Application of Pichia kluyveri in removing the bitterness of ginseng

Abstract

The present invention relates to the field of food processing technology, and in particular to the application of Pichia kluyveri in removing the bitterness of ginseng. The present application provides an application of Pichia kluyveri fermentation broth in removing the bitterness of ginseng products. The present application also provides a method for preparing a low-bitter ginseng product, comprising the following steps: soaking fresh ginseng slices in disodium hydrogen phosphate-citric acid buffer and Pichia kluyveri fermentation broth; steaming the soaked ginseng slices for the first time, then soaking them in a chitosan solution, and steaming them for the second time after drying to obtain the ginseng product. The present application first soaks fresh ginseng slices in disodium hydrogen phosphate-citric acid buffer and Pichia kluyveri fermentation broth, then steaming them for the first time, then soaking them in a chitosan solution, and steaming them for the second time after drying, which can transform the most important bitter substance Rb1 in ginseng and greatly reduce the bitterness of ginseng.

Description

Technical Field

[0001] The invention relates to the technical field of food processing, in particular to application of Pichia kluyveri in removing the bitterness of ginseng and a preparation method of low-bitter ginseng. Background Art

[0002] Ginseng has the effects of calming the mind, improving intelligence, replenishing qi and blood, and improving immunity. Since ginseng was approved as a new resource food in 2012, foods processed with ginseng as raw materials have emerged in an endless stream. Ginseng contains ginsenosides, alcohol, sugars and other ingredients, which have the effects of nourishing the five internal organs and calming the nerves.

[0003] The existing technology usually steams ginseng to increase the content of rare saponins such as Rg3, Rg5, and Rk1, which have excellent anti-cancer and anti-dementia effects. However, this method cannot remove the inherent bitterness of ginseng.

[0004] In recent years, studies have shown that saponins in ginseng are the main source of its bitterness. Recent research results show that a total of five bitter compounds were obtained in ginseng extracts, namely ginsenoside Rg1, ginsenoside Rf, ginsenoside Rb1, 20(S)-ginsenoside Rg2 and ginsenoside Rb3. These bitter compounds are secondary metabolites contained in ginseng itself, rather than produced during the production and purification process. The contribution of key bitter compounds in ginseng extracts was ranked by taste dilution analysis, and it was found that ginsenoside Rb1 and 20(S)-ginsenoside Rg2 in ginseng extracts were the main bitter substances, and compared with 20(S)-ginsenoside Rg2, ginsenoside Rb1 had a smaller bitter recognition threshold.

[0005] Based on this, in the research and development of ginseng products, the content of Rb1 should be reduced as much as possible so that it can be converted into other saponins with less bitterness or saponins that have no bitterness. Summary of the invention

[0006] In view of this, the technical problem to be solved by the present invention is to provide an application of Pichia kluyveri in removing the bitterness of ginseng and a preparation method of low-bitter ginseng. Pichia kluyveri can transform Rb1, the main bitter substance in ginseng, to reduce the bitterness of ginseng.

[0007] The present application provides the use of Pichia kluyveri fermentation broth in removing the bitterness of ginseng products.

[0008] Pichia kluyveri is a new type of strain. In the present application, fresh ginseng is treated with it in the presence of disodium hydrogen phosphate-citric acid buffer, which can transform Rb1, the main bitter substance in ginseng, and greatly reduce the bitterness of ginseng.

[0009] The present application does not specifically limit the Pichia kluyveri, and in the specific embodiment, the Pichia kluyveri is the Pichia kluyveri with the accession number of CCTCCM2021087. However, after attempts, other Pichia kluyveri strains can also achieve similar effects.

[0010] The culture medium of Pichia kluyveri includes a carbon source and a nitrogen source, and the method for preparing the fermentation broth includes activating the strain, inoculating it on the culture medium, and culturing it. As a feasibility case, the method for preparing the Pichia kluyveri fermentation broth includes: inoculating Pichia kluyveri into MRS culture medium, fermenting it at 37°C for 24 hours, and then ultrasonically disrupting it to obtain the Pichia kluyveri fermentation broth.

