using lactic acid bacteria

[HO] Table 19

[Table 19]

[Table ]

Free amino acid contents of fermentation broth obtained by fermenting sea tangle extract-containing sea tangle using yeasts

Table 20

[Table 20]

[Table ]

Free amino acid contents of fermentation broth obtained by fermenting sea tangle extract-containing sea tangle using lactic acid bacteria and yeasts

[112] Example 5: Preparation of high-concentration GABA-containing fermented sea tangle powder from sea tangle fermentation broth

[113] The sea tangle fermentation broths prepared in Examples 1 to 4 were centrifuged or microfiltered using an external-circulation-loop membrane system according to the intended use and pore size, and then concentrated under reduced pressure at 15 torr and 60 ⁰C. Then, a vehicle was added to the concentrate at a concentration determined according to the desired GABA content, and the mixture was powdered by spray drying. Herein, as the vehicle, maltodextrin, skimmed milk powder, lactose, casein or the like was used.

[114] Example 6: Change of sugar composition of functional polysaccharides according to fermentation

[115] In this Example, in order to verify the presence and reduction of functional polysaccharides in the whole process for fermenting sea tangle using microorganisms, that is, the process for preparing a sea tangle fermentation broth containing GABA and functional oligosaccharides (sulfur-containing seaweed polysaccharides, such as Fucoidan, or sulfur-containing sugars), the following test was carried out.

[116] Specifically, dry sea tangle pieces (1-3 cm²) desalted by washing twice with cold water was mixed with water at a ratio of 1:5-1:15 and stirred. The stirred material was primarily autoclaved at 121 ⁰C for 15-30 minutes and cooled to 30 ⁰C, thus obtaining a medium. Then, lactic acid bacteria (Lactobacillus brebis) previously cultured in MRS medium for 18 hours were inoculated into the medium in an amount of 2 vol% based on the total volume of the medium, and the inoculated medium was fermented at 25-35 0C for 2-4 days. After completion of the fermentation process, the fermented medium was secondarily autoclaved at 121 ⁰C for 20 minutes to kill the lactic acid bacteria and was cooled, thus preparing a sea tangle fermentation broth containing GABA and functional low-molecular- weight oligosaccharides. This fermentation broth was compared with the sea tangle extract (before fermentation) collected after primarily au- toclaving the sea tangle and cooling the autoclaved sea tangle to 30 ⁰C (before inoculation with lactic acid bacteria).

[117] As a result, slight increases or decreases in the sugar compositions and contents of constituent sugars before and after fermentation were observed. These results suggest that the constituent sugars were consumed, degraded and produced by the microorganisms during the whole fermentation process of sea tangle. In addition, these results indicate that sulfur-containing polysaccharides exhibiting functionality were degraded into low-molecular- weight saccharides so as to be present in the form of constituent monosaccharides including the sulfur-containing monosaccharide fucose.

[118] Table 21 [Table 21] [Table ] Results of monosaccharide analysis

[119] 1) % is given as a percentage relative to the total amount of monosaccharides. [120] Table 22 [Table 22] [Table ] Results of sulfur content analysis

[121] * s-c: sulfur content [122] **s-c/carbo(%): percentage of sulfur content relative to the amount of carbohydrates in the samples Industrial Applicability

[123] As described above, according to the present invention, GABA can be produced in a high yield compared to the prior art by using natural glutamate-containing seaweed as a main material.

Claims

[I] A method for preparing a fermented seaweed product, comprising the steps of:

(1) autoclaving seaweed at 120-125 ⁰C for 15-30 minutes to prepare a medium;

(2) inoculating the medium with at least one microorganism of lactic acid bacteria or yeasts, and fermenting the medium in aerobic or anaerobic conditions depending on the inoculated microorganism to induce the conversion of glutamate into gamma- aminobutyric acid (GABA) and the degradation of seaweed polysaccharides into monosacchariodes and oligosaccharides; and

(3) autoclaving the fermentation product at 120-125 ⁰C for 15-30 minutes. [2] The method of Claim 1, wherein the seaweed is selected from the group consisting of Hizikia fusiforme, Sargassum fulvellum, laver, agar-agar (Gelidium amansiϊ), Seaweed tenax, green laver, Codium fragile, Porphyra tenera,

Seaweed fulvescen, Ecklonia cava, sea oak, and carrageenin. [3] The method of Claim 1, wherein rice bran is added to the medium in an amount of 1-3 wt% based on the total weight of the medium. [4] The method of Claim 1, wherein a glutamate-containing natural or synthetic material is added to the medium. [5] The method of Claim 4, wherein the glutamate-containing natural material is selected from the group consisting of an oyster, an oyster extract, a sea tangle extract, mixtures thereof, a concentrate of each of an oyster and a sea tangle, and a concentrate of the mixture. [6] The method of Claim 5, wherein the glutamate-containing natural material is added in an amount of 1-10 wt% based on the total weight of the medium. [7] The method of Claim 4, wherein the glutamate-containing synthetic material is

MSG. [8] The method of Claim 7, wherein the glutamate-containing synthetic material is added in an amount of 1-10 wt% based on the total weight of the medium. [9] The method of Claim 1, wherein the lactic acid bacteria are Lactobacillus brevis

BJ-20 (KCTCl 1377BP). [10] The method of Claim 1, wherein the yeasts are Saccharomyces cerevisiae.

[I I] The method of Claim 1, wherein the microorganism in step (2) is inoculated in an amount of 0.1-5 vol% based on the volume of the medium.

[12] The method of Claim 1, wherein, if the lactic acid bacteria together with the yeasts are inoculated in step (2), the lactic acid bacterial and the yeasts are mixed at a ratio of 1-3 : 3-1.

[13] The method of Claim 1, wherein the fermenting in step (2) is carried out at 25-40

⁰C for 2-4 days. [14] A fermented seaweed product obtained according to a method set forth in any one of Claims 1 to 13.

[15] A method for preparing a fermented seaweed seasoning, comprising the steps of:

(1) filtering the fermented seaweed product of Claim 14 to separate it into a fermentation broth and a fermentation residue and collecting the fermentation broth; microfiltering the fermentation broth; and (3) adding a food additive to the mi- crofiltered fermentation broth and powdering the food additive-containing fermentation broth.

[16] The method of Claim 15, wherein the microfiltering in step (2) is carried out using an external-circulation-loop vacuum membrane that filters a material having a molecular weight of less than 60 kDa.

[17] A fermented seaweed seasoning obtained by a method set forth in Claim 15 or

16.

[18] A method for preparing fermented seaweed powder, comprising the steps of: (1) filtering the fermented seaweed product of Claim 14 to separate it into a fermentation broth and a fermentation residue; (2) microfiltering the fermentation broth to collect a fermentation residue; and (3) drying and powdering the fermentation residues of steps (1) and (2).

[19] The method of Claim 18, wherein the microfiltering in step (2) is carried out using an external-circulation-loop vacuum membrane that filters a material having a molecular weight of less than 60 kDa.

[20] Fermented seaweed powder obtained by a method set forth in Claim 18 or 19.