Preparation method of konjak vinegar

Abstract

The application discloses a preparation method of konjak vinegar, which comprises the following steps: firstly, konjak powder is subjected to enzymolysis and saccharification by using a glucanase; then, alcohol fermentation and acetic acid fermentation are sequentially performed; meanwhile, purified konjak powder is supplemented before the acetic acid fermentation to perform deep fermentation; finally, konjak vinegar is prepared by using a fructose-glucose syrup to adjust the flavor. The process disclosed by the application has higher production efficiency, the prepared product has low trimethylamine acetate content and high safety, and compared with traditional fruit vinegar, the prepared konjak vinegar has slightly thick taste and contains more functional components such as mannose oligosaccharide, has high acceptance and can play a certain disease prevention effect, and has wide application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of konjac food processing, and particularly relates to a preparation method of konjac vinegar. BACKGROUND

[0002] Konjac is a perennial herbaceous plant of Araceae, and has a long planting history in the southwest and central and western regions of China. Konjac tofu and konjac vermicelli can be prepared from konjac tubers. With the development of technology, konjac powder is extracted from konjac tubers, which greatly improves the economic value of konjac. The main component of konjac powder is konjac glucomannan, which is a polysaccharide composed of D-pyran mannose and D-pyran glucose connected by a β-1, 4-glycosidic chain, and the molar ratio of D-glucose to D-mannose is 1:1.6-1:1.8. Konjac glucomannan is soluble in water, has high hydrophilicity, gelling property and film-forming property, and can be used to make heat-reversible gel products represented by konjac jelly. In addition, konjac glucomannan can form a film on the surface of the intestine, balance the absorption of sugars and oils in the intestine, and also can reduce the absorption and utilization of sugars, lipids and other substances in the intestine by wrapping or adsorbing, and the short-chain fatty acids produced by the decomposition of konjac glucomannan by bacteria can promote intestinal peristalsis.

[0003] With the improvement of living standards, people's awareness of green food and organic food is constantly improving, and the reasonable and healthy dietary concept of urban people is gradually established. Konjac and konjac powder prepared food has low fat, lubricates the intestines, delays or even prevents the increase of cholesterol and monosaccharides, and therefore is loved by consumers. In the competitive fruit juice market, fruit vinegar beverages have opened up a new trend of health in the fruit juice market this summer, and their market advantages will become increasingly apparent. Among them, 30%-40% of the vinegar on the market is fruit vinegar, which shows that the fruit vinegar market in China has great development potential. Therefore, konjac powder is considered to be used to prepare konjac vinegar. However, konjac contains anti-nutritional substances such as alkaloids and tannins, as well as odor substances such as trimethylamine and camphor, which seriously affect the taste of konjac food. At the same time, when konjac powder is used to ferment konjac vinegar, trimethylamine in konjac will react with H + reaction, generating trimethylamine acetate [(CH3)3NH] + (CH3COO -), acetic acid trimethylamine in the process of brewing vinegar can be further converted into toxic quaternary ammonium salt and other amine substances, trimethylamine itself can also react with epoxide in vinegar to generate quaternary ammonium salt. Studies have shown that quaternary ammonium salt compound residues can harm animal health, and residual quaternary ammonium salt disinfectants in food are harmful to human nasal epithelial cells, can cause and aggravate rhinitis; at the same time, it also damages the inner ear, eyes, respiratory system and digestive system; in addition, residual quaternary ammonium salt compounds can lead to bacterial drug resistance (including pathogenic bacteria), and quaternary ammonium salt compounds in food can accelerate the drug resistance of intestinal bacteria, which cannot be ignored for human health. Therefore, it is very important to limit the content of quaternary ammonium salt substances, and to reduce the content of trimethylamine in konjac, so as to reduce the content of quaternary ammonium salt and amine substances in konjac vinegar. It is an urgent problem to be solved in the field of konjac vinegar preparation at present.

