JP2020031597A - Food material derived from pleurotus mycelium - Google Patents

Abstract

To provide compositions suppressing discoloration and off-flavor of food, which are obtained by a simple operation using, as raw materials, mushrooms that are generally ingested as food, and to provide compositions rich in useful substances.SOLUTION: The mycelium of Pleurotus basidiomycete, desirably of Pleurotus djamor is cultured and the mycelium is extracted with a solvent such as water. Since this extract is rich in ergothioneine and polyphenol, and has the effect of suppressing discoloration and off-flavor of food, it can be used as a food material.SELECTED DRAWING: None

Description

The present invention relates to a food material obtained by processing a fungus of the genus Pleurotus, which has an effect of preventing discoloration of a food, an effect of suppressing off-flavor, and an antibacterial effect.

  Mushrooms have been consumed as food since ancient times. On the other hand, since mushrooms have unique physical properties and various useful components, they are also known to be processed into food materials or used as raw materials for functional substances.

  For example, it has been reported that a food material having a meat-like texture can be obtained by processing mushroom fruit bodies (Patent Document 1).

As a functional substance, extracting an IgE production inhibitor from various mushrooms (Patent Literature 2), extracting ergothioneine from basidiomycetes (Patent Literature 3), and extracting a tokiiro pigment from a fruit body of Pleurotus ostreatus It is known that an extract of mycelium of ascomycetes and basidiomycetes can be used as an antibacterial agent for food and drink (Patent Document 4). In addition, it has been reported that a composition containing ergosterol peroxide is extracted from the fruit body of Pleurotus cornucopiae and used as a discoloration prevention and antioxidant for food (Patent Document 6).

However, when a mushroom extract is used as a food material, its smell or discoloration may be a problem. For example, when extracting a β-glucan-containing composition from a fruiting body of a mushroom such as Agaricus, it is reported that in order to remove the odor component, solvent extraction is performed after roasting with heated steam (Patent Document) 7). Further, it has been reported that a pH adjuster or a storage stabilizer is added to an ergothioneine-containing composition extracted from a fruit body of a mushroom to prevent odor and discoloration with time (Patent Document 8).

Furthermore, when mushroom fruit bodies are used as an extraction raw material, there is a problem that cultivation takes a considerable number of days to obtain a sufficient amount of mushrooms.

JP, 2018-50607, A JP-A-2003-2811 JP 2014-223051 A JP 2000-119975 A JP 2013-237699 A JP 2009-183266 A JP 2006-282847 A JP 2012-242013 A

An object of the present invention is to obtain a composition using mushrooms as a raw material, which suppresses discoloration and off-flavor of food by a simple operation that does not require days and does not go through steps such as deodorization. Another object is to obtain a composition containing a useful compound. It is desirable that the mushrooms used as a raw material are generally taken as food.

The present inventors have found that, when basidiomycetes of the genus Pleurotus are cultured in mycelium, the mycelium contains a high content of ergothioneine and polyphenol, and the mycelium is freeze-dried and then extracted with water. It has been found that the extract composition contains a high content of ergothioneine and polyphenol, and that the extract composition has an antibacterial effect in addition to a function of suppressing discoloration and off-flavor of food.

That is, the present invention relates to the following (1) to (7).
(1) A basidiomycete basidiomycete mycelium containing at least 1 mg / g per dry weight of ergothioneine and at least 2 mg / g per dry weight of polyphenol.
(2) Pleurotus basidiomycete extract containing at least 5 mg / g of ergothioneine per dry weight.
(3) An Oyster mushroom basidiomycete extract containing at least 5 mg / g of ergothioneine per dry weight and at least 10 mg / g of polyphenol per dry weight.
(4) The extract according to (2) or (3), wherein the basidiomycete basidiomycete is Pleurotus djamor.
(5) A food discoloration inhibitor containing the Oyster mushroom basidiomycete extract according to any of (2) to (4).
(6) An off-flavour-suppressing material for food containing the Oyster mushroom basidiomycete extract according to any of (2) to (4).
(7) An agent for improving the shelf life of food containing the Oyster mushroom basidiomycete extract according to any of (2) to (4).

