Method for delaying postharvest physiological deterioration of cassava and reducing superoxide anion levels in cassava by ferrozine treatment

Abstract

The present invention provides a method for delaying the post-harvest physiological deterioration of cassava by ferrozine treatment and reducing the level of superoxide anion in cassava, which belongs to the technical field of post-harvest preservation of cassava. The method for delaying the post-harvest physiological deterioration of cassava by ferrozine treatment and reducing the level of superoxide anion in cassava is to contact and treat cassava with a ferrozine solution to reduce the level of superoxide anion in cassava, thereby effectively preventing the post-harvest physiological browning and deterioration of cassava, and thus facilitating the maintenance of good storage quality of cassava. The present invention is highly practical, easy to operate, and can effectively extend the storage time of cassava, and has good development and application value in the links of 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 the level of superoxide anions in cassava by treating with ferrozine. Background Art

[0002] Cassava (Manihot esculenta Crantz) belongs to the Euphorbiaceae family, Manihot esculenta, and is one of the world's three major tubers (cassava, potato, and 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)". PPD is prone to occur in fresh cassava tissues during processing and storage, resulting in tuber dehydration, browning, and rotting. The storage period of fresh cassava is extremely short (1 to 2 days), which restricts the comprehensive industrial utilization of cassava after harvest and seriously affects its value as an industrial raw material. Therefore, PPD is currently a bottleneck restricting the development of the cassava industry.

[0003] Based on the important impact of cassava PPD on the development of the cassava industry, domestic and foreign scholars have conducted a lot of research on cassava PPD in recent years. Zhang Peng and Ling Erjun's research group expressed egg white lysozyme (HEWL) in cassava to inhibit the enzymatic activity of polyphenol oxidase, which can significantly delay the occurrence of PPD, providing new ideas and technologies for the preservation of cassava after harvest. In addition, by exogenous application of abscisic acid (ABA), it was confirmed that ABA can effectively delay the occurrence of post-harvest decay of cassava, and a regulatory model for ABA to delay post-harvest decay of cassava by regulating the accumulation of reactive oxygen species was proposed. There are other methods for storing post-harvest cassava tubers in the field, such as sand burial and trench preservation. These burial methods can extend the storage period of fresh cassava as an industrial raw material. Although this technology can extend the shelf life of cassava to 2 months, cassava tubers will deteriorate after storage and are no longer suitable as raw materials for industrial production. Because traditional methods require too much labor, management is difficult, and the prevention and control effect is unstable, they cannot be used on a large scale. Summary of the invention

[0004] In view of the above problems, the present invention provides a method for delaying the post-harvest physiological deterioration of cassava and reducing the level of superoxide anion in cassava by treating ferrozine. Through a chemical substance screening method, it is found that ferrozine has good effect in preventing and treating the post-harvest physiological deterioration of cassava, has the characteristics of strong practicability and simple operation for cassava storage, can effectively prevent the browning and deterioration of cassava after harvest, thereby extending the storage period of cassava, improving the value and economic benefits of cassava as an industrial raw material, and has good development and application prospects.

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

[0006] A method for delaying post-harvest physiological deterioration of cassava by treating with ferrozine, the method comprising contacting fresh cassava with a ferrozine solution to delay post-harvest physiological deterioration of the cassava; wherein the contact may be any method of contacting the cassava with ferrozine, such as soaking, infiltration or immersion;

[0007] Post-harvest decay of cassava is mainly a first-stage physiological deterioration and a second-stage soft rot caused by microorganisms. The present invention found that ferrozine mainly slows down the first stage of post-harvest physiological decay of cassava, including physiological deterioration such as browning, and ultimately achieves the purpose of delaying post-harvest physiological deterioration of cassava.

[0008] Furthermore, the concentration of the ferrozine solution is >0.1 mg / mL, preferably 1-10 mg / mL.

[0009] Furthermore, the solvent of ferrozine is water.

