Treatment method for preventing brown stain of peeled glutinous Chinese yam

Abstract

The invention provides a treatment method for preventing peeled glutinous Chinese yam from browning, and relates to the technical field of Chinese yam preservation. The treatment method comprises the following steps: soaking Chinese yams in ice water before peeling, soaking the Chinese yams in a rinsing agent prepared from a glutinous rice fermentation solution, zinc acetate, citric acid, white vinegar and D-sodium erythorbate, treating the Chinese yams in a protective solution prepared from sterile water, roxburgh rose polyphenol, calcium chloride, chitosan, konjaku flour and sodium alginate, and storing the Chinese yams at normal temperature or low temperature after the treatment is finished. According to the method, the defects in the prior art are overcome, the loss of starch content is reduced while browning of the fresh-cut glutinous Chinese yams is effectively prevented, the taste of the glutinous Chinese yams is ensured, and the fresh-cut storage value of the glutinous Chinese yams is improved.

Description

Technical Field

[0001] The invention relates to the technical field of yam preservation, and in particular to a processing method for preventing glutinous yam from browning after peeling. Background Art

[0002] Chinese yam is a vegetable that can be used as both medicine and food. It is rich in nutrients and has a good market. However, Chinese yam is generally harvested once a year. In order to meet the market supply of Chinese yam throughout the year, most of the Chinese yam is stored and preserved after being harvested in the season. The existing storage and preservation method of Chinese yam is mainly to refrigerate the whole Chinese yam for preservation. However, since the whole Chinese yam is relatively long, it is easy to cause it to break during storage, transportation and even harvesting. Direct storage of broken Chinese yam will cause deterioration, seriously affecting the quality of Chinese yam. Therefore, at this stage, some Chinese yams are peeled and cut fresh for preservation.

[0003] After fresh-cut yam, its surface will produce two kinds of browning, enzymatic browning and non-enzymatic browning, which greatly affects the sensory experience of fresh-cut yam. On this basis, it is very important to prevent the fresh-cut yam from browning. The existing anti-browning methods mainly include physical methods, chemical methods and biotechnology methods; the physical methods mainly include temperature regulation and pressure control, such as refrigerating or blanching the fresh-cut yam, which can inhibit the browning of the yam to a certain extent; the chemical method mainly uses chemical inhibitors to competitively bind to phenolic substrates with enzymes, thereby changing the structure of the phenolic substrates; the biotechnology method mainly uses enzymes or plant extracts to inhibit the activity of phenolase.

[0004] The existing processing methods can inhibit the browning of fresh-cut yam to a certain extent, but the overall control time is limited, and most of these methods are used to process crisp yam, preventing browning while ensuring the crisp taste of the yam. However, due to the high starch content of glutinous yam, the general processing method often causes a large amount of starch loss, causing the fresh-cut yam to lose its soft and glutinous taste after being stored for a period of time, thus affecting the quality of the glutinous yam. Therefore, further research is needed on the storage and anti-browning of fresh-cut glutinous yam. Summary of the invention

[0005] In view of the shortcomings of the existing technology, the present invention provides a processing method for preventing glutinous yam from browning after peeling, which effectively prevents the fresh-cut glutinous yam from browning while reducing the loss of starch content, thereby ensuring the taste of the glutinous yam and improving the storage value of the fresh-cut glutinous yam.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions: A method for preventing glutinous yam from browning after peeling, the method comprising the following steps: S1. Peeling of yam: Wash the fresh yam, place it in ice water for 15-20 minutes, then take it out, rinse it with clean water and peel it. The peeled yam is set aside; S2. Prepare a rinse agent according to the following ingredients: glutinous rice fermentation solution + zinc acetate 4-6g / L + citric acid 400-600mg / L + white vinegar 40-60mg / L + D-sodium isoascorbate 40-60mg / L; wherein the glutinous rice fermentation solution is obtained by grinding glutinous rice, adding water, fermenting with Lactobacillus plantarum and Trichoderma koningii, and then boiling and filtering; S3. Prepare protective solution according to the following ingredients: sterile water + roxburghii polyphenol 10-20 mg / L + calcium chloride 15-20 g / L + chitosan 200-400 mg / L + konjac powder 10-20 g / L + sodium alginate 4-10 g / L; S4, preliminary soaking treatment: the peeled yam is placed in a rinse agent and soaked at 40-50°C for 10-15 minutes, then placed in sterile water and ultrasonically treated in an ice water bath, and then placed in a room temperature rinse agent and soaked for 5-10 minutes, then taken out, and the preliminary soaked yam is set aside; S5, secondary soaking treatment: rinse the above-mentioned primary soaked yam with sterile water, soak it in a protective liquid for 30-40 seconds, then take it out to obtain the secondary soaked yam for use; S6. Static packaging: The twice soaked yam is placed at 50-60°C for 20-30 minutes, then packaged with polyethylene packaging film, and then placed in a room temperature environment or a cold storage at 2-5°C for freshness preservation.

