Method for delaying postharvest physiological deterioration of cassava and reducing superoxide anion levels in cassava by treatment with copper-containing solution

Abstract

The invention provides a method for delaying physiological deterioration of cassava after harvest and reducing the level of superoxide anion in cassava by treating with a copper-containing solution, belonging to the technical field of post-harvest preservation of cassava. The method is to treat cassava with a copper-containing solution to reduce the level of superoxide anion in cassava, so as to delay physiological deterioration of cassava after harvest, thereby effectively preventing physiological browning and deterioration of cassava after harvest, and thus facilitating the maintenance of good storage quality of cassava. The invention has strong practicability, is easy to operate, can effectively prolong the storage time of cassava, and has good development and application value in the storage, transportation and industrial production of cassava as an industrial raw material.

Description

Technical Field

[0001] The invention belongs to the technical field of post-harvest cassava preservation, and in particular relates to a method for delaying post-harvest physiological deterioration of cassava and reducing superoxide anion levels of cassava by treating with a copper-containing solution. Background Art

[0002] Cassava (Cassava) belongs to the Euphorbiaceae family, Manihot esculenta, is one of the world's three major tubers (cassava, potato, sweet potato), and is also a specialty crop in tropical regions. As a common industrial raw material, cassava tubers can be used to prepare industrial products such as alcohol, adhesives, and biofuels. Cassava has the characteristics of drought resistance, barrenness tolerance, wide adaptability, and does not compete with grain for land. Therefore, cassava is a high-yield and high-quality industrial raw material. Unlike other tuber crops, cassava tubers have a very short shelf life and usually begin to deteriorate 1 to 3 days after harvesting. This unique phenomenon is called "postharvest physiological deterioration (PPD)". During storage and processing, fresh cassava tissues quickly develop PPD (1 to 3 days), causing the tubers to brown and rot and deteriorate, thereby restricting the comprehensive industrial utilization of cassava after harvest, causing direct economic losses of more than US$200 million each year, and greatly restricting the development of the cassava industry. Effectively curbing the occurrence of PPD has become a major production problem that needs to be urgently solved in the development of the cassava industry.

[0003] The occurrence of cassava PPD is strongly associated with the level of reactive oxygen species. Studies have shown that the occurrence of cassava PPD is accompanied by the outbreak of various types of reactive oxygen species (ROS), including hydrogen peroxide (H2O2), superoxide anion (O2 - ), etc. These reactive oxygen levels are important markers for the post-harvest physiological deterioration of cassava. In most cases, researchers inhibit the outbreak of reactive oxygen to curb post-harvest physiological decay, such as calcium signals and plant hormones (such as jasmonate, abscisic acid, ethylene, gibberellin), reduced substances (such as melatonin, cyanogenic glycosides, phenylpropanoids, flavonoids, coumarins, carotenoids and other molecules) and proteases (such as polyphenol oxidase, phenylalanine ammonia lyase, peroxidase, etc.). The prior art also discloses that multiple chemical reagents such as cobalt chloride, potassium iodide, and ferrozine can effectively curb the post-harvest physiological deterioration of cassava, and there are some physical storage methods for post-harvest cassava tubers, such as freezing, low pressure, biofilm covering, sand burial, etc. Because physical methods are difficult to manage and control, the prevention and control effects are unstable, and the cost of organic chemical molecules such as hormones is too high. Therefore, it is necessary to continue to develop low-cost, efficient and safe chemical molecules that inhibit the post-harvest physiological deterioration of cassava. Summary of the invention

[0004] In view of the above problems, the present invention provides a method for delaying the physiological deterioration of cassava after harvest by treating with a copper-containing solution and reducing the level of superoxide anions in cassava, and specifically relates to a method for promoting (low concentration) or delaying (high concentration) the physiological deterioration of cassava after harvest by treating with a copper-containing solution and a method for reducing the level of superoxide anions in cassava by treating with a copper-containing solution (such as Bordeaux mixture). Through a chemical substance screening method, it is found that a copper ion and / or cuprous ion solution (such as Bordeaux mixture) effectively promotes or prevents the physiological deterioration of cassava after harvest, especially a high-concentration copper ion and / or cuprous ion solution (such as Bordeaux mixture) can effectively prevent the browning and deterioration of cassava after harvest. The method has the characteristics of strong practicability and simple operation for cassava storage, thereby extending the storage period of cassava, improving the value and economic benefits of cassava as an industrial raw material, and having good development and application prospects.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is:

