Sweet potato storage and preservation method

Abstract

The invention discloses a sweet potato storage and preservation method, and belongs to the technical field of sweet potato storage and preservation. The sweet potato storage and fresh-keeping method comprises the following steps: (1) putting sweet potatoes into a fixing unit (5) for pretreatment to obtain pretreated sweet potatoes; (2) putting the pretreated sweet potatoes into a fresh-keeping soaking pool (12), and soaking the sweet potatoes in a hyaluronic acid fermentation liquor solution for 20-30 minutes to obtain soaked sweet potatoes; and (3) taking out the soaked sweet potatoes, air-drying the sweet potatoes through an air sweeping mechanism (10), and storing the sweet potatoes in a storage mechanism (3). The hyaluronic acid fermentation liquor is applied to the storage and fresh-keeping process of the sweet potatoes for the first time, and hyaluronic acid in the hyaluronic acid fermentation liquor, various amino acids, glucose and other substances have a synergistic effect, so that the moisture loss of the sweet potatoes and the rotting morbidity of the sweet potatoes are better reduced, and the storage period of the sweet potatoes can be more effectively prolonged. Moreover, the hyaluronic acid fermentation liquor is used as a fresh-keeping preparation, so that the fresh-keeping agent is green and safe.

Description

Technical Field

[0001] The invention relates to a sweet potato storage and fresh-keeping method, and belongs to the technical field of sweet potato storage and fresh-keeping. Background Art

[0002] Sweet potatoes are important food, economic and industrial crops in the world. They are widely planted around the world because of their high yield, rich nutrition and strong adaptability. Newly harvested sweet potatoes have high water content, thin skin and vigorous respiration, which require strict conditions in the storage process. Any small negligence may cause the tubers to shrink, rot and deteriorate, lose their commercial value, and cause serious economic losses. In addition, the supply of sweet potatoes is affected by seasonality, and the price difference between off-season and peak season is large. Therefore, storage is needed to ensure the long-term supply of sweet potatoes and maximize their economic value.

[0003] At present, the common methods to extend the storage period of sweet potatoes include high temperature healing, sulfur fumigation, spraying carbendazim and quicklime to slow down the shrinkage and decay of tubers. However, high temperature healing has high requirements on the structure of storage warehouses, and it is expensive and difficult to popularize; sulfur fumigation, carbendazim and quicklime will leave residues in potato peels and the environment, causing secondary pollution and green safety issues.

[0004] Hyaluronic acid (HA), also known as hyaluronic acid, is a high molecular weight linear macromolecular acidic mucopolysaccharide. There are hydrogen bonds between the monosaccharides in the hyaluronic acid molecular chain. Low concentrations of hyaluronic acid can form a unique honeycomb network structure that allows it to absorb about 1000 times its own water. It has a strong water retention and moisture lock function and is called a natural moisturizing factor. Hyaluronic acid can effectively promote crop growth, increase organic matter accumulation, and enhance crop stress resistance and storage resistance, but the preservation cost of hyaluronic acid is very high. Therefore, providing a simple, convenient and low-cost sweet potato storage method is extremely important for the market supply and industrial development of sweet potatoes. Summary of the invention

[0005] In view of the deficiencies in the prior art, the object of the present invention is to provide a method for storing and preserving sweet potatoes, so as to prolong the storage and preservation time of the sweet potatoes.

[0006] In order to solve the above technical problems, the technical solution provided by the present invention is: A method for storing and preserving sweet potatoes comprises the following steps: (1) placing the sweet potatoes in a fixed unit (5) for pretreatment to obtain pretreated sweet potatoes; (2) placing the pretreated sweet potatoes into a fresh-keeping soaking tank (12) and soaking them in the hyaluronic acid fermentation solution for 20-30 minutes to obtain soaked sweet potatoes; (3) The soaked sweet potatoes are picked up, air-dried by the air sweeping mechanism (10), and stored in the storage mechanism (3).

[0007] Furthermore, in step (1), the pretreatment operation is: putting the sweet potatoes into a water storage tank (9), soaking them in clean water, then lifting them up, then rinsing them through a spray head (11), and finally air-drying them through an air sweeping mechanism (10). Air drying can save time for natural drying and improve efficiency.

[0008] Furthermore, in step (2), the hyaluronic acid fermentation liquid solution is prepared by diluting the hyaluronic acid fermentation liquid with water by 100-1000 times. The effective effect of hyaluronic acid fermentation liquid is generally 100-1000 times after dilution with water. If the dilution multiple is too high, the preservation effect is poor. If the dilution multiple is too low, the cost will be increased and the efficacy will also be reduced.

