JP5561579B2 - Natto and its manufacturing method - Google Patents

Description

The present invention relates to natto with reduced natto odor and increased palatability, a method for producing the same, a method for reducing natto odor, and the use of 1,5-D-anhydrofructose for the purpose.

Natto is a fermented food manufactured by fermenting steamed soybeans with natto bacteria, and originally fermented by wrapping steamed soybeans in boiled rice cakes, but now they are cultured on steamed soybeans. It is a common practice to inoculate and ferment it in a container made of foamed polystyrene. Natto manufactured in this way is sold at food departments such as supermarkets. Natto ferments soybeans with natto bacteria, soy protein digestibility increases, umami components are generated and palatability increases, and odor components are generated by metabolism of amino acids and the like, producing a unique natto odor. As a result of these effects of natto, soybeans are healthy and highly fermented fermented foods that are consumed in a wide range of ages in Japan. On the other hand, natto does not have a sterilization process that kills Bacillus natto after production, so when it is stored for a long time or at a high temperature, fermentation by Bacillus natto proceeds too much, and ammonia and lower fatty acids are produced, resulting in an unpleasant natto odor. Odor increases. Since many people dislike natto due to this unpleasant odor, if this unpleasant odor is improved, it is expected to lead to further consumption expansion of natto and extension of the natto quality retention period. The unpleasant odor of natto is mainly caused by the metabolism of nitrogen-containing components such as amino acids into ammonia by natto bacteria, and the generation of ammonia by over-fermentation during distribution and storage rather than during fermentation is the major cause of this unpleasant odor. It has become. Various studies have been made to improve the odor of natto. For example, it grows at the fermentation temperature around 40 ° C., which is the same as that of general natto bacteria, but generally around 20-30 ° C. By creating mutant strains that can suppress the activity of microorganisms compared to fungi, and producing natto with the strain, fermentation at 40 ° C proceeds sufficiently, but fermentation does not proceed even if stored at room temperature after fermentation. Patent Document 1 and Patent Document 2 describe a method for producing natto that suppresses the production of ammonia by fermentation, a method for mutating natto bacteria, and producing natto with a strain that produces a small amount of ammonia. On the other hand, the addition of an antibacterial agent to natto is hardly studied because the growth of natto bacteria is suppressed and fermentation does not proceed.

Several methods for producing natto, which are characterized by adding sugars, have been proposed. For example, invention to ferment by adding oligosaccharides to steamed soybeans in the manufacturing process in order to have an intestinal action (Patent Document 3), in order to increase the stringiness of natto, sugar before the manufacturing process or eating natto The invention of adding alcohol (Patent Document 4) and the invention of adding trehalose to fermented steamed soybean to enhance nattokinase (Patent Document 5) have been proposed. It does not reduce odor. On the other hand, inventions for adding food materials have been made for the purpose of reducing the odor of ammonia in natto. For example, there is an invention (Patent Document 6) in which turmeric that is used as a spice and has health functions such as antibacterial action and liver function improvement effect is added to natto, but this invention adds turmeric to natto. However, since it is stated that the addition of turmeric is also effective by adding it immediately before eating, antibacterial properties are not involved in this ammonia odor suppression effect, but turmeric used as a spice This is considered to be the masking effect of ammonia odor due to the volatile components.

A method (Patent Document 7) has been proposed in which a fermentation medium containing saccharides and fruits or cereals is added to natto to reduce the odor characteristic of natto (Patent Document 7). Since it is added, the added sugar itself does not show the effect.

A method of adding catechins for the purpose of low bromination of natto (Patent Document 8) has been proposed. Catechin is an antioxidant, but this effect is described as being due to the ability of catechin to adsorb alcohol, and most other antioxidants do not have an effect on the low bromination of natto.

A method for producing natto with reduced ammonia odor, characterized in that sugars that can be utilized as a carbon source by natto bacteria such as xylose, ribose, and maltose, is added to soybean before fermentation (Patent Document 9). ing. The saccharide added in this invention is described as having an effect of a saccharide that is assimilated by natto bacteria in preference to nitrogen sources such as amino acids, and exhibits a saccharide and antibacterial properties that are not assimilated by natto bacteria. Carbohydrates do not appear to have this effect.