[0010] Furthermore, the method comprises washing and draining the cassava, then soaking it in a ferrozine aqueous solution, taking it out and directly storing it to prevent the physiological deterioration of the cassava after harvest. The specific steps are as follows:

[0011] 1) Harvesting: dig out the cassava, keep the cassava stem intact and the outer skin undamaged, and get the dug cassava;

[0012] 2) Cleaning: Clean and drain the cassava and set aside. Be careful not to damage the outer skin of the cassava when cleaning.

[0013] 3) Soaking: Soak the cassava in feroxine solution;

[0014] 4) Storage: After the soaking process is completed, take out the cassava and place it directly in the storage room for storage.

[0015] Further, in step 3), the volume of the feroxine solution used for each cassava soaking treatment is 15-25 mL;

[0016] The soaking time is 1~30min;

[0017] In step 4), the storage temperature is 25±2°C and the relative humidity is 65~85%.

[0018] A method for reducing the level of superoxide anions in cassava by ferrozine, the method comprising contacting collected fresh cassava with a ferrozine solution to reduce the level of superoxide anions in the cassava; wherein the contacting can be any method that can contact the cassava with ferrozine, such as soaking, infiltration or immersion.

[0019] Further, the concentration of the ferrozine solution is >0.1 mg / mL, preferably 1 to 10 mg / mL;

[0020] The detection method of superoxide anion level in cassava was NBT staining method;

[0021] In the NBT staining method, the NBT staining solution is a water solvent, and the concentration of NBT is 1 mg / mL.

[0022] Furthermore, the solvent of ferrozine is water.

[0023] Furthermore, the method comprises washing and draining the cassava, and then soaking the cassava in a ferrozine aqueous solution to reduce the level of superoxide anions in the cassava. The specific steps are as follows:

[0024] 1) Harvesting: dig out the cassava, keep the cassava stem intact and the outer skin undamaged, and get the dug cassava;

[0025] 2) Cleaning: Clean and drain the cassava;

[0026] 3) Soaking: Soak the cassava in feroxine solution to reduce the level of superoxide anion in cassava.

[0027] Further, in step 3), the volume of the feroxine solution used for each cassava soaking treatment is 15-25 mL;

[0028] The soaking time is 1 to 30 minutes.

[0029] The beneficial effects of the method of delaying the post-harvest physiological deterioration of cassava and reducing the level of superoxide anions in cassava by ferrozine treatment of the present invention are:

[0030] The present invention uses ferrozine to delay the physiological deterioration of cassava after harvest, which can prevent the cassava from browning and rotting after harvest, significantly delay the occurrence of physiological deterioration of cassava after harvest, effectively prolong the storage period of cassava, and improve the value and economic benefits of cassava industrial raw materials;

[0031] The method of delaying post-harvest physiological deterioration of cassava by treating with ferrozine of the present invention can effectively inhibit post-harvest physiological decay, and the reagents used are low in cost, easy to operate, and highly practical.

[0032] 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 ferrozine of the present invention 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;

[0033] The method of reducing the level of superoxide anions in cassava by ferrozine provides a method for using ferrozine to quickly reduce superoxide anions and effectively curb the post-harvest physiological deterioration of cassava. The collected fresh cassava tubers can be soaked in a ferrozine aqueous solution to effectively avoid the post-harvest physiological deterioration of cassava.

[0034] 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.

