Dark soy sauce and preparation method thereof

Abstract

The invention discloses dark soy sauce and a preparation method thereof, and belongs to the technical field of condiment manufacturing. The preparation method provided by the invention comprises the following steps: taking a sugar source, boiling until the absorbance A610 is 0.003-0.006, adding water, uniformly stirring, and concentrating under reduced pressure to obtain concentrated caramel color; uniformly mixing the concentrated caramel color with the clarified soy sauce to obtain pre-sun soy sauce A; adding the edible mushroom salt aqueous solution into the pre-sun soy sauce A to obtain pre-sun soy sauce B; and sun-curing the pre-sun soy sauce B to obtain a sun-cured semi-finished product, then filtering the sun-cured semi-finished product, and blending to obtain the dark soy sauce. The dark soy sauce prepared by the preparation method provided by the invention is low in bitterness and rich and strong in flavor.

Description

Technical Field

[0001] The invention belongs to the technical field of condiment manufacturing, and in particular relates to dark soy sauce and a preparation method thereof. Background Art

[0002] Soy sauce is generally divided into two types: light soy sauce and dark soy sauce. Dark soy sauce is suitable for coloring dishes, and caramel color is often used as a raw material. In the preparation process of caramel color, caramelization and Maillard reaction mainly occur. In the above reaction, pentose dehydration reaction generates furfural, 5-hydroxymethylfurfural, etc. A considerable number of studies have shown that furfural has a bitter taste, which leads to a certain bitterness in dark soy sauce products and reduces the flavor preference of the product. Therefore, it is necessary to find a preparation technology for low-bitter dark soy sauce to improve the quality of dark soy sauce products.

[0003] Different technologies for removing bitterness from food are provided in the prior art, mainly including the following six categories: the first category is adsorption and separation through activated carbon, resin, etc.; for example, patent CN202210788561.7 introduces a method for adding microporous activated carbon and plasma-modified activated carbon fiber to soy sauce to adsorb bitter substances and prepare low-bitterness soy sauce. This solution requires separation operation after adding activated carbon to ensure that the activated carbon after adsorption does not flow into the final product. There are problems of increasing production steps, increasing processing costs and mixing the final product. At the same time, activated carbon will indiscriminately adsorb macromolecular substances in soy sauce. For dark soy sauce, its colored pigment molecules will also be adsorbed, affecting the coloring effect, so this technology is not suitable for removing bitterness from dark soy sauce. The second category is to embed and complex bitter molecules through amylopectin or cyclodextrin; for example, patent CN201180061158.4 introduces a technology for adding amylopectin to reduce bitterness. The principle of this type of method is to use amylopectin or cyclodextrin to embed and complex bitter components to avoid contact with bitter receptors, but there will also be problems of embedding and complexing other components, which will affect the flavor of the final product, so there are certain limitations in practical application. The third category is enzymatic debittering, specifically using enzymes to remove hydrophobic amino acids from polypeptides; for example, patent CN200610017190.3 introduces a method of using a double enzyme method to prepare a low molecular weight, non-bitter soybean peptide product. However, most enzymatic processes can only target the bitterness formed by hydrophobic amino acids, with high specificity, and have no obvious effect on the bitterness caused by other chemical substances. The fourth category is to inhibit the generation of bitter substances; for example, patent CN20191105171.3 introduces a method of adding phenolic acid to the caramel color preparation process to inhibit the bitter substances generated during the reaction. However, the phenolic acid added by this method has a high market cost, which brings about the problem of increased production costs. The fifth category is to add bitter taste inhibitors. For example, patent CN201810413312.3 introduces a method of using isobutyl angelicae to inhibit bitter substances from citrus, coffee, tea, etc. However, bitter inhibitors have a certain specificity in inhibiting bitter substances, and generally only have a bitterness inhibitory effect on one or several bitter substances. And most bitter inhibitors have special flavors, which will damage the original flavor of the food after addition. The sixth category is to add sweeteners and other masks. For example, patent CN202210070282.7 introduces a method of adding sucralose and anhydrous citric acid to mask soy protein hydrolysate. However, the use of sweeteners will affect the original flavor of the food. Although the bitterness is masked by sweeteners, the bitter substances are not eliminated and are still detected by taste receptors and recognized by the brain, and the masking effect is unstable.

[0004] Therefore, how to stably and efficiently reduce the bitterness without affecting the coloring and flavor effects of dark soy sauce has become a research hotspot. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art and provide a dark soy sauce that can effectively remove bitterness and enhance flavor and a preparation method thereof.

[0006] To achieve the above object, the technical solution adopted by the present invention is: a method for preparing dark soy sauce, the preparation method comprising the following steps:

[0007] (1) Take the sugar source and cook until the absorbance is A 610 After the concentration is 0.003-0.006, add water and stir evenly, then concentrate under reduced pressure to obtain concentrated sugar color;

[0008] (2) uniformly mixing the concentrated sugar color and the clarified soy sauce to obtain pre-sun soy sauce A;

[0009] (3) adding the edible fungus salt solution to the pre-sun-dried soy sauce A to obtain the pre-sun-dried soy sauce B;

[0010] (4) Sun-drying the pre-sun soy sauce B to obtain a sun-dried semi-finished product, then filtering the sun-dried semi-finished product and blending it to obtain dark soy sauce.