[0006] A method for reducing the level of superoxide anions in cassava, wherein the method for reducing the level of superoxide anions in cassava is to contact the cassava with a copper-containing solution to reduce the level of superoxide anions in the cassava;

[0007] The copper-containing solution contains at least one of a compound containing copper ions and a compound containing cuprous ions; the total concentration of copper ions and / or cuprous ions in the copper-containing solution is greater than 10 mmol / L and less than 100 mmol / L;

[0008] That is, when the copper-containing solution contains only one or more compounds having copper ions, the total concentration of copper ions in the copper-containing solution is greater than 10 mmol / L and less than 100 mmol / L; when the copper-containing solution contains only one or more compounds having cuprous ions, the total concentration of cuprous ions in the copper-containing solution is greater than 10 mmol / L and less than 100 mmol / L; when the copper-containing solution contains both one or more compounds having copper ions and one or more compounds having cuprous ions, the total concentration of copper ions and cuprous ions in the copper-containing solution is greater than 10 mmol / L and less than 100 mmol / L;

[0009] The solvent of the copper-containing solution is water;

[0010] The cupric ions and / or cuprous ions in the copper-containing solution come from at least one of cuprous chloride, cupric chloride, copper sulfate or Bordeaux mixture.

[0011] Further, the total concentration of cupric ions and / or cuprous ions in the copper-containing solution is 25-100 mmol / L;

[0012] That is, when the copper-containing solution contains only one or more compounds having cupric ions, the total concentration of cupric ions in the copper-containing solution is 25~100mmol / L; when the copper-containing solution contains only one or more compounds having cuprous ions, the total concentration of cuprous ions in the copper-containing solution is 25~100mmol / L; when the copper-containing solution contains both one or more compounds having cupric ions and one or more compounds having cuprous ions, the total concentration of cupric ions and cuprous ions in the copper-containing solution is 25~100mmol / L.

[0013] Furthermore, when the copper-containing solution is Bordeaux liquid, the concentration of Bordeaux liquid is ≥1%, that is, the Bordeaux liquid powder contained in the Bordeaux liquid is ≥10 mg / mL, preferably 1-2.5%.

[0014] Further, the method for reducing the level of superoxide anion in cassava comprises the following specific steps:

[0015] 1) Harvesting: dig out the cassava, keep the cassava stem intact and the outer skin undamaged, and get the dug cassava;

[0016] 2) Cleaning: Clean and drain the cassava;

[0017] 3) Soaking: Soaking cassava in a copper solution to reduce the level of superoxide anions in cassava.

[0018] Furthermore, in step 3), the soaking time is 1 to 30 minutes;

[0019] The method for reducing the superoxide anion level of cassava also includes, after the immersion treatment with the copper-containing solution is completed, taking out the cassava and directly storing it at a temperature of 25±2° C. and a relative humidity of 65-85%.

[0020] A method for delaying physiological deterioration of cassava after harvest by treating with a copper-containing solution, the method comprising contacting cassava with the copper-containing solution to reduce the level of superoxide anions in the cassava, thereby delaying physiological deterioration of the cassava after harvest;

[0021] The copper-containing solution contains at least one of a compound containing copper ions and a compound containing cuprous ions; the total concentration of copper ions and / or cuprous ions in the copper-containing solution is greater than 10 mmol / L and less than 100 mmol / L;

[0022] That is, when the copper-containing solution contains only one or more compounds having copper ions, the total concentration of copper ions in the copper-containing solution is greater than 10 mmol / L and less than 100 mmol / L; when the copper-containing solution contains only one or more compounds having cuprous ions, the total concentration of cuprous ions in the copper-containing solution is greater than 10 mmol / L and less than 100 mmol / L; when the copper-containing solution contains both one or more compounds having copper ions and one or more compounds having cuprous ions, the total concentration of copper ions and cuprous ions in the copper-containing solution is greater than 10 mmol / L and less than 100 mmol / L;

[0023] The solvent of the copper-containing solution is water;

[0024] The cupric ions and / or cuprous ions in the copper-containing solution come from at least one of cuprous chloride, cupric chloride, copper sulfate or Bordeaux mixture.