[0011] The preparation steps for each liter of MRS culture medium include: adding 10 g of peptone, 10 g of beef extract, 5 g of yeast extract, 20 g of glucose, 5 g of sodium acetate, 2 g of diammonium citrate, 1 g of Tween-80, 0.4 g of dipotassium hydrogen phosphate, 0.58 g of magnesium sulfate, 0.29 g of manganese sulfate, 20.0 g of calcium carbonate, and 15 g of agar to distilled water to make the volume to 1 L, adjusting the pH to 6.3, heating after stirring, boiling for 2 minutes, and sterilizing at 121°C and 0.1 MPa for 30 minutes.

[0012] The present application also provides a method for preparing a low-bitter ginseng product, comprising the following steps:

[0013] soaking fresh ginseng slices in disodium hydrogen phosphate-citric acid buffer and Pichia kluyveri fermentation liquid;

[0014] The soaked ginseng slices are steamed for the first time, then soaked in a chitosan solution, dried, and steamed for the second time to obtain a ginseng product.

[0015] The present application first soaks fresh ginseng slices in disodium hydrogen phosphate-citric acid buffer and Pichia kluyveri fermentation broth, then steams them for the first time, then soaks them in chitosan solution, and steams them for the second time after drying, so as to transform Rb1, the main bitter substance in ginseng, and greatly reduce the bitterness of ginseng.

[0016] The present application uses fresh ginseng as raw material, washes it, drains it, removes the branch roots, whiskers and rhizome, slices the main root, and uses it for soaking.

[0017] After obtaining the fresh ginseng slices, soak them in a sodium hydrogen phosphate-citric acid buffer solution, and then add a Pichia kluyveri fermentation broth for treatment. In some specific implementations, the pH value of the sodium hydrogen phosphate-citric acid buffer solution is 5 to 8, preferably 6 to 7. In some specific implementations, the mass ratio of the fresh ginseng slices, the sodium hydrogen phosphate-citric acid buffer solution, and the Pichia kluyveri fermentation broth is 1:20 to 50:5 to 15, preferably 1:25 to 45:10 to 15.

[0018] In some specific implementations, the fresh ginseng slices are preferably soaked in sodium hydrogen phosphate-citric acid buffer and Pichia kluyveri fermentation broth under ultrasonic treatment, and ultrasonic treatment can increase the removal effect of bitter substances. In some specific implementations, the temperature of the ultrasonic treatment is 35-55°C, the ultrasonic frequency is 10-15KHz, and the ultrasonic time is 30min-90min, preferably 40min-80min, and more preferably 50min-70min.

[0019] After the treatment, the ginseng is steamed for the first time to increase the content of rare saponins. In some specific implementations, the temperature of the first steaming is 85°C to 95°C for 1 hour to 3 hours. High temperature steaming is beneficial to increase the content of rare saponins in ginseng.

[0020] After the first steaming is completed, the obtained ginseng is soaked in a chitosan solution to further remove the bitter substances in the ginseng. In some specific implementations, the concentration of the chitosan is 5wt%~30wt%, preferably 10wt%~25wt%; the soaking time is preferably 8h~15h, more preferably 10h~12h.

[0021] After soaking in the chitosan solution, the ginseng is dried at room temperature for 1 hour to 4 hours. After drying, the ginseng is steamed for the second time at a temperature of 60 to 70° C. for 0.5 to 1.5 hours.

[0022] In some specific implementations, before the second steaming, the dried ginseng is preferably left standing at 30° C. to 40° C. for 15 to 30 hours. Leaving the ginseng standing under the above conditions is conducive to removing the bitterness.