[0011] In the method for preparing dark soy sauce provided by the present invention, the sugar source is boiled to an absorbance of A 610 The content of 0.003-0.006 is then reduced in pressure and concentrated, and then mixed evenly with clarified soy sauce, and then added with edible fungus salt water solution and then sun-dried. This can effectively reduce the bitterness of the dark soy sauce while improving the flavor of the dark soy sauce, achieving excellent comprehensive effects.

[0012] Specifically, the sugar source undergoes caramelization and Maillard reaction during the cooking process. In this reaction, the pentoses in the sugar source undergo a dehydration reaction to generate furfural, and the hexoses undergo a dehydration reaction to generate 5-hydroxymethylfurfural (HMF). A large number of studies have shown that the above two substances have a significant bitter taste, which is one of the reasons for the bitter taste of dark soy sauce; and the formation of furfural and 5-hydroxymethylfurfural is positively correlated with the degree of cooking of the sugar source. The higher the degree of cooking, the greater the absorbance, the greater the degree of dehydration of the sugar source, the more corresponding furfural and 5-hydroxymethylfurfural are generated, and the greater the bitterness intensity. On the one hand, the present invention controls the absorbance A after the sugar source is cooked. 610 0.003-0.006, that is, the cooking absorbance is reduced by more than 40% (the cooking absorbance of conventional dark soy sauce caramel color A 610is 0.010 or more), which can reduce the generation of furfural and 5-hydroxymethylfurfural from the source on the basis of ensuring the color rate of the subsequent dark soy sauce; on the other hand, after cooking, by reducing pressure and concentrating (negative pressure evaporation), the furfural and 5-hydroxymethylfurfural contained in the cooked sugar color can be effectively removed, further reducing the content of bitter substances and reducing the bitterness of the sugar color. At the same time, by adding edible fungus salt water solution before sun-drying, the two are mixed and sun-dried, and the flavor amino acids and other substances of the edible fungi can be slowly released into the dark soy sauce, making it taste sweeter and more flavorful, and can also cover up the bitterness to a certain extent; in addition, the sun-drying process can also further reduce the volatile bitter substances; thereby improving the flavor of the dark soy sauce as a whole and reducing the bitterness of the dark soy sauce.

[0013] As a preferred embodiment of the preparation method of the present invention, the sugar source includes at least one of white sugar, starch sugar and fructose syrup.

[0014] As a preferred embodiment of the preparation method of the present invention, in the step (1), the cooking pressure is 0.03-0.09 MPa, and the cooking temperature is 132-152°C.

[0015] Preferably, during the cooking, the mass ratio of the sugar source to the water is 1:(0.2-0.4).

[0016] Preferably, stirring is maintained during the cooking process, and the stirring speed is 20 to 40 rpm.

[0017] As a preferred embodiment of the preparation method of the present invention, in the step (1), water is added and stirred evenly, and the mass ratio of the added water to the sugar source is (0.1-0.15):1.

[0018] The present invention has found that when the cooking process is controlled to the absorbance A 610 While further controlling the cooking pressure and temperature and the absorbance to reach 0.003-0.006, when the mass ratio of water added and the mass ratio of sugar source are within the above range, the production of bitter flavoring substances such as furfural and 5-hydroxymethylfurfural can be more effectively reduced.

[0019] As a preferred embodiment of the preparation method of the present invention, in the step (1), the pressure of the reduced pressure concentration is (-75) to (-95) kPa, and the temperature of the reduced pressure concentration is 90 to 100°C.

[0020] As a preferred embodiment of the preparation method of the present invention, in the step (1), the mass of the water volatilized by reduced pressure concentration accounts for 5-10% of the mass of the sugar source.

[0021] The present invention has found that controlling the pressure and temperature and the degree of decompression in the vacuum concentration process within the above range can effectively reduce the bitter substances in the system and reduce the impact on the quality of sugar color.

[0022] Preferably, in the step (1), after the reduced pressure concentration, a filtering step is further included, and the filtration is performed using a 60-mesh filter bag.

[0023] As a preferred embodiment of the preparation method of the present invention, in the step (2), the mass ratio of concentrated sugar color to clarified soy sauce is (14-24):(76-86).

[0024] The present invention has found that when the mass ratio of concentrated sugar color to clarified soy sauce is within the above range, dark soy sauce with better comprehensive performance can be obtained.

[0025] As a preferred embodiment of the preparation method of the present invention, the preparation method of the edible fungus saline solution is: adding the cleaned edible fungi into saline and boiling for 3 to 5 minutes to obtain the edible fungus saline solution.

[0026] Preferably, the edible fungi include at least one of straw mushrooms, shiitake mushrooms and oyster mushrooms.

[0027] As a preferred embodiment of the preparation method of the present invention, the mass percentage of salt in the salt water is 23-25%.

[0028] As a preferred embodiment of the preparation method of the present invention, the mass ratio of the edible fungi to the saline solution is (30-40):(60-70).