[0025] Further, the total concentration of cupric ions and / or cuprous ions in the copper-containing solution is 25-100 mmol / L;

[0026] That is, when the copper-containing solution contains only one or more compounds having cupric ions, the total concentration of cupric ions in the copper-containing solution is 25~100mmol / L; when the copper-containing solution contains only one or more compounds having cuprous ions, the total concentration of cuprous ions in the copper-containing solution is 25~100mmol / L; when the copper-containing solution contains both one or more compounds having cupric ions and one or more compounds having cuprous ions, the total concentration of cupric ions and cuprous ions in the copper-containing solution is 25~100mmol / L.

[0027] Furthermore, when the copper-containing solution is Bordeaux liquid, the concentration of Bordeaux liquid is ≥1%, that is, the Bordeaux liquid powder contained in the Bordeaux liquid is ≥10 mg / mL, preferably 1-2.5%.

[0028] Furthermore, the method for delaying the physiological deterioration of cassava after harvest by treatment with a copper-containing solution comprises the following specific steps:

[0029] S1. Harvesting: dig out the cassava, keep the cassava stem intact and the outer skin undamaged, and get the dug cassava;

[0030] S2. Cleaning: Clean the dug cassava and drain it for later use;

[0031] S3. Soaking: Soak cassava in a copper solution to reduce the level of superoxide anions in cassava, thereby delaying the physiological deterioration of cassava after harvest.

[0032] Furthermore, in step S3, the soaking time is 1 to 30 minutes;

[0033] The method for delaying post-harvest physiological deterioration of cassava by treating with a copper-containing solution also includes taking out the cassava after the soaking treatment with the copper-containing solution and directly storing it at a temperature of 25±2° C. and a relative humidity of 65-85%.

[0034] The beneficial effects of the method for delaying postharvest physiological deterioration of cassava and reducing the level of superoxide anions in cassava by treating with a copper-containing solution of the present invention are:

[0035] Based on superoxide anion (O2 - ) is an important reason for the physiological deterioration of cassava after harvest. The method of reducing the level of superoxide anion in cassava by using the copper-containing solution of the present invention (such as containing at least one of a compound having copper ions and a compound having cuprous ions, such as Bordeaux mixture) can effectively and quickly reduce the level of superoxide anion, which is the main active oxygen component, and can significantly inhibit the occurrence of physiological deterioration of cassava after harvest at a certain concentration;

[0036] The method for reducing the level of superoxide anions in cassava is a method for quickly reducing superoxide anions by using a copper-containing solution, thereby effectively preventing the physiological deterioration of cassava after harvest. The collected fresh cassava can be soaked in the copper-containing solution, thereby effectively preventing the physiological deterioration of cassava after harvest.

[0037] The method of delaying the physiological deterioration of cassava after harvest by treating it with a copper-containing solution (such as a compound containing copper ions and a compound containing cuprous ions, such as Bordeaux mixture) can prevent the cassava from browning and rotting after harvest, significantly delay the occurrence of physiological deterioration of cassava after harvest, effectively extend the storage period of cassava, and improve the value and economic benefits of cassava industrial raw materials;

[0038] The method of delaying post-harvest physiological deterioration of cassava by treating it with a copper-containing solution (such as a compound containing copper ions and a compound containing cuprous ions, such as Bordeaux mixture) of the present invention can effectively inhibit post-harvest physiological decay, the reagent used is low in cost, the operation is simple, and the method has strong practicality.

[0039] The invention has strong practicability, is easy to operate, and can effectively prolong the storage time of cassava, and has good development and application value in the storage, transportation and industrial production of cassava as an industrial raw material.