[0007] Preferably, a ceramic knife is used for peeling in step S1.

[0008] Preferably, the method for preparing the glutinous rice fermentation solution in step S2 comprises the following steps: S2-1, grind the glutinous rice, add 6-10 times of clean water, and then add Lactobacillus plantarum to ferment for 8-10 hours to obtain a preliminary fermented material for use; S2-2, adding Trichoderma koningii to the above-mentioned primary fermentation material, and continuing the fermentation process for 4-6 hours to obtain a secondary fermentation material for standby use; S2-3, cooking the secondary fermentation material at 100-110° C. for 20-30 min, and then squeezing and filtering to obtain a glutinous rice fermentation solution.

[0009] Preferably, the amount of Lactobacillus plantarum added in step S2-1 is 0.2%-0.3% of the total mass of the glutinous rice.

[0010] Preferably, the amount of Trichoderma koningii added in step S2-2 is 0.1%-0.2% of the total mass of the glutinous rice.

[0011] Preferably, the time from peeling to placing the peeled yam in the rinse agent is ≤ 2 minutes.

[0012] Preferably, the power of the ultrasonic treatment in step S4 is 200-400 W, and the time of the ultrasonic treatment is 20-30 s.

[0013] Preferably, the sterile water rinsing time in step S5 is 10-15 seconds.

[0014] Preferably, the immersion treatment in the protective liquid in step S5 is performed at room temperature.

[0015] Preferably, the thickness of the polyethylene packaging film in step S6 is 0.01-0.03 mm.

[0016] The present invention provides a processing method for preventing glutinous yam from browning after peeling, which has the advantages of: The method soaks the yam in ice water and then peels it and soaks it in a rinsing agent, thereby effectively inhibiting the surface oxidation browning of the yam. Meanwhile, the heat preservation soaking and ultrasonic cleaning effectively remove the mucus on the surface of the yam, which is convenient for the subsequent surface treatment of the yam with a protective liquid. After the protective liquid treatment, further oxidation and starch loss during storage are effectively prevented. Meanwhile, the yam is placed at a temperature of 50-60°C for a period of time to remove excess moisture, accelerate the synthesis of starch in the yam, make up for the starch lost due to soaking and cleaning, ensure the soft and glutinous taste of the yam, and comprehensively ensure the preservation effect of the fresh-cut glutinous yam. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the color change of the yam surface 3 minutes after peeling the yam in Example 1 of the present invention and Comparative Example 1; Figure 2 This is a schematic diagram of the browning of yam after the yam was treated with the methods of experimental groups 1-7 in the embodiments of the present invention and stored at room temperature for 30 days; Figure 3 This is a schematic diagram of the browning of yam after it was treated with the methods of experimental groups 1-7 in the embodiments of the present invention and stored at 4° C. for 90 days. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention is clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] The Lactobacillus plantarum used in the following examples was purchased from Xi'an Meihe Biotechnology Co., Ltd. with the item number MH-2104016076; and the Trichoderma corningii was purchased from Wuhan Huaerna Biotechnology Co., Ltd. with the item number WN-Jj83546.

[0020] Example 1

[0021] 1. Preparation of glutinous rice fermentation solution: 1.1. Fermentation solution A: (1) Grind glutinous rice, add 6 times of clean water, and then add 0.2% of the total weight of glutinous rice Lactobacillus plantarum for fermentation for 10 hours to obtain a preliminary fermented material for use; (2) adding 0.1% of the total weight of glutinous rice to the primary fermentation material, and continuing the fermentation process for 6 hours to obtain a secondary fermentation material for later use; (3) The secondary fermentation material is boiled at 100°C for 30 min, and then squeezed and filtered to obtain fermentation solution A.

