Method for preserving konjac dried slice for preparing konjac powder

Abstract

The application provides a preservation method for preparing konjac powder from konjac dried slices, and belongs to the technical field of konjac processing. The method sprays an ethanol aqueous solution on the konjac dried slices, the mass of the ethanol aqueous solution accounts for 5-10% of the mass of the konjac dried slices, covers the konjac dried slices with a plastic film, and then places the konjac dried slices for 10-14 hours, and then removes the plastic film for storage. Compared with the konjac powder prepared from the fresh and dried konjac dried slices directly stored without any treatment or the konjac powder prepared from the konjac dried slices soaked and stored by using an ethanol solution, the apparent viscosity of the konjac powder prepared by the method is significantly improved, the flour yield is obviously improved, and the storage stability of the konjac dried slices is better.

Description

Technical Field

[0001] This invention belongs to the field of food processing technology, and particularly relates to the field of konjac processing technology, specifically to a method for preserving dried konjac slices used in the preparation of konjac powder. Background Technology

[0002] Konjac is a complex plant organism with a rich carbohydrate content, low in calories, and higher in protein than potatoes and sweet potatoes. It is also rich in trace elements, including vitamins A and B, and is particularly rich in glucomannan, which has effects such as weight loss, lowering blood pressure, lowering blood sugar, and promoting bowel movements. Therefore, konjac is usually processed into konjac flour, which is then used to make natural food additives, pharmaceutical additives, and health products. Furthermore, konjac flour has high expansion and adhesion, making it widely used in the pharmaceutical, chemical, and textile industries. It can be used to make adhesives, emulsifiers, preservatives, moisture retainers, insecticides, paper strengthening agents, and hemostatic sponges. Konjac also has special applications in environmental protection. Fully biodegradable films, soluble and edible films, interior and exterior wall coatings, and preservatives produced from konjac are of great significance in eliminating white pollution and other environmental pollution.

[0003] The processing of konjac flour generally involves washing, slicing, and color-protecting fresh konjac, followed by heating and drying to obtain dried konjac flakes. These flakes are then used as raw material for crushing, grinding, and impurity separation to obtain konjac flour. Because fresh konjac is harvested within a very concentrated period, it is often processed into dried konjac flakes at the production site to reduce its moisture content to below 15%. These flakes are then sold to konjac flour factories for further grinding, enabling year-round processing. Therefore, dried konjac flakes often have a shelf life of one year or even several years. However, during long-term storage, the viscosity of the konjac flour made from dried konjac flakes often decreases significantly, and the flour yield drops considerably. Currently, there is no better method to solve these technical problems.

[0004] Publication No. 113229471A discloses a method for processing color-protecting, sulfur-free dried konjac slices. The method involves washing and peeling fresh konjac, then slicing it into slices. The container is then opened, and the slices are placed in 40%-50% edible alcohol for a period of time. The soaked slices are then removed and placed in a dehydrator. The dehydration process is performed quickly. The slices are then removed from the dehydrator and placed in a vacuum dryer. This method prevents oxidation and discoloration of the konjac slices by soaking them in edible alcohol, and avoids the introduction of sulfur dioxide. It does not address the issue of preserving the dried slices to improve the viscosity and yield of the resulting konjac flour. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method for preserving dried konjac slices used in the preparation of konjac flour. This method is extremely simple, low-cost, provides better storage stability of dried slices, and effectively improves the viscosity and powder yield when preparing konjac flour from dried slices.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for preserving dried konjac slices used in the preparation of konjac flour includes the following steps:

[0008] Spray an ethanol-water solution onto the dried konjac slices, wherein the ethanol-water solution accounts for 5% to 10% of the mass of the dried konjac slices. Cover with plastic film and leave for 10 to 14 hours, then remove the plastic film for storage.

[0009] Preferably, the konjac chips are freshly dried konjac chips.

[0010] Preferably, the storage environment has a temperature of 15–20°C and a humidity of 65%–70%.

[0011] Preferably, the volume percentage of the ethanol aqueous solution is 75% to 95%.

[0012] Preferably, the volume percentage of the ethanol-water solution is 75-85%, and the mass of the ethanol-water solution accounts for 8% to 10% of the mass of the dried konjac slices.