[0040] The cassava treated by the method of the present invention can be used as an industrial raw material for the production of subsequent industrial products (such as alcohol, adhesives, biofuels, etc.). BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1It is a diagram of the effect of post-harvest physiological deterioration of cassava and a quantitative statistical diagram of post-harvest physiological browning of cassava after treatment with different concentrations of copper chloride aqueous solutions in Example 1 of the present invention (repeated for 4 different cassava slices); wherein, the left figure is a diagram of the effect of post-harvest physiological deterioration of cassava, and the right figure is a quantitative statistical diagram of post-harvest physiological browning of cassava; in the concentration of copper chloride aqueous solution (mM) in the left and right figures, 0 represents the control group (i.e., the concentration of copper chloride in the distilled water used for treatment is 0 mmol / L), 0.1 represents the first treatment group (i.e., the concentration of copper chloride in the copper chloride aqueous solution used for treatment is 0.1 mmol / L), 1 represents the second treatment group (i.e., the concentration of copper chloride in the copper chloride aqueous solution used for treatment is 1 mmol / L), 10 represents the third treatment group (i.e., the concentration of copper chloride in the copper chloride aqueous solution used for treatment is 10 mmol / L), 50 represents the fourth treatment group (i.e., the concentration of copper chloride in the copper chloride aqueous solution used for treatment is 50 mmol / L), 100 represents the fifth treatment group (i.e., the concentration of copper chloride in the copper chloride aqueous solution used in the treatment is 100 mmol / L);

[0042] Figure 2 It is a diagram and a quantitative statistical diagram of the physiological deterioration effect of cassava after being treated with different copper-containing solutions in Example 2 of the present invention (repeated for 10 different cassava slices); wherein, the left diagram is a diagram of the physiological deterioration effect of cassava after being harvested, and the right diagram is a quantitative statistical diagram; in both the left and right diagrams, distilled water represents the control group, cuprous chloride represents treatment group one (i.e., the concentration of cuprous chloride in the cuprous chloride aqueous solution used for treatment is 50 mmol / L), cupric chloride represents treatment group two (i.e., the concentration of cupric chloride in the cupric chloride aqueous solution used for treatment is 50 mmol / L), copper sulfate represents treatment group three (i.e., the concentration of copper sulfate in the copper sulfate aqueous solution used for treatment is 50 mmol / L), and Bordeaux mixture represents treatment group four (i.e., the concentration of Bordeaux mixture powder in the Bordeaux mixture used for treatment is 10 mg / mL);

[0043] Figure 3 The superoxide anion (O2) of cassava after being treated with different copper-containing solutions and distilled water for 10 min in Example 3 of the present invention - ) stained with nitro tetrazolium blue (NBT); wherein, distilled water represents the control group, cuprous chloride represents the experimental group 1 (i.e., the concentration of cuprous chloride in the cuprous chloride aqueous solution used for treatment is 50 mmol / L), cupric chloride represents the experimental group 2 (i.e., the concentration of cupric chloride in the cupric chloride aqueous solution used for treatment is 50 mmol / L), copper sulfate represents the experimental group 3 (i.e., the concentration of copper sulfate in the copper sulfate aqueous solution used for treatment is 50 mmol / L), and Bordeaux mixture represents the experimental group 4 (i.e., the concentration of Bordeaux mixture powder in the Bordeaux mixture used for treatment is 10 mg / mL);

[0044] Figure 4The superoxide anion (O2) in cassava per unit tissue after different time periods of treatment of cassava with copper chloride and control distilled water in Example 4 of the present invention. - ) with nitro blue tetrazolium (NBT) staining and absorbance values; the left figure shows the NBT staining of cassava tissue extracts at different periods after treatment with copper chloride and control distilled water, and the right figure shows the statistics of NBT staining absorbance values ​​per unit weight of tissue (3 biological replicates); among them, distilled water represents the control group, and copper chloride represents the treatment group (i.e., the concentration of copper chloride in the copper chloride aqueous solution used in the treatment group is 50 mmol / L). DETAILED DESCRIPTION

[0045] The technical solutions in the embodiments of the present invention are described clearly and completely below. In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention can also be implemented in other ways different from those described herein, and those skilled in the art can make similar generalizations without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0046] Cuprous chloride, cupric chloride, cupric sulfate, and nitrotetrazolyl blue chloride (NBT) were all analytically pure. Cuprous chloride, cupric chloride, and cupric sulfate were provided by Macklin's reagent. Bordeaux mixture powder was provided by American Shannon Co., Ltd. All distilled water used was deionized distilled water.