Reduction of ammonia odor of natto by adding a fructose polymer has been proposed (Patent Document 10). A fructose polymer is obtained by polymerizing 2 to 80 fructose, and anhydrofructose is a monosaccharide. The physical properties are clearly different.

As described above, various methods have been proposed for reducing the odor of ammonia in natto, but at present, the effect is low and a more effective method is required.

1,5-AF is a carbohydrate that can be produced by decomposing starch, glycogen, or the like with α-1,4-glucan lyase, and has functionalities such as antioxidant properties, antibacterial properties, and coloring properties. Inventions have been made to add to foods to maintain and improve the quality of foods. The antibacterial activity of 1,5-AF is more effective against gram-positive bacteria such as natto than gram-negative bacteria. For example, 1% 1,5-AF is added to the medium for Bacillus cereus. It has been reported that the growth is completely inhibited (Patent Document 11). From this, it is expected that adding 1,5-AF to natto fermented with natto bacteria will inhibit fermentation, and no attempt has been made to add 1,5-AF to natto.

1,5-AF has been proposed as a sugar donor to amino compounds (Patent Document 12). In this invention, the reaction of 1,5-AF with an amino compound is performed in a powder state in which an aqueous solution containing 1,5-AF and an amino compound is freeze-dried. In addition, it is a generally known fact that a reducing sugar reacts with an amino acid. Among saccharides, 1,5-AF is reported to have a high reactivity, but it has a high viscosity like natto. The reaction of 1,5-AF with amino compounds in the molecule has not been reported.

JP-A-1-191655 JP-A-6-269281 JP 2003-235492 A JP 2005-204620 A JP 2006-166812 A JP2009-39109A JP2008-206453 JP-A-8-173077 JP-A-4-287655 JP-A-2005-333856 JP 2001-89377 A JP 2001-213891 A

To provide a method for producing natto that has no adverse effects on fermentation of natto and reduces the odor of natto generated during distribution and storage, and an improved natto.

As a result of diligent investigations on this problem, the present inventors have found that by containing 1,5-AF, it is possible to produce natto with a reduced specific natto odor, thereby completing the present invention. The present invention relates to a method for producing natto characterized by including 1,5-AF in the production process of natto, and natto with reduced natto odor obtained thereby.

The odor of natto has a great influence on the taste of the product. Since particularly strong natto odor reduces the commercial value of natto, by adding 1,5-AF to natto, it is possible to suppress a decrease in palatability due to natto odor, and an increase in natto odor Deterioration can be suppressed and the expiration date can be extended.

Means for Solving the Invention

As a result of intensive studies to achieve the object, the inventors have found that natto odor can be suppressed by adding 1,5-AF to natto, and the present invention has been completed based on this finding. It came to do.
Hereinafter, the present invention will be described in detail.
In the present invention, natto means thread-drawn natto and refers to fermented and matured fermented and matured natto bacteria after steaming soybeans. . The natto raw beans are not particularly limited, and examples include soybeans, black beans, peas, broad beans, and the like.
1,5-AF used in the present invention can be prepared by degrading starch or starch syrup with the enzyme α-1,4-glucan lyase, but the purity and properties of 1,5-AF used here are not particularly limited and are aqueous solutions. The 1,5-AF preparation may contain starch, maltodextrin, other sugars, salts, proteins, lipids, and the like. Alternatively, heat-treated 1,5-AF may be used.
The content of 1,5-AF is preferably about 0.01 to 3% by weight of 1,5-AF, preferably 0.05 to 0.5%, more preferably natto 0.1-0.3 weight% is good. Since 1,5-AF is an antibacterial carbohydrate, addition of a large amount affects the growth of Bacillus natto, resulting in poor fermentation. In addition, 1,5-AF may be added to the steamed raw soybean in the production process by spraying 1,5-AF dissolved in water or the like, or added to the natto fungus and sprayed on the raw soybean. You may do it. The raw material soybean here means cooked soybean. Furthermore, you may add 1,5-AF aqueous solution by spraying etc. after completion | finish of fermentation. The temperature and time of fermentation may be the same as the conditions at the time of manufacturing ordinary natto, for example, about 18 hours at 40 ° C., but are not limited to these conditions. Further, the aging temperature after fermentation is aging at 2 to 10 ° C. for 30 to 50 hours, but is not limited to this condition.
The natto produced by these methods is suppressed from increasing natto odor, and the odor of natto is reduced from the results of sensory tests. The period is extended.