[0023] The present application first soaks fresh ginseng slices in sodium hydrogen phosphate-citric acid buffer and Pichia kluyveri fermentation broth, then steams them for the first time, then soaks them in chitosan solution, and steams them for the second time after drying, which can transform the most important bitter substance Rb1 in ginseng and greatly reduce the bitterness of ginseng. The experimental results show that the content of bitter substance Rb1 in ginseng products prepared by the method provided in the present application is greatly reduced, and the bitterness and bitter aftertaste are also greatly reduced, which improves the taste of ginseng products; while not adding sodium hydrogen phosphate-citric acid buffer, replacing Pichia kluyveri with fermented Lactobacillus, or steaming first and then treating with Pichia kluyveri fermentation broth, the bitter substance Rb1 cannot be reduced to a low level. DETAILED DESCRIPTION

[0024] The present invention provides an application of Pichia kluyveri in removing the bitterness of ginseng and a method for preparing low-bitter ginseng. Those skilled in the art can refer to the content of this article and appropriately improve the process parameters to achieve it. It should be particularly noted that all similar replacements and modifications are obvious to those skilled in the art, and they are all considered to be included in the present invention. The method and application of the present invention have been described through preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the method and application of this article without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.

[0025] The present invention will be further described below in conjunction with embodiments:

[0026] In the following embodiments, the Pichia kluyveri fermentation broth is the Pichia kluyveri fermentation broth with a preservation number of CCTCCM 2021087: Pichia kluyveri is inoculated into MRS medium, fermented at 37° C. for 24 h, and then ultrasonically disrupted to obtain the Pichia kluyveri fermentation broth.

[0027] Example 1

[0028] Wash the fresh ginseng with a ginseng washing machine, drain and get clean fresh ginseng; remove the branch roots, whiskers and rhizome of the clean fresh ginseng, get the main root, and slice it;

[0029] The ginseng was soaked in a 50-fold sodium hydrogen phosphate-citric acid buffer solution with a pH value of 6.5, and 5-fold Pichia kluyveri fermentation liquid was added, and ultrasonic treatment was performed at a frequency of 10 KHz for 60 minutes;

[0030] The soaked ginseng was placed in an electric heating steamer at 85°C for 2 hours to obtain cooked ginseng; the cooked ginseng was then soaked in a chitosan solution with a concentration of 15wt% for 10 hours;

[0031] The cooked ginseng was dried at room temperature for 2 h, then left to stand at a constant temperature of 30°C for 20 h, and steamed again at 60°C for 1 h to obtain a ginseng product.

[0032] Example 2

[0033] Wash the fresh ginseng with a ginseng washing machine and drain to obtain clean fresh ginseng; remove the branch roots, whiskers and rhizome of the clean fresh ginseng to obtain the main root;

[0034] The ginseng was soaked in a sodium hydrogen phosphate-citric acid buffer solution with a pH value of 7 and a 30-fold weight, and a Pichia kluyveri fermentation broth with a 10-fold weight was added, and ultrasonic treatment was performed at a frequency of 10 KHz for 80 minutes;

[0035] The soaked ginseng was placed in an electric heating steamer at 85°C for 2 hours to obtain cooked ginseng; the cooked ginseng was then soaked in a chitosan solution with a concentration of 20wt% for 15 hours;

[0036] The cooked ginseng was dried at room temperature for 1 hour, then allowed to stand at a constant temperature of 35°C for 20 hours, and steamed again at 60°C for 1 hour to obtain a ginseng product.

[0037] Example 3

[0038] Wash the fresh ginseng with a ginseng washing machine, drain and get clean fresh ginseng; remove the branch roots, whiskers and rhizome of the clean fresh ginseng, get the main root, and slice it;

[0039] The ginseng was soaked in a sodium hydrogen phosphate-citric acid buffer solution with a pH value of 7.5 and a 20-fold weight, and a Pichia kluyveri fermentation broth with a 15-fold weight was added, and an ultrasonic treatment was performed at a frequency of 10 KHz for 60 minutes;

[0040] The soaked ginseng was placed in an electric heating steamer at 85°C for 2 hours to obtain cooked ginseng; the cooked ginseng was then soaked in a chitosan solution with a concentration of 15wt% for 10 hours;

[0041] The cooked ginseng was dried at room temperature for 2 h, then left to stand at a constant temperature of 30°C for 20 h, and steamed again at 60°C for 1 h to obtain a ginseng product.