[0009] Furthermore, in step (2), the hyaluronic acid fermentation broth solution is prepared by diluting the hyaluronic acid fermentation broth with water by 500-700 times.

[0010] Furthermore, the hyaluronic acid content in the hyaluronic acid fermentation liquid is 1%, and the water content is ≥90%.

[0011] Furthermore, the hyaluronic acid fermentation broth includes the following components: amino acids, glucose, and glucose oxidase.

[0012] Furthermore, the total content of the amino acids, glucose and glucose oxidase is 1-1.5%.

[0013] The amino acids in the hyaluronic acid fermentation broth can extend the shelf life of sweet potatoes, promote cell metabolism, slow down tissue aging, and thus extend the shelf life of sweet potatoes. Glucose has a certain hydrophilicity and can combine with water molecules to retain moisture, reduce water loss, maintain a fresh taste and texture, and can also provide certain nutrients for microorganisms. However, at a suitable concentration, this nutrient supply is not enough to support the large-scale reproduction of microorganisms. Instead, it will inhibit the growth and metabolism of some harmful microorganisms to a certain extent, reduce the corruption of microorganisms on sweet potatoes, and glucose can regulate the osmotic pressure of food, change the environment of microbial cells, and affect the normal physiological activities of microorganisms, thereby playing a role in preservation; glucose also participates in the Maillard reaction, which can improve the color and flavor of food to a certain extent, so that the food maintains a good appearance and taste during storage, which helps to extend the shelf life of sweet potatoes. Glucose oxidase, as an ideal deoxidizing preservative, can effectively prevent the occurrence of oxidation, and can also prevent further oxidation of sweet potatoes that have been partially oxidized and deteriorated.

[0014] Furthermore, the amino acids include phenylalanine, glutamic acid, lysine, valine and glycine.

[0015] Furthermore, the total content of amino acids is 0.3-0.5%.

[0016] Phenylalanine can inhibit the growth of decay bacteria, slow down the decay rate, and activate the antioxidant enzymes of fruits and vegetables, improve the antioxidant properties of sweet potatoes, and extend the shelf life. Glutamic acid and lysine also have food preservation effects. Lysine can enhance its water retention and improve the quality of sweet potatoes. Valine is a branched-chain amino acid with antibacterial and antioxidant effects and has a good food preservation effect. Glycine is acidic and can reduce the pH value of food, inhibit the growth of bacteria and mold to a certain extent, and is widely used in the fields of food, medicine, and cosmetics. Glycine also has an antioxidant effect. It can stabilize the oxygen molecules in sweet potatoes by capturing free radicals, thereby delaying the oxidation reaction and effectively preventing corruption.

[0017] Furthermore, in step (3), the storage mechanism is a dark incubator, and the temperature inside the incubator is maintained at 11-13° C. and the relative humidity is maintained at 60-80%.

[0018] A device for storing and preserving sweet potatoes comprises a pulley mechanism (1) and a flushing mechanism (7); a cable (4) is provided at the bottom of the pulley mechanism (1); the other end of the cable (4) is fixedly connected to a fixing unit (5); a spray head (11) is fixedly provided on the flushing mechanism (7); a fresh-keeping soaking tank (12) is fixedly provided on the right side of a water storage tank (9); an air inlet (6) and an air outlet (2) are fixedly provided on the upper part of the flushing mechanism (7); and an air sweeping mechanism (10) is fixedly provided on the air inlet (6).

[0019] Furthermore, the flushing mechanism (7) comprises a water tank (9) and a spray head (11), wherein the water tank (9) comprises a filter screen (8) which can be raised and lowered. The sweet potatoes are soaked in the water tank to wash away most of the mud and sand, and then the surface of the sweet potatoes is cleaned by spraying with the spray head. The filter screen can filter out mud and sand and other impurities after the sweet potatoes are soaked and rinsed, thereby reducing the pollution of the clean water tank and the waste of water resources. The filter screen is subsequently cleaned to clean the impurities on the surface of the filter screen, thereby ensuring the filtering efficiency of the filter screen and realizing the repeated use of the water tank and the filter screen. The air sweeping mechanism can accelerate the air drying speed of the sweet potatoes, save the time of natural drying, and improve efficiency.

