A kind of preservation processing method of water shield

Abstract

The present invention belongs to the field of fresh-keeping technology, and particularly relates to a fresh-keeping treatment method for water shield, the steps of which include high-temperature killing, cooling and rinsing, acid fresh-keeping, grading, and color preservation. Among them, one or both of citric acid and malic acid are used to prepare an acid fresh-keeping liquid to prevent water shield from deteriorating, and one or both of cysteine ​​and reduced glutathione are used to prepare a color preservation liquid to effectively inhibit the discoloration of water shield. The present application selects a suitable processing time to carry out fresh-keeping treatment on water shield, which is beneficial to improving the freshness rate of water shield and extending the shelf life; at the same time, the fresh-keeping treatment of water shield is carried out in a targeted and step-by-step manner, which avoids or reduces the conflict of effects between related reagents when acting on water shield, and the fresh-keeping effect is more obvious.

Description

Technical Field

[0001] The invention belongs to the technical field of fresh-keeping, and particularly relates to a fresh-keeping treatment method for water shield. Background Art

[0002] Brasenia schrenkiana, also known as Brasenia schrenkiana, Brasenia schrenkiana, and Brasenia schrenkiana, is a perennial aquatic herb rich in acidic polysaccharides, proteins, amino acids, vitamins, and trace elements, and has both medicinal and edible value. Brasenia schrenkiana has a high water content and is easily damaged and rotten, so it is not resistant to storage and transportation. The storage period is usually 3-5 days, which severely limits its sales and processing.

[0003] At present, the preservation methods of water shield in China include acetic acid method, freezing method, ultra-high pressure method, sodium copper chlorophyll method, etc. At present, the most commonly used method for water shield preservation is still acetic acid preservation method. Due to the use of glacial acetic acid, it has a light sour taste when eaten, and it is difficult to taste the original flavor of water shield. Moreover, in the acidic environment of acetic acid, the pectin polysaccharide of water shield will slowly hydrolyze into water-soluble oligosaccharides and dissolve in water, thereby reducing the quality of water shield. The water shield freezing preservation method has the disadvantages of excessive investment, high cost, inconvenient storage and transportation. After thawing, the water shield cannot be fully restored to its original state, and the nutritional components of water shield are lost in large quantities, affecting the flavor and quality of water shield, and even making it inedible. The ultra-high pressure preservation method of water shield also has the disadvantages of large equipment investment and long pressure rise and fall cycle. The copper salt color protection method of water shield is easy to cause excessive copper ions, which may denature the protein in water shield, inactivate the biological enzyme, and cause safety hazards. At the same time, the color of water shield not only reflects the freshness of the dish to a certain extent, but also can bring consumers the initial and most intuitive experience. Therefore, color is also a relatively important indicator in the preservation of water shield. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a method for preserving water shield, comprising the following steps:

[0005] (1) High temperature killing

[0006] The temperature for killing green is 90°C~100°C, and the killing time is 2~5 minutes. It can be killed by immersing in hot water. After killing green, take it out and quickly filter out the hot water.

[0007] (2) Cooling and rinsing

[0008] Rinse the water shield processed in step (1) with cold water and then soak it in cold water.

[0009] The cold shower time is 10 to 20 minutes, and the soaking time in cold water is 2 to 4 hours. The cold water temperature is 5°C to 20°C.

[0010] (3) Acid preservation

[0011] Adding an acid preservative solution to the water shield treated in step (2), wherein the acid preservative solution is an aqueous solution of one or both of citric acid and malic acid with a mass concentration of 0.5-2%,

[0012] The acid preservation treatment is carried out at room temperature (25°C, the same below), and 50 to 200 parts by weight of the above acid preservation solution is added to every 100 parts by weight of water shield.

[0013] (4) Classification

[0014] The water shield processed in step (3) is graded and selected according to the length of the petiole and the leaf blade, and is generally divided into four grades: S grade, M grade, L grade and general grade. During the grading and selection process, unqualified products with sand mixed in the colloid of the tender shoots and leaves and products that do not meet the specified grade are removed.

[0015] In many traditional processing procedures, water shield is first graded and then preserved. However, during the grading operation, water shield is almost fully exposed to the air environment and is prone to deterioration.

[0016] In this regard, in the present application, after pretreatment, the water shield is first subjected to an overall fresh-keeping treatment, which effectively inhibits the water shield from being affected by the environment during the grading operation, overcomes the above-mentioned problems, and is conducive to the long-term preservation of the dish.