[0013] Preferably, an ethanol aqueous solution is sprayed onto the dried konjac slices, covered with plastic film, and left for 12 hours.

[0014] Preferably, an ethanol-water solution is sprayed using a spraying device with an atomizing nozzle.

[0015] To address the problems in the background technology, the inventors creatively used a high-concentration alcohol spray method to treat konjac dried slices, followed by covering them with a plastic film. Research found that konjac powder made from either freshly treated konjac slices or konjac slices that had been treated and stored for a period of time exhibited significantly higher apparent viscosity compared to konjac powder made from untreated konjac slices, while also increasing the powder yield. Here, the volume percentage of the ethanol-water solution is preferably 75%–95%, more preferably 75%–85%; the mass of the ethanol-water solution accounts for 5%–10% of the mass of the konjac dried slices, more preferably 8%–10%.

[0016] The preparation process and method for the konjac slices and konjac powder are the same as those in the prior art, and those skilled in the art can choose the appropriate method according to specific needs. The type of konjac is not particularly limited, such as common varieties like flower konjac, white konjac, and sweet konjac.

[0017] The method of this invention does not require changing the original preparation process of konjac slices and konjac powder. It only requires processing fresh konjac slices. The method is extremely simple, has very low processing cost, and is easy to operate. After being processed by the method of this invention, the longer the storage time of the konjac slices, the more significant the increase in the apparent viscosity of the prepared konjac powder compared to the apparent viscosity of konjac powder prepared from untreated konjac slices, which can effectively improve the storage stability of konjac slices. Detailed Implementation

[0018] The following description, in conjunction with embodiments, clearly and completely describes the technical solutions of this application, so that those skilled in the art can fully understand this application. Obviously, the described embodiments are merely some preferred embodiments of this application, and not all embodiments. Any equivalent modifications or substitutions made by those skilled in the art to the following embodiments without creative effort are within the protection scope of this application.

[0019] Examples 1-9

[0020] A method for improving the viscosity and powder yield when preparing konjac flour from dried konjac slices includes the following steps:

[0021] Spray a 75%–95% (volume percentage, using a sprayer with atomizing nozzles) ethanol aqueous solution onto freshly dried konjac slices (moisture content 13%), cover with plastic film and leave for 12 hours, then store in an environment of 15–20℃ and 65%–70% humidity; the ethanol aqueous solution accounts for 5%–10% of the mass of the dried konjac slices.

[0022] Comparative Examples 1-3

[0023] The method for processing dried konjac slices includes the following steps: taking the same freshly dried konjac slices as in the example, soaking them in a 75% to 95% (v / v) ethanol aqueous solution for 12 hours, and then storing them in an environment with a temperature of 15 to 20°C and a humidity of 65% to 70%.

[0024] Comparative Example 4

[0025] The processing method for dried konjac slices includes the following steps: Take dried konjac slices that have been stored for half a year and soak them in an 85% (v / v) ethanol aqueous solution for 12 hours.

[0026] Comparative Example 5

[0027] The processing method for dried konjac slices includes the following steps: soak dried konjac slices that have been stored for one year in an 85% (v / v) ethanol aqueous solution for 12 hours.

[0028] Comparative Example 6

[0029] The processing method for dried konjac slices includes the following steps: spraying dried konjac slices stored for half a year with an 85% (volume percentage) ethanol aqueous solution accounting for 8% of the weight of the dried slices, covering them with plastic film and leaving them for 12 hours.

[0030] Comparative Example 7

[0031] The processing method for dried konjac slices includes the following steps: spraying 85% (volume percentage) ethanol aqueous solution (8% by weight of dried slices) onto dried konjac slices that have been stored for one year, covering them with plastic film and leaving them for 12 hours.