ADVANTAGE OF THE INVENTION According to this invention, the odorless and discoloration-free composition can be acquired by the simple process of mycelium culture of Oyster mushroom basidiomycete, and solvent extraction from mycelium. The composition has an antibacterial effect in addition to an effect of suppressing discoloration and off-flavor of food.
In addition, since this composition contains a very large amount of ergothioneine and a large amount of polyphenol, it can be expected to have an antioxidant function for living organisms, and can be used as a raw material of high-purity ergothioneine.

  The extract of the present invention is obtained from Basidiomycetes of the genus Pleurotus. Basidiomycetes belonging to the genus Pleurotus include oyster mushrooms, eryngii, Ushiratake mushrooms, Tamagitake mushrooms, Tokiiro oyster mushrooms, Himalayan oyster mushrooms, etc. Among them, it is preferable to use Pleurotus djamor.

The culture of Basidiomycetes belonging to the genus Pleurotus may be performed by a known method.
For example, a spore suspension of Pleurotus basidiomycetes is inoculated into a liquid medium and cultured. The culture may be divided into two or more stages of seed culture and main culture.

The components of the liquid medium are not particularly limited, but include, for example, sucrose, polypeptone, yeast extract, monopotassium phosphate, magnesium sulfate, a surfactant and the like, and are prepared by appropriately combining these.
After inoculating the prepared liquid medium with a mycelium of Pleurotus basidiomycete, the mycelium is grown by, for example, stirring and culturing at 28 to 30 ° C. for 7 to 14 days.

The mycelium is separated from the culture solution after the culture. Examples of the separation method include filtration using filter paper, membrane, diatomaceous earth, and the like, and centrifugation. The obtained mycelium may be washed with a solvent such as ethanol.

The mycelium of Pleurotus basidiomycetes obtained in this way contains ergothioneine in a dry weight of about 1 mg / g or more, preferably 2 mg / g or more, depending on the bacterial species and culture conditions. Further, it contains polyphenols in an amount of about 2 mg / g or more, preferably 4 mg / g or more per dry weight.

The obtained mycelium is freeze-dried or mechanically pulverized, and then immersed in a solvent to extract the extract. The solvent is preferably safe as food, and particularly preferably water, a mixture of alcohol and water. When water is used as the extraction solvent, the temperature is preferably 80 to 100 ° C, and the immersion time is preferably 20 to 120 minutes. The suspension after immersion is separated into a mycelium residue and an extract solution by centrifugation or filtration.

The thus obtained extract solution of Pleurotus basidiomycetes contains ergothioneine. This solution may be concentrated and dried to obtain a dried powder of Pleurotus basidiomycetes extract.
The ergothioneine content in the extract varies depending on the bacterial species, culture conditions and extraction conditions, but is generally at least 5 mg / g per dry weight.

The obtained Oyster mushroom basidiomycete extract may be used as a raw material for obtaining high-purity ergothioneine. When used as a raw material for high-purity ergothioneine, the ergothioneine content in the extract is preferably higher, preferably 5 mg / g or more per dry weight, more preferably 8 mg / g or more per dry weight.

The Pleurotus basidiomycetes extract contains, in addition to ergothioneine, 10 mg / g or more per dry weight of polyphenol. When the extract is added to food, the extract significantly suppresses discoloration of the food, suppresses off-flavor, and has an effect of imparting a preferable flavor depending on the amount of the extract. Further, it has an effect of suppressing the growth of various bacteria, and thus can be suitably used as a food material.

<Quantification of ergothioneine>
A test sample is obtained by diluting the Oyster mushroom basidiomycete extract obtained by the above method with water at an appropriate concentration.
A HILIC column is used for HPLC, and a mixture of 10 mM ammonium acetate and acetonitrile 1: 4 is used for the mobile phase. The flow rate is 0.5 mL / min, the column temperature is 40 ° C., and a peak derived from ergothioneine is detected by absorption at 220 nm with a UV detector.
Separately, the peak area of an ergothioneine sample of a predetermined concentration is measured by HPLC, and the amount of ergothioneine in the test sample is calculated by comparing the peak areas appearing at the same time.

