A method for controlling long storage of sweet potato after harvest

Abstract

The application provides a method for controlling long mildew of postharvest sweet potato, which comprises the following steps: placing the sweet potato in a closed space filled with carbon dioxide, then continuously fumigating the sweet potato with cinnamyl aldehyde, and finally storing the sweet potato in a room temperature environment. The application adopts the combination of carbon dioxide and cinnamyl aldehyde to store the postharvest sweet potato, which can effectively prolong the storage time of the postharvest sweet potato, and the carbon dioxide treatment can close the stomata on the surface of the sweet potato, so that the flavor of the sweet potato is not affected after the cinnamyl aldehyde fumigation. The method has the advantages of safety, high efficiency, green environmental protection and the like.

Description

Technical Field

[0001] This invention relates to the field of sweet potato storage, and more particularly to a method for controlling mold growth in sweet potatoes during post-harvest storage. Background Technology

[0002] Sweet potato, also known as yam or sweet potato, is the world's seventh largest food crop. It is rich in nutrients, containing various bioactive components with numerous health benefits, including antioxidant, liver-protective, anti-inflammatory, anti-tumor, anti-diabetic, antibacterial, anti-obesity, and anti-aging properties. It is a globally recognized nutritious food.

[0003] Because fresh sweet potato tubers have a high water content, large volume, and crisp texture, they are easily bruised and infected with pathogens during harvesting, transportation, and storage. Furthermore, changes in temperature, humidity, and gas concentration in the storage environment cause sweet potatoes to wilt, sprout, mold, and rot during storage, leading to changes in their sensory and internal quality and rendering them uncommercial. In addition, sweet potatoes are greatly affected by seasonality, resulting in an imbalance between peak and off-peak seasons. Therefore, storage is necessary to ensure long-term supply.

[0004] Currently, my country mainly uses cellars to store sweet potatoes. Before storing them, the floor and walls of the old cellar are disinfected by spraying with a 1%–2% copper sulfate solution. Then, undamaged sweet potatoes free from pathogens are selected, and the storage volume should be less than 2 / 3 of the cellar space. A sweet potato preservative should also be sprayed on the sweet potatoes as needed. In traditional cellar storage, the temperature and humidity cannot be accurately controlled, leading to short storage periods, poor post-storage quality, and even cellar rot. Pesticide residues in the sweet potato products also pose a risk. Therefore, a green and safe preservation method is needed for storing sweet potatoes.

[0005] Cinnamaldehyde is the main component of cinnamon essential oil produced from aromatic plants. It has highly effective antibacterial activity and can affect the distribution of fatty acids, enzyme activity, and membrane fluidity on the cell membrane of microorganisms, thereby enhancing their permeability, damaging the cell membrane, causing intracellular substances to leak out, inhibiting ATPase and cell division, and ultimately leading to bacterial death.

[0006] Stomata are channels through which water and carbon dioxide enter and exit plants, and through which oxygen is released. The number, distribution, and morphology of stomata are closely related not only to transpiration, photosynthesis, and respiration, but also directly affect a plant's resistance to biotic and abiotic stresses. Furthermore, plants lose over 90% of their water through stomata. Simultaneously, stomata are also the primary channels through which bacteria and fungi enter plants. Recent research indicates that stomata can actively close when they sense microbial invasion to limit bacterial entry.

[0007] Existing technologies include the use of carbon dioxide or cinnamaldehyde for food preservation. However, when applied to exposed foods such as sweet potatoes, the use of cinnamaldehyde can alter the flavor of the food itself.

[0008] Therefore, there is a need to provide a method that can both preserve exposed foods such as sweet potatoes for a long time without affecting the flavor of the food itself, in order to overcome the shortcomings of existing technologies. Summary of the Invention

[0009] This invention provides a method for controlling mold growth in sweet potatoes during post-harvest storage. The method uses carbon dioxide and cinnamaldehyde to treat the sweet potatoes. First, carbon dioxide is used to close the pores on the surface of the sweet potatoes, preventing the flavor of the sweet potatoes from being affected when cinnamaldehyde is used for fumigation. This method can not only effectively extend the storage time of sweet potatoes, but also does not affect the flavor of the sweet potatoes themselves. Moreover, the method is simple to operate.