[0029] The present invention has found that, by subjecting the edible fungi to the above treatment and subsequently mixing them with the pre-sun-dried soy sauce A, the flavor substances therein can slowly penetrate into the soy sauce, thereby improving the flavor of the dark soy sauce.

[0030] As a preferred embodiment of the preparation method of the present invention, in the step (3), the mass ratio of the edible fungi to the pre-sun-dried soy sauce A is (1-1.5): (98.5-99).

[0031] The present invention has been found that by controlling the mass ratio of the edible fungi to the pre-sun-dried soy sauce A within the above range, excellent effects of masking bitterness and enhancing flavor can be achieved simultaneously.

[0032] As a preferred embodiment of the preparation method of the present invention, in the step (4), the drying time is 100 to 150 days.

[0033] As a preferred embodiment of the preparation method of the present invention, in the step (4), the mass of the semi-finished product after sun-drying is 85-90% of the mass of the soy sauce B before sun-drying.

[0034] The present invention has found that the comprehensive flavor of the dark soy sauce can be fully improved by controlling the sun-drying time and the quality of the semi-finished product after sun-drying to 85-90% of the soy sauce B before sun-drying.

[0035] As a preferred embodiment of the preparation method of the present invention, the preparation method of the clarified soy sauce is: crushed and steamed soybeans are mixed with roasted and crushed wheat to make koji and ferment, and after the fermentation is completed, the soy sauce stock solution is obtained, and then the soy sauce stock solution is heated and centrifuged, and the supernatant is collected to obtain clarified soy sauce.

[0036] Preferably, the mass ratio of the crushed and steamed soybeans to the roasted and crushed wheat is (6.5-7.5):(2.5-3.5).

[0037] Preferably, during the mixed koji making process, the amount of koji added is 0.35-0.50wt%.

[0038] Preferably, the mixing and koji making time is 38 to 55 hours.

[0039] Preferably, the fermentation process is as follows: after the mixed koji making is completed, Daqu is obtained, and saline solution with a mass of 1.10 to 1.30 times of the Daqu is added to the Daqu for fermentation for 80 to 150 days.

[0040] Preferably, the mass percentage of salt in the saline solution is 23.2-24.6%.

[0041] Preferably, the heating temperature is 80-92° C., and the heating time is 2-8 hours.

[0042] Preferably, the centrifugal temperature is 38-40° C., and the centrifugal speed is 4000-5000 rpm.

[0043] In addition, the present invention also provides a dark soy sauce, which is prepared by the preparation method provided by the present invention.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] 1. The preparation method of dark soy sauce provided by the present invention combines the generation law of bitter substances, controls the sugar source to cook until the absorbance A 610 The ratio of the bitterness of the dark soy sauce to the soy sauce is 0.003 to 0.006, that is, the dehydration degree of the sugar source is reduced, and the generation of bitter substances such as furfural and 5-hydroxymethylfurfural is inhibited from the source, and the bitterness inhibition effect is significant; and the process flow is simple, avoiding the influence of the existing bitter removal technology on the flavor of the dark soy sauce itself by adding exogenous substances such as bitter masking agents, cyclodextrin and other embedding complexes;

[0046] 2. In the preparation method of dark soy sauce provided by the present invention, the boiled sugar color is concentrated under reduced pressure, which can avoid the loss of soy sauce flavor caused by first mixing the sugar color and clarified soy sauce and then concentrating it in the prior art, and at the same time, bitter substances can be effectively removed by negative pressure evaporation, thereby improving the comprehensive flavor of the dark soy sauce;

[0047] 3. In the preparation method of the dark soy sauce provided by the present invention, an edible fungus saline solution is added before sun-drying. The flavoring amino acids, polysaccharides and other substances in the edible fungus saline solution are slowly released into the dark soy sauce after a long period of sun-drying, so that the obtained dark soy sauce has a sweet taste and a better flavor. At the same time, the rich mushroom aroma can also cover up some bitter substances, further improving the comprehensive flavor of the dark soy sauce. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 The present invention is a schematic diagram of the preparation process of dark soy sauce according to Example 1. DETAILED DESCRIPTION

[0049] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0050] Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0051] Example 1

[0052] The embodiment of the present invention provides a dark soy sauce, and the preparation process diagram of the dark soy sauce is as follows: Figure 1 As shown, the preparation method is as follows:

[0053] (1) Preparation of concentrated sugar color

[0054] S1. Add 30kg of white sugar to 10kg of water and stir and cook in a 50L reactor. The cooking temperature is 135°C, the cooking pressure is 0.03-0.04MPa, and the stirring speed is 20rpm. During the cooking process, sample and detect the absorbance A of the sugar color at regular intervals. 610 When the pressure reaches 0.004, the reaction is terminated, and 3 kg of water is added to the cooked sugar color. After adding water, the pressure is gradually reduced to normal pressure and stirred evenly at a stirring speed of 20 rpm to obtain the sugar color;

[0055] S2, adjusting the pressure in the reactor to -75 kPa and the temperature to 92°C, and then evaporating and concentrating. When the evaporated water accounts for 5% of the mass of the sugar source, the concentration is terminated, and the filtrate is collected through a 60-mesh filter bag to obtain concentrated sugar color;