Examples are shown below, but the present invention is not limited to these examples.

Example 1
3 ml of 1,5-AF aqueous solution of 180 mg / ml was added to 30 g of commercial ground natto and mixed well. 10 g of this was taken and mixed well with 50 g of steamed soybeans taken in a plastic container. On the other hand, 10 g was taken from 30 g of commercially available ground natto added with 3 ml of water and mixed well, and mixed with 50 g of boiled soybeans as before. Thereafter, the cells were cultured at 38 ° C. for 24 hours and stored at 4 ° C. for 8 days. The amount of ammonia in natto was 10 g of natto ground in a mortar, and 1 g of the natto was precisely measured into a 50 ml centrifuge tube with a lid, 10 ml of pure water was added and well dispersed and stirred with a Teflon stick. Thereafter, the stick was washed with a small amount of pure water, and the volume was adjusted to 40 ml with ethanol. A portion of this was taken and centrifuged at 10,000 G for 10 minutes, and the supernatant was diluted 10 times with water. The amount of ammonia in the diluted solution was quantified using F-kit ammonia (JK International Co., Ltd.). The results are shown in Figure-1. Thus, by adding 1,5-AF to natto, the production of ammonia, which is a typical component of natto odor, could be effectively suppressed.

Example 2
Prepare a natto fungus solution by diluting 1 g of commercially available natto inoculum with 40 liters of water, measure 13 ml of the natto fungus solution, and add 4% 1,5-AF aqueous solution to it (1) 5 ml (2) 10 ml (3) 30 ml was added. Three batches of 1 kg of cooked soybeans were sprayed with the natto fungus solution prepared in advance and the mixed solutions (1) to (3) of 1,5-AF, and the whole amount was added. Thereafter, 50 g of soybean sprayed with 1,5-AF and natto was sprayed into a fired polystyrene tray in each test zone and fermented at 39 ° C. for 18 hours. After fermentation, it was stored in a refrigerator at 10 ° C. for 9 days. The natto was taken out of the refrigerator, allowed to stand at room temperature for 1 hour, and then sensually evaluated by eight panelists. First, natto was stirred with chopsticks 20 times, and then natto was pinched and lifted about 40 cm to observe stickiness. The scent was then squeezed and the firmness and taste of the beans were examined. The stickiness was evaluated as to whether or not a difference from natto without 1,5-AF was observed. As a result, as shown in Table-1 to Table-3, there was no difference in stickiness, taste and hardness.

(Table-1) Natto stickiness

(Table-2) Taste of Natto

(Table-3) Hardness of natto

About the natto odor, the sample with the strongest natto odor was selected from 1,5-AF non-added natto and 1,5-AF added natto. As a result, as shown in Table 4, 6 out of 8 panelists evaluated that the natto odor of natto to which 1,5-AF was not added was strong.

(Table-4) Natto odor

* Number of people out of 8 who judged that the natto odor was strongest

Changes in ammonia content in natto

Claims (5)

Natto containing 1,5-D-anhydrofructose added before fermentation of natto.     The natto according to claim 1, comprising 0.01 to 1% by weight of 1,5-D-anhydrofructose. Natto with reduced odor of natto containing 1,5-D-anhydrofructose added before fermentation of natto . A method for producing natto, characterized by adding 1,5-D-anhydrofructose before bringing natto bacteria into contact with raw soybeans. A method for reducing the natto odor , comprising 1,5-D-anhydrofructose before bringing natto bacteria into contact with raw soybeans.