Efficient method for preparing black garlic

Abstract

The invention provides an efficient method for preparing black garlic. The efficient method comprises the following steps: (1) peeling and cleaning garlic; (2) soaking with a seaweed extract solution; (3) low-temperature pretreatment; (4) performing high-temperature and high-humidity treatment; and (5) drying. According to the method disclosed by the invention, the content of sulfur-containing compounds such as alliin can be kept in the browning process, and melanoidin components with better effects such as oxidation resistance and the like are produced.

Description

Field of the Invention

[0001] The present application belongs to the field of food, and specifically, the present application provides an efficient method for preparing black garlic. Background Art

[0002] Black garlic is a common processed garlic food in East Asian countries such as China and South Korea. Black garlic is made from garlic through fermentation or Maillard reaction under high temperature and humidity. It is rich in protein / amino acids, polysaccharides, and trace elements. Chinese studies have shown that the polyphenols and polysaccharides in black garlic can provide significant antioxidant effects; alliin components, such as alliin and deoxyalliin, have clear anti-tumor and immune-regulating effects.

[0003] Melanoidins are a class of nitrogen-containing macromolecular compounds with different structures, molecular weights and ingredients that are produced by the Maillard reaction during food processing. In addition to affecting the color and flavor of food, melanoidins also have antioxidant and immune-enhancing effects.

[0004] The preparation process of black garlic takes a long time, during which the content of various active ingredients and the physical properties of the product are in a state of change. Balancing various indicators and quickly obtaining black garlic products with balanced properties in all aspects is an important research direction in this field. Summary of the invention

[0005] In response to the above problems, the applicant tried to introduce a small amount of red algae extract ingredients by soaking, and used the various phycobiliproteins and sulfated polysaccharides contained in the red algae to affect the Maillard reaction, thereby improving the nutritional / health care components of black garlic products.

[0006] On the one hand, the present application provides an efficient method for preparing black garlic, the method comprising:

[0007] (1) cutting off the stem portion of the garlic, peeling off the outermost 1-2 layers of the skin, and washing the garlic to obtain washed garlic;

[0008] (2) soaking the washed garlic obtained in step (1) in a seaweed extract solution for 10-30 minutes to obtain soaked garlic;

[0009] (3) freezing the soaked garlic obtained in step (2) for 18-36 hours to obtain low-temperature pretreated garlic;

[0010] (4) treating the low-temperature pretreated garlic obtained in step (3) at 70-75° C. and 70-80% humidity for 11-13 days;

[0011] (5) Drying.

[0012] Furthermore, the seaweed extract solution in step (2) is a 1-3% w / v red algae extract solution.

[0013] Furthermore, the preparation method of the red algae extract is:

[0014] (A) adding red algae to water with a mass of 3 to 5 times that of the red algae, and performing a freeze-thaw process 2 to 3 times to obtain a freeze-thaw mixture;

[0015] (B) filtering and centrifuging the freeze-thaw mixture obtained in step (A) to remove residual algae and impurities to obtain an extract;

[0016] (C) concentrating and freeze-drying the extract obtained in step (B) to obtain a red algae extract.

[0017] Furthermore, the red algae is Porphyra yezoensis or Gracilarias joestedtii.

[0018] Furthermore, in step (2), the washed garlic obtained in step (1) is soaked in a 2% w / v red algae extract solution for 20 minutes.

[0019] Furthermore, in step (3), the soaked garlic obtained in step (2) is frozen for 24 hours.

[0020] Furthermore, in step (4), the low-temperature pretreated garlic obtained in step (3) is treated at high temperature and high humidity at 70° C. and 75° C. for 13 days;

[0021] Furthermore, in step (5), the drying is performed until the moisture content is less than 45%.

[0022] Furthermore, the method also includes (6) sterilization and packaging.

[0023] On the other hand, the present application provides a black garlic product prepared using the above method.

[0024] On the other hand, the present application provides a melanoidin component extracted from the above black garlic product.

[0025] Furthermore, the method for extracting the above-mentioned melanoidin component includes: peeling the black garlic; adding it to a 20-30% ethanol solution at a solid-liquid ratio of 1:15-30g:mL and mixing it evenly; stirring and extracting in a 40-50°C water bath for 40-60 minutes; extracting 2-3 times and combining the extracts; filtering, concentrating and then freeze-drying.