[0056] (2) Preparation of clarified soy sauce

[0057] S3, mixing the crushed and steamed soybeans and the roasted and crushed wheat in a mass ratio of 7:3, then adding 0.35wt% of koji seeds thereto and making koji at 30±2°C for 39h to obtain Daqu;

[0058] S4, adding 1.25 times the mass of salt water (the mass percentage of salt in the salt water is 23.2%) to the Daqu, and then placing it in a fermentation tank for fermentation for 85 days;

[0059] S5, after fermentation is completed, the soy sauce stock solution is released from the bottom of the fermentation tank, and the soy sauce stock solution is heated to 92 ° C and maintained for 2.5 h, then cooled to 39 ± 1 ° C and centrifuged at a speed of 5000 rpm, and the supernatant is collected to obtain clarified soy sauce;

[0060] (3) Preparation of edible fungus salt water

[0061] 30 parts by weight of fresh shiitake mushrooms were cleaned, drained and placed in 70 parts by weight of saline solution (the mass percentage of salt in the saline solution was 25%), boiled in a stainless steel pot for 3 minutes and then naturally cooled to room temperature to obtain an edible fungus saline solution;

[0062] (4) Preparation of dark soy sauce

[0063] S6, placing the concentrated caramel color in a storage tank, then adding clarified soy sauce and stirring evenly at a rotation speed of 30 rpm to obtain pre-sun soy sauce A, wherein the mass ratio of the concentrated caramel color to the clarified soy sauce is 15:85;

[0064] S7, adding the edible fungus salt solution into the pre-sun soy sauce A to obtain the pre-sun soy sauce B, wherein the mass ratio of fresh shiitake mushrooms to pre-sun soy sauce A is 1:99;

[0065] S8, placing the soy sauce B before sun exposure in a glass sun exposure pool for natural sun exposure for 100 to 110 days to obtain a semi-finished product after sun exposure, wherein the mass of the semi-finished product after sun exposure is 90% of the mass of the soy sauce B before sun exposure;

[0066] S9. The semi-finished product after sun-drying is filtered through an 80-mesh filter bag, and the filtrate is collected and blended to obtain dark soy sauce.

[0067] Example 2

[0068] The embodiment of the present invention provides a dark soy sauce, and the preparation method of the dark soy sauce is as follows:

[0069] (1) Preparation of concentrated sugar color

[0070] S1. Add 50kg of fructose syrup (F55) to 20kg of water and stir and cook in a 100L reactor. The cooking temperature is 145°C, the cooking pressure is 0.06-0.07MPa, and the stirring speed is 30rpm. During the cooking process, sample and detect the absorbance A of the sugar color at regular intervals. 610 The reaction was terminated when the pressure reached 0.006, and 7.5 kg of water was added to the cooked sugar color. After adding water, the pressure was gradually reduced to normal pressure and stirred evenly at a stirring speed of 40 rpm to obtain the sugar color.

[0071] S2, adjusting the pressure in the reactor to -85 kPa and the temperature to 95°C, and then evaporating and concentrating. When the evaporated water accounts for 8% of the mass of the sugar source, the concentration is terminated, and the filtrate is collected through a 60-mesh filter bag to obtain concentrated sugar color;

[0072] (2) Preparation of clarified soy sauce

[0073] S3, mixing the crushed and steamed soybeans and the roasted and crushed wheat in a mass ratio of 6.5:3.5, then adding 0.45wt% of koji seeds thereto and making koji at 30±2°C for 41h to obtain Daqu;

[0074] S4, adding 1.10 times the mass of salt water to the Daqu (the mass percentage of salt in the salt water is 24.0%) and placing it in a fermentation tank for fermentation for 105 days;

[0075] S5, after fermentation is completed, the soy sauce stock solution is released from the bottom of the fermentation tank, and the soy sauce stock solution is heated to 85°C and maintained for 4.5h, then cooled to 39±1°C and centrifuged at a speed of 4500rpm, and the supernatant is collected to obtain clarified soy sauce;

[0076] (3) Preparation of edible fungus salt water

[0077] 40 parts by weight of fresh straw mushrooms were cleaned, drained and placed in 60 parts by weight of saline solution (the mass percentage of salt in the saline solution was 23%), boiled in a stainless steel pot for 4 minutes and then naturally cooled to room temperature to obtain an edible fungus saline solution;

[0078] (4) Preparation of dark soy sauce

[0079] S6, placing the concentrated caramel color in a storage tank, then adding clarified soy sauce and stirring evenly at a rotation speed of 40 rpm to obtain pre-sun soy sauce A, wherein the mass ratio of the concentrated caramel color to the clarified soy sauce is 20:80;

[0080] S7, adding the edible fungus salt solution into the pre-sun soy sauce A to obtain the pre-sun soy sauce B, wherein the mass ratio of fresh shiitake mushrooms to pre-sun soy sauce A is 1.3:98.7;

[0081] S8, placing the soy sauce B before sun exposure in a glass sun exposure pool for natural sun exposure for 120 to 130 days to obtain a semi-finished product after sun exposure, wherein the mass of the semi-finished product after sun exposure is 88% of the mass of the soy sauce B before sun exposure;

[0082] S9. The semi-finished product after sun-drying is filtered through an 80-mesh filter bag, and the filtrate is collected and blended to obtain dark soy sauce.