[0022] 1.2. Fermentation solution B: (1) Grind glutinous rice, add 10 times of clean water, and then add 0.3% of the total weight of glutinous rice Lactobacillus plantarum for fermentation for 8 hours to obtain a preliminary fermented material for use; (2) adding 0.2% of the total weight of glutinous rice to the primary fermentation material, and continuing the fermentation process for 4 hours to obtain a secondary fermentation material for later use; (3) The secondary fermentation material is boiled at 110°C for 20 min, and then squeezed and filtered to obtain fermentation solution B.

[0023] 1.3. Fermentation solution C: (1) Grinding glutinous rice, adding 10 times of clean water, and then adding 0.3% of the total weight of glutinous rice Lactobacillus plantarum and 0.2% of the total weight of glutinous rice Trichoderma koningii for fermentation for 10 hours to obtain a fermented material for use; (2) The fermented material is boiled at 110°C for 20 min, and then squeezed and filtered to obtain fermentation solution C.

[0024] 1.4. Preparation of glutinous rice paste: Grind the glutinous rice, add 10 times of clean water, cook at 110℃ for 20min, squeeze and filter to get glutinous rice paste; 2. Preparation of rinse agent: Prepare different rinse agents according to the formula in Table 1 below: Table 1

[0025] 3. Preparation of protective liquid: Prepare different protective solutions according to the formula in Table 2 below: Table 2

[0026] Embodiment 2: Glutinous yam peeling post-processing: (1) Wash the fresh yam, place it in ice water and let it stand for 15 minutes, then take it out and peel it with a ceramic knife. The peeled yam is set aside; (2) The peeled yam was quickly placed in a rinse agent, soaked at 40°C for 15 minutes, then placed in sterile water and ultrasonically treated at 200W for 30 seconds in an ice water bath, then placed in a room temperature rinse agent and soaked for 5 minutes, and then taken out to obtain the preliminary soaked yam; (3) The yam that was initially soaked was rinsed with sterile water for 15 seconds, and then soaked in a protective solution at room temperature for 40 seconds before being taken out to obtain the second soaked yam for use; (4) The twice-soaked yam is placed at 50°C for 30 minutes, and then packaged with a polyethylene packaging film with a thickness of 0.02±0.01 mm, and then stored.

[0027] Example 3

[0028] Glutinous yam peeling post-processing: (1) Wash the fresh yam, place it in ice water and let it stand for 20 minutes, then take it out and peel it with a ceramic knife. The peeled yam is set aside; (2) The peeled yam is quickly placed in a rinse agent, soaked at 50°C for 10 minutes, then placed in sterile water and ultrasonically treated at 400W for 20 seconds in an ice water bath, then placed in a room temperature rinse agent and soaked for 10 minutes, and then taken out to obtain the preliminary soaked yam; (3) The yam that was initially soaked was rinsed with sterile water for 15 seconds, and then soaked in a protective solution at room temperature for 40 seconds before being taken out to obtain the second soaked yam for use; (4) The twice-soaked yam is placed at 60°C for 20 minutes, and then packaged with a polyethylene packaging film with a thickness of 0.02±0.01 mm, and then stored.

[0029] Comparative Example 1: Glutinous yam peeling process: Wash the fresh yam, and then use a ceramic knife to peel the yam.

[0030] Detection Select the commercially available iron stick yam as the glutinous yam raw material for the following tests: 1. Peel the yam using the methods of Example 1 and Comparative Example 1, respectively, and observe the changes on the surface of the peeled yam within 3 minutes after peeling. The specific results are shown in Tables 3 and Figure 1 As shown: Table 3

[0031] 2. The treatment methods of the above-mentioned embodiment 2 and embodiment 3 are respectively adopted, and different rinsing agents and protective liquids are selected for treatment. The specific selection of rinsing agents and protective liquids is shown in the following Table 4: Table 4

[0032] Set the yam browning level according to Table 5 below: Table 5

[0033] 2.1. The yam in each experimental group was stored at room temperature (12-20°C) for 10 days, 20 days and 30 days, and then taken out, washed and the browning level of each group was observed (3 yams in each group, and the average value was taken). The starch content of the yam before peeling and after storage was tested. The specific results are shown in Tables 6 and 7 below: Table 6

[0034] Table 7

[0035] It can be seen from the above table that under room temperature storage, experimental group 1 and experimental group 2 had a lower degree of browning within the storage time of 30 days, and the overall starch loss was also lower.