[0047] During the harvesting process, cassava is very prone to physical (mechanical) damage, and slicing is also a kind of mechanical (physical) damage to cassava, which can accelerate the deterioration of cassava after harvest. Therefore, in order to facilitate the observation of the whole process of cassava physiological deterioration and quickly obtain the test results, cassava slices are used as experimental materials in the embodiments of the present invention.

[0048] Example 1 A method for delaying postharvest physiological deterioration of cassava by copper chloride treatment

[0049] This embodiment is a method for controlling the physiological deterioration of cassava after harvest by copper chloride treatment, comprising the following specific steps:

[0050] S1. Harvesting: Carefully dig out the cassava, keeping the cassava stem intact and the outer skin undamaged, and get the dug cassava;

[0051] S2, cleaning: clean the dug cassava with clean water and drain it for later use, and prevent the outer skin of the cassava from being damaged during cleaning to obtain the cleaned cassava;

[0052] Slice: Slice the cleaned cassava into slices to obtain cassava slices with a thickness of 5-10mmol / L;

[0053] S3, soaking: the cassava slices were divided into six groups, namely control group and treatment group one to five, with about 4 cassava slices in each group (biological replicates);

[0054] Among them, the control group was immersed in distilled water;

[0055] Treatment groups one to six were immersed in copper chloride aqueous solutions with different concentration gradients; the concentration gradients of copper chloride in the copper chloride aqueous solutions were 0.1 mmol / L, 1 mmol / L, 10 mmol / L, 50 mmol / L, and 100 mmol / L, respectively.

[0056] During immersion, the volume of distilled water or copper chloride aqueous solution with different concentration gradients was 20 mL, and the immersion time was 2 min.

[0057] S4. Storage: After soaking, the treated cassava slices were placed in a culture room at 25±2°C and a relative humidity of 65-85%. The color changes of the cassava slices were observed and recorded at 0h, 24h and 48h. The results were as follows: Figure 1 shown.

[0058] Depend on Figure 1 As can be seen from the left figure, as time goes by, the browning of cassava slices in the control group deteriorates significantly. Treatment with copper chloride aqueous solution at a concentration of 0.1-10 mmol / L can promote the occurrence of post-harvest physiological browning deterioration in cassava from group 1 to group 3, especially after treatment with copper chloride aqueous solution at a concentration of 1 mmol / L, the browning enhancement effect is most obvious. However, as the concentration of copper chloride aqueous solution increases, copper chloride aqueous solution can significantly inhibit the post-harvest physiological deterioration browning of cassava, especially at a concentration of 50 mmol / L and above, the inhibitory effect is more obvious, and the higher the concentration, the more obvious the inhibitory effect.

[0059] The grayscale of cassava slices was analyzed by ImageJ software. Figure 1As shown in the right figure, it can be seen that the average grayscale of the cassava slices in the control group increased from the initial 39.4 to 65.8 (1.67 times) at 24h and 82.1 (2.08 times) at 48h, and the grayscale value of the cassava slices was significantly increased after treatment with a low concentration (0.1~1mmol / L) of copper chloride aqueous solution at 24h and 48h; when the copper chloride concentration was increased to 10 mmol / L, copper chloride began to inhibit the post-harvest physiological deterioration (the grayscale value at 48h was equivalent to the grayscale of the control), and the copper chloride aqueous solution at a concentration of 50 mmol / L could significantly inhibit the browning of cassava, and the copper chloride aqueous solution at a concentration of 100 mmol / L could almost completely inhibit the browning of cassava, and the browning grayscale values ​​at 24h and 48h were equivalent to those at 0h. These results indicate that low concentrations of copper chloride (<10mmol / L) can promote browning of cassava, while high concentrations (>10mmol / L) can effectively inhibit the post-harvest physiological deterioration of cassava tubers, especially concentrations of 50 mmol / L and above (including concentrations >100mmol / L that were not verified in this example) are more effective in inhibiting the post-harvest physiological deterioration of cassava tubers.