[0004] Chinese patent CN 105199939 B discloses a preparation method of low-acetic acid trimethylamine rich konjac high F-value oligopeptide vinegar, which first uses black aspergillus culture solution and aspergillus oryzae lysis to treat konjac powder to prepare konjac glucomannan-konjac high F-value oligopeptide, and then adds other raw materials to carry out saccharification, alcohol fermentation and acetic acid fermentation to prepare konjac vinegar. The main method is to use high temperature treatment to make trimethylamine in konjac powder volatilize and escape to reduce the content of acetic acid trimethylamine. Chinese patent CN103805493A discloses a preparation method of konjac oligomannose sweet potato vinegar, which mainly uses fermentation of lactobacillus, saccharomyces cerevisiae and aroma yeast to reduce the content of acetic acid trimethylamine. However, the above-mentioned scheme uses konjac powder or directly uses konjac to prepare fermentation raw materials, which itself contains a large amount of trimethylamine, and the subsequent operation can only reduce the content of part of trimethylamine, and cannot completely remove it. At the same time, when konjac powder or konjac is directly fermented, the types and content of impurities are large, which is not completely controllable in the whole preparation process of konjac vinegar, and still has great safety hidden danger. SUMMARY

[0005] In view of the above technical problems, the present application provides a preparation method of konjac vinegar, which uses purified konjac powder to carry out saccharification and alcohol fermentation first, and then carries out acetic acid fermentation after adjusting the alcohol concentration to prepare a konjac vinegar food with low content of trimethylamine.

[0006] In order to achieve the above-mentioned purpose, the present application provides a preparation method of konjac vinegar, which comprises the following steps:

[0007] (1) adding water in the saccharification pot, adding konjac powder while stirring, adding glucanase after heating to 45-50℃, constant temperature stirring for 10-15 min, and then filtering twice to obtain filtrate;

[0008] (2) the filtrate is heated to boiling while stirring, and after being kept for 50-80 min, homogenized, filtered, and cooled to obtain a first fermentation stock solution;

[0009] (3) the above-mentioned fermentation yeast is added to the first fermentation stock solution, and after being fermented for 7-15 d, a fermentation liquor is obtained;

[0010] (4) the fermentation liquor obtained in step (3) is sterilized and distilled to obtain a konjac-alcohol solution;

[0011] (5) the alcohol concentration in the konjac-alcohol solution obtained in step (4) is adjusted, then konjac powder is added, and after being stirred, filtered, and homogenized, a second fermentation stock solution is obtained;

[0012] (6) acetic acid bacteria are inoculated into the second fermentation stock solution, and after being fermented at 30-33 ℃ for 7-10 d, a konjac vinegar fermentation liquor is obtained;

[0013] (7) the acidity and sweetness of the konjac vinegar fermentation liquor are determined, fruit glucose syrup is added to adjust the flavor, and after being homogenized and sterilized, konjac vinegar is obtained.

[0014] Preferably, the mass ratio of water to konjac powder in step (1) is 40-42:1, and the amount of glucanase is 0.03%-0.07% of the mass of water.

[0015] Preferably, the secondary filtration in step (1) is coarse filtration with an 80-mesh filter screen and fine filtration with a 100-mesh filter screen.

[0016] Preferably, the fermentation condition in step (3) is that the temperature is kept at 20-25 ℃, and 5% of the volume of the fermentation liquor is oxygen.

[0017] Preferably, the amount of the above-mentioned fermentation yeast in step (3) is 0.3%-0.5% of the first fermentation stock solution.

[0018] Preferably, the alcohol concentration in step (5) is 10%-16%, and the amount of konjac powder is 0.8%-1.2% of the mass of the second fermentation stock solution.

[0019] Preferably, the inoculation amount of acetic acid bacteria in step (6) is 3%-5% of the second fermentation stock solution; the acetic acid bacteria are activated bacteria liquid, and the mass ratio of bacteria to sterile water in the bacteria liquid is 1:8-10.

[0020] Preferably, the konjac powder is purified konjac powder with a glucomannan content of 80%-90% and a particle size of 40-120 mesh, and more than 90% of the particles have a particle size of 40-120 mesh.