[0035] 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

[0036] Figure 1 It is a diagram of the physiological deterioration effect of postharvest cassava after treatment with the ferrozine aqueous solution in Example 1 of the present invention; wherein, in the concentration coordinate of ferrozine (mg / mL), 0 represents the control group (i.e., the concentration of ferrozine in the distilled water used for treatment is 0 mg / mL), 0.01 represents the first group of ferrozine treatment groups (i.e., the concentration of the ferrozine aqueous solution used for treatment is 0.01 mg / mL), 0.1 represents the second group of ferrozine treatment groups (i.e., the concentration of the ferrozine aqueous solution used for treatment is 0.1 mg / mL), 1 represents the third group of ferrozine treatment groups (i.e., the concentration of the ferrozine aqueous solution used for treatment is 1 mg / mL), and 10 represents the fourth group of ferrozine treatment groups (i.e., the concentration of the ferrozine aqueous solution used for treatment is 10 mg / mL);

[0037] Figure 2 It is a quantitative statistical graph of postharvest physiological browning of cassava after treatment with the ferrozine aqueous solution in Example 1 of the present invention; wherein, in the concentration coordinate of ferrozine (mg / mL), 0 represents the control group (i.e., the concentration of ferrozine in the distilled water used for treatment is 0 mg / mL), 0.01 represents the first group of ferrozine treatment groups (i.e., the concentration of the ferrozine aqueous solution used for treatment is 0.01 mg / mL), 0.1 represents the second group of ferrozine treatment groups (i.e., the concentration of the ferrozine aqueous solution used for treatment is 0.1 mg / mL), 1 represents the third group of ferrozine treatment groups (i.e., the concentration of the ferrozine aqueous solution used for treatment is 1 mg / mL), and 10 represents the fourth group of ferrozine treatment groups (i.e., the concentration of the ferrozine aqueous solution used for treatment is 10 mg / mL);

[0038] Figure 3 The dyeing effect diagram and dyeing statistical diagram of cassava superoxide anion after treatment with ferrozine aqueous solution and distilled water for 30 minutes in Example 2 of the present invention; the left figure is the dyeing effect diagram, and the right figure is the NBT dyeing statistical diagram; distilled water represents the control group, and ferrozine represents the experimental group. DETAILED DESCRIPTION

[0039] 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.

[0040] Pheromone and nitrotetrazolyl blue chloride (NBT) were both domestic analytical grade. Pheromone was provided by Sinopharm Chemical Reagent Co., Ltd. All distilled water used was deionized distilled water.

[0041] 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.

[0042] Example 1 A method for delaying postharvest physiological deterioration of cassava by treating with ferrozine

[0043] This embodiment is a method for delaying postharvest physiological deterioration of cassava by treating with ferrozine, comprising the following specific steps:

[0044] S1. Harvesting: Carefully dig out the cassava, keeping the cassava stem intact and the outer skin undamaged, and get the dug cassava;

[0045] 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;

[0046] S3, slicing: slicing the cleaned cassava into cassava slices with a thickness of 5-10 mm;

[0047] S4, soaking: the cassava slices were divided into five groups, from one to four ferrozine-treated groups, with about 20 cassava slices in each group (biological replicates);

[0048] Among them, the control group was immersed in distilled water;

[0049] The first to fourth ferrozine-treated groups were immersed in ferrozine aqueous solutions with different concentration gradients; the concentration gradients of the ferrozine aqueous solution were 0.01 mg / mL, 0.1 mg / mL, 1 mg / mL, and 10 mg / mL, respectively.

[0050] During soaking, the volume of distilled water or ferrozine aqueous solution with different concentration gradients is 20 mL. After soaking for 30 minutes, the samples are taken out and placed in a plastic tray.

[0051] S5. Storage: After soaking, the treated cassava slices were placed in a culture room at 25±2°C and a relative humidity of 65-85% for storage. The color changes of the cassava slices were observed and recorded at 0h, 24h and 48h. The results were as follows: Figure 1 The grayscale of cassava slices was analyzed by ImageJ software, and the results were as follows Figure 2 shown.

[0052] Depend on Figure 1 and Figure 2 It can be seen that in the control group, ferrozine treatment group 1 (i.e., ferrozine concentration of 0.01 mg / mL) and ferrozine treatment group 2 (i.e., ferrozine concentration of 0.1 mg / mL), the cassava slices all turned brown at 24 hours of storage, and the degree of browning of the cassava slices gradually increased with time, indicating that compared with the control group, low concentration of ferrozine (i.e., concentration ≤0.1 mg / mL) failed to delay the physiological deterioration of cassava after harvest.

