JPS61139357A - Preparation of natto (fermented soybean) - Google Patents

Abstract

PURPOSE:To obtain NATTO (fermented soybean) free from characteristic odor, having moderate springiness, and excellent taste, flavor and palatability, by heating barley with saturated steam under pressure, and mixing the pressure- cooked barley to steamed soybean. CONSTITUTION:Barley is heated with saturated steam of 2-6kg/cm<2>G pressure for 30sec-20min without immersing in water before heating, and the pressure is released slowly to obtain pressure-cooked barley. The barley is soaked to effect the swelling, and added to steamed soybean prepared by conventional method at a proper ratio, preferably about 10-50wt%, and the mixture is inoculated with seed bacillus, and fermented by conventional method.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to a method for producing natto containing barley that has excellent flavor and texture.

Conventional Techniques With the development of health-oriented foods, attempts have been made to mix various foods into natto. Regarding barley, for example, JP-A-54-67057, JP-A-56-1!54
Natto containing barley, such as that disclosed in Publication No. 964, is known.

The conventional method for producing natto with barley is to mix soybeans with washed barley or rolled oats, soak them in water, drain the water, steam them, and then sprinkle seeds and seedlings on this mixture and ferment it. This is where you get natto.

Problems to be Solved by the Invention When soybeans and barley are mixed and steamed as in the past, heating the soybeans under conditions that give the soybeans an appropriate degree of softness will cause the barley to become hard, since barley has a hard structure among grains. This is undesirable because it leaves a sticky residue and the resulting product has a poor texture.

Also, if you use pressed rolled barley and steam it in the same way, the rolled barley will become sticky, especially if you do not mix the soybeans and rolled barley evenly before steaming, the rolled barley will adhere to each other and form blocks, which will cause the soybeans to be cooked evenly. There were drawbacks such as the inability to mix.

Means for Solving the Problems The inventors of the present invention are considering a method for processing barley. Just by soaking the heated barley in water, it absorbs enough water to swell and soften, making it edible. When mixed with soybeans that have been washed, soaked, and steamed using conventional methods, the barley can be mixed evenly and easily without sticking to each other. He discovered that by fermenting this mixture by ingesting an inoculum, natto with excellent flavor and texture could be obtained, and he completed the present invention.

That is, in the present invention, when producing natto, barley is
Mixing the pressure-heated barley obtained by heating under pressure for 30 seconds or more and within 20 minutes using saturated steam of cWIll-G or more and 6 kg Ici ・G or less, and then gradually decompressing it with the steamed soybeans. This is a method for producing natto that is characterized by:

The present invention will be explained in detail below.

The barley used in the present invention may be either barley from which the floating skin is difficult to remove, or bare barley from which the peel is easily removed and the grains are easily shed, and may be either brown barley or refined barley. When brown barley is used, it may be polished after pressure heating.

And this barley was not soaked in water, but the pressure was 2k.
Heat treatment is performed for 30 seconds or more and 20 minutes or less using saturated steam of g/Cze.G or more and 6 kg/C-.G or less.

The above pressure and heat treatment conditions are appropriately selected within the above pressure and time ranges, taking into consideration the degree of gelatinization, swelling degree, hardness, etc. of the barley after the pressure and heat treatment, but the pressure is 2 kg/cWII-G. If the heating time is less than 30 seconds, the gelatinization degree of the pressure-heated barley obtained will not increase, and the resulting barley will be hard and have a low degree of swelling. Also, the barley is hard and does not swell, resulting in a bad texture.

Conversely, the pressure is 6 kg/crl-G and the heating time is 2.
Pressure-heated barley obtained for more than 0 minutes is colored or burnt, resulting in only natto that is dark in color, has a burnt odor, and has a bitter taste.

The pressurizing and heating apparatus used in the present invention may be of any shape or structure, regardless of whether it is a continuous type or a batch type. Further, the saturated steam used in the present invention can be used without any problem as long as it does not contain any air or contains a small amount of air.

Next, after the barley is pressurized and heated using saturated steam in this manner, the pressure is gradually decompressed and the barley particles are discharged without swelling to obtain pressurized and heated barley.

