Low-temperature vacuum dehydration and preservation process for fresh corn

Abstract

The invention relates to the technical field of food preservation, in particular to a low-temperature vacuum dehydration and preservation process for fresh corn. Comprising the following steps: draining fresh corns, and soaking the drained fresh corns in a fresh corn preservative for 10-15 minutes; the fresh corn preservative is prepared from the following components in parts by weight: 5.5 to 8.2 parts of corn pollen polysaccharide, 2 to 5 parts of sodium diacetate, 1.5 to 2.5 parts of lysozyme, 4 to 12 parts of chitosan, 2 to 4 parts of tea polyphenol, 6 to 18 parts of sorbitol, 2 to 4 parts of potassium sorbate, 0.6 to 1.2 parts of span-80, 2.2 to 5.6 parts of tween-80 and 10 to 15 parts of edible soybean oil. And taking out, draining, and storing at 0-4 DEG C. The invention provides a biological fresh-keeping process for fresh corn, which is simple in method, low in cost and good in fresh-keeping effect.

Description

Technical Field

[0001] This invention relates to the field of food preservation technology, and more specifically, to a low-temperature vacuum dehydration and preservation process for fresh corn. Background Technology

[0002] Sweet corn is the fresh ear of corn harvested when it reaches the milk stage. It is rich in carbohydrates, protein, dietary fiber, vitamins, and other nutrients, and has a unique flavor that makes it popular with consumers. Sweet corn can be eaten directly or processed into canned goods, frozen foods, or beverages. my country has over 1 million hectares of sweet corn planted, with more than 1,000 sweet corn production and processing enterprises. Currently, domestic demand for sweet corn is increasing year by year, and demand from countries such as Japan, South Korea, and Europe is also growing, making them major export markets for Chinese sweet corn. The sweet corn industry has become a new green industry in my country, with a rapidly growing market and broad development prospects.

[0003] After harvest, fresh corn kernels undergo rapid respiration, resulting in quick changes in nutritional composition and easy water loss, leading to a decline in quality and a short shelf life, which impacts production and sales. Therefore, preservation is necessary to extend shelf life. There are various techniques for storing and preserving fresh corn, such as heating, ambient temperature, irradiation, modified atmosphere packaging, vacuum packaging, refrigeration, and freezing. Each method has its advantages and disadvantages. For example, ambient temperature, vacuum packaging, modified atmosphere packaging, and irradiation are simple, practical, and low-cost, but their preservation time is short, failing to meet the needs of long-distance transportation and year-round market supply. Low-temperature preservation techniques offer longer storage times but also have drawbacks, including high costs, susceptibility to microbial contamination, and the inability to maintain the taste and flavor of fresh corn for extended periods.

[0004] With the continuous improvement of my country's cold chain structure, it is now possible to facilitate the low-temperature storage and transportation of fresh corn. However, the preservation of fresh corn is extremely difficult. Even if freshly harvested corn is stored and transported at a low temperature of 0-5℃, it can only be maintained for 2-3 days while ensuring its taste, nutritional quality, and storage quality. If it is kept at room temperature for 5 hours, its quality will change rapidly. This is mainly due to the decline in edible quality before entering the cold chain caused by microbial contamination. The short storage period of fresh corn after entering the cold chain cannot meet the needs of consumers across the country to obtain fresh corn through cross-regional and long-term cold chain transportation, transshipment, and market sales.

[0005] CN1374027A discloses a method for preserving glutinous corn products. This method involves washing the glutinous corn, blanching it to protect its color, using a biological color-protecting agent and a colorant, flavoring it, and then packaging it in a high-oxygen-barrier soft bag, vacuum-sealing it, sterilizing it at 120℃ for 20 minutes, cooling it, and then storing it. This preservation method uses vacuum packaging, which is costly and prone to bag bulging. Artificial flavoring of the fresh corn after blanching and color protection masks its original taste and flavor, thus reducing the quality of the fresh corn. Summary of the Invention

[0006] This invention provides a low-temperature vacuum dehydration and preservation process for fresh corn, offering a simple, low-cost, and effective biological preservation method for fresh corn.