[0060] Example 2 Method for delaying postharvest physiological deterioration of cassava by treating with different cupric ion / cuprous ion compounds

[0061] This embodiment is a method for controlling the physiological deterioration of cassava after harvest by treating with different copper-containing solutions, including the following specific steps:

[0062] S1. Harvesting: Carefully dig out the cassava, keeping the cassava stem intact and the outer skin undamaged, and get the dug cassava;

[0063] S2, cleaning: clean the dug cassava with clean water and drain it for later use, and prevent the outer skin of the cassava from being damaged during cleaning to obtain the cleaned cassava;

[0064] Slice: Slice the cleaned cassava into slices to obtain cassava slices with a thickness of 5-10mmol / L;

[0065] S3, soaking: the cassava slices were divided into five groups, namely, control group and treatment group one to four, with about 10 cassava slices in each group (biological replicates);

[0066] Among them, the control group was immersed in distilled water;

[0067] Treatment groups 1 to 4 were treated with 50 mmol / L aqueous cuprous chloride solution, 50 mmol / L aqueous cupric chloride solution, 50 mmol / L aqueous copper sulfate solution, and 10 mg / mL Bordeaux mixture (i.e., 1% m / V), respectively.

[0068] During immersion, the volume of distilled water or different copper-containing solutions used was 20 mL, and the immersion time was 2 min.

[0069] S4. Storage: After soaking, the treated cassava slices were placed in a culture room at 25±2°C and a relative humidity of 65-85%. The color changes of the cassava slices were observed and recorded at 0h, 24h and 48h. The results were as follows: Figure 2 shown.

[0070] Depend on Figure 2 As can be seen from the left figure, the browning of cassava slices in the control group deteriorated significantly over time. The treatment groups 1 to 4 treated with different copper-containing solutions (cuprous chloride aqueous solution, cupric chloride aqueous solution, copper sulfate aqueous solution and Bordeaux mixture) can significantly inhibit the physiological deterioration and browning of cassava after harvest.

[0071] The grayscale of cassava slices was analyzed by ImageJ software. Figure 2 As shown in the right figure, it can be seen that the average gray scale of the cassava slices in the control group increased from 48.4 at 0h to 78.5 (1.62 times) at 24h and 112.6 (2.32 times) at 48h, while the average gray scale increased to 1.15, 1.16, 1.15 and 1.39 times of the initial gray scale at 24h and 1.59, 1.67, 1.63 and 1.77 times at 48h under the treatment of 50 mmol / L cuprous chloride aqueous solution, 50 mmol / L cupric chloride aqueous solution, 50 mmol / L copper sulfate aqueous solution and 1% Bordeaux mixture, respectively, which is much lower than the increase in gray scale after the distilled water treatment of the control group. These results show that different forms of copper ion / cuprous ion compounds can effectively inhibit the occurrence of post-harvest physiological deterioration browning of cassava.

[0072] Example 3 A method for rapidly reducing the level of superoxide anion in cassava by treating with different copper-containing solutions

[0073] Superoxide anion (O2 -) and other active oxygen bursts are important reasons for the physiological deterioration of cassava after harvest. In the study, nitro tetrazolium blue chloride (NBT) is often used to stain superoxide anions (blue), and the higher the level of superoxide anions, the deeper the blue. In this example, the newly collected cassava root slices in Example 1 were used for experiment. The control group was treated with distilled water immersion. Experimental groups 1 to 4 were treated with 50 mmol / L cuprous chloride aqueous solution, 50 mmol / L cupric chloride aqueous solution, 50 mmol / L copper sulfate aqueous solution and 10 mg / mL Bordeaux mixture for immersion. The cassava slices in the control group were adjacent to the cassava slices in experimental groups 1 to 4. During the immersion treatment, the volume of distilled water or copper-containing solution used was 20 mL, and the immersion time was 2 min. After the immersion treatment, the cassava slices were kept away from light for 30 min, and then 1 mg / mL nitro tetrazolium blue chloride (NBT) solution was taken out and added dropwise. They were stained at room temperature away from light for 10 min, and then photographed. The results are as follows Figure 3 shown.