[0021] The beneficial effects of the present application are as follows:

[0022] 1. In view of the problem that konjac or konjac powder contains a high concentration of trimethylamine and other harmful substances or impurities, resulting in a high content of trimethylamine acetate in the produced konjac vinegar, the purified konjac powder is used as the raw material for konjac vinegar production fermentation. The purified konjac powder is a product after multiple purification of edible alcohol, and the content of trimethylamine is low and there is no obvious odor. At the same time, the solution containing purified konjac powder is heated and boiled during the saccharification process, and is maintained for 50-80 min, so that the small amount of trimethylamine contained in the purified konjac powder is further volatilized and escaped, so as to reduce the content of trimethylamine acetate or even eliminate it. The application does not use additional chemical reagents to remove trimethylamine, which ensures the safety of the preparation process of konjac vinegar.

[0023] 2. In the application, the purified konjac powder is first decomposed into oligosaccharides and monosaccharides by glucanase, providing a large amount of sugar source for subsequent fermentation, then alcohol fermentation and acetic acid fermentation are carried out in turn, improving the utilization rate of purified konjac powder, and without introducing other raw materials during the fermentation process, reducing the influence of impurities and the uncertainty of fermentation, and reducing the production cost.

[0024] 3. Compared with the traditional fermentation process, the application concentrates the solution before acetic acid fermentation, which not only improves the substrate concentration and enhances the acetic acid fermentation efficiency, but also has a sterilization effect and removes the residual fermentation bacteria. At the same time, the use of purified konjac powder as the reaction substrate can delay the fermentation speed and improve the fermentation degree. Because konjac powder will hydrolyze when it meets acid, the fermentation speed of the fermentation system gradually recovers with the gradual progress of the reaction, until the reaction is completed.

[0025] 4. The konjac vinegar prepared by the application contains a large amount of functional ingredients such as mannose oligosaccharides, which can improve the human body's immunity and prevent diseases caused by lack of mannose glycosylation enzymes to a certain extent. At the same time, the konjac vinegar prepared by the application is slightly thick and has a lighter sour taste, which is more easily accepted by consumers, so it has important commercial value. DETAILED DESCRIPTION

[0026] The technical solutions of the application will be further explained and described in combination with specific embodiments. It should be noted that the following embodiments are only preferred embodiments of the application, and should not be understood as limiting the application. The protection scope of the application should be based on the content recited in the claims. The modifications and replacements of the technical solutions of the application made by those skilled in the art without creative labor fall within the protection scope of the application.

[0027] Konjac flour: the purified konjac flour with 80%-90% of glucomannan content and more than 90% of particles with particle size of 40-120 mesh is produced by using alcohol wet method, and the purified konjac flour is purified twice by 30% edible alcohol and once by 50% edible alcohol in the purification process, and the total purification time is more than 2h.

[0028] Example 1

[0029] (1) 40 parts of water was added into a saccharification pot, and local shearing was carried out at a rotation speed of 15000 rpm / min, and the purified konjac flour with a mesh size of 120 was poured into the saccharification pot, and the temperature was increased to 45℃ while stirring, then glucomannanase (0.03% of the mass of water) was added, and constant temperature stirring was carried out for 10 min to obtain a feed liquid; the feed liquid was coarsely filtered through an 80 mesh filter screen, and then finely filtered through a 100 mesh filter screen to obtain a filtrate;

[0030] (2) the filtrate obtained in step (1) was heated to boiling while stirring at 450 rpm / min, and kept for 50 min, then passed through a high-pressure homogenizer, and then finely filtered through a 120 mesh filter screen, and then the liquid temperature was cooled to 20℃ through a heat exchanger to obtain a first fermentation stock solution;

[0031] (3) the first fermentation stock solution was transferred to an alcohol fermentation tank, and 0.3% of the above fermentation yeast was added, the temperature was kept at 20-25℃, and 5% of the volume of the first fermentation stock solution was introduced into oxygen, and the fermentation was carried out for 7 days to obtain a fermentation liquor;