<Quantification of polyphenol>
Using a Pleurotus basidiomycetes extract as a sample, the polyphenol content is determined by the Folin-Denis method.

The Oyster mushroom basidiomycete extract of the present invention contains ergothioneine and polyphenol, both of which are substances having an antioxidant function, and thus can be used as materials for functional foods. In addition, by adding the Oyster mushroom basidiomycete extract of the present invention to food, mixing, and surface treatment, the off-flavor of the food can be suppressed, discoloration can be prevented, and the shelf life can be improved. .

Foods that are expected to be mainly effective in preventing discoloration include raw meat (meat such as beef, pork and chicken), raw fish (fish such as tuna and yellowtail, crustaceans such as shrimp and crab), and fruits (Cut fruits such as apples, bananas and melons, pickled in syrup, etc.), vegetables (cut vegetables such as lettuce and cabbage, lightly pickled eggplants, potatoes, lotus root, avocado, etc.), processed cereals (noodles, bread, cooked rice) , Mochi, etc.), processed fats and oils (mayonnaise, margarine, etc.), processed meats (ham, sausage, etc.), processed fishery products (kamaboko, chikuwa, fried sweets, etc.), dairy products (butter, cheese, yogurt, etc.), fruit processing Products (jam, marmalade, etc.), confectionery (chocolate, cookies, cakes, jelly, etc.), various beverages (juice, coffee, tea, green tea, carbonated beverages, etc.) , Seasoning (soy sauce, source, mirin, etc.), and the variety of food.

Main foods that are expected to have the effect of suppressing off-flavor include meat products (meat raw materials such as beef, pork, and chicken, processed products), and marine products (raw fish, tsumire).

As a method for adding the Oyster mushroom basidiomycete extract of the present invention to a food, there are methods such as mixing into a food, spraying on a surface, application, and immersion.
When mixed with foods mainly for the purpose of preventing discoloration, it is desirable that the concentration of ergothioneine per food be 50 ppm or more.When performing surface treatment such as spraying, coating, and dipping, spray liquid, coating liquid, and dipping It is desirable that the liquid has an ergothioneine concentration of 50 ppm or more.
When the main purpose is to suppress off-flavor, it is desirable to add the polyphenol content per food so as to be 30 ppm or more.

Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

<Example 1>
<Preculture of Basidiomycetes>
The Pleurotus ostreatus strain (Pleurotus djamor) was cultured on a PDA flat medium until it grew sufficiently.

<Seed culture>
A piece of the medium in which the mycelium is growing on the precultured flat medium is scraped together with the medium with a sterile spatula, and a sterilized liquid medium (glucose 3%, polypeptone 0.5%, yeast extract 0.3%, monopotassium phosphate 0.1%) , Magnesium sulfate 0.05%, Tween80 0.1%) in 100 mL, and cultured in a 300 mL flask at 28 ° C. and 125 rpm for 14 days to obtain a seed culture solution.

<Main culture>
The obtained seed culture was separated into solid and liquid by centrifugation (7000 rpm, 10 minutes) to collect mycelia. Physiological saline solution is added to the collected mycelium and crushed with a glass homogenizer. Transfer 3 mL of the crushed liquid into 300 mL of the main medium (glucose 3%, polypeptone 0.5%, yeast extract 0.3%, monopotassium phosphate 0.1%, magnesium sulfate 0.05%, Tween80 0.1%), and in a 2L Erlenmeyer flask at 28 ° C and 125 rpm. Primary culture was performed for 7 days. Thereafter, methionine, cysteine, and histidine were added at a final concentration of 5 mM, and the cells were further cultured at 28 ° C. and 125 rpm for 7 days to perform secondary culture.
The culture termination liquid was centrifuged to separate the filtrate into mycelium.

25 g of the obtained wet mycelium was washed with physiological saline and freeze-dried to obtain 2 g of a dried mycelium of Pleurotus ostreatus. This was suspended in 50 mL of hot water and stirred at 90 ° C. for 30 minutes. The suspension after the hot water treatment was separated into a mycelium extraction residue of basidiomycetes and an extract solution by centrifugation.