[0083] Example 3

[0084] The embodiment of the present invention provides a dark soy sauce, and the preparation method of the dark soy sauce is as follows:

[0085] (1) Preparation of concentrated sugar color

[0086] S4. Add 100 kg of white sugar to 35 kg of water and stir and cook in a 200 L reactor. The cooking temperature is 150°C, the cooking pressure is 0.08-0.09 MPa, and the stirring speed is 40 rpm. During the cooking process, sample and detect the absorbance A of the sugar color at regular intervals. 610 When the pressure reaches 0.005, the reaction is terminated, and 13 kg of water is added to the cooked sugar color. After adding water, the pressure is gradually reduced to normal pressure and stirred evenly at a stirring speed of 45 rpm to obtain the sugar color;

[0087] S5, adjusting the pressure in the reactor to -95 kPa and the temperature to 98°C, and then evaporating and concentrating. When the evaporated water accounts for 10% of the mass of the sugar source, the concentration is terminated, and the filtrate is collected through a 60-mesh filter bag to obtain concentrated sugar color;

[0088] (2) Preparation of clarified soy sauce

[0089] S3, mixing the crushed and steamed soybeans and the roasted and crushed wheat in a mass ratio of 7.5:2.5, then adding 0.50wt% of koji seeds thereto and making koji at 30±2°C for 53h to obtain Daqu;

[0090] S4, adding 1.30 times the mass of salt water (the mass percentage of salt in the salt water is 24.5%) to the Daqu, and then placing it in a fermentation tank for fermentation for 145 days;

[0091] S5. After the fermentation is completed, the soy sauce stock solution is released from the bottom of the fermentation tank, and the soy sauce stock solution is heated to 80° C. and maintained for 7 h, then cooled to 39±1° C. and centrifuged at a speed of 4000 rpm to collect the supernatant to obtain clarified soy sauce;

[0092] (3) Preparation of edible fungus salt water

[0093] 35 parts by weight of fresh oyster mushrooms were cleaned, drained and placed in 65 parts by weight of saline solution (the mass percentage of salt in the saline solution was 24%), boiled in a stainless steel pot for 5 minutes and then naturally cooled to room temperature to obtain an edible fungus saline solution;

[0094] (4) Preparation of dark soy sauce

[0095] S6, placing the concentrated caramel color in a storage tank, then adding clarified soy sauce and stirring evenly at a rotation speed of 45 rpm to obtain pre-sun soy sauce A, wherein the mass ratio of the concentrated caramel color to the clarified soy sauce is 23:77;

[0096] S7, adding the edible fungus salt solution into the pre-sun soy sauce A to obtain the pre-sun soy sauce B, wherein the mass ratio of fresh shiitake mushrooms to pre-sun soy sauce A is 1.5:98.5;

[0097] S8, placing the soy sauce B before sun exposure in a glass sun exposure pool for natural sun exposure for 140 to 150 days to obtain a semi-finished product after sun exposure, wherein the mass of the semi-finished product after sun exposure is 85% of the mass of the soy sauce B before sun exposure;

[0098] S9. The semi-finished product after sun-drying is filtered through an 80-mesh filter bag, and the filtrate is collected and blended to obtain dark soy sauce.

[0099] Comparative Example 1

[0100] The comparative example of the present invention provides a dark soy sauce, and the preparation method of the dark soy sauce is as follows:

[0101] (1) Preparation of sugar color

[0102] S1. Add 30kg of white sugar to 10kg of water and stir and cook in a 50L reactor. The cooking temperature is 135°C, the cooking pressure is 0.03-0.04MPa, and the stirring speed is 20rpm. During the cooking process, sample and detect the absorbance A of the sugar color at regular intervals. 610 The reaction was terminated when the pressure reached 0.012, and 3 kg of water was added to the cooked sugar color. After adding water, the pressure was gradually reduced to normal pressure and stirred evenly at a stirring speed of 20 rpm to obtain the sugar color.

[0103] (2) Preparation of clarified soy sauce

[0104] S2, mixing the crushed and steamed soybeans and the roasted and crushed wheat in a mass ratio of 7:3, then adding 0.35wt% of koji seeds thereto and making koji at 30±2°C for 39h to obtain Daqu;

[0105] S3, adding 1.25 times the mass of salt water to the Daqu (the mass percentage of salt in the salt water is 23.2%), and then placing it in a fermentation tank for fermentation for 85 days;

[0106] S4, after the fermentation is completed, the soy sauce stock solution is released from the bottom of the fermentation tank, and the soy sauce stock solution is heated to 92 ° C and maintained for 2.5 hours, then cooled to 39 ± 1 ° C and centrifuged at a speed of 5000 rpm, and the supernatant is collected to obtain clarified soy sauce;