[0074] Depend on Figure 3 It can be seen that the cassava slices in the control group treated with distilled water were significantly dyed blue, indicating that the level of superoxide anions in this part was high, while the cassava slices treated with cuprous chloride aqueous solution, cupric chloride aqueous solution, and copper sulfate aqueous solution hardly turned blue after NBT staining; similarly, the NBT staining of cassava slices treated with Bordeaux mixture also decreased significantly, indicating that the use of copper-containing solutions containing at least one of compounds with copper ions and compounds with cuprous ions, such as cuprous chloride, cupric chloride, copper sulfate, and Bordeaux mixture, can quickly reduce the level of superoxide anions in cassava tubers.

[0075] Example 4 A method for continuously reducing the level of superoxide anion in cassava by treating with different cupric ion / cuprous ion compounds

[0076] This embodiment is a method for treating different copper ion / cuprous ion compounds or mixtures to delay the physiological deterioration of cassava after harvest and a method for copper ion / cuprous ion to reduce the level of superoxide anion in cassava, including the following specific steps:

[0077] 1) Harvesting: dig out the cassava, keep the cassava stem intact and the outer skin undamaged, and get the dug cassava;

[0078] 2) Cleaning: Clean and drain the cassava and set aside. Be careful not to damage the outer skin of the cassava when cleaning.

[0079] 3) Soaking: Soak the cassava in distilled water and a 50 mmol / L copper chloride aqueous solution, respectively; the volume of distilled water or copper chloride aqueous solution used for each cassava soaking treatment is 20 mL, and the soaking time is 2 min;

[0080] 4) Storage: After the soaking treatment is completed, the cassava is taken out and placed directly in a culture room at 25±2℃ and a relative humidity of 65~85% for storage;

[0081] 5) Sampling: About 2 g of cassava tissues were collected from the distilled water control and copper chloride solution treatment at 0 h, 24 h, and 48 h after storage, with 3 replicates for each treatment and each time period;

[0082] 6) Extraction: After thoroughly mixing and grinding the cassava tissue with 2 mL of superoxide anion extraction solution (from the superoxide anion free radical detection kit R30342-100T), centrifuge at 4°C and 10,000 g for 10 min, and aspirate the supernatant;

[0083] 7) Detection: Mix 150 μL of supernatant with 50 μL of 0.5 mg / mL NBT solution, react at room temperature for 10 min, take a photo, and measure the absorbance at 630 nm (A630) in an ELISA reader;

[0084] 8) Calculation: The relative NBT staining value per unit weight (1 g) of tissue was calculated using the formula C = A630 / fresh weight × 2000 μL / 150 μL to display the level of superoxide anions in the tissue.

[0085] The dyeing condition after the extract reacts with NBT is as follows Figure 4 As shown in the left figure, the cassava tissue extract treated with distilled water in the control group was significantly stained with NBT at 0h, 24h and 48h, while the cassava tissue extract treated with copper chloride aqueous solution in the treatment group almost completely failed to turn NBT blue, which is consistent with the cassava chip staining results in Example 3. Further, the statistical results of A630 per unit weight of tissue show that Figure 4 In the right figure, at 0h, 24h and 48h stages, the cassava tissues treated with distilled water in the control group had higher absorbance values, while the A630 absorbance values ​​of the cassava tissues treated with copper chloride aqueous solution in the treatment group were significantly lower than those treated with distilled water, and there was no significant change in the values ​​in the three time periods, indicating that copper chloride can sustainably and effectively curb the production of superoxide anions.