[0010] The specific technical solution is as follows:

[0011] A method for controlling mold growth in sweet potatoes during post-harvest storage includes:

[0012] (1) Place the sweet potato in a sealed space filled with carbon dioxide gas to close the pores on the surface of the sweet potato.

[0013] (2) Expel carbon dioxide gas from the sealed space and continuously fumigate the sweet potatoes with cinnamaldehyde. The sweet potatoes are stored at room temperature during the fumigation process.

[0014] Furthermore, in step (1), the volume concentration of the carbon dioxide is 15% to 25%.

[0015] Preferably, the volume concentration of the carbon dioxide is 15% to 20%.

[0016] Further preferred, the volume concentration of carbon dioxide is 20%.

[0017] Under these optimal conditions: the stomata on the sweet potato skin are fully closed, reducing the entry of external microorganisms into the sweet potato and preventing infectious diseases. When the carbon dioxide concentration is too low, the stomata on the sweet potato skin cannot close or close insufficiently, failing to effectively prevent the entry of microorganisms and thus reducing the effectiveness of controlling infectious diseases. At the same time, while a high carbon dioxide concentration can fully close the stomata on the sweet potato skin, excessively high carbon dioxide concentration will cause the sweet potato to produce ethanol during storage, leading to rot and reducing its storage time.

[0018] Furthermore, in step (1), the carbon dioxide treatment time is 2 to 4 days.

[0019] Preferably, the carbon dioxide treatment time is 2 days.

[0020] Under these optimal conditions, sweet potatoes are well stored. If the storage time is too short, the pores on the sweet potato skin cannot close sufficiently; if the storage time is too long, the sweet potatoes will be in a closed space filled with carbon dioxide for a long time, which is not conducive to the storage of sweet potatoes.

[0021] Furthermore, in step (2), the carbon dioxide gas in the sealed space is discharged using the exhaust vent of the sealed space.

[0022] Furthermore, in step (2), the volume concentration of cinnamaldehyde volatilization is 300–600 μL / L.

[0023] Preferably, the volume concentration of cinnamaldehyde volatilization is 300–500 μL / L.

[0024] Further optimization yielded a cinnamaldehyde volatilization volume concentration of 500 μL / L.

[0025] Under these optimal conditions: cinnamaldehyde has a significant antibacterial effect; however, low concentrations of cinnamaldehyde may result in incomplete antibacterial activity, while high concentrations may have a greater impact on the flavor of sweet potatoes.

[0026] Furthermore, the continuous fumigation time is 1 to 4 days.

[0027] Preferably, the continuous fumigation time is 2 days.

[0028] Furthermore, in step (2), the relative humidity in the room temperature environment is 80%-95%.

[0029] Furthermore, the relative humidity in the room temperature environment is 85%-95%.

[0030] Further preferred, the relative humidity in the room temperature environment is 90%.

[0031] Under these optimal conditions, sweet potatoes can be stored well. If the humidity is too low, the tubers are prone to dehydration, wilting, wrinkling, and becoming pithy, which affects their edible quality. If the humidity is too high, pathogens can easily multiply, causing the sweet potatoes to rot.

[0032] The amount and duration of carbon dioxide gas used in this invention, along with the use of cinnamaldehyde, were determined through screening. If the treatment time of carbon dioxide gas is too short, it will not only fail to completely close the pores of the sweet potato skin, thus failing to effectively prevent microorganisms from entering the sweet potato, but it will also fail to effectively prevent cinnamaldehyde from entering the sweet potato and affecting its flavor during subsequent fumigation.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] (1) This invention uses a combination of carbon dioxide and cinnamaldehyde to treat post-harvest sweet potatoes. By using carbon dioxide to close the pores on the surface of the sweet potatoes, microorganisms are prevented from entering the sweet potatoes and causing mold growth. The use of cinnamaldehyde fumigation inhibits bacteria and prolongs the storage time of the sweet potatoes. At the same time, by using carbon dioxide to close the pores on the surface of the sweet potatoes, the volatilized cinnamaldehyde during the subsequent fumigation is prevented from entering the sweet potatoes and affecting their flavor. This not only effectively prolongs the storage time of the sweet potatoes, but also does not affect their flavor.

