A method for preserving cowpea

Abstract

The present application relates to the technical field of fruit and vegetable storage and preservation, and provides a cowpea preservation method, which comprises the following steps: (1) pre-cooling cowpeas after bundling; and (2) storing the cowpeas after film packaging. The treatment can effectively reduce the rust spot degree of cowpeas, inhibit the discoloration and weight loss, and maintain a high hardness, soluble solids content and chlorophyll fluorescence. The cowpea preservation technology provided by the present application is simple and convenient to operate, low in cost, good in preservation effect, green and safe, and has a wide application prospect.

Description

Technical Field

[0001] This invention relates to the field of fruit and vegetable storage and preservation technology, and in particular to a method for preserving cowpeas. Background Technology

[0002] Cowpeas, belonging to the Fabaceae family, are annual herbaceous plants, also known as pink beans, long-podded beans, and long-string beans, and are widely cultivated in various provinces and regions. Cowpeas contain easily digestible plant protein, carbohydrates, dietary fiber, and water-soluble vitamins, but they are not suitable for storage at room temperature, generally having a shelf life of only 2-3 days. If not processed promptly after harvesting, cowpeas will quickly wilt, develop rust spots, rot, and become fibrous, resulting in significant economic losses. Furthermore, the use of chemically synthesized preservatives raises safety concerns. Therefore, efficient and pollution-free cowpea storage and preservation technology has become a bottleneck restricting the development of the cowpea industry and urgently needs to be addressed. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preserving cowpeas and extending their shelf life.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0005] This invention provides a method for preserving cowpeas, characterized by comprising the following steps:

[0006] (1) After bundling the cowpeas, pre-cool them;

[0007] (2) Store after film packaging;

[0008] Preferably, the thickness of the film in step (2) is 0.035–0.037 mm, and the water vapor transmission rate is 2.83–4.91 × 10⁻⁶ mm. -11 gm -1 s -1 Pa -1 The oxygen permeability is: 1.46~2.36×10 -3 gm -2 s -1 The carbon dioxide permeability is: 1.32~1.94×10 -3 gm -2 s -1 .

[0009] Preferably, the cowpeas mentioned in step (1) are cowpeas that are 10 to 15 days after flowering, with plump pods, uniform thickness and color, and free from pests, diseases and mechanical damage. The pre-cooling treatment is carried out on the same day after harvesting.

[0010] Preferably, in step (1), 8 to 12 cowpeas are bundled together.

[0011] Preferably, the pre-cooling treatment in step (1) involves cooling the cowpea core temperature to 4.5–8.5°C.

[0012] Preferably, in step (2), the cowpeas are packaged in groups of 2 to 4 bundles.

[0013] Preferably, the storage temperature in step (2) is 7.5–8.5°C and the relative humidity is 80–90%.

[0014] Preferably, the film mentioned in step (2) is any one of polyethylene modified atmosphere packaging bag, biaxially oriented polypropylene packaging bag, polyvinyl chloride packaging bag, polyvinylidene chloride packaging bag, and polyvinyl alcohol fiber packaging bag.

[0015] The present invention also provides the application of the method in the preservation of cowpeas.

[0016] The beneficial effects of this invention are:

[0017] This invention provides a method for cold storage and preservation of cowpeas. The method includes the following steps: (1) pre-cooling the harvested cowpeas after bundling them; (2) storing them in preservation bags, wherein the thickness of the film is 0.035-0.037 mm and the water vapor transmission rate is 2.83-4.91×10⁻⁶. -11 gm -1 s -1 Pa -1 The oxygen permeability is: 1.46~2.36×10 -3 gm -2 s -1 The carbon dioxide permeability is: 1.32~1.94×10 -3 gm -2 s -1 This treatment effectively reduces rust spots on cowpeas, inhibits fading and weight loss, and maintains high firmness, soluble solids content, and chlorophyll fluorescence. The cowpea preservation technology provided by this invention is simple and convenient to operate, low in cost, has good preservation effects, and is green and safe, with broad application prospects. Attached Figure Description

[0018] Figure 1 The effects of different treatments on the appearance of 'Quansheng Green King' cowpeas.