[0026] On the other hand, the present application provides the use of the above-mentioned melanoidin component in the preparation of health products with antioxidant and / or immune-enhancing effects.

[0027] In addition to the Cangshan garlic material used in the examples, based on the similarity of the basic components of garlic, the method of the present application can be used for various garlic varieties after appropriate changes, including but not limited to Soviet garlic, soft leaf garlic, Puning garlic, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is the changing trend of reducing sugar and total phenols in black garlic during high temperature and high humidity treatment.

[0029] Figure 2 This is the changing trend of sulfur-containing compounds in black garlic during high temperature and high humidity treatment.

[0030] Figure 3 This is the changing trend of browning degree of black garlic during high temperature and high humidity treatment. Figure 4 The effect of soaking in different red algae extracts on the total amount of alliin and deoxyalliin. DETAILED DESCRIPTION

[0031] Embodiment 1 Basic preparation method of black garlic

[0032] Cangshan garlic harvested from the same planting enterprise in Shandong during the same period was selected as the raw material (the quality grade used in each group of experiments was the same).

[0033] (1) Cut off the stem of garlic, peel off the outermost 1-2 layers of skin, and wash;

[0034] (2) freezing the washed garlic obtained in step (1) for 24 hours to obtain low-temperature pretreated garlic;

[0035] (3) treating the low-temperature pretreated garlic obtained in step (2) at a high temperature and high humidity at 70° C. and 75% humidity;

[0036] (4) Dry until the product has a moisture content of about 45%.

[0037] Detection of total phenols, alliin, deoxyalliin and γ-glutamylcysteine:

[0038] Take different cloves from the batch of black garlic to be tested and chop them; accurately weigh 15g of the sample and add it into 100mL of water containing 10% methanol; crush it in a food processor; ultrasonically extract it at room temperature for 30 minutes; filter and take the filtrate; centrifuge and dilute to 200mL as a black garlic extract sample for detecting total phenols, alliin, deoxyalliin, and γ-glutamylcysteine.

[0039] The analysis was performed on a LC-20A chromatograph (Shimadzu) using a C18 column (Venusil MP C18); methanol and 0.1% phosphoric acid in a volume ratio of 1:9 were used as the mobile phase, and the detection was performed at 220 nm; standard solutions were prepared using alliin, deoxyalliin, and γ-glutamylcysteine ​​standards purchased from Shanghai Shidande, and a standard curve was drawn. The average value of three parallel samples was detected.

[0040] The total phenols were detected by Folin-Ciocalteu method: 1 mL of sample was mixed with 1 mL of Folin-Ciocalteu reagent and 3 mL of 20% Na2CO3, reacted in a 50°C water bath for 30 minutes, and the light absorption at 765 nm was measured; a standard solution was prepared with gallic acid and a standard curve was drawn. The average value of three parallel samples was detected.

[0041] Detection of reducing sugar:

[0042] Take different cloves from the batch of black garlic to be tested and chop them; accurately weigh 10g of the sample and add it to 100mL of water; crush it in a food processor; extract it in boiling water for 30 minutes; centrifuge and take the supernatant; take 10mL of the supernatant and dilute it to 200mL as the black garlic extract sample for detecting reducing sugar.

[0043] DNS method detection: 1mL sample is mixed with 1mL DNS solution; react in a boiling water bath for 3 minutes, cool and then make up to the volume to measure the light absorption at 540nm; prepare standard solution with glucose and draw a standard curve. The average value of three parallel samples is tested.

[0044] Browning degree determination

[0045] Use Trinsic Colorimeter (TS8290) to test L, a, b values ​​(average value of the cross-section of 5 random garlic cloves):

[0046] Browning degree = [(L sample - L standard) 2 +(a sample - a standard) 2 +(b sample - b standard) 2 ] 1 / 2

[0047] The test results showed that reducing sugar and total phenols were basically stable on the 10th to 12th day of high temperature and high humidity treatment, with no significant changes ( Figure 1 ); For sulfur compounds, although the level of γ-glutamylcysteine ​​has been increasing significantly in the first 13 days, alliin and deoxyalliin, which have clear health benefits (the biological / health benefits of γ-glutamylcysteine ​​are far less than those of alliin and deoxyalliin), have a peak after reaching the 5th to 7th day and then have a decline of more than 20% ( Figure 2 ); combined with the change in browning degree ( Figure 3), in order to achieve ideal levels in browning degree (one of the most important apparent qualities of black garlic), reducing sugar and total phenols, high temperature and high humidity treatment for more than 13 days, at least more than 10 days, but at this time the content of alliin and deoxyalliin will inevitably be lost.