[0053] In the three ferrozine treatment groups (i.e., ferrozine concentration of 1 mg / mL), although the cassava slices turned brown at the 24th hour of storage, the degree of browning was less than that of the control group at 48 hours of storage, indicating that compared with the control group, medium concentration of ferrozine can delay the physiological deterioration of cassava after harvest.

[0054] Furthermore, in the four groups treated with ferrozine (i.e., the concentration of ferrozine was 10 mg / mL), the cassava roots began to brown at 48 hours of storage, but the degree of browning was significantly less than that of the control group. This shows that compared with the control group, high concentrations of ferrozine (i.e., concentrations ≥ 10 mg / mL) can significantly delay the physiological deterioration of cassava after harvest, and the effect is obvious.

[0055] Example 2 A method of reducing superoxide anion (O2 - ) Horizontal method

[0056] Superoxide anion (O2 - ) is an important reason for the physiological deterioration of cassava after harvest. Nitrotetrazolyl blue chloride (NBT) is often used in research to stain superoxide anions (blue). The higher the level of superoxide anions, the darker the blue.

[0057] In this example, the newly collected cassava root slices in Example 1 were used for experiment. The control group was treated by soaking in distilled water, and the experimental group was treated by soaking in a 10 mg / mL ferrozine aqueous solution. The cassava slices in the control group and the cassava slices in the experimental group were adjacent slices, as follows:

[0058] S1. Harvesting: Carefully dig out the cassava, keeping the cassava stem intact and the outer skin undamaged, and get the dug cassava;

[0059] 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;

[0060] S3, slicing: slicing the cleaned cassava into cassava slices with a thickness of 5-10 mm;

[0061] S4. Soaking: The cassava slices were divided into seven groups, namely control group and experimental group, with about 20 cassava slices in each group (biological replicates);

[0062] Among them, the control group was immersed in distilled water;

[0063] The experimental group was immersed in a 10 mg / mL ferrozine aqueous solution;

[0064] When soaking, the volume of distilled water or ferrozine aqueous solution used is 20 mL. After soaking for 30 minutes, take out and place in a plastic tray;

[0065] S5. Storage: After soaking, the treated cassava slices were placed in a culture room at 25±2°C and a relative humidity of 65-85% for storage. After 30 min of storage, the slices were taken out and the changes of superoxide anions were detected. The measurement was repeated 3 times for each group.

[0066] S6. Determination of superoxide anion content in cassava: Take the treated cassava slices in the above experimental group and control group, spray 1 mg / mL nitrotetrazolyl blue chloride (NBT) aqueous solution evenly on the surface of the cassava slices, and after color development at room temperature and in the dark for 30 minutes, observe the color development of superoxide anion in cassava, and use Image J software to analyze the gray value of the stained cassava slices. The results are shown in Figure 3 .

[0067] Depend on Figure 3It can be seen that in the control group, the surface of the cassava slices had a very obvious blue color reaction, indicating that its superoxide anion content was high. In the experimental group, the cassava slices had only a weak color reaction, and the blue depth was significantly less than that of the control group, indicating that the surface superoxide anion content was low. These results show that compared with the control group, cassava treated with ferrozine can effectively inhibit the production of superoxide anions in cassava cells, thereby delaying the physiological deterioration of cassava, and the effect is obvious.

[0068] Based on the fact that the level of active oxygen is an important cause of the physiological deterioration of cassava after harvest, ferrozine 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. Therefore, the present invention provides a method for delaying the physiological deterioration of cassava after harvest and reducing the level of superoxide anion in cassava by ferrozine treatment, which uses ferrozine to quickly reduce superoxide anion, thereby effectively curbing the occurrence of physiological deterioration of cassava after harvest. The collected fresh cassava is soaked in a ferrozine aqueous solution to effectively reduce the level of superoxide anion and avoid the occurrence of physiological deterioration of cassava after harvest.