[0019] Figure 2 To evaluate the effects of different treatments on the rust spot index (A) and color a of cowpeas * Effects of value (B), hardness (C), soluble solids content (D), Fv / Fm (E), and weight loss rate (F). Detailed Implementation

[0020] This invention provides a method for preserving cowpeas, characterized by comprising the following steps:

[0021] (1) After bundling the cowpeas, pre-cool them;

[0022] (2) Store after film packaging;

[0023] In this invention, the thickness of the film in step (2) is preferably 0.035–0.037 mm, more preferably 0.036 mm; the water vapor transmission rate is preferably 2.83–4.91 × 10⁻⁶ mm. -11 gm -1 s -1 Pa -1 More preferably, it is 3.1–4.2 × 10⁻⁶. -11 gm -1 s -1 Pa -1 A further preferred value is 3.5 × 10⁻⁶. -11 gm -1 s -1 Pa -1 The preferred oxygen permeability is 1.46–2.36 × 10⁻⁶. -3 gm -2 s -1 More preferably, it is 1.7 to 2.1 × 10⁻⁶. -3 gm -2 s -1 A further preferred value is 1.85 × 10⁻⁶. -3 gm -2 s -1 The preferred carbon dioxide transmission rate is 1.32–1.94 × 10⁻⁶. -3 gm -2 s -1 More preferably, it is 1.45~1.65×10 -3 gm -2 s -1 A further preferred value is 1.55 × 10⁻⁶. -3 gm -2 s -1 .

[0024] In this invention, the cowpeas mentioned in step (1) are preferably cowpeas 10 to 15 days after flowering, more preferably cowpeas 11 to 14 days after flowering, and even more preferably cowpeas 13 days after flowering; the cowpeas are preferably cowpeas with plump pods, uniform thickness and color, and free from pests, diseases and mechanical damage, and the pre-cooling treatment is carried out on the same day after harvesting.

[0025] In this invention, when bundling in step (1), it is preferable to bundle 8 to 12 cowpeas together, more preferably 9 to 11 cowpeas together, and even more preferably 10 cowpeas together.

[0026] In this invention, the pre-cooling treatment in step (1) is preferably to cool the cowpea core temperature to 4.5-8.5°C, more preferably to cool the cowpea core temperature to 7.5-8.5°C, and even more preferably to cool the cowpea core temperature to 8°C.

[0027] In this invention, the packaging in step (2) is preferably done in groups of 2 to 4 bundles of cowpeas, and more preferably in groups of 3 bundles of cowpeas.

[0028] In this invention, the storage temperature in step (2) is preferably 7.5 to 8.5°C, more preferably 8°C; the relative humidity of the storage is preferably 80 to 90%, more preferably 83 to 87%, and more preferably 85%.

[0029] In this invention, the film mentioned in step (2) is preferably any one of polyethylene modified atmosphere packaging bag, biaxially oriented polypropylene packaging bag, polyvinyl chloride packaging bag, polyvinylidene chloride packaging bag, and polyvinyl alcohol fiber packaging bag, and is more preferably a polyethylene modified atmosphere packaging bag.

[0030] In this invention, the storage time of the cowpeas is preferably 20-30 days, more preferably 22-28 days, and even more preferably 25 days.

[0031] The present invention also provides the application of the method in the preservation of cowpeas.