[0017] (5) Color protection and freshness preservation

[0018] Adding a color-preserving and fresh-keeping liquid to the water shield retained after step (4), wherein the color-preserving and fresh-keeping liquid is an aqueous solution of one or both of cysteine ​​and reduced glutathione with a mass concentration of 0.5-2%,

[0019] The color protection and fresh-keeping treatment is carried out at room temperature, and 5 to 20 parts by weight of the above color protection and fresh-keeping liquid are added to every 100 parts by weight of water shield.

[0020] While protecting the color and keeping fresh, these water shields are pasteurized.

[0021] Generally, fresh-keeping treatment involves mixing the required reagents together and treating the dishes, and not separately. However, the applicant has found that separating cysteine ​​or reduced glutathione from the acid fresh-keeping solution and treating the water shield separately can extend the color preservation period of the water shield. This may be because this measure avoids the conflict of effects between cysteine ​​or reduced glutathione and the ordinary acid fresh-keeping solution when acting on the water shield.

[0022] (6) Encapsulating the water shield processed in step (5).

[0023] The beneficial effects of the present application are: selecting the appropriate processing time to carry out preservation treatment on the water shield is conducive to improving the freshness rate of the water shield and extending the shelf life; at the same time, the water shield is carried out in a targeted and step-by-step manner to avoid or reduce the conflict of effects between related reagents when acting on the water shield, the preservation effect is more obvious, and the amount of preservatives used is also reduced. The shelf life can normally reach more than 18 months. DETAILED DESCRIPTION

[0024] The fresh-keeping treatment method of water shield of the present invention comprises:

[0025] (1) High temperature killing

[0026] After killing the green in hot water at 90°C to 100°C for 2 to 5 minutes, remove and quickly filter out the hot water.

[0027] (2) Cooling and rinsing

[0028] After the water shield treated in step (1) is rinsed with cold water at 5°C to 20°C for 10 to 20 minutes, it is then soaked in cold water at 5°C to 20°C for 2 to 4 hours.

[0029] (3) Acid preservation

[0030] Add a 0.5-2% aqueous solution of one or both of citric acid and malic acid in a mass ratio of 100:50-200 to the water shield treated in step (2), mix thoroughly,

[0031] (4) Classification

[0032] The water shield processed in step (3) is divided into four grades according to the length of petioles and leaves: S grade, M grade, L grade and general grade. During the grading and selection process, unqualified products with sand mixed in the colloid of tender shoots and leaves and products that do not meet the specified grade are removed.

[0033] (5) Color protection and freshness preservation

[0034] Adding a 0.5-2% aqueous solution of one or both of cysteine ​​and reduced glutathione in a mass ratio of 100:5-20 to the water shield retained after step (4), mixing well and then pasteurizing.

[0035] (6) Encapsulating the water shield processed in step (5).

[0036] Specific examples are:

[0037] Example 1

[0038] (1) High temperature killing

[0039] Soak the fresh water shield after preliminary cleaning in sufficient boiling water for 2 minutes, remove the water shield and quickly filter out the hot water.

[0040] (2) Cooling and rinsing

[0041] After filtering the hot water from the water shield in step (1), immediately place it in continuously running clean cold water for 10 minutes until the water shield is fully cooled, and then immerse it in sufficient cold water for 2 hours. The cold water temperature is 5°C.

[0042] (3) Acid preservation

[0043] The water shield from step (2) was taken out and the soaking water on the water shield was fully squeezed out, and a room temperature aqueous solution of citric acid with a mass concentration of 2% was added to the water shield according to 50% of the weight of the water shield at that time, and mixed thoroughly so that the water shield could fully absorb the solution. The water shield was taken out and the pH value on the surface of the water shield was measured with a pH test paper, and the pH value was 3.2 (the pH value was measured at 5 different locations in this batch of water shield, and the average value was taken, the same below).

[0044] (4) Classification

[0045] The water shield processed in step (3) is divided into four grades according to the length of petioles and leaves: S grade, M grade, L grade and general grade. During the grading and selection process, unqualified products with sand and mud mixed in the colloid of tender shoots and leaves and products that do not meet the specified grade are removed.

[0046] (5) Color protection and freshness preservation

[0047] To the water shield retained after step (4), add a room temperature aqueous solution of cysteine ​​with a mass concentration of 2% according to 10% of the weight of the water shield at this time, mix thoroughly so that the water shield can fully absorb it, and then remove the water shield for pasteurization.

[0048] (6) Encapsulating the water shield processed in step (5).