[0020] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention is the first to apply hyaluronic acid fermentation liquid to the storage and preservation process of sweet potatoes, effectively preventing the loss of water and weight of sweet potato tubers after harvest, and significantly reducing the incidence of tuber rot during the storage of sweet potatoes. In addition, the use of hyaluronic acid fermentation liquid as a preservative is green and safe.

[0021] (2) The hyaluronic acid fermentation liquid used in the present invention contains, in addition to the effective ingredient hyaluronic acid, a variety of amino acids and glucose and other substances. Hyaluronic acid works synergistically with these substances to better reduce the water loss of sweet potatoes and the incidence of tuber rot, and can more effectively extend the storage period of tubers.

[0022] (3) The method provided by the present invention is to dilute the hyaluronic acid fermentation liquid into a solution and directly apply it. The operation is simple and convenient, and the subsequent steps of purifying and removing impurities of the hyaluronic acid fermentation liquid, which are costly in the preparation process of hyaluronic acid, are omitted, thereby greatly reducing the application cost and being low in price.

[0023] (4) The fresh-keeping device provided by the present invention realizes automated operation, saves labor and time, saves the manpower cost of processing work during sweet potato storage, improves work efficiency, and has a wide range of application space and market prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a diagram of a device for storing and preserving sweet potatoes; Among them, 1. sliding mechanism; 2. air outlet; 3. storage mechanism; 4. cable; 5. fixing unit; 6. air inlet; 7. flushing mechanism; 8. filter; 9. water storage tank; 10. air sweeping mechanism; 11. sprinkler head; 12. fresh-keeping soaking tank. DETAILED DESCRIPTION

[0025] The specific examples given below are only for further describing the present invention in detail, but should not be construed as limiting the scope of protection of the present invention.

[0026] In the present invention, unless otherwise specified, the materials and reagents used are all obtained from commercial sources, and the experimental methods used are all conventional techniques.

[0027] The hyaluronic acid fermentation broth in the following examples was produced by Shandong Freda Biotechnology Co., Ltd., and had a hyaluronic acid content of 1%, a total content of amino acids, glucose, and glucose oxidase of 1-1.5%, and a total content of phenylalanine, glutamic acid, lysine, valine, and glycine of 0.3-0.5%.

[0028] Example 1 A method for storing and preserving sweet potatoes comprises the following steps: (1) placing the sweet potatoes in a fixed unit (5) for pretreatment to obtain pretreated sweet potatoes; the pretreatment operation is as follows: placing the sweet potatoes in a water storage tank (9), soaking them in clean water, lifting them out, rinsing them with a spray head (11), and then air-drying them with a sweeping mechanism (10); (2) placing the pretreated sweet potatoes in a fresh-keeping soaking tank (12) and soaking them in a hyaluronic acid fermentation solution for 30 minutes to obtain soaked sweet potatoes; the hyaluronic acid solution is prepared by diluting a hyaluronic acid fermentation solution having a hyaluronic acid content of 1% with water by 100 times; (3) The soaked sweet potatoes are picked up, air-dried by the air sweeping mechanism (10), and stored in the storage mechanism (3).

[0029] Example 2 A method for storing and preserving sweet potatoes comprises the following steps: (1) placing the sweet potatoes in a fixed unit (5) for pretreatment to obtain pretreated sweet potatoes; the pretreatment operation is as follows: placing the sweet potatoes in a water storage tank (9), soaking them in clean water, lifting them out, rinsing them with a spray head (11), and then air-drying them with a sweeping mechanism (10); (2) placing the pretreated sweet potatoes in a fresh-keeping soaking tank (12) and soaking them in a hyaluronic acid fermentation solution for 20 minutes to obtain soaked sweet potatoes; the hyaluronic acid solution is prepared by diluting a hyaluronic acid fermentation solution having a hyaluronic acid content of 1% with water by 1000 times; (3) The soaked sweet potatoes are picked up, air-dried by the air sweeping mechanism (10), and stored in the storage mechanism (3).

[0030] Example 3 A method for storing and preserving sweet potatoes comprises the following steps: (1) placing the sweet potatoes in a fixed unit (5) for pretreatment to obtain pretreated sweet potatoes; the pretreatment operation is as follows: placing the sweet potatoes in a water storage tank (9), soaking them in clean water, lifting them out, rinsing them with a spray head (11), and then air-drying them with a sweeping mechanism (10); (2) placing the pretreated sweet potatoes in a fresh-keeping soaking tank (12) and soaking them in a hyaluronic acid fermentation solution for 25 minutes to obtain soaked sweet potatoes; the hyaluronic acid solution is prepared by diluting a hyaluronic acid fermentation solution having a hyaluronic acid content of 1% with water by 500 times; (3) The soaked sweet potatoes are picked up, air-dried by the air sweeping mechanism (10), and stored in the storage mechanism (3).