[0032] The konjac slices treated according to the methods in Examples 1-9 were collected after being covered with plastic film and left for 12 hours, after being stored for 6 months, and after being stored for 1 year. These dried konjac slices were then pulverized and ground using a konjac flour mill, followed by cyclone separation for air separation, purification, and sieving to obtain konjac flour with a glucomannan content of over 80% and a particle size of 0.125mm-0.425mm (120-40 mesh) of over 90%. The konjac slices treated according to the methods in Comparative Examples 1-3 were then soaked for 12 hours, 6 months, and 1 year, respectively, before being pulverized and ground using a konjac flour mill. These were then subjected to cyclone separation for air separation, purification, and sieving to prepare konjac flour with a glucomannan content of over 80% and a particle size of 0.125mm-0.425mm (120-40 mesh) of over 90%. The konjac flakes treated in Comparative Examples 4 and 5 were pulverized and ground using a konjac flour mill, then purified by cyclone separation, and sieved to obtain konjac flour with a glucomannan content of over 80% and a particle size of over 90% (0.125mm–0.425mm, 120-40 mesh). The konjac flakes from Comparative Examples 6 and 7, which had been left to stand for 12 hours, were pulverized and ground using a konjac flour mill, then purified by cyclone separation, and sieved to obtain konjac flour with a glucomannan content of over 80% and a particle size of over 90% (0.125mm–0.425mm, 120-40 mesh).

[0033] Referring to the viscosity determination method in NYT494-2010 "Konjac Flour", the apparent viscosity of various konjac flours mentioned above was tested. Referring to the flour yield calculation method in NYT1124-2006 "Konjac Flour Mill", the flour yield of konjac slices obtained after different processing methods was tested. The test results are shown in Table 1 and Table 2.

[0034] Table 1. Effect of treatment methods on apparent viscosity of konjac flour in the examples and comparative examples.

[0035]

[0036]

[0037]

[0038] As shown in Table 1, the konjac powder prepared immediately after processing with the methods described in the examples exhibits varying degrees of increase in apparent viscosity compared to konjac powder prepared from freshly dried konjac slices without any treatment. The minimum increase is 3.6%, and the maximum is 18.2%. Compared to konjac powder prepared immediately after processing with the methods described in Comparative Examples 1-3, the apparent viscosity increases by at least 7.5% and by a maximum of 29.4%. After treatment with the comparative examples, the apparent viscosity of konjac powder prepared from freshly processed konjac slices not only does not increase compared to konjac powder prepared from freshly dried konjac slices without any treatment, but actually decreases.

[0039] Konjac powder prepared from konjac slices treated with the methods described in the examples and stored for six months showed a significantly higher apparent viscosity compared to konjac powder prepared from konjac slices stored for six months without any treatment. The apparent viscosity increased by at least 49.0% and at most 74.5%. Compared to konjac powder prepared from konjac slices treated with the methods described in Comparative Examples 1-3 and stored for six months, the apparent viscosity increased by at least 101.9% and at most 178.0%. Konjac powder prepared from konjac slices treated with the methods described in the examples and stored for one year showed a significantly higher apparent viscosity compared to konjac powder prepared from konjac slices stored for one year without any treatment. The apparent viscosity increased by at least 294.0% and at most 380.0%. Compared to konjac powder prepared from konjac slices treated with the methods described in Comparative Examples 1-3 and stored for one year, the apparent viscosity increased by at least 405.1% and at most 605.9%. This indicates that the processing method of the present invention can effectively improve the apparent viscosity of konjac powder prepared from konjac slices stored for a long time; in particular, the longer the storage time of the konjac slices, the greater the increase in viscosity of the konjac powder prepared after processing. After treating the konjac slices according to the method in the embodiments, the apparent viscosity of konjac powder prepared from konjac slices stored for half a year is at least 50.0% higher than that of konjac powder prepared from konjac slices treated by the method of Comparative Example 4, and can be increased by up to 75.7%. After treating the konjac slices according to the method in the embodiments, the apparent viscosity of konjac powder prepared from konjac slices stored for one year is at least 302.0% higher than that of konjac powder prepared from konjac slices treated by the method of Comparative Example 5, and can be increased by up to 389.8%. Data from Example 5, the control group, and Comparative Examples 6 and 7 show that, in Comparative Examples 6 and 7, after spraying konjac dried slices stored for six months and one year with an 85% ethanol aqueous solution (8% of the dried slices' mass) for 12 hours, the apparent viscosity of the konjac dried slices was increased compared to those without any treatment. However, compared to the konjac powder prepared from konjac dried slices in Example 5 that were first sprayed with an 85% ethanol aqueous solution (8% of the dried slices' mass), covered with plastic film, left to stand for 12 hours, and then stored for six months and one year, the apparent viscosity was still greatly reduced. This indicates that the storage stability of konjac dried slices treated by the method of the present invention is significantly improved compared to the storage stability of freshly dried konjac dried slices stored without any treatment.