[0035] (2) The method provided by the present invention has the advantages of convenient operation, low cost, safety, high efficiency and green environmental protection. The sweet potatoes after treatment have good storage effect, which provides a new way to maintain the quality of sweet potatoes after harvest. Attached Figure Description

[0036] Figure 1 The flowchart is a method for controlling mold growth in sweet potatoes during post-harvest storage provided in Embodiment 1 of the present invention.

[0037] Figure 2 This diagram shows the stomata closure of sweet potatoes after carbon dioxide treatment according to the present invention.

[0038] Figure 3 Untreated sweet potatoes.

[0039] Figure 4 Sweet potatoes that have been treated with carbon dioxide and cinnamaldehyde and then stored.

[0040] Figure 5 Figure 2 shows the changes in ethanol metabolism in sweet potatoes after treatment with different concentrations of CO2. Figure A compares the activities of ADH (ethanol dehydrogenase) in the three groups; Figure B compares the ethanol content in the three groups.

[0041] Figure 6 The CRS represents the variation in the rot rate of sweet potatoes during storage. The CRS represents sweet potatoes treated with a combination of carbon dioxide and cinnamaldehyde, while the CK represents untreated sweet potatoes.

[0042] Figure 7 The CRS represents the change in starch content of sweet potatoes during storage. The CRS represents sweet potatoes treated with carbon dioxide and cinnamaldehyde, while the CK represents untreated sweet potatoes.

[0043] Figure 8 The sugar content of sweet potatoes changes during storage. CRS represents sweet potatoes treated with carbon dioxide and cinnamaldehyde, while CK represents untreated sweet potatoes.

[0044] Figure 9The graph shows the changes in the main flavor compounds of sweet potatoes under four different treatments. CRS represents sweet potatoes treated with a combination of CO2 and cinnamaldehyde, CS represents sweet potatoes treated with CO2 alone, RS represents sweet potatoes treated with cinnamaldehyde alone, and CK represents untreated sweet potatoes. Propanal represents propanal; 2-Propanol represents 2-propanol; Acetoin represents 3-hydroxy-2-butanone; 6-Methyl-2-heptanone represents 6-methyl-2-heptanone; Acetophenone represents acetophenone; 2,3-Butanediol represents 2,3-butanediol; 2-Cyclopenten-1-one represents 2-cyclopentenone; and Cinnamaldehyde represents cinnamaldehyde. Detailed Implementation

[0045] The present invention will be further described below with reference to specific embodiments. The following are only specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto.

[0046] Example 1

[0047] A method for controlling mold growth in sweet potatoes during post-harvest storage includes the following steps:

[0048] (1) Place 5 kg of sweet potatoes in a sealed space filled with carbon dioxide gas with a volume concentration of 20% for 2 days to close the pores on the surface of the sweet potatoes.

[0049] (2) Remove carbon dioxide gas from the sealed space and fumigate the sweet potato with cinnamaldehyde at a volatilization volume concentration of 500 μL / L for 2 days. The sweet potato is stored in a room temperature environment with a relative humidity of 90% during the fumigation process.

[0050] Example 2

[0051] A method for controlling mold growth in sweet potatoes during post-harvest storage includes the following steps:

[0052] (1) Place 6 kg of sweet potatoes in a sealed space filled with carbon dioxide gas for 2 days to close the pores on the surface of the sweet potatoes.

[0053] (2) Expel carbon dioxide gas from the sealed space and fumigate the sweet potato with cinnamaldehyde at a volatilization volume concentration of 500 μL / L for 2 days. The sweet potato is stored in a room temperature environment with a relative humidity of 90% during the fumigation process.