[0049] Example 2

[0050] (1) High temperature killing

[0051] Soak the fresh water shield after preliminary cleaning in sufficient boiling water for 5 minutes, remove the water shield and quickly filter out the hot water.

[0052] (2) Cooling and rinsing

[0053] After filtering the hot water from the water shield in step (1), immediately place it in a continuously running stream of clean cold water for 20 minutes until the water shield is fully cooled, and then immerse it in sufficient cold water for 5 hours, with the cold water temperature being 20°C.

[0054] (3) Acid preservation

[0055] The water shield from step (2) was removed and the soaking water on the water shield was fully squeezed out, and a room temperature aqueous solution of malic acid with a mass concentration of 0.5% was added to the water shield in an amount of twice the weight of the water shield at that time, and after being mixed thoroughly so that the water shield can fully absorb the solution, the water shield was removed and the pH value on the surface of the water shield was measured with a pH test paper to be 4.8.

[0056] (4) Classification

[0057] The water shield processed in step (3) is divided into four grades according to the length of petioles and leaves: S grade, M grade, L grade and general grade. During the grading and selection process, unqualified products with sand and mud mixed in the colloid of tender shoots and leaves and products that do not meet the specified grade are removed.

[0058] (5) Color protection and freshness preservation

[0059] To the water shield retained after step (4), add a room temperature aqueous solution of reduced glutathione with a mass concentration of 0.5% according to 20% of the weight of the water shield at this time, mix thoroughly so that the water shield can fully absorb it, and then remove the water shield for pasteurization.

[0060] (6) Encapsulating the water shield processed in step (5).

[0061] Example 3

[0062] (1) High temperature killing

[0063] Soak the fresh water shield after preliminary cleaning in sufficient boiling water for 4 minutes, remove the water shield and quickly filter out the hot water.

[0064] (2) Cooling and rinsing

[0065] After filtering the hot water from the water shield in step (1), immediately place it in continuously running clean cold water for 15 minutes until the water shield is fully cooled, and then immerse it in sufficient cold water for 4 hours. The cold water temperature is 10°C.

[0066] (3) Acid preservation

[0067] The water shield from step (2) was removed and the soaking water on the water shield was fully squeezed out, and a room temperature aqueous solution consisting of 1% by mass citric acid and 1% by mass malic acid was added to the water shield according to the weight of the water shield at this time (1 times), and after being mixed thoroughly so that the water shield can fully absorb the water shield, the water shield was removed and the pH value on the surface of the water shield was measured with a pH test paper to be 4.0.

[0068] (4) Classification

[0069] The water shield processed in step (3) is divided into four grades according to the length of petioles and leaves: S grade, M grade, L grade and general grade. During the grading and selection process, unqualified products with sand and mud mixed in the colloid of tender shoots and leaves and products that do not meet the specified grade are removed.

[0070] (5) Color protection and freshness preservation

[0071] To the water shield retained after step (4), add a room temperature aqueous solution consisting of 0.5% cysteine ​​and 0.5% reduced glutathione at a mass concentration of 10% of the weight of the water shield at this time, mix thoroughly so that the water shield can fully absorb it, then remove the water shield and pasteurize it.

[0072] (6) Encapsulating the water shield processed in step (5).

[0073] Example 4

[0074] (1) High temperature killing

[0075] Soak the fresh water shield after preliminary cleaning in sufficient boiling water for 3 minutes, remove the water shield and quickly filter out the hot water.

[0076] (2) Cooling and rinsing

[0077] After filtering the hot water from the water shield in step (1), immediately place it in a continuously running stream of clean cold water for 20 minutes until the water shield is fully cooled, and then immerse it in sufficient cold water for 3 hours, with the cold water temperature being 10°C.

[0078] (3) Acid preservation

[0079] The water shield from step (2) was removed and the soaking water on the water shield was fully squeezed out, and a room temperature aqueous solution of malic acid with a mass concentration of 1% was added to the water shield according to the weight of the water shield at this time (1 times), and after being mixed thoroughly so that the water shield can fully absorb the malic acid, the water shield was removed and the pH value on the surface of the water shield was measured with a pH test paper, and it was 3.8.

[0080] (4) Classification

[0081] The water shield processed in step (3) is divided into four grades according to the length of petioles and leaves: S grade, M grade, L grade and general grade. During the grading and selection process, unqualified products with sand and mud mixed in the colloid of tender shoots and leaves and products that do not meet the specified grade are removed.