[0107] (3) Preparation of dark soy sauce

[0108] S5, after the caramel color and clarified soy sauce are stirred and mixed in a mass ratio of 15:85, the concentration is evaporated under a vacuum degree of -75kPa and a temperature of 92°C, and the concentration is terminated when the volatile water accounts for 5% of the caramel color mass, and filtered through a 60-mesh filter bag, and the filtrate is collected to obtain the soy sauce before sun exposure;

[0109] S6. Place the soy sauce before sun-drying in a glass sun-drying pool for natural sun-drying for 100 to 110 days to obtain a semi-finished product after sun-drying, wherein the mass of the semi-finished product after sun-drying is 90% of the mass of the soy sauce before sun-drying, and then filter the semi-finished product after sun-drying through an 80-mesh filter bag, collect the filtrate and mix it to obtain dark soy sauce.

[0110] Comparative Example 2

[0111] The comparative example of the present invention provides a dark soy sauce, and the only difference between the preparation method of the dark soy sauce and that of Example 1 is that the dark soy sauce is boiled until the absorbance A 610 It is 0.012.

[0112] Comparative Example 3

[0113] The comparative example of the present invention provides a dark soy sauce, and the only difference between the preparation method of the dark soy sauce and that of Example 1 is that the dark soy sauce is boiled until the absorbance A 610 is 0.001.

[0114] Comparative Example 4

[0115] The comparative example of the present invention provides a dark soy sauce, and the only difference between the preparation method of the dark soy sauce and that of Example 1 is that the sugar color is mixed with the clarified soy sauce and then concentrated under reduced pressure.

[0116] Comparative Example 5

[0117] The comparative example of the present invention provides a dark soy sauce, and the only difference between the preparation method of the dark soy sauce and that of Example 1 is that no edible fungus salt solution is added.

[0118] Effect Example 1

[0119] Effect Example of the Present Invention The content of furfural in the dark soy sauce prepared in Examples 1 to 3 and Comparative Examples 1 to 5 was detected by the testing method:

[0120] 1) Instruments and reagents:

[0121] (1) SHIMADZU LC-20A2300 high performance liquid chromatograph-diode array detector;

[0122] (2) Desktop ultrasonic cleaner;

[0123] (3) BT125D electronic balance (Sartorial);

[0124] (4) High-speed refrigerated centrifuge;

[0125] (5)Refrigerator;

[0126] (6) Methanol (Merek chromatographic grade);

[0127] (7) Acetonitrile (Fisher chromatographic grade);

[0128] (8) Deionized water;

[0129] 10% methanol extractant: measure 100 mL of methanol and 900 mL of deionized water, mix well and set aside.

[0130] 2) Standard substances

[0131] Furfural (99%, Sisma);

[0132] Standard stock solution: accurately weigh 0.02021 g into a 100 mL brown volumetric flask, dissolve in 10% methanol and dilute to the mark. The concentration of the obtained standard stock solution is 200 mg / L.

[0133] Standard working solution: Pipette 0.125, 0.500, 2.00, 4.00, 8.00, and 12.5 mL of furfural standard stock solution into a 50 mL brown volumetric flask, dilute to volume with 10% methanol to obtain a series of standard working solutions with concentrations of 0.50, 2.0, 8.0, 16.0, 32, and 50 mg / L, respectively.

[0134] 3) Sample pretreatment

[0135] Weigh 5-10g (accurate to 0.0001g) of sample into a 100mL volumetric flask, add 80mL of 10% methanol extractant, perform ultrasonic-assisted extraction for 10min, cool to room temperature, make up to volume with 10% methanol extractant, filter with a 0.45μm organic filter membrane, and measure the filtrate on the machine.

[0136] 4) Chromatographic conditions

[0137] Chromatographic column: Diamonsil C18 (4.6 mm × 250 mm, 5 μm); column temperature: 35 ° C; injection volume: 20 μL; detection wavelength: 285 nm; flow rate: 1.0 ml / min; mobile phase: methanol / water (16:84, volume ratio),

[0138] The obtained results are shown in Table 1;

[0139] Table 1

[0140]

[0141] As can be seen from Table 1, the content of furfural, a bitter substance, in the dark soy sauce prepared by the technical solution of the present invention is low, which is reduced by more than 94% compared with Comparative Example 1. That is, the technical solution provided by the present invention can significantly reduce the content of bitter substances in the dark soy sauce, reduce the bitter taste of the dark soy sauce, and effectively improve the taste of the product.