[0032] (4) the fermentation liquor obtained in step (3) was sterilized by UHT sterilization method, and then distilled by retort to obtain a konjac-alcohol solution;

[0033] (5) the konjac-alcohol solution obtained in step (4) was adjusted to an alcohol concentration of 10% by using a sterilized 0.1%-0.2% purified konjac flour water solution, and 0.8% of the total mass of the solution was added, and the rotation speed was kept at 1500 rpm / min for local high-speed shearing, and then filtered through a 100 mesh filter screen, and the filtrate was reserved, and then passed through a high-pressure homogenizer to obtain a second fermentation stock solution;

[0034] (6) the second fermentation stock solution was transferred to an acetic acid fermentation tank, and 4% of activated acetic acid bacteria liquid (the mass ratio of bacteria to sterile water in the bacteria liquid was 1:9) was added, and the temperature was kept at 30℃ for 7 days of fermentation to obtain a konjac vinegar fermentation liquor; wherein 3% of the mass of the fermentation liquor was introduced into oxygen every 24h during the fermentation;

[0035] (7) the acidity and sweetness of the konjac vinegar fermentation liquor were measured, and the flavor was adjusted by adding an appropriate amount of fructose syrup, and then homogenized and sterilized to obtain konjac vinegar.

[0036] Example 2

[0037] (1) In the saccharifying pot, 42 parts of water was added, and local shearing was carried out at a rotation speed of 18000 rpm / min, and purified konjac powder passing through a 120-mesh sieve was poured in, and the temperature was raised to 50°C while stirring, then glucanase (0.05% of the mass of water) was added, and constant temperature stirring was carried out for 10 min to obtain a feed liquid; the feed liquid was coarsely filtered through an 80-mesh filter screen, and then finely filtered through a 100-mesh filter screen to obtain a filtrate;

[0038] (2) The filtrate obtained in step (1) was heated to boiling while stirring at 450 rpm / min, and after being kept for 80 min, it was passed through a high-pressure homogenizer, and then finely filtered through a 120-mesh filter screen, and then the liquid temperature was cooled to 26°C through a heat exchanger to obtain a first fermentation stock solution;

[0039] (3) The first fermentation stock solution was transferred to an alcohol fermentation tank, and 0.5% of the above-mentioned fermentation yeast was added, the temperature was kept at 20-25°C, and 5% of the volume of the first fermentation stock solution was introduced as oxygen, and the fermentation was carried out for 10 days to obtain a fermentation liquor;

[0040] (4) The fermentation liquor obtained in step (3) was sterilized by UHT sterilization method, and then distilled by retort to obtain a konjac-alcohol solution;

[0041] (5) The konjac-alcohol solution obtained in step (4) was adjusted to an alcohol concentration of 13% with a sterilized 0.1%-0.2% purified konjac powder water solution, and 1.0% of the total mass of the solution was added as purified konjac powder, and local high-speed shearing was carried out at a rotation speed of 18000 rpm / min, and then filtered through a 100-mesh filter screen to retain the filtrate, and then passed through a high-pressure homogenizer to obtain a second fermentation stock solution;

[0042] (6) The second fermentation stock solution was transferred to an acetic acid fermentation tank, and 4% of activated acetic acid bacteria liquid (the mass ratio of bacteria to sterile water in the bacterial liquid was 1:9) was added, and the temperature was kept at 30°C for 10 days of fermentation to obtain a konjac vinegar fermentation liquor;

[0043] (7) The acidity and sweetness of the konjac vinegar fermentation liquor were determined, and an appropriate amount of high fructose corn syrup was added to adjust the flavor, and then homogenized and sterilized to obtain konjac vinegar.

[0044] Example 3

[0045] The method and steps were the same as in Example 1, except that the amount of glucanase in step (1) was changed to 0.07% of the mass of water; and in step (5), the alcohol concentration in the konjac-alcohol solution was adjusted to 16%, and 1.00% of the total mass of the solution was added as purified konjac powder, and the prepared konjac vinegar was obtained.