[0032] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0033] In the following embodiments and comparative examples, the materials involved include:

[0034] Fully biodegradable bag (hereinafter referred to as Bag A): a supermarket-specific fruit and vegetable preservation bag, thickness: 0.035mm, water vapor transmission rate: 19.31×10 -11 gm -1 s -1 Pa -1 Oxygen permeability: 2.18 × 10⁻⁶ -3 gm -2 s -1 Carbon dioxide transmission rate: 1.91 ± 0.34 × 10⁻⁶ -3 gm -2 s -1 ;

[0035] The polyethylene modified atmosphere packaging bag (hereinafter referred to as bag B) was sourced from the Subtropical Crops Research Institute of Guangxi Zhuang Autonomous Region. Its thickness was 0.036 mm, and its water vapor transmission rate was 3.87 × 10⁻⁶ mm. -11 gm -1 s -1 Pa -1 Oxygen permeability: 1.91 × 10⁻⁶ -3 gm -2 s -1 Carbon dioxide transmission rate: 1.63 × 10⁻⁶ -3 gm -2 s -1 ;

[0036] The cowpea variety used in the examples and comparative examples was 'Quansheng Lvwang' cowpea, all of which were harvested at the same time from Ledong Li Autonomous County, Hainan Province. Cowpeas that were 15 days after flowering, with plump pods, uniform thickness and color, and free from pests, diseases, and mechanical damage were selected as experimental materials and transported to the laboratory for preservation treatment on the day of harvest.

[0037] Example 1

[0038] After harvesting, rinse the cowpeas with clean water, air dry them, and bundle them together with rubber bands in groups of 10. Pack them into bags of 3 bundles each. Perform 6 parallel replicates. The specific processing method is as follows:

[0039] Treatment (Bag B): Pack directly in Bag B and then store in a constant temperature and humidity incubator at 8℃ and 85% relative humidity for 25 days.

[0040] Example 2

[0041] After harvesting, rinse the cowpeas with clean water, air dry them, and bundle them together with rubber bands in groups of 10. Pack them into bags of 3 bundles each. Perform 6 parallel replicates. The specific processing method is as follows:

[0042] Treatment (Bag B + 5℃ pre-cooling): Immerse the cowpeas in ice water to rapidly cool the core temperature to 5℃, then remove and dry them before packaging them in Bag B and storing them in a constant temperature and humidity incubator at 8℃ and 85% relative humidity for 25 days.

[0043] Example 3

[0044] After harvesting, rinse the cowpeas with clean water, air dry them, and bundle them together with rubber bands in groups of 10. Pack them into bags of 3 bundles each. Perform 6 parallel replicates. The specific processing method is as follows:

[0045] Treatment (Bag B + 8℃ pre-cooling): Immerse the cowpeas in ice water to rapidly cool the core temperature to 8℃, then remove and dry them before packaging them in Bag B and storing them in a constant temperature and humidity incubator at 8℃ and 85% relative humidity for 25 days.

[0046] Comparative Example 1

[0047] After harvesting, rinse the cowpeas with clean water, air dry them, and bundle them together in groups of 10 with rubber bands. Repeat the process 6 times. The specific treatment method is as follows:

[0048] Treatment (control): Cowpeas were placed directly into a constant temperature and humidity incubator at 8℃ and 85% relative humidity for 25 days.

[0049] Comparative Example 2

[0050] After harvesting, rinse the cowpeas with clean water, air dry them, and bundle them together with rubber bands in groups of 10. Pack them into bags of 3 bundles each. Perform 6 parallel replicates. The specific processing method is as follows:

[0051] Treatment (Bag A): Pack directly in Bag A, then store in a constant temperature and humidity incubator at 8℃ and 85% relative humidity for 25 days.

[0052] Comparative Example 3

[0053] After harvesting, rinse the cowpeas with clean water, air dry them, and bundle them together with rubber bands in groups of 10. Pack them into bags of 3 bundles each. Perform 6 parallel replicates. The specific processing method is as follows:

[0054] Treatment (A bag + 5℃ pre-cooling): Immerse the cowpeas in ice water to rapidly cool the core temperature to 5℃, then remove and dry them before packaging them in A bag and storing them in a constant temperature and humidity incubator at 8℃ and 85% relative humidity for 25 days.