[0142] Effect Example 2

[0143] Effect Example of the Invention The aroma components of the dark soy sauce prepared in Example 1, Comparative Example 1, Comparative Example 4 and Comparative Example 5 were investigated, and the testing method was:

[0144] 1) Reagents

[0145] (1) Dimethyl-triheptanone;

[0146] (2) Methanol (chromatographic grade);

[0147] 2) Instruments and equipment

[0148] (1) Gas chromatograph-mass spectrometer model 6890-5973;

[0149] (2) DB-WAX capillary column (30m*0.25mm*0.25um);

[0150] (3) Model 85-2 digital display temperature-controlled magnetic stirrer;

[0151] (4) 57330-U solid-phase microextraction (SPME) manual injection handle;

[0152] (5) 100um polydimethylsiloxane (PDMS) extraction fiber;

[0153] 3) Inspection method

[0154] Sample pretreatment: Take an 8cm rotor and put it into a dried solid phase microextraction bottle, add 20μL of 166mL dimethyl triheptanone methanol and 8mL soy sauce sample, put it into a water bath at 60℃ for 10min, use a 100um PDMS extraction needle at a speed of 1100r / min and 60℃ for 45min, desorb for 5min, when the extraction head is used for the first time, age it at the specified temperature until there is no impurity peak, and burn the needle for 10min between two samples;

[0155] GC-MS conditions: DB-WAXUI capillary column (30m*025mm*0.25μm). Inlet temperature 230℃, non-split mode. Carrier gas is high-purity helium (He), flow rate 1mL / min. Temperature program: starting temperature 40℃, hold for 2min, increase to 180℃ at 8℃ / min, hold for 0min, then increase to 220℃ at 3℃ / min, hold for 7min, and run for 5min. The ion source is electron ionization (ED source), ion source temperature 230℃, electron energy 70eV, connection port temperature 250℃; mass scanning range 33~330amu;

[0156] Qualitative and quantitative methods: The unknown compounds were searched by sequential retrieval of the 02.L mass spectrometry data of the National Institute of Standards and Technology (NIST) and comparison with standard spectra, and the content of the substance was calculated using the concentration of the internal standard (dimethyltrione-methanol) and the peak area of ​​each substance detected.

[0157] The test results are shown in Table 2;

[0158] Table 2

[0159]

[0160]

[0161] As can be seen from Table 2, the dark soy sauce prepared by the preparation method provided by the present invention is rich in aroma substances, and 29 aroma components are detected, which is 12 more than the 17 in the control example, an increase of 70%, which significantly improves the richness of the aroma; in addition, the content of volatile compounds is increased from 55.7ppb to 109.4ppb, an increase of more than 90%, that is, the dark soy sauce prepared by the preparation method provided by the present invention significantly improves the richness of the product aroma.

[0162] Effect Example 3

[0163] Effect Example of the Invention The flavor amino acid content of the dark soy sauce prepared in Example 1, Comparative Example 1, Comparative Example 4 and Comparative Example 5 was investigated, and the testing method was:

[0164] 1) Materials and instruments

[0165] (1) Amino acid standards (2.5 μmol / mL) from Sigma, USA;

[0166] (2) Buffers B1, B2, B3, B4, and B5 (chromatographic grade) were purchased from Hitachi, Japan;

[0167] (3) Hitachi L8900 fully automatic amino acid analyzer; chromatographic column: Hitachi sodium ion crosslinking resin 4.6mm*60mm;

[0168] 2) Test methods

[0169] (1) Sample processing

[0170] Weigh 2.00mL of soy sauce sample, add 1.00mL of 15% sulfosalicylic acid to precipitate protein, dilute to 25.00mL volumetric flask with water, shake well, take a portion and place in a centrifuge tube, centrifuge at 10000r / min for 10min. Take 1mL and dilute to 25.00mL volumetric flask, add water to dilute to volume, shake well, take a certain amount and filter for sample injection.

[0171] (2) Plotting of amino acid standard curve

[0172] Use standard samples to prepare a series of standard solutions of different concentrations, filter press and test them, and calculate and draw the standard curve.

[0173] (3) Chromatographic detection conditions

[0174] Chromatographic column: Hitachi sodium ion cross-linking resin 4.6mm*60mm; flow rate: 0.40mL / min (pump1), 0.35mL / min (pump2); detection wavelength: 570nm and 440nm; column temperature: 57℃; injection volume: 20μL; mobile phase was eluted according to gradient; analysis time 35min.

[0175] The test results are shown in Table 3;

[0176] Table 3

[0177]

[0178]

[0179] As can be seen from Table 3, by adding edible fungus salt solution before sun-drying, the content of flavor amino acids in the prepared dark soy sauce is significantly increased, and the content of flavor amino acids in Example 1 is increased by 39% compared with that in Comparative Example 1; that is, the obtained product is sweeter and can further mask the bitter taste, thereby improving the taste quality of the product.

[0180] Effect Example 4

[0181] Effect Example of the Invention The evaluation results of the dark soy sauce prepared in Example 1 and Comparative Example 1 were explored, and the evaluation process was as follows:

[0182] 1) Evaluation method:

[0183] (1) Equipment preparation: sensory spoon, white porcelain plate, measuring cup (20 mL);

[0184] (2) Specific operations:

[0185] Aroma: Use a measuring cup to take 10 mL of the sample and place it in a clean and dry white porcelain dish. Shake it gently and put your nose close to the white porcelain dish to smell its aroma.

[0186] Taste: Use a dry and clean sensory spoon to take an appropriate amount of soy sauce and put it in your mouth at the tip of your tongue. Gently purse your lips to let the taste spread from the tip of your tongue to the surface and root of your tongue. Feel the fresh, salty, sour, sweet, bitter and other flavors of the product. After evaluating each sample, rinse your mouth thoroughly with warm water before evaluating the next sample.