[0046] Comparative Example 1

[0047] The method and steps were the same as in Example 1, except that the adjustment of the alcohol concentration in step (5) was omitted, and the prepared konjac vinegar was obtained.

[0048] Example 2 Influence of glucanase on quality of konjac vinegar

[0049] The method and procedure are the same as in Example 1, except that no glucanase is added in step (1) to prepare konjac vinegar.

[0050] Example 3 Influence of glucanase dosage on quality of konjac vinegar

[0051] The method and procedure are the same as in Example 1, except that the dosage of glucanase in step (1) is changed from 0.03% of the mass of water to 0.1% of the mass of water to prepare konjac vinegar.

[0052] Example 4 Influence of quality of konjac powder on quality of konjac vinegar

[0053] The method and procedure are the same as in Example 1, except that the purified konjac powder in step (1) is changed to konjac powder to prepare konjac vinegar.

[0054] Example 5 Influence of filtration on quality of konjac vinegar

[0055] The method and procedure are the same as in Example 1, except that the filtration steps in steps (1) and (2) are deleted.

[0056] Results: The konjac vinegar prepared in the above examples and comparative examples was subjected to sensory index and nutritional detection, and the results are shown in the following table:

[0057]

Claims

1. A method of preparing konjac vinegar, characterized by: The method comprises the following steps: (1) adding konjac powder into water while stirring, adding glucanase after the temperature is raised to 45-50 DEG C, stirring at constant temperature for 10-15 min, and obtaining filtrate after twice filtration; (2) raising the temperature of the filtrate to boiling while stirring, keeping for 50-80 min, and obtaining first fermentation stock solution after homogenization, filtration and cooling; (3) adding the above-mentioned fermentation yeast into the first fermentation stock solution, and obtaining fermentation liquor after fermentation for 7-15 d; (4) sterilizing and distilling the fermentation liquor obtained in step (4) to obtain konjac-alcohol solution; (5) adjusting the alcohol concentration of the konjac-alcohol solution obtained in step (4), then adding konjac powder, stirring, filtering and homogenizing to obtain second fermentation stock solution; (6) inoculating acetic acid bacteria into the second fermentation stock solution, and obtaining konjac vinegar fermentation liquor after fermentation for 7-10 d at 30-33 DEG C; (7) measuring the acidity and sweetness of the konjac vinegar fermentation liquor, adding flavor adjusting agent, homogenizing and sterilizing to obtain konjac vinegar. The alcohol concentration in step (5) is 10%-16%, and the amount of konjac powder is 0.8%-1.2% of the mass of the second fermentation stock solution. The konjac powder is purified konjac powder with a glucosan content of 80%-90% and a particle size of 40-120 mesh, and the particles with a particle size of 40-120 mesh account for more than 90%.

2. The method of claim 1, wherein the konjak vinegar is prepared by the steps of: The mass ratio of water to konjac powder in step (1) is 40-42:1, and the amount of glucanase is 0.03%-0.07% of the mass of water. ​ 3. The method for preparing konjac vinegar according to claim 1, characterized in that: The twice filtration in step (1) is coarse filtration with a 80 mesh filter and fine filtration with a 100 mesh filter.

4. The method of claim 1, wherein the konjak vinegar is prepared by the steps of: The fermentation conditions in step (3) are keeping the temperature at 20-25 DEG C and introducing oxygen with a volume of 5% of the fermentation liquor for fermentation. ​ 5. The method of claim 1, wherein the konjak vinegar is prepared by the steps of: The amount of the above-mentioned fermentation yeast in step (3) is 0.3%-0.5% of the first fermentation stock solution. ​ 6. The method for preparing konjac vinegar according to claim 1, characterized in that: The inoculation amount of acetic acid bacteria in step (6) is 3%-5% of the second fermentation stock solution; the acetic acid bacteria is activated bacteria liquid, and the mass ratio of bacteria to sterile water in the bacteria liquid is 1:8-10.

7. The method for preparing konjac vinegar according to claim 1, characterized in that: The flavor adjusting agent in step (7) is fructose syrup.

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