[0048] Example 2 Effect of soaking with red algae extract

[0049] There are many studies on the use of laver and black garlic to prepare food and condiments in the Korean food industry. The applicant tried to use red algae extracts containing a variety of phycobiliproteins (red algae contain phycoerythrocyanin, phycocyanin, and allophycocyanin) and sulfated polysaccharides to affect the Maillard reaction to accelerate the browning process, and change the content of sulfur compounds in black garlic products and the efficacy of Maillard reaction products.

[0050] The red algae selected were Porphyra yezoensis, Gelidium amansii, Gracilaria sjoestedtii, and Eucheuma denticulatum, all of which were purchased from breeding companies. In order to distinguish similar red algae species such as Porphyra haitanensis and Gracilaria euphorbia, manual control identification and sorting were used to ensure that the raw materials were Porphyra yezoensis, Gelidium amansii, Gracilaria sjoestedtii, and Eucheuma denticulatum. The manually identified raw materials were drained, cut into pieces, and frozen for later use. The same batch of red algae raw materials were used in the experiment.

[0051] Preparation method of red algae extract:

[0052] Add the frozen red algae into 4 times the mass of water, thaw in a 30°C water bath, freeze at -20°C, and thaw in a 30°C water bath to obtain a dark red mixture; stir the obtained mixture at low speed at room temperature overnight; filter with gauze and centrifuge to remove residual algae; partially evaporate the solution and then freeze-dry to obtain the red algae water extract.

[0053] The protein content and total sugar content in several red algae extracts were tested by Kjeldahl nitrogen determination and sulfuric acid-phenol method. The results are shown in Table 1:

[0054] Table 1 Protein content and total sugar content in several red algae extracts

[0055] Protein content Sugar Content Porphyra yezoensis extract 35.4％ 50.2％ Gelidium agar extract 25.4％ 57.3％ Graminoides Lemaneiformis Extract 28.2％ 58.7％ Eucheuma Extract 26.7％ 59.1％

[0056] The protein content in Porphyra yezoensis is higher than that in Gelidium agarifolia, Gracilaria lemaneiformis and Eucheuma, but the sugar content is lower.

[0057] Before freezing, the washed garlic was soaked in a 2% w / v red algae extract solution for 20 minutes, and then frozen and subjected to high temperature and high humidity treatment according to the method in Example 1 to prepare black garlic products. In terms of total phenols, reducing sugars and browning degree, the change trends in Example 1 were basically maintained. In terms of alliin and deoxyalliin, Figure 4 As shown, among the four red algae extracts, immersion in Porphyra yezoensis extract and Gracilaria lemaneiformis extract produced a significant protective effect on both. The total content did not decrease significantly after the 7th day, but instead showed a slight upward trend between the 9th and 13th days, while Gelidium amansoniae and Eucheuma were basically unaffected; therefore, this effect may depend on the combination of specific sulfur-containing phycobiliproteins and sulfated polysaccharides, especially the type of polysaccharides.

[0058] The applicant subsequently verified the effects of other concentrations of Porphyra yezoensis extract and Gracilaria lemaneiformis extract, and the results showed that concentrations of 1-5% could achieve similar effects (the fishy smell caused by too high a concentration may affect the flavor of the product).

[0059] Example 3 Extraction and Effect of Black Garlic Melanin-like Components

[0060] According to the general understanding in the field of food processing and health products, the production and properties of melanoidins are mainly affected by the substrate of the Maillard reaction:

[0061] Melanoidin extraction method:

[0062] The melanoidin components in black garlic were extracted by ethanol extraction method: peel the black garlic; add it to 20% ethanol solution at a solid-liquid ratio of 1:20 (g / mL) and mix well; stir and extract in a 40℃ water bath for 60 minutes; extract twice and combine the extracts; filter, concentrate and freeze-dry, weigh and calculate the yield of the peeled black garlic. The average value of three parallel samples was tested.