[0055] Comparative Example 4

[0056] After harvesting, rinse the cowpeas with clean water, air dry them, and bundle them together with rubber bands in groups of 10. Pack them into bags of 3 bundles each. Perform 6 parallel replicates. The specific processing method is as follows:

[0057] Treatment (Bag A + 8℃ pre-cooling): Immerse the cowpeas in ice water to rapidly cool the core temperature to 8℃, then remove and dry them before packaging them in Bag A and storing them in a constant temperature and humidity incubator at 8℃ and 85% relative humidity for 25 days.

[0058] Experimental Example 1

[0059] During the storage of Examples 1-3 and Comparative Examples 1-4, the cowpea rust index was observed and statistically analyzed every 5 days.

[0060] Rust Spot Index: Randomly select one bundle (10 beans) from each treatment group, assess and record the percentage of rust spot area on the surface of the bean relative to the total area of ​​the bean, and classify the rust spot severity into 5 levels based on the percentage:

[0061] Grade 0: No rust spots;

[0062] Level 1: <10%;

[0063] Level 2: 10%–25%;

[0064] Level 3: 25%–50%;

[0065] Level 4: >50%.

[0066] The rust spot index is calculated by the formula: Rust spot index = Σ(rust spot grade × number of cowpeas in that grade) / (4 × total number of cowpeas).

[0067] like Figure 1 As shown, in Comparative Example 1, the control cowpeas, after being stored at 8°C for 15 days, exhibited severe rust spots, with the pods turning from green to yellow and severely dehydrated, rendering them completely unmarketable. Cowpeas packaged in both types of preservation bags maintained good quality. It was observed that the appearance quality of cowpeas packaged in bag B (Examples 1-3) was superior to that in bag A (Comparative Examples 2-4) after no pre-cooling, pre-cooling at 5°C, and pre-cooling at 8°C. After 25 days of storage, cowpeas packaged in bag A under all three treatments (Comparative Example 2 without pre-cooling, Comparative Example 3 with pre-cooling at 35°C, and Comparative Example 4 with pre-cooling at 48°C) showed severe discoloration and dehydration, with very severe rust spots. In contrast, after three pre-treatments (no pre-cooling, pre-cooling at 5°C, and pre-cooling at 8°C), the appearance quality of cowpeas packaged in bag B was significantly improved, with the cowpeas treated in Example 3 (bag B + pre-cooling at 8°C) exhibiting the best appearance quality.

[0068] Changes in rust spot index during cowpea storage are as follows: Figure 2 As shown in Figure A, the rust index of the control group cowpeas in Comparative Example 1 increased rapidly during storage, reaching 0.55±0.02 on day 25. Compared with the control, both packaging with bags A and B inhibited the increase in rust index to varying degrees. The cowpea rust index in Comparative Example 2 (packaged with bag A and without pre-cooling) was the highest among the treated groups, reaching 0.46±0.02 on day 25. The rust index of the cowpeas treated in Examples 1-3 was significantly lower than that in Comparative Examples 2-4, with the lowest rust index in the packaging combination of Example 3 (pre-cooled at 8℃ + bag B), reaching only 0.3±0.01 on day 25. Figure 2 A).

[0069] Experimental Example 2

[0070] During the storage period of Examples 1-3 and Comparative Examples 1-4, the color intensity (a) of cowpeas was observed and statistically analyzed every 5 days. * value.

[0071] Color: The color of cowpea pods was determined using a Minolta CR-400 colorimeter. Measurements were taken once for each of the top, middle, and bottom sections of each pod. Colorimetric a * The values, from smallest to largest, represent colors from green to red.