[0007] In a first aspect, the present invention provides a low-temperature vacuum dehydration and preservation process for fresh corn, comprising the following steps: (1) Harvesting and processing: Fresh corn is harvested with husks 21-23 days after tasseling. The harvested fresh corn is cleaned by removing the outermost contaminated leaves from the husks and removing the dirty parts from the silks. (2) Spray cooling: Spray the harvested fresh corn for 15-30 minutes, with the spray water temperature being 0-3℃; (3) Rapid cooling: Immediately after spray cooling, immerse fresh corn intermittently in a 0-3℃ ice-water mixture for 3-10 minutes; (4) Controlling water and keeping warm: Take out the fresh corn and drain it for 2-3 hours. The draining temperature is 0-4℃. (5) After draining the fresh corn, soak it in the fresh corn preservative for 10-15 minutes; The fresh corn preservative comprises, by weight: 5.5-8.2 parts corn pollen polysaccharide, 2-5 parts sodium diacetate, 1.5-2.5 parts lysozyme, 4-12 parts chitosan, 2-4 parts tea polyphenols, 6-18 parts sorbitol, 2-4 parts potassium sorbate, 0.6-1.2 parts Span-80, 2.2-5.6 parts Tween-80, and 10-15 parts edible soybean oil. (6) Remove and drain, and store under vacuum conditions of 10-50 Pa and temperature of 0-4℃; (7) Packing: Lay a layer of plastic film at the bottom of the box, place the fresh corn with the tips facing up on the plastic film in the box, lay a layer of slush between the fresh corn, and place two ice packs above the tips of the fresh corn. (8) Storage and transportation: Boxes of fresh corn can be stored and transported in the cold chain.

[0008] Preferably, the fresh corn preservative comprises, by weight: 6.5-8.0 parts corn pollen polysaccharide, 2-3 parts sodium diacetate, 2.0-2.5 parts lysozyme, 6-8 parts chitosan, 3-4 parts tea polyphenols, 8-12 parts sorbitol, 2-3 parts potassium sorbate, 0.8-1.2 parts Span-80, 2.5-4.0 parts Tween-80, and 12-15 parts edible soybean oil.

[0009] Preferably, step (2) should be completed within 4 hours after harvesting.

[0010] Preferably, the degree of deacetylation of the chitosan is ≥85%.

[0011] Preferably, the lysozyme has an enzyme activity of 10,000-20,000 U / g.

[0012] Preferably, the corn pollen polysaccharide is an active polysaccharide isolated and purified from corn silks with a mass percentage concentration of 15%-20%.

[0013] Preferably, in step (6), the storage humidity is 80-85% during storage.

[0014] Preferably, in step (8), the pre-cooling temperature of the cold chain is -3 to 5°C, and the relative humidity is maintained at 90 to 95%.

[0015] In summary, the present invention has the following beneficial effects: The preservative in this invention includes corn pollen polysaccharide, lysozyme, chitosan, tea polyphenols, sorbitol, potassium sorbate, Span-80, Tween-80, and edible soybean oil. This compound formula combines antibacterial, antioxidant, and film-forming properties, inhibiting microbial growth and oxidation reactions from multiple angles, delaying quality deterioration. The preservative can inhibit moisture loss, reducing moisture loss by up to 18.6% and quality loss by 19.9%, thus maintaining the fresh and tender texture of the corn. The core advantage of this preservative lies in the synergistic effect of corn pollen polysaccharide, chitosan, and tea polyphenols, supplemented by the auxiliary functions of sorbitol, potassium sorbate, Span-80, and Tween-80, effectively extending shelf life and maintaining quality.

[0016] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit the scope of protection of the present invention. Detailed Implementation

[0017] The present invention will be further described in detail below with reference to the embodiments. It should be noted that: unless otherwise specified, the conditions in the following embodiments are carried out according to conventional conditions or the conditions recommended by the manufacturer. Unless otherwise specified, the raw materials used in the following embodiments can be obtained from commercially available sources.