[0040] Table 2 shows the effect of treatment methods on the powder yield of konjac flakes in the examples and comparative examples.

[0041]

[0042]

[0043]

[0044] As shown in Table 2, for freshly dried konjac slices, spraying with a 75% ethanol aqueous solution at 10% of the weight of the dried slices or spraying with an 85% ethanol aqueous solution at 8%–10% of the weight of the dried slices significantly improves the powder yield of the freshly treated konjac slices. When konjac slices treated using the methods described in the examples are stored for six months and then processed into konjac powder, the powder yield is at least 3.4% higher and can be as high as 9.2% higher than that of konjac slices that have not undergone any treatment and have been stored for six months. Compared to the treatment method for konjac slices in Comparative Example 4, the powder yield is at least 4.9% higher and can be as high as 10.8% higher. The konjac flour prepared from konjac slices processed using the method described in the examples and stored for one year showed a flour yield that was at least 10.9% higher and up to 17.4% higher than that of konjac slices processed from untreated konjac slices stored for one year. Compared to the treatment method in Comparative Example 5, the flour yield was at least 11.6% higher and up to 18.2% higher. Data from the control group and Comparative Examples 6 and 7 showed that spraying konjac slices stored for six months and one year with an 85% (v / v) ethanol aqueous solution (8% by weight of the dried slices) and covering them with plastic film for 12 hours did not significantly improve the flour yield. This indicates that treating konjac slices using the method described in this invention before storage effectively improves the flour yield when preparing konjac flour from long-term stored konjac slices; especially, the longer the storage time of the konjac slices, the greater the increase in flour yield after treatment.

[0045] During the experiments, the inventors also discovered that treating freshly dried konjac slices with a low-concentration (10%–20% by volume) ethanol aqueous solution, whether by spraying or soaking, or processing konjac slices that had been treated and stored for a period of time before being used to prepare konjac powder, did not improve the apparent viscosity of the konjac powder or the yield of the konjac slices. For freshly dried konjac slices that had not undergone any treatment, after storage for a period of time, soaking them in either a low-concentration (10%–20% by volume) or a high-concentration (75%–95% by volume) ethanol aqueous solution before preparing konjac powder did not improve the apparent viscosity of the konjac powder or the yield of the konjac slices. Spraying freshly dried konjac slices that had not undergone any treatment with an 85% (v / v) ethanol aqueous solution (8% by weight of the dried slices) and covering them with plastic film for 12 hours slightly improved the apparent viscosity of the konjac powder, but had almost no effect on improving the yield of the konjac powder.

[0046] The embodiments described above are merely preferred embodiments of this application and are not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by anyone skilled in the art. Any simple equivalent changes and modifications made based on the scope of protection of this application and the content of the specification should be included within the scope of protection of this application.

Claims

1. A method for preserving dried konjac slices used in the preparation of konjac flour, characterized in that, Spray an ethanol-water solution onto dried konjac slices. The volume percentage of the ethanol-water solution is 75% to 95%, and the mass of the ethanol-water solution accounts for 5% to 10% of the mass of the dried konjac slices. Cover with plastic film and leave for 10 to 14 hours. Then remove the plastic film and store. The dried konjac slices are freshly dried konjac slices.

2. The method for preserving dried konjac slices used in the preparation of konjac flour according to claim 1, characterized in that, The volume percentage of the ethanol-water solution is 75-85%, and the mass of the ethanol-water solution accounts for 8% to 10% of the mass of the dried konjac slices.

3. The method for preserving dried konjac slices used in the preparation of konjac flour according to claim 1, characterized in that, Spray an ethanol-water solution onto dried konjac slices, cover with plastic film, and let stand for 12 hours.

4. The method for preserving dried konjac slices used in the preparation of konjac flour as described in claim 1, characterized in that, An ethanol-water solution was sprayed using a spray device with atomizing nozzles.

5. The method for preserving dried konjac slices used in the preparation of konjac flour as described in claim 1, characterized in that, The storage environment has a temperature of 15~20℃ and a humidity of 65%~70%.

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