[0072] Figure 2 In Example B, the chromaticity a* value of cowpeas on the day of harvest was -17.24±0.41. As storage progressed, the chromaticity a* value gradually increased. In Comparative Example 1, the chromaticity a* value of the control group cowpeas increased to -10.66±1.12 by day 25 of storage. Compared to the control, Examples 1-3 (packaged in bag A) and Comparative Examples 2-4 (packaged in bag B) all delayed the increase in chromaticity a* value to varying degrees. Furthermore, the chromaticity a* values ​​of cowpeas treated in Examples 1-3 were lower than those in Comparative Examples 2-4. Among all treatments, Example 3 (bag B + 8℃ pre-cooling) showed the most significant inhibitory effect on the increase in chromaticity a* value, with a chromaticity a* value of -15.11±0.52 on day 25 of storage, effectively inhibiting the fading of cowpeas during storage. Figure 2 B).

[0073] Experimental Example 3

[0074] During the storage of the above Examples 1-3 and Comparative Examples 1-4, the hardness of the cowpeas was observed and statistically analyzed every 5 days.

[0075] Hardness: Measured using a TA.XT Plus texture analyzer with a probe diameter of 2 mm. Hardness is expressed in Newtons (N).

[0076] The initial firmness of cowpeas was 11.25 ± 0.19 N. The firmness of the control fruit decreased rapidly in the first 15 days of storage, and then remained stable. Figure 2 C). Examples 1-3 using bag A packaging and Comparative Examples 2-4 using bag B packaging all inhibited the decrease in cowpea hardness to varying degrees. By the 25th day of storage, the hardness of cowpeas treated with Comparative Example 2 (bag A), Example 1 (bag B), Comparative Example 3 (bag A + 5°C pre-cooling), Example 2 (bag B + 5°C pre-cooling), Comparative Example 4 (bag A + 8°C pre-cooling), and Example 3 (bag B + 8°C pre-cooling) were 2.84, 3.76, 3.09, 3.91, 3.76, and 4.25 times that of the control cowpeas, respectively. Among them, the combination of bag B + 8°C pre-cooling in Example 3 had the best inhibitory effect on the decrease in cowpea hardness. Figure 2 C).

[0077] Test Example 4

[0078] During the storage of the above Examples 1-3 and Comparative Examples 1-4, the soluble solids content of cowpeas was observed and statistically analyzed every 5 days.

[0079] Soluble solids content: The pods were chopped and ground in a mortar and pestle. The juice was centrifuged at 8000×g for 5 min, and a drop of the supernatant was measured using a handheld refractometer. The results are expressed as the mass fraction of soluble solids in the pods.

[0080] Changes in soluble solids content during cowpea storage, such as Figure 2 As shown in Figure D, the initial value was 5.77 ± 0.03%, and the soluble solids content gradually decreased with storage. On day 25 of storage, the cowpeas in Comparative Example 3 (bag A + 5°C pre-cooling) had the lowest soluble solids content, only 3.23 ± 0.02%. In Examples 1-3, after day 25 of storage, the cowpeas all exhibited high soluble solids content, demonstrating good maintenance of the soluble solids content. Example 3 (bag B + 8°C pre-cooling) had the highest soluble solids content, at 3.73 ± 0.02%. Figure 2 D).

[0081] Experimental Example 5

[0082] During the storage of the above Examples 1-3 and Comparative Examples 1-4, the Fv / Fm of cowpeas was observed and counted every 5 days.

[0083] Fv / Fm: Measured in Fv / Fm mode using a handheld chlorophyll fluorometer (reflecting the maximum quantum yield of photosystem II).

[0084] The Fv / Fm value of cowpeas on the day of harvest was 0.81±0.01. As storage progressed, the Fv / Fm value of cowpeas gradually decreased. Figure 2 E). On day 25 of storage, the cowpeas treated with Comparative Example 2 (bag A), Example 1 (bag B), Comparative Example 3 (bag A + 5°C pre-cooling), Example 2 (bag B + 5°C pre-cooling), Comparative Example 4 (bag A + 8°C pre-cooling), and Example 3 (bag B + 8°C pre-cooling) were 7.64%, 24.11%, 18.23%, 24.71%, 20.59%, and 30.01% higher than the control cowpeas described in Comparative Example 1, respectively. Figure 2 E). The results showed that the treatments in Examples 1 to 3 were effective in maintaining chloroplast photosynthetic efficiency, with the combination of bag B + 8℃ pre-cooling treatment described in Example 3 being the most effective in maintaining chloroplast photosynthetic efficiency.