[0031] Example 4 A method for storing and preserving sweet potatoes comprises the following steps: (1) placing the sweet potatoes in a fixed unit (5) for pretreatment to obtain pretreated sweet potatoes; the pretreatment operation is as follows: placing the sweet potatoes in a water storage tank (9), soaking them in clean water, lifting them out, rinsing them with a spray head (11), and then air-drying them with a sweeping mechanism (10); (2) placing the pretreated sweet potatoes in a fresh-keeping soaking tank (12) and soaking them in a hyaluronic acid fermentation solution for 25 minutes to obtain soaked sweet potatoes; the hyaluronic acid solution is prepared by diluting a hyaluronic acid fermentation solution having a hyaluronic acid content of 1% by 700 times with water; (3) The soaked sweet potatoes are picked up, air-dried by the air sweeping mechanism (10), and stored in the storage mechanism (3).

[0032] Experimental Example 1 1. Pretreatment of sweet potato tubers Select Xushu 50 tubers that are basically the same size after harvest, healthy and free of disease and damage, and treat 3 tubers in each treatment. Clean their surfaces and drain the water. Then use an ordinary weighing balance to weigh the fresh weight of the 3 tubers in each treatment and record the initial weight of the tubers.

[0033] 2. Prepare solution (1) Preparation of hyaluronic acid fermentation broth solution: Use the hyaluronic acid fermentation broth (hyaluronic acid content is 1%) produced by Shandong Freda Biotechnology Co., Ltd., take 1 mL of hyaluronic acid fermentation broth, and dilute it with deionized water by 100, 300, 500, 700, 900, and 1000 times respectively to prepare the hyaluronic acid fermentation broth solution.

[0034] (2) Preparation of hyaluronic acid solution: Use 98% pure hyaluronic acid powder from Shandong Freda Biotechnology Co., Ltd., and prepare a solution with a hyaluronic acid content of 1% with deionized water. Then dilute it with deionized water by 100, 300, 500, 700, 900, and 1000 times to prepare the hyaluronic acid solution.

[0035] Because hyaluronic acid is an active macromolecule, the required solution is best prepared before use.

[0036] 3. Solution treatment of potato tubers After pretreatment, 3 tubers for each treatment were immersed in the prepared hyaluronic acid fermentation solution and hyaluronic acid solution for 30 minutes to ensure that the tubers were completely immersed in the solution. After immersion, the tubers were taken out and the surface moisture was gently wiped with a paper towel. The 3 tubers in the control group were not immersed. All test tubers were placed in a storage facility, and the control group and the treatment group were stored separately. The storage facility was a dark incubator, and the temperature in the box was maintained at 11~13℃ and the relative humidity was 60~80%.

[0037] 4. Statistics The tubers were weighed every 20 days, and the incidence of tuber rot was investigated after 6 months, and the data were statistically analyzed.

[0038] The sweet potato tubers processed in the above embodiment were weighed and measured at different time periods, and the incidence of tuber rot was investigated. The statistical analysis results are shown in Tables 1 and 2: Table 1. Statistical results of weight of potato tubers treated with hyaluronic acid fermentation solution and hyaluronic acid solution As can be seen from Table 1, the potato tubers of the control group are not soaked, and the water loss rate of the potato tubers increases significantly after storage for 80 days, which is basically consistent with the time point at which the sweet potato loses water and the commodity rate decreases after the market storage. Compared with the control group that is not soaked, the method provided by the present invention is used to process the sweet potato tubers, which can effectively reduce the water loss rate of the tubers and effectively extend the storage time, especially after storage for 80 days, the water loss rate of the sweet potato tubers significantly decreases. And compared with the sweet potato tubers treated with hyaluronic acid solution, the present invention uses hyaluronic acid fermentation liquid solution to process the sweet potato tubers, which has a better effect in reducing the water loss rate of the tubers, especially the hyaluronic acid fermentation liquid solution prepared by diluting the hyaluronic acid fermentation liquid with water 500-700 times. It can be seen that the present invention uses hyaluronic acid fermentation liquid diluent to carry out sweet potato tubers, which can significantly reduce the water loss rate of the tubers and greatly extend the storage fresh-keeping period of the sweet potato.