[0187] 2) Standard: Two samples were grouped together and 15 specially trained evaluators conducted comparative evaluations. The samples were ranked based on four dimensions: aroma intensity, aroma preference, bitterness, and taste preference.

[0188] The results obtained are shown in Table 4;

[0189] Table 4

[0190] Evaluation Dimensions Total number of assessors Example 1 / Number of people Comparison ratio 1 / number of people Preferred ratio / % Aroma intensity 15 12 3 80 Aroma preference 15 12 3 80 Bitter taste 15 11 4 73 Taste preference 15 11 4 73

[0191] As can be seen from Table 4, the dark soy sauce prepared by the technical solution of the present invention has improved flavor and significantly reduced bitterness, with an evaluation preference ratio of more than 70%; and an evaluation preference ratio of 80% for aroma intensity and preference.

[0192] Effect Example 5

[0193] Effect Example of the Invention The indicators of the dark soy sauce prepared in Examples 1 to 3 and Comparative Example 3 were investigated, including the following parts:

[0194] 1. Amino acid nitrogen: Test according to GB5009.235-2016 "National Food Safety Standard Determination of Amino Acid Nitrogen in Food";

[0195] 2. Total nitrogen and soluble salt-free solids: Tested in accordance with GB18186-2000 brewed soy sauce;

[0196] 3. Total acid: Test according to GB12456-2021 "National Food Safety Standard Determination of Total Acid in Food";

[0197] 4. Absorbance: Test according to the method specified in Appendix A of GB1886.64-2015 "National Food Safety Standard Food Additive Caramel Color";

[0198] 5. Viscosity: measured using a Brookfield DV-II viscometer, with the following conditions: No. 2 rotor, 100 rpm, 25°C;

[0199] The test results are shown in Table 5;

[0200] Table 5

[0201]

[0202] It can be seen from Table 5 that the dark soy sauce prepared by the preparation method of the present invention has a higher content of amino acid nitrogen and excellent comprehensive performance; while the color rate of Comparative Example 3 is lower and the coloring effect is poor, and it is not suitable for use as dark soy sauce.

[0203] Finally, it should be noted that the above embodiments are intended to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing dark soy sauce, characterized in that: The preparation method comprises the following steps: (1) Take the sugar source and cook until the absorbance is A 610 After the concentration is 0.003-0.006, add water and stir evenly, then concentrate under reduced pressure to obtain concentrated sugar color; (2) uniformly mixing the concentrated sugar color and the clarified soy sauce to obtain pre-sun soy sauce A; (3) adding the edible fungus salt solution to the pre-sun-dried soy sauce A to obtain the pre-sun-dried soy sauce B; (4) Sun-drying the pre-sun soy sauce B to obtain a sun-dried semi-finished product, then filtering the sun-dried semi-finished product and blending it to obtain dark soy sauce.

2. The method for preparing dark soy sauce according to claim 1, characterized in that: In the step (1), the cooking pressure is 0.03-0.09 MPa and the cooking temperature is 132-152° C. And / or, water is added and stirred evenly, and the mass ratio of the added water to the sugar source is (0.1-0.15):

1.

3. The method for preparing dark soy sauce according to claim 1, characterized in that: In the step (1), the pressure of the reduced pressure concentration is (-75) to (-95) kPa, and the temperature of the reduced pressure concentration is 90 to 100° C.; And / or, the mass of water volatilized by reduced pressure concentration accounts for 5-10% of the mass of the sugar source.

4. The method for preparing dark soy sauce according to claim 1, characterized in that: In the step (2), the mass ratio of concentrated sugar color to clarified soy sauce is (14-24):(76-86).

5. The method for preparing dark soy sauce according to claim 1, characterized in that: The preparation method of the edible fungus salt water solution is as follows: adding the cleaned edible fungi into salt water and boiling for 3 to 5 minutes to obtain the edible fungus salt water solution.

6. The method for preparing dark soy sauce according to claim 5, characterized in that: The mass percentage of salt in the saline solution is 23-25%; And / or, the mass ratio of the edible fungi to the saline solution is (30-40):(60-70).

7. The method for preparing dark soy sauce according to claim 5, characterized in that: In the step (3), the mass ratio of the edible fungi to the pre-sun-dried soy sauce A is (1-1.5):(98.5-99).

8. The method for preparing dark soy sauce according to claim 1, characterized in that: In the step (4), the drying time is 100 to 150 days; And / or, the mass of the semi-finished product after sun-drying is 85-90% of the mass of the soy sauce B before sun-drying.

9. The method for preparing dark soy sauce according to claim 1, characterized in that: The preparation method of the clarified soy sauce comprises the following steps: mixing crushed and steamed soybeans with roasted and crushed wheat to make koji, and fermenting the mixture; obtaining a soy sauce stock solution after the fermentation is completed; then heating the soy sauce stock solution and centrifuging the solution; and collecting a supernatant to obtain the clarified soy sauce.

10. A dark soy sauce, characterized in that: The method is described in any one of claims 1 to 9.

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