[0054] In step (1), different gradient experiments with different carbon dioxide volume concentrations are set up, specifically: high concentration carbon dioxide group (HCD): 20% ± 1% O2, 60% CO2; medium concentration carbon dioxide group (MCD): 20% ± 1% O2, 20% CO2; no carbon dioxide group (CK): 20% ± 1% O2, 0% ± 1% CO2.

[0055] The alcohol dehydrogenase activity and ethanol content of sweet potatoes obtained from each treatment in the gradient experiment were determined. ADH was measured using an alcohol dehydrogenase (ADH) assay kit, and ethanol content was determined using gas chromatography-mass spectrometry (GC-MS). The results are shown in the attached figure. Figure 5 As shown.

[0056] like Figure 5 As shown in Figure A, the ADH (alcohol dehydrogenase) activity in the HCD group was significantly higher than that in the MCD and CK groups; the difference between the MCD and CK groups was small, indicating that this concentration of CO2 in the short-term MCD group did not cause sweet potatoes to produce ethanol, which may be beneficial for sweet potato storage.

[0057] As attached Figure 5 As shown in Figure B, on day 10 of CO2 treatment, the ethanol content in the HCD group was significantly higher than that in the MCD and CK groups, but the difference in ethanol content between the MCD and CK groups was small.

[0058] In summary, high concentrations of CO2 will cause sweet potato tubers to produce more ethanol, thus causing irreversible damage to the tubers. However, treatment with about 20% CO2 will not cause sweet potato tubers to produce more ethanol. Using CO2 treatment within this range can close the stomata on the surface of the sweet potato, reducing the entry of microorganisms into the sweet potato and causing it to rot, while preventing the sweet potato tubers from producing too much ethanol, which is detrimental to the storage of sweet potatoes.

[0059] Example 3

[0060] A method for controlling mold growth in sweet potatoes during post-harvest storage includes the following steps:

[0061] (1) Place 2 kg of sweet potatoes in a sealed space filled with carbon dioxide gas to close the pores on the surface of the sweet potatoes.

[0062] (2) Expel carbon dioxide gas from the sealed space and fumigate the sweet potatoes with cinnamaldehyde for 2 days. Store the sweet potatoes at room temperature during the fumigation process.

[0063] The volume concentrations of carbon dioxide were 0%, 10%, 15%, 20%, 25%, and 30%, respectively.

[0064] The number of days for carbon dioxide treatment were 1 day, 2 days, 3 days, and 4 days, respectively.

[0065] The volatilization volume concentrations of cinnamaldehyde were 0 μL / L, 200 μL / L, 500 μL / L, and 800 μL / L, respectively.

[0066] The relative humidity levels at room temperature were 75%, 80%, 85%, 90%, 95%, and 98%, respectively.

[0067] Sweet potatoes were treated with different carbon dioxide volume concentrations, carbon dioxide treatment days, cinnamaldehyde volatilization volume concentrations, and relative humidity at room temperature (treatments 1–17). Sensory evaluation, changes in sweet potato state, and changes in flavor compounds were performed on the treated sweet potatoes. The specific results are as follows:

[0068] (1) Sensory evaluation

[0069] The appearance, aroma, sweetness, chewiness, and off-flavor of sweet potatoes were evaluated using a nine-point pleasure scale. The evaluation results are shown in Table 1.

[0070] Table 1. Sensory evaluation results of sweet potatoes under different treatments.

[0071]

[0072]

[0073] The results showed that the sweet potatoes stored under the treatment condition 2 had the best sensory evaluation effect.

[0074] (2) Evaluation of changes in sweet potato state and flavor compounds

[0075] The changes in rot rate, starch content, and sugar content of sweet potatoes under different treatments were evaluated. The CK group consisted of untreated sweet potatoes, and the CRS group consisted of sweet potatoes under treatment 2. 1 kg of sweet potatoes from each group were collected at storage times of 0, 10, 20, 30, and 40 days for testing. The rot rate was determined by the presence of mold spots exceeding 5 mm in width on the surface of the sweet potato, which was considered rotten. The rot percentage was expressed as the percentage of rotten sweet potatoes out of the total sweet potatoes. The changes in starch and sugar content were determined using colorimetric methods. The changes in rot rate, starch content, and sugar content of sweet potatoes under the same treatment are shown in Tables 2-4. Figures 6-8 The starch content in Table 3 is per kilogram; the sugar content in Table 4 is per kilogram; the results are as follows:

[0076] Table 2. Changes in the rot rate of sweet potatoes under different treatments.