[0039] Table 2. Statistical results of potato tuber rot incidence treated with hyaluronic acid fermentation solution and hyaluronic acid solution As can be seen from Table 2, compared with the control group without soaking treatment, soaking the sweet potato pieces in hyaluronic acid fermentation liquid solution and hyaluronic acid solution can reduce the rot incidence of potato pieces, but the present invention uses hyaluronic acid fermentation liquid solution to soak the sweet potato pieces, and the rot incidence of sweet potato pieces is lower, wherein the hyaluronic acid fermentation liquid solution prepared by diluting the hyaluronic acid fermentation liquid by 500-700 times with water has the best effect. It can be seen that the present invention uses hyaluronic acid fermentation liquid diluent to soak the sweet potato pieces, which can significantly reduce the rot incidence of potato pieces and greatly prolong the storage and fresh-keeping period of sweet potatoes.

[0040] In summary, the present invention uses the sweet potato treated with hyaluronic acid fermentation liquid solution, not only the moisture in the tuber and the fresh weight of the tuber are effectively protected, but also the incidence of tuber rot is effectively controlled, greatly reduced, and the storage and fresh-keeping period of the sweet potato is greatly extended. In addition, the present invention uses hyaluronic acid fermentation liquid to dilute the solution and directly apply it, eliminating the subsequent processes such as purification and impurity removal of the hyaluronic acid fermentation liquid that are expensive in the preparation process of hyaluronic acid, greatly reducing the application cost, the use method is simple to operate, the cost required for the reagent is low, and the residue and pollution of pesticides can also be reduced.

Claims

1. A method for storing and preserving sweet potatoes, characterized in that: The following steps are involved: (1) placing the sweet potatoes in a fixed unit (5) for pretreatment to obtain pretreated sweet potatoes; (2) placing the pretreated sweet potatoes into a fresh-keeping soaking tank (12) and soaking them in the hyaluronic acid fermentation solution for 20-30 minutes to obtain soaked sweet potatoes; (3) The soaked sweet potatoes are picked up, air-dried by the air sweeping mechanism (10), and stored in the storage mechanism (3).

2. The method for storing and preserving sweet potatoes according to claim 1, wherein: In step (1), the pretreatment operation is as follows: putting the sweet potatoes into a water storage tank (9), soaking them in clean water and then lifting them out, washing them with a spray head (11), and then air-drying them with a sweeping mechanism (10).

3. The method for storing and preserving sweet potatoes according to claim 1, wherein: In step (2), the hyaluronic acid fermentation broth solution is prepared by diluting the hyaluronic acid fermentation broth with water by 100-1000 times.

4. The method for storing and preserving sweet potatoes according to claim 3, wherein: In step (2), the hyaluronic acid fermentation broth solution is prepared by diluting the hyaluronic acid fermentation broth with water by 500-700 times.

5. The method for storing and preserving sweet potatoes according to claim 3 or 4, characterized in that: The hyaluronic acid content in the hyaluronic acid fermentation liquid is 1%, and the water content is ≥90%.

6. The method for storing and preserving sweet potatoes according to claim 5, characterized in that: The hyaluronic acid fermentation liquid comprises the following components: amino acids, glucose and glucose oxidase.

7. The method for storing and preserving sweet potatoes according to claim 6, wherein: The amino acids include phenylalanine, glutamic acid, lysine, valine and glycine.

8. The method for storing and preserving sweet potatoes according to claim 1, wherein: In step (3), the storage mechanism is a dark incubator, and the temperature inside the incubator is maintained at 11-13° C. and the relative humidity is maintained at 60-80%.

9. A device for the sweet potato storage and preservation method according to claim 1, characterized in that: The invention comprises a pulley mechanism (1) and a flushing mechanism (7), wherein a cable (4) is provided at the bottom of the pulley mechanism (1), the other end of the cable (4) is fixedly connected to a fixing unit (5), a spray head (11) is fixedly provided on the flushing mechanism (7), a fresh-keeping soaking pool (12) is fixedly provided on the right side of a water storage tank (9), an air inlet (6) and an air outlet (2) are fixedly provided on the upper part of the flushing mechanism (7), and an air sweeping mechanism (10) is fixedly provided on the air inlet (6).

10. The device for storing and preserving sweet potatoes according to claim 9, characterized in that: The flushing mechanism (7) comprises a clean water tank (9) and a spray device (11), wherein the clean water tank (9) contains a liftable filter screen (8).

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