[0036] 2.2. The yams in the above experimental groups were stored in a cold storage at 4°C for 10 days, 45 days, and 90 days. After being taken out, they were washed and the browning level of each group was observed (3 yams in each group, and the average value was taken). The starch content of the yams before peeling and after storage was tested. The specific results are shown in Tables 8 and 9 below: Table 8

[0037] Table 9

[0038] It can be seen from the above table that experimental group 1 and experimental group 2 can effectively inhibit the browning of yam under low-temperature storage at 4°C, and the shelf life can reach 90 days. It can also effectively reduce the loss of starch and ensure that the yam has a soft and glutinous taste after storage.

[0039] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preventing glutinous yam from browning after peeling, characterized in that: The processing method comprises the following steps: S1. Peeling of yam: Wash the fresh yam, place it in ice water for 15-20 minutes, then take it out, rinse it with clean water and peel it. The peeled yam is set aside; S2. Prepare a rinse agent according to the following ingredients: glutinous rice fermentation solution + zinc acetate 4-6g / L + citric acid 400-600mg / L + white vinegar 40-60mg / L + D-sodium isoascorbate 40-60mg / L; wherein the glutinous rice fermentation solution is obtained by grinding glutinous rice, adding water, fermenting with Lactobacillus plantarum and Trichoderma koningii, and then boiling and filtering; S3. Prepare protective solution according to the following ingredients: sterile water + roxburghii polyphenol 10-20 mg / L + calcium chloride 15-20 g / L + chitosan 200-400 mg / L + konjac powder 10-20 g / L + sodium alginate 4-10 g / L; S4, preliminary soaking treatment: the peeled yam is placed in a rinse agent and soaked at 40-50°C for 10-15 minutes, then placed in sterile water and ultrasonically treated in an ice water bath, and then placed in a room temperature rinse agent and soaked for 5-10 minutes, then taken out, and the preliminary soaked yam is set aside; S5, secondary soaking treatment: rinse the above-mentioned primary soaked yam with sterile water, soak it in a protective liquid for 30-40 seconds, then take it out to obtain the secondary soaked yam for use; S6. Static packaging: The twice soaked yam is placed at 50-60°C for 20-30 minutes, then packaged with polyethylene packaging film, and then placed in a room temperature environment or a cold storage at 2-5°C for freshness preservation.

2. The method for preventing browning of peeled glutinous yam according to claim 1, characterized in that: In the step S1, a ceramic knife is used for peeling.

3. The method for preventing glutinous yam from browning after peeling according to claim 1, characterized in that: The method for preparing the glutinous rice fermentation solution in step S2 comprises the following steps: S2-1, grind the glutinous rice, add 6-10 times of clean water, and then add Lactobacillus plantarum to ferment for 8-10 hours to obtain a preliminary fermented material for use; S2-2, adding Trichoderma koningii to the above-mentioned primary fermentation material, and continuing the fermentation process for 4-6 hours to obtain a secondary fermentation material for standby use; S2-3, cooking the secondary fermentation material at 100-110° C. for 20-30 min, and then squeezing and filtering to obtain a glutinous rice fermentation solution.

4. The method for preventing browning of peeled glutinous yam according to claim 3, characterized in that: The amount of Lactobacillus plantarum added in step S2-1 is 0.2%-0.3% of the total mass of the glutinous rice.

5. The method for preventing glutinous yam from browning after peeling according to claim 3, characterized in that: In the step S2-2, the amount of Trichoderma koningii added is 0.1%-0.2% of the total mass of the glutinous rice.

6. The method for preventing glutinous yam from browning after peeling according to claim 1, characterized in that: The time from peeling to placing the peeled yam in the rinse agent is ≤2 minutes.

7. The method for preventing glutinous yam from browning after peeling according to claim 1, characterized in that: The power of the ultrasonic treatment in step S4 is 200-400W, and the time of the ultrasonic treatment is 20-30s.

8. The method for preventing glutinous yam from browning after peeling according to claim 1, characterized in that: The sterile water rinsing time in step S5 is 10-15 seconds.

9. The method for preventing glutinous yam from browning after peeling according to claim 1, characterized in that: The immersion treatment in the protective liquid in step S5 is performed at room temperature.

10. The method for preventing glutinous yam from browning after peeling according to claim 1, characterized in that: The thickness of the polyethylene packaging film in step S6 is 0.01-0.03 mm.

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