[0063] Melanoidin Antioxidant Effect Test:

[0064] Melanoidin components were prepared into a 0.05% w / v solution as a test sample, and a commercially available kit was used to detect the DPPH free radical scavenging rate: 2.5 mL of the liquid sample was mixed with 2.5 mL of DPPH anhydrous ethanol solution (reaction solution) or 2.5 mL of anhydrous ethanol (control reaction solution); the reaction was carried out at 25° C. in the dark for 30 minutes; the absorbance of the reaction solution, the control reaction solution, and the reference solution (2.5 mL of anhydrous ethanol plus 2.5 mL of DPPH anhydrous ethanol solution) at 519 nm was measured by a spectrophotometer;

[0065] DPPH free radical scavenging rate = (1-(A reaction solution-A control reaction solution) / A reference solution) × 100%; the average value of three experiments was taken.

[0066] Macrophage proliferation activity assay:

[0067] Mouse mononuclear macrophage RAW264.7 was purchased from Sean Biotechnology to verify the immune-enhancing activity of melanoidin.

[0068] The cells were cultured in serum-containing DMEM medium until the logarithmic growth phase; 1×105 The cells (100 μL) were cultured at 37°C for 2 hours to adhere to the wall, and the culture medium was aspirated; 100 μL of DMEM culture medium containing 0.05 mg / mL melanoidin and serum was added, and serum DMEM culture medium without melanoidin was used as a control (100% standard); cultured at 37°C for 24 hours (culture environment atmosphere: 5% carbon dioxide).

[0069] Add 10 μL of 5 mg / mL MTT working solution and continue culturing for 4 hours; discard the culture medium, add 150 μL of DMSO solution after washing, and measure the 570 nm OD value after shaking for 15 minutes (according to the actual counting test in advance, the low concentration of melanoidin used has no obvious effect on the OD570 detection of cell density); average the three groups in parallel.

[0070] The black garlic product treated with high temperature and high humidity for 15 days according to the method of Example 1 and the black garlic product treated with high temperature and high humidity for 13 days after being soaked in Porphyra yezoensis extract and Gracilaria lemaneiformis extract in Example 2 were verified. The results are shown in Table 2:

[0071] Table 2 The yield of black garlic melanin-like components and their antioxidant and immune-enhancing effects

[0072]

[0073] The results showed that soaking in Porphyra yezoensis extract and Gracilaria lemaneiformis extract had no significant effect on the yield of melanoidin components, but significantly improved the antioxidant and immune-enhancing effects of melanoidin components, especially soaking in Gracilaria lemaneiformis extract. This provides a good basis for the preparation of melanoidin extracts for related health products.

Claims

1. An efficient method for preparing black garlic, characterized in that, The method comprises: (1) cutting off the stem portion of the garlic, peeling off the outermost 1-2 layers of the skin, and washing the garlic to obtain washed garlic; (2) soaking the washed garlic obtained in step (1) in a seaweed extract solution for 10-30 minutes to obtain soaked garlic; (3) freezing the soaked garlic obtained in step (2) for 18-36 hours to obtain low-temperature pretreated garlic; (4) treating the low-temperature pretreated garlic obtained in step (3) at high temperature and high humidity at 70-75° C. and 70-80% humidity for 11-13 days; (5) Drying.

2. The method according to claim 1, wherein the seaweed extract solution in step (2) is a 1-3% w / v red algae extract solution.

3. The method according to claim 2, wherein the preparation method of the red algae extract is: (A) adding red algae to water with a mass of 3 to 5 times that of the red algae, and performing a freeze-thaw process 2 to 3 times to obtain a freeze-thaw mixture; (B) filtering and centrifuging the freeze-thaw mixture obtained in step (A) to remove residual algae and impurities to obtain an extract; (C) concentrating and freeze-drying the extract obtained in step (B) to obtain a red algae extract.

4. The method according to claim 3, wherein the red algae is Porphyra yezoensis or Gracilaria sjoestedtii.

5. The method according to claim 2, wherein in step (2), the washed garlic obtained in step (1) is soaked in a 2% w / v red algae extract solution for 20 minutes.

6. The method according to claim 1, wherein in step (3), the soaked garlic obtained in step (2) is frozen for 24 hours.

7. The method according to claim 1, wherein in step (4), the low-temperature pretreated garlic obtained in step (3) is treated at high temperature and high humidity at 70° C. and 75° C. for 13 days.

8. The method according to claim 1, wherein the step (5) is drying to a moisture content of less than 45%.

9. The method according to claim 1, further comprising (6) sterilization and packaging.

10. The black garlic product prepared using the method described in any one of claims 1 to 9.

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