[0086] Furthermore, since cuprous chloride, cupric sulfate, Bordeaux mixture, etc. contain a copper-containing solution containing at least one of a compound having copper ions and a compound having cuprous ions, the NBT staining result after treating cassava is similar to that of cupric chloride, it can be inferred that cuprous chloride, cupric sulfate, Bordeaux mixture, etc. contain a copper-containing solution containing at least one of a compound having copper ions and a compound having cuprous ions can also effectively and continuously curb the generation of superoxide anions.

[0087] Based on the fact that the level of active oxygen is an important reason for the physiological deterioration of cassava after harvest, the copper-containing solution effectively and quickly reduces the level of superoxide anion, the main active oxygen component, and can significantly inhibit the occurrence of physiological deterioration of cassava after harvest at a certain concentration. Therefore, the present invention provides a method for delaying the physiological deterioration of cassava after harvest by treating with a copper-containing solution and a method for reducing the level of superoxide anion in cassava, which uses a copper-containing solution to quickly reduce superoxide anion, thereby effectively curbing the occurrence of physiological deterioration of cassava after harvest. The collected fresh cassava tubers are soaked in a copper-containing solution to effectively reduce the level of superoxide anion and avoid the occurrence of physiological deterioration of cassava after harvest.

[0088] Examples 5-8 A method for delaying postharvest physiological deterioration of cassava by treating with a copper-containing solution and a method for reducing superoxide anion levels in cassava

[0089] Examples 5 to 8 are respectively a method for delaying postharvest physiological deterioration of cassava by treatment with a copper-containing solution and a method for reducing the level of superoxide anion in cassava, which are basically the same as Example 1, and a method for reducing the level of superoxide anion in cassava by cupric chloride, which is basically the same as Example 1, except that some process parameters are different, as shown in Tables 1 to 4 for details:

[0090] Table 1 List of process parameters in Examples 5 to 8

[0091]

[0092] Table 2 List of process parameters in Examples 9 to 12

[0093]

[0094] Table 3 List of process parameters in Examples 13 to 16

[0095]

[0096] Table 4 List of process parameters in Examples 17 to 20

[0097]

[0098] The contents and results of other parts of Examples 5 to 20 are basically the same as those of Example 1 and will not be repeated here.

[0099] Obviously, the described embodiments are only some embodiments of the present invention, not all 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.

Claims

1. A method for reducing the level of superoxide anion in cassava to delay the physiological deterioration of cassava, characterized in that: The method for reducing the level of superoxide anion in cassava is to contact the cassava with a copper-containing solution to reduce the level of superoxide anion in cassava; the physiological deterioration is physiological browning; The copper-containing solution contains at least one of a compound containing copper ions and a compound containing cuprous ions; the total concentration of copper ions and / or cuprous ions in the copper-containing solution is greater than 10 mmol / L and less than 100 mmol / L; The solvent of the copper-containing solution is water; The cupric ions and / or cuprous ions in the copper-containing solution come from at least one of cuprous chloride, cupric chloride, copper sulfate or Bordeaux mixture.

2. The method for reducing the level of superoxide anion in cassava to delay the physiological deterioration of cassava according to claim 1, characterized in that: The total concentration of cupric ions and / or cuprous ions in the copper-containing solution is 25-100 mmol / L.

3. The method for reducing the level of superoxide anion in cassava to delay the physiological deterioration of cassava according to claim 1, characterized in that: When the copper-containing solution is Bordeaux liquid, the concentration of Bordeaux liquid shall be ≥ 1%.

4. The method for reducing the level of superoxide anion in cassava to delay the physiological deterioration of cassava according to any one of claims 1 to 3, characterized in that: The method for reducing the level of superoxide anions in cassava comprises the following specific steps: 1) Harvesting: dig out the cassava, keep the cassava stem intact and the outer skin undamaged, and get the dug cassava; 2) Cleaning: Clean and drain the cassava; 3) Soaking: Soaking cassava in a copper solution to reduce the level of superoxide anions in cassava.

5. The method for reducing the level of superoxide anion in cassava to delay the physiological deterioration of cassava according to claim 4, characterized in that: In step 3), the soaking time is 1 to 30 minutes; The method for reducing the superoxide anion level of cassava also includes taking out the cassava and directly storing it after the immersion treatment with the copper-containing solution is completed.

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