[0085] Experimental Example 6

[0086] During the storage of the above Examples 1-3 and Comparative Examples 1-4, the Fv / Fm of cowpeas was observed and counted every 5 days.

[0087] Weight loss rate: Calculated using the formula: Weight loss rate / % = (m0 - m) / % t ) / m0×100. Where: m0, the initial mass of the cowpeas; m t The mass of cowpeas after storage time t.

[0088] Changes in weight loss rate of cowpeas during storage, as follows Figure 2As shown in Figure F, the weight loss rate of the control cowpeas rapidly increased to 3.21% on the 5th day of storage, and then continued to rise, reaching 46.73% by the end of storage (25 days). Compared with the control group described in Comparative Example 1, Examples 1-3 using bag A packaging and Comparative Examples 2-4 using bag B packaging all reduced the weight loss rate of cowpeas to varying degrees; compared with bag A packaging (Comparative Examples 2-4), the treatments using bag B packaging in Examples 1-3 (bag B, bag B + 5°C pre-cooling, bag B + 8°C pre-cooling) resulted in a lower weight loss rate of cowpeas, which effectively reduced weight loss during cowpea storage. Among them, the combination treatment of bag B + 8°C pre-cooling in Example 3 had the lowest weight loss rate, only 2.04 ± 0.11% by the 25th day of storage. Figure 2 F).

[0089] As demonstrated by the above embodiments and experimental examples, this invention provides a method for cold storage and preservation of cowpeas. This method effectively reduces the degree of rust spots on cowpeas, inhibits fading and weight loss, and maintains high firmness, soluble solids content, and chlorophyll fluorescence. This method effectively maintains the storage quality of cowpeas and extends their shelf life. The cowpea preservation technology provided by this invention is simple and convenient to operate, low in cost, has good preservation effect, and is green and safe, possessing broad application prospects.

[0090] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preserving cowpeas, characterized in that, Includes the following steps: (1) After bundling the cowpeas, pre-cool them; (2) Store after film packaging; The pre-cooling treatment mentioned in step (1) involves immersing the cowpeas in ice water to lower the core temperature to 4.5~8.5℃; The thickness of the film mentioned in step (2) is 0.035~0.037 mm, and the water vapor transmission rate is 2.83~4.91×10⁻⁶. -11 gm - 1 s -1 Pa -1 The oxygen permeability is: 1.46~2.36×10⁻⁶ -3 gm -2 s -1 The carbon dioxide transmission rate is: 1.32~1.94×10⁻⁶ -3 gm -2 s -1 ; The storage temperature in step (2) is 7.5~8.5℃ and the relative humidity is 80~90%.

2. The method for preserving cowpeas according to claim 1, characterized in that, The cowpeas mentioned in step (1) are cowpeas that are 10-15 days after flowering, with plump pods, uniform thickness and color, and free from pests, diseases and mechanical damage. The pre-cooling treatment is carried out on the same day after harvesting.

3. The method for preserving cowpeas according to claim 1, characterized in that, When bundling in step (1), each bundle consists of 8 to 12 cowpeas.

4. The method for preserving cowpeas according to claim 1, characterized in that, In step (2), the cowpeas are packaged in groups of 2 to 4 bundles.

5. The method for preserving cowpeas according to claim 1, characterized in that, The film mentioned in step (2) is any one of the following: modified atmosphere packaging bag, biaxially oriented polypropylene packaging bag, polyvinyl chloride packaging bag, polyvinylidene chloride packaging bag, and polyvinyl alcohol fiber packaging bag.

6. The application of the method according to any one of claims 1 to 5 in the preservation of cowpeas.

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