[0077]

[0078] Combine Table 2 and Appendix Figure 6 It can be seen that the decay rate of the CRS group was lower than that of the CK group. This indicates that treating sweet potatoes with a combination of carbon dioxide and cinnamaldehyde is beneficial for their storage.

[0079] Table 3. Changes in starch content of sweet potatoes under different treatments.

[0080]

[0081]

[0082] Combine Table 3 and Appendix Figure 7 It can be seen that the starch content in both groups showed a decreasing trend, which is consistent with the changes in starch content of sweet potatoes during storage. The change in starch content in the CRS group was not significantly different from that in the CK group. This indicates that treating sweet potatoes with a combination of carbon dioxide and cinnamaldehyde does not affect their starch content.

[0083] Table 4. Changes in sugar content of sweet potatoes under different treatments.

[0084]

[0085] Combine Table 4 and Appendix Figure 8 It can be seen that the sugar content changes in both groups showed an upward trend, which is consistent with the sugar content changes of sweet potatoes during storage. The sugar content changes in the CRS group were not significantly different from those in the CK group. This indicates that treating sweet potatoes with a combination of carbon dioxide and cinnamaldehyde does not affect their sugar content.

[0086] (3) Evaluation of changes in sweet potato flavor compounds

[0087] Flavor compounds of sweet potatoes in the CK, CRS, CS, and RS groups were evaluated. The CRS group consisted of sweet potatoes treated for 2 cycles, the CS group consisted of sweet potatoes treated for 13 cycles, the RS group consisted of sweet potatoes treated for 4 cycles, and the CK group consisted of untreated sweet potatoes. One kg of sweet potato from each group was used for analysis. A rapid gas chromatography-electronic nose was used to determine the flavor compounds and cinnamaldehyde content. The changes in flavor compounds and cinnamaldehyde content of sweet potatoes under different treatments in the four groups are shown in Table 5 and Appendix. Figure 9 The flavor compounds in the table are per kilogram, and the treatment lasted for 20 days. The results are as follows:

[0088] Table 5. Changes in the main flavor compounds and cinnamaldehyde content of sweet potatoes under different treatments.

[0089]

[0090] As attached Figure 9 The figure shows the changes in the main flavor compounds of sweet potatoes under four different treatments. As can be seen from the figure, compared with CK, the flavor compounds of sweet potatoes in RS group were damaged, while the flavor compounds of sweet potatoes in CRS group did not change much. This indicates that the combined treatment of sweet potatoes with cinnamaldehyde and CO2 can effectively avoid the damage to the flavor compounds of sweet potatoes caused by cinnamaldehyde, and will not affect the flavor of sweet potatoes themselves.

Claims

1. A method for controlling mold growth in sweet potatoes during post-harvest storage, characterized in that, include: (1) Place the sweet potato in a sealed space filled with carbon dioxide gas to close the pores on the surface of the sweet potato; the volume concentration of the carbon dioxide is 15% to 20%, and the treatment time of the carbon dioxide is 2 to 4 days. (2) Expel carbon dioxide gas from the sealed space and continuously fumigate the sweet potato with cinnamaldehyde. The sweet potato is stored at room temperature during the fumigation process. The volume concentration of cinnamaldehyde volatilization is 300 μL / L to 600 μL / L, and the relative humidity at room temperature is 80% to 95%.

2. The method for controlling mold growth in post-harvest stored sweet potatoes as described in claim 1, characterized in that, In step (2), the volume concentration of cinnamaldehyde volatilization is 300-500 μL / L.

3. The method for controlling mold growth in post-harvest stored sweet potatoes as described in claim 1, characterized in that, In step (2), the continuous fumigation time is 1 to 4 days.

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