[0069] Example 3 A method for delaying postharvest physiological deterioration of cassava and reducing superoxide anion levels in cassava by treating with ferrozine

[0070] This embodiment is a method for delaying postharvest physiological deterioration of cassava and reducing superoxide anion levels in cassava by ferrozine treatment, comprising the following specific steps:

[0071] 1) Harvesting: dig out the cassava, keep the cassava stem intact and the outer skin undamaged, and get the dug cassava;

[0072] 2) Cleaning: Clean and drain the cassava and set aside. Be careful not to damage the outer skin of the cassava when cleaning.

[0073] 3) Soaking: Soaking the cassava in a 10 mg / mL ferrozine aqueous solution to reduce the level of superoxide anions in the cassava; wherein the volume of the ferrozine aqueous solution used for each cassava soaking treatment is 20 mL, and the soaking treatment time is 30 min;

[0074] 4) Storage: After the soaking treatment is completed, the cassava is taken out and directly placed in a culture room at 25±2℃ and relative humidity of 65~85% for storage.

[0075] In this embodiment, ferrozine is used to treat cassava, thereby reducing the level of superoxide anions and preventing the occurrence of postharvest physiological decay of cassava.

[0076] Examples 4-7 Methods for delaying postharvest physiological deterioration of cassava and reducing superoxide anion levels in cassava by ferrozine treatment

[0077] Examples 4 to 7 are respectively a method for treating cassava with ferrozine to delay postharvest physiological deterioration and reduce the level of superoxide anion in cassava, which is basically the same as Example 3, except that some process parameters are different, as shown in Table 1:

[0078] Table 1 List of process parameters in Examples 4 to 7

[0079]

[0080] The contents and results of other parts of Examples 4 to 7 are the same as those of Example 3 and will not be repeated here.

[0081] 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 delaying postharvest physiological deterioration of cassava by ferrozine treatment, characterized in that: The method for delaying the physiological deterioration of cassava after harvest by ferrozine treatment is to contact cassava with ferrozine solution to delay the physiological deterioration of cassava after harvest; The concentration of the ferrozine solution is 1-10 mg / mL; the solvent of ferrozine is water.

2. The method for delaying postharvest physiological deterioration of cassava by ferrozine treatment according to claim 1, characterized in that: The method for delaying the post-harvest physiological deterioration of cassava by ferrozine treatment 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: Soak the cassava in feroxine solution; 4) Storage: After the soaking process is completed, remove the cassava and store it directly.

3. The method for delaying postharvest physiological deterioration of cassava by ferrozine treatment according to claim 2, characterized in that: In step 3), the soaking time is 1 to 30 minutes; In step 4), the storage temperature is 25±2°C and the relative humidity is 65~85%.

4. A method for reducing the level of superoxide anions in cassava by using ferrozine to delay the physiological deterioration of cassava after harvest, characterized in that: The method of reducing the level of superoxide anions in cassava by ferrozine is to contact cassava with a ferrozine solution to reduce the level of superoxide anions in cassava; The concentration of the ferrozine solution is 10 mg / mL; the solvent of ferrozine is water.

5. The method of claim 4 for reducing the level of superoxide anion in cassava to delay the physiological deterioration of cassava after harvest by using ferrozine, characterized in that: The method for reducing the level of superoxide anions in cassava by ferrozine 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: Soak the cassava in feroxine solution to reduce the level of superoxide anion in cassava.

6. The method of claim 5 for reducing the level of superoxide anion in cassava to delay the physiological deterioration of cassava after harvest by using ferrozine, characterized in that: In step 3), the soaking time is 1 to 30 minutes.

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