The resulting P. oyster mushroom extract solution was concentrated 10-fold to obtain a concentrated solution of P. oyster mushroom extract solution having a solid concentration of 12% by weight (sample 1). Sample 1 contained ergothioneine at 1040 ppm and polyphenol at 1847 ppm.
Accordingly, the mycelium of Pleurotus ostreatus contains 2.6 mg / g of ergothioneine per dry weight and 4.6 mg / g of polyphenol per dry weight. Further, the obtained oyster mushroom extract contained ergothioneine at 8.7 mg / g per dry weight and polyphenol at 15.4 mg / g per dry weight.

<Example 2>
A cooking test was performed using the concentrated solution (sample 1) of the Japanese oyster mushroom extract solution obtained in Example 1.

The cut eggplant was immersed in a lightly pickled seasoning liquid containing 5% of lightly pickled sample 1 for 1 hour. Thereafter, the solution was drained and stored refrigerated for one day. For the eggplant after storage, the color tone was compared with the eggplant similarly immersed in a lightly pickled seasoning liquid to which sample 1 was not added. The control eggplant turned brown, while the eggplant immersed in the seasoning solution to which sample 1 had been added had no discoloration and maintained the cut state.

-Beef sample 1 was applied to the surface of the meat equivalent to 5% by weight, and stored at 10 ° C for 1 day. With respect to the color tone of the beef after storage, the color tone was compared with that of the sample to which the sample 1 was not applied. The control beef turned brown, whereas the beef to which sample 1 was applied remained bright red.

-2% of Sample 1 was added to the meat dumpling seeds before the meat dumpling firing and mixed, followed by firing. Thereafter, it was stored at 10 ° C. for 1 day, and the flavor was sensory evaluated. As a result, as compared with a control in which Sample 1 was not added, the meat odor was reduced and a favorable flavor including umami was imparted.

<Example 3>
・ Antibacterial effect (growth inhibition test)
A MRS medium was inoculated with a strain isolated from a commercially available takuan pickle so as to be about 10 ³ / mL. Each 5 mL of this suspension was placed in two L-shaped tubes, one of which was used as a control, and the other was added with 100 μL of a Japanese oyster mushroom extract solution (sample 1) to conduct a growth test.
The test was performed using a biophoto recorder TVS062CA (ADVANTEC) with shaking culture at 30 ° C. for 30 hours, and proliferation was examined by increasing the absorbance (OD value: 660 nm).

Table 1 shows the results of the control and the examples. It shows the difference in the absorbance (OD value: 660 nm) of the culture solution before and after 30 hours of culture, and the higher the value, the more the bacteria grow and the lower the growth inhibitory effect.
As shown in Table 1, it was shown that Sample 1 has an antibacterial effect.

As described above, the basidiomycetes extract of the genus Pleurotus ostreatus of the present invention contains ergothionein and polyphenol, so that it can be used as a material for a functional food having an antioxidant function, and as a raw material for high-purity ergothioneine. Can also be used.
In addition, it has excellent discoloration suppressing effect, off-flavor suppressing effect, and antibacterial effect on the added food, so that it can be suitably used as a food material.

Claims (7)

A mycelium of Basidiomycetes belonging to the genus Pleurotus, containing ergothioneine in an amount of 1 mg / g or more per dry weight and polyphenol of 2 mg / g or more per dry weight. An Oyster mushroom basidiomycete extract containing at least 5 mg / g ergothioneine per dry weight. An Oyster mushroom basidiomycete extract containing at least 5 mg / g per dry weight of ergothioneine and at least 10 mg / g per dry weight of polyphenol. The extract according to claim 2 or 3, wherein the Pleurotus basidiomycete is Pleurotus djamor. A food discoloration inhibitor comprising the Oyster mushroom basidiomycete extract according to any one of claims 2 to 4. An off-flavour suppressor for food, comprising the Oyster mushroom basidiomycete extract according to any one of claims 2 to 4. A food shelf life improver containing the Pleurotus basidiomycetes extract according to any one of claims 2 to 4.