[0042] Comparative Example 1

[0043] The difference from Example 1 is that no disodium hydrogen phosphate-citric acid buffer is added.

[0044] Comparative Example 2

[0045] The difference from Example 1 is that Pichia kluyveri is replaced by Lactobacillus fermentum.

[0046] Comparative Example 3

[0047] Wash the fresh ginseng with a ginseng washing machine, drain and get clean fresh ginseng; remove the branch roots, whiskers and rhizome of the clean fresh ginseng, get the main root, and slice it;

[0048] The soaked ginseng was placed in an electric heating steam cabinet at 85°C for 2 hours to obtain cooked ginseng;

[0049] The ginseng was soaked in a sodium hydrogen phosphate-citric acid buffer solution with a pH value of 6.5 and a 50-fold weight, and a Pichia kluyveri fermentation broth was added, and ultrasonic treatment was performed at a frequency of 10 KHz for 25 minutes; the cooked ginseng was then soaked in a chitosan solution with a concentration of 15wt% for 10 hours;

[0050] The cooked ginseng was dried at room temperature for 2 h, then left to stand at a constant temperature of 30°C for 20 h, and steamed again at 60°C for 1 h to obtain a ginseng product.

[0051] The bitterness data of the ginseng products of Examples 1 to 3 and Comparative Examples 1 to 3 were measured using electronic tongue technology. The results are shown in Table 1:

[0052] Table 1 Bitterness data of ginseng products of Examples 1 to 3 and Comparative Examples 1 to 3

[0053]

[0054] It can be seen from Table 1 that, compared with the comparative example, the ginseng product provided by the example has good performance in terms of richness, bitterness and bitter aftertaste.

[0055] The obtained ginsenoside Rb1 was measured on the ginseng products. The results are shown in Table 2. Table 2 shows the Rb1 measurement results of the ginseng products prepared in the examples and comparative examples of the present application.

[0056] Table 2 Ginsenoside Rb1 determination results

[0057]

[0058] It can be seen from Table 2 that the method provided in the present application greatly reduces the content of ginsenoside Rb1.

[0059] The above are only preferred embodiments of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a low-bitter ginseng product, comprising the following steps: Soaking fresh ginseng slices in disodium hydrogen phosphate-citric acid buffer, and then adding Pichia kluyveri fermentation broth to soak; the Pichia kluyveri fermentation broth is obtained by inoculating Pichia kluyveri into a culture medium for fermentation and then subjecting it to ultrasonic disruption; The soaked ginseng slices are steamed for the first time, then soaked in a chitosan solution, dried, and steamed for the second time to obtain a ginseng product.

2. The preparation method according to claim 1, characterized in that: The pH value of the disodium hydrogen phosphate-citric acid buffer is 5-8.

3. The preparation method according to claim 2, characterized in that: The mass ratio of the fresh ginseng slices, disodium hydrogen phosphate-citric acid buffer and Pichia kluyveri fermentation liquid is 1:20-50:5-15.

4. The preparation method according to claim 3, characterized in that: The fresh ginseng slices are soaked in disodium hydrogen phosphate-citric acid buffer and Pichia kluyveri fermentation liquid under ultrasonic treatment; The temperature of the ultrasonic treatment is 35-55° C., the ultrasonic frequency is 10-15 KHz, and the ultrasonic time is 30 min-90 min.

5. The preparation method according to claim 4, characterized in that: The concentration of the chitosan is 5wt%-30wt%.

6. The preparation method according to claim 1, characterized in that: Before the second steaming, the dried ginseng is left to stand at 30°C to 40°C for 15 to 30 hours.

7. The preparation method according to claim 1, characterized in that: The first steaming temperature is 85~95℃ and the time is 1~3 hours; The second steaming temperature is 60~70℃ and the time is 0.5~1.5h.

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