In this case, the pressure may be gradually decompressed to such an extent that it takes at least 10 seconds to return the barley to normal pressure after steaming it under pressure. Pressure-heated barley may be obtained by returning to pressure.

This prevents the destruction of barley iia due to swelling, and when water is absorbed, barley grains have appropriate interstitial elasticity, are less sticky, do not stick, and can be easily mixed with steamed soybeans when heated under pressure. Barley is obtained. The pressure-heated barley thus obtained is polished if necessary, and then used to produce natto.

First, pressurized and heated barley is soaked in water for an appropriate period of time, for example. The barley thus swollen by water absorption is added in an appropriate amount, preferably 10-50% (W/-V), to steamed soybeans obtained by washing, soaking, draining, and steaming in a conventional manner and mixed.

The pressurized and heated barley according to the present invention has already undergone sufficient gelatinization and is swollen and softened, but it maintains elasticity and can be easily mixed with steamed soybeans without sticking to each other. can.

Next, this mixture is inoculated with an inoculum. In this case, in normal natto production, the steamed high-temperature soybeans are cooled and then inoculated with starter bacteria, but in the method of the present invention, the steamed high-temperature soybeans are inoculated with cold, pressure-heated barley after steaming. Simply mixing will lower the product temperature to an appropriate temperature, and cooling for seed inoculation is not necessary.

After inoculation, the product is fermented in the usual manner.

The present invention will be explained below with reference to experimental examples.

Experimental Example 1 100g of refined barley per test plot was wrapped in cloth and placed in a small horizontal autoclave (inner diameter: 150φm/
m, length: 200 m/m), sealed and heated under pressure using saturated steam under the treatment conditions listed in Table 1, and then the steam pressure was released to obtain pressurized and heated white barley.

After washing each pressurized and heated refined barley with water,
The barley was soaked in water for 16 hours and drained to obtain white barley soaked under pressure and heat.

Table 1 shows the gelatinization degree of the pressure-heated whitened barley, the degree of swelling of the soaked whitened barley, the hardness, and the sensory evaluation.

As a control, untreated rolled barley and milled barley were treated in the same manner as above after measuring the degree of gelatinization.

Table 1 (Note 1) Degree of gelatinization: Each sample was pulverized to 100~
Make a powder of about 120 mesh, and add 1 g each to ASB.
A C 100 ml Erlenmeyer flask containing no sample powder was prepared.

Pour 50 ml of distilled water into each flask, stir well for A and B to make them uniform, then boil A flask over an open flame for 15 minutes, cool quickly, and add A, B, C,
Each flask was placed in a constant temperature bath at 20°C and the product temperature was adjusted to 20°C. 115ml of 5% diastase solution in each flask
Quickly add 1 at a time and raise the temperature of the thermostat, 37
After incubating at ℃ for 2 hours, 2 ml of 1N hydrochloric acid was added quickly in the same way, and then distilled water was added to make each solution 100 ml.
1 and filtered using filter paper to obtain test solutions a, b, and c corresponding to A, B, and C1, respectively.

Reducing sugars in each test solution were measured using a conventional method, and the degree of gelatinization was calculated using the following formula.

(Note 2) Swelling degree: Each sample was immersed in water, drained, and weighed, and calculated using the following formula.

Swelling degree (%) = (Note 3) Hardness... 30 grains of each sample were pressed on a tabletop plate (0 to
The grains were spread out one by one and placed on a weighing table (2000 g range), and each of the 10 grains was crushed with the index finger, and the scale of the crushed grain was read to determine the hardness. This was repeated 5 times and the average value for a total of 50 grains was shown.

As shown in Table 1, refined barley was heated using saturated steam at a pressure of 2 kg/cm'@G or higher, 6 kg/cm'
・As a result of treatment under G or lower, 30 seconds or more, and 20 minutes or less, the degree of gelatinization has progressed sufficiently and digestibility is good, and the product swells and softens easily when immersed in water at room temperature. Refined barley was obtained and became edible.

Experimental Example 2 Natto was produced using each type of barley obtained by pressurizing and heating 150 g of refined barley per test plot in the same manner as in Experimental Example 1. First, 500g of soybeans per test plot were heated to 20°C.
Soak in water for 14 hours, let it absorb enough water, drain, and autoclave (manufactured by Sanjo Seisakusho, diameter: 80 cm, depth:
100cm) at a pressure of 0.7kg/Cm”・G and 30
Steamed for minutes.