[0018] Example Example 1

[0019] A low-temperature vacuum dehydration and preservation process for fresh corn includes the following steps: (1) Harvesting and processing Sweet corn is harvested 21-23 days after tasseling, with the husks still attached. At this time, the husks are green, the skin is firm, the corn is juicy, and the sugar content is high, resulting in the best flavor. The silks at the top of the ear are also preserved. After harvesting, the husks and silks are cleaned. The outermost layer of contaminated leaves is removed from the husks, and the dirty parts of the silks are removed. This process helps to remove bacteria and prevents the corn from providing a suitable environment for microbial growth during storage. (2) Spray cooling After harvesting, the fresh corn is sprayed and cooled for 15 minutes. The spray water temperature is 0-1℃. In order to prevent the corn quality from deteriorating, effectively clean the surface of the fresh corn, and lower the temperature of the fresh corn, this process should be carried out within 4 hours after harvesting. (3) Rapid cooling Immediately after spraying and cooling, the fresh corn is intermittently immersed in a 0-1℃ ice-water mixture for 3 minutes for further cooling. (4) Water control and heat preservation Remove the fresh corn and drain it for 3 hours at a temperature of 0-1℃. (5) After draining the fresh corn, soak it in a fresh corn preservative for 10 minutes, wherein, ①Preparation of basic preservative solution I A lysozyme solution was prepared by dissolving lysozyme with an enzyme activity of 20,000 U / g in sterile double-distilled water. A chitosan solution was prepared by dissolving chitosan with a deacetylation degree ≥85% in 0.5% glacial acetic acid solution. The lysozyme solution and chitosan solution were mixed evenly to prepare a solution with a chitosan concentration of 1.6% and a lysozyme concentration of 0.3%. The pH was adjusted to 5.2, and the enzymatic hydrolysis reaction was carried out at 45℃ for 3 hours to prepare the basic preservation solution I. ②Preparation of basic preservative solution II Chitosan with a deacetylation degree ≥85% was dissolved in a 0.5% glacial acetic acid solution to prepare a chitosan solution. Corn pollen polysaccharide (an active polysaccharide isolated and purified from corn pollen with a mass percentage concentration of 18%), tea polyphenols, sorbitol, sodium diacetate, and potassium sorbate were dissolved in sterile double-distilled water, and the chitosan solution was added to prepare a basic preservation solution II with a chitosan mass percentage concentration of 2.0%, a corn pollen polysaccharide mass percentage concentration of 3.0%, a tea polyphenol mass percentage concentration of 0.6%, and a sorbitol mass percentage concentration of 6.0%. ③Preparation of basic preservative solution III Span-80, Tween-80 and edible soybean oil were added to sterile double-distilled water to prepare a mixture with a mass percentage concentration of 0.6% for Span-80, 2.4% for Tween-80 and 10.0% for edible soybean oil. After homogenization for 15 minutes, the mixture was allowed to stand for 40 minutes to prepare the basic preservation solution III. ④ Compound fresh corn preservative After mixing the basic preservative solution II and the basic preservative solution III at a volume ratio of 4:1, a composite solution of basic preservative solution II and III is obtained. Then, the composite solution of basic preservative solution II and III is mixed with the basic preservative solution I at a volume ratio of 1:1 to prepare a fresh corn preservative. The fresh corn preservative comprises the following components by weight: 5.5 parts corn pollen polysaccharide, 2 parts sodium diacetate, 1.5 parts lysozyme, 4 parts chitosan, 2 parts tea polyphenols, 6 parts sorbitol, 2 parts potassium sorbate, 0.6 parts Span-800, 2.2 parts Tween-802, and 10 parts edible soybean oil. (6) Remove and drain, and store under vacuum conditions of 10-50 Pa and temperature of 0-4℃; (7) Packing: Lay a layer of plastic film at the bottom of the box, place the fresh corn with the tips facing up on the plastic film in the box, lay a layer of slush between the fresh corn, and place two ice packs above the tips of the fresh corn. (8) Storage and transportation: Boxes of fresh corn can be stored and transported in the cold chain.

[0020] Example 2

[0021] A low-temperature vacuum dehydration and preservation process for fresh corn includes the following steps: (1) Harvesting and processing Sweet corn is harvested