[0082] (5) Color protection and freshness preservation

[0083] To the water shield retained after step (4), add a room temperature aqueous solution of cysteine ​​with a mass concentration of 1% according to 15% of the weight of the water shield at this time, mix thoroughly so that the water shield can fully absorb it, and then remove the water shield for pasteurization.

[0084] (6) Encapsulating the water shield processed in step (5).

[0085] Example 5

[0086] (1) High temperature killing

[0087] Soak the fresh water shield after preliminary cleaning in sufficient boiling water for 4 minutes, remove the water shield and quickly filter out the hot water.

[0088] (2) Cooling and rinsing

[0089] After filtering the hot water from the water shield in step (1), immediately place it in a continuously running stream of clean cold water for 15 minutes until the water shield is fully cooled, and then immerse it in sufficient cold water for 3.5 hours, with the cold water temperature being 12°C.

[0090] (3) Acid preservation

[0091] The water shield from step (2) was removed and the soaking water on the water shield was fully squeezed out, and a room temperature aqueous solution consisting of 0.8% by mass citric acid and 0.7% by mass malic acid was added to the water shield in an amount of 1.2 times the weight of the water shield at that time, and mixed thoroughly so that the water shield could fully absorb the solution. The water shield was removed and the pH value on the surface of the water shield was measured with a pH test paper to be 3.3.

[0092] (4) Classification

[0093] The water shield processed in step (3) is divided into four grades according to the length of petioles and leaves: S grade, M grade, L grade and general grade. During the grading and selection process, unqualified products with sand and mud mixed in the colloid of tender shoots and leaves and products that do not meet the specified grade are removed.

[0094] (5) Color protection and freshness preservation

[0095] To the water shield retained after step (4), add a room temperature aqueous solution consisting of 0.7% cysteine ​​and 0.8% reduced glutathione at a weight concentration of 15% of the water shield weight at this time, mix thoroughly so that the water shield can fully absorb it, then remove the water shield and pasteurize it.

[0096] (6) Encapsulating the water shield processed in step (5).

[0097] Comparative Example 1

[0098] After mixing cysteine ​​and citric acid, the water shield was treated for freshness preservation. The other conditions were the same as those in Example 1:

[0099] (1) High temperature killing

[0100] Fresh water shield from the same batch as in Example 1 was preliminarily washed and immersed in sufficient boiling water for 2 minutes, the water shield was removed and the hot water was quickly filtered off.

[0101] (2) Cooling and rinsing

[0102] After filtering the hot water from the water shield in step (1), immediately place it in continuously running clean cold water for 10 minutes until the water shield is fully cooled, and then immerse it in sufficient cold water for 2 hours. The cold water temperature is 5°C.

[0103] (3) Acid preservation

[0104] The water shield from step (2) is removed and the soaking water on the water shield is fully squeezed out, and a room temperature aqueous solution consisting of 1.67% by mass concentration of citric acid and 0.34% by mass concentration of cysteine ​​is added to the water shield in an amount of 60% by mass of the water shield at this time, and the mixture is mixed sufficiently so that the water shield can fully absorb the citric acid, and then the water shield is removed.

[0105] (4) Classification

[0106] The water shield processed in step (3) is divided into four grades according to the length of petioles and leaves: S grade, M grade, L grade and general grade. During the grading and selection process, unqualified products with sand and mud mixed in the colloid of tender shoots and leaves and products that do not meet the specified grade are removed.

[0107] (5) The water shield retained after step (4) is pasteurized and then packaged.

[0108] Comparative Example 2

[0109] Reduced glutathione and malic acid were mixed and then used to preserve water shield. The remaining conditions were the same as those in Example 2:

[0110] (1) High temperature killing

[0111] Fresh water shield from the same batch as in Example 2 was preliminarily washed and immersed in sufficient boiling water for 5 minutes, the water shield was removed and the hot water was quickly filtered off.

[0112] (2) Cooling and rinsing

[0113] After filtering the hot water from the water shield in step (1), immediately place it in a continuously running stream of clean cold water for 20 minutes until the water shield is fully cooled, and then immerse it in sufficient cold water for 5 hours, with the cold water temperature being 20°C.

[0114] (3) Acid preservation

[0115] The water shield from step (2) is removed and the soaking water on the water shield is fully squeezed out, and a room temperature aqueous solution consisting of 0.46% malic acid and 0.046% reduced glutathione is added to the water shield in an amount of 2.2 times the weight of the water shield at this time, and mixed thoroughly so that the water shield can fully absorb the malic acid. Then, the water shield is removed.