To each of the obtained steamed soybeans, the above-mentioned pressure-heated white barley soaked in water for 14 hours and drained was added and mixed,
Bacillus natto was inoculated at a temperature of about 60°C.

Next, the above mixtures were poured into 100g containers prepared in advance at an initial temperature of 42°C, and after reaching 48°C after a leap of 6 to 8 o'clock, the temperature was adjusted to 45 to 48°C and fermentation was continued for about 16 hours. After ripening, the fermented soybeans were cooled to 5°C to obtain natto.

The yield of each natto obtained, the hardness of the barley particles in the natto, and the sensory evaluation are shown in Table 2.

As a control, 500 g of soybeans and 150 g of untreated rolled barley were washed separately, immersed in water for 14 hours, drained, then mixed, and then steamed for 30 minutes at a pressure of 0, 7 kg/cm''G. and unprocessed white barley 15
A test plot in which 0g of the rice was treated in the same manner was selected, and both test plots were cooled to 60° C. after steaming, and then inoculated with Bacillus natto. Thereafter, the same treatment as above was performed and the results are shown in Table 2.

Table 2 (Note) The hardness of barley grains in natto was measured in the same manner as in Experimental Example 1.

As shown in Table 2, natto made by mixing each type of barley treated within the range of the treatment conditions of the present invention has a large yield of natto because the barley particles sufficiently absorb water and swell, and the natto is sensually free from the characteristic odor of natto. It had a tingling sensation and was white in color, had a moderate elasticity despite being softened, had a good taste, and had a good texture.

On the other hand, refined barley mixed with soybeans and steamed has hard barley grains with little swelling, and products made using rolled barley have barley particles that adhere to each other and are difficult to mix uniformly with soybeans, resulting in a poor texture. Met.

Example The present invention will be explained below with reference to Examples.

Wrap 5 kg of refined barley in cloth and place it in a small horizontal autoclave (inner diameter: 150φm/m, depth: 200m/m)
The mixture was sealed and heated under pressure for 4 minutes using saturated steam at a pressure of 4 kg/Cm'.G. Then, the exhaust pulp is gradually opened and the pressure is lowered to atmospheric pressure in 30 seconds.
．． 05 kg was obtained.

5 kg of the pressure-heated white barley and 15 kg of soybeans were separately immersed in water at 20° C. for 15 hours, sufficiently absorbed, and then drained. Then, only the soybeans were placed in an autoclave (manufactured by Sanjo Seisakusho, diameter: 80 cm, depth: 100 cm) and steamed at pressures of 1 and 0 kg/cwt.G for 30 minutes.

The above-mentioned soaked and drained white barley was added to the obtained steamed soybeans, mixed, and inoculated with Bacillus natto.Then, the mixture was divided into 100 g containers each, fermented at 48°C for 16 hours, and then heated to 5°C. It was cooled and aged to obtain 42 kg of natto.

The obtained natto had no peculiar odor, was fair in color, had sufficiently swollen barley particles, and had good flavor and texture.

Effects of the invention The natto obtained by mixing the pressurized and heated barley according to the invention is as follows:
Compared to conventional natto, which is obtained by steaming a mixture of soybeans, the barley is pressure-heated in advance under optimal conditions, so it absorbs enough water, swells, and softens just by soaking it in room-temperature water before use. It has moderate elasticity and can be mixed evenly with steamed soybeans. Furthermore, by mixing hot soybeans and cold soybeans, the product temperature immediately drops to an appropriate temperature, making it possible to inoculate seed bacteria. Therefore, the burden of cooling required in the conventional method can be reduced. The obtained natto does not have a peculiar odor, is not only white in color, but also has a high yield in both weight and volume, has good mycelium surroundings, has appropriate elasticity, and has good flavor and texture. I can do it.

Claims (1)

[Claims] When producing natto, barley is heated under pressure using saturated steam of 2 kg/cm^2.G or more and 6 kg/cm^2.G or less for at least 30 seconds and for up to 20 minutes, and then gradually depressurized. A method for producing natto, which comprises mixing the resulting pressure-heated barley with steamed soybeans.