[0116] (4) Classification

[0117] The water shield processed in step (3) is divided into four grades according to the length of petioles and leaves: S grade, M grade, L grade and general grade. During the grading and selection process, unqualified products with sand and mud mixed in the colloid of tender shoots and leaves and products that do not meet the specified grade are removed.

[0118] (5) The water shield retained after step (4) is pasteurized and then packaged.

[0119] Comparative Example 3

[0120] Cysteine, reduced glutathione, citric acid and malic acid were mixed together and then used to preserve water shield. The remaining conditions were the same as those in Example 2.

[0121] (1) High temperature killing

[0122] Fresh water shield from the same batch as in Example 3 was preliminarily washed and immersed in sufficient boiling water for 4 minutes, the water shield was removed and the hot water was quickly filtered off.

[0123] (2) Cooling and rinsing

[0124] After filtering the hot water from the water shield in step (1), immediately place it in continuously running clean cold water for 15 minutes until the water shield is fully cooled, and then immerse it in sufficient cold water for 4 hours. The cold water temperature is 10°C.

[0125] (3) Freshness preservation

[0126] The water shield from step (2) is removed and the soaking water on the water shield is fully squeezed out, and a room temperature aqueous solution consisting of 0.91% citric acid, 0.91% malic acid, 0.046% cysteine, and 0.046% reduced glutathione is added to the water shield in an amount of 1.1 times the weight of the water shield at this time, and the mixture is mixed thoroughly so that the water shield can fully absorb the solution, and then the water shield is removed.

[0127] (4) Classification

[0128] The water shield processed in step (3) is divided into four grades according to the length of petioles and leaves: S grade, M grade, L grade and general grade. During the grading and selection process, unqualified products with sand and mud mixed in the colloid of tender shoots and leaves and products that do not meet the specified grade are removed.

[0129] (5) The water shield retained after step (4) is pasteurized and then packaged.

[0130] After the processing of the above embodiments and comparative examples, the water shield was unpacked, stored in transparent vacuum closed tubes, and placed in a simulated continuous room temperature and sunshine environment for sensory testing. The test results after 30 days, 100 days, and 180 days were recorded. The standards for the sensory testing are shown in Table 1, and the test results are shown in Table 2:

[0131] Table 1

[0132]

[0133] Table 2

[0134]

[0135] From the above table, when the storage days are not very long, the freshness of Comparative Examples 1 to 3 is relatively close to that of Examples 1 to 5; however, when the storage time is extended to several months, Comparative Examples 1 to 3 deteriorate, especially in the color of water shield, while the freshness of Examples 1 to 5 does not decrease significantly, which fully demonstrates the pertinence of the step-by-step freshness treatment of this scheme in terms of color protection.

Claims

1. A method for preserving water shield, characterized in that: The following steps are included: (1) High temperature killing The fixing temperature is 90°C to 100°C, and the fixing time is 2 to 5 minutes; (2) Cooling and rinsing; Rinse the water shield processed in step (1) with cold water, and then soak it in cold water for 2 to 4 hours; (3) Acid preservation Adding an acid preservative solution to the water shield treated in step (2), wherein the acid preservative solution is prepared from citric acid and malic acid; (4) Classification The water shield processed in step (3) is screened and graded according to the length of petiole and leaf blade. (5) Color protection and freshness preservation Add a color-protecting and fresh-keeping liquid to the water shield retained in step (4), and after the treatment, remove the water shield and perform pasteurization treatment, wherein the color-protecting and fresh-keeping liquid is prepared from cysteine ​​and reduced glutathione.

2. The method for preserving water shield according to claim 1, characterized in that: The water temperature of the cold water in step (2) is 5°C to 20°C.

3. The method for preserving water shield according to claim 1, characterized in that: The mass concentration of the acid preservative solution in step (3) is 0.5-2%.

4. The method for preserving water shield according to claim 1, characterized in that: In step (3), 50 to 200 parts by weight of the acid preservative solution is added to every 100 parts by weight of the water shield.

5. The method for preserving water shield according to claim 1, characterized in that: The mass concentration of the color-protecting and fresh-keeping liquid in step (5) is 0.5-2%.

6. The method for preserving water shield according to claim 1, characterized in that: In step (5), 5 to 20 parts by weight of the color-protecting and fresh-keeping liquid is added to every 100 parts by weight of the water shield.

7. The method for preserving water shield according to claim 1, characterized in that: The method further comprises, The water shield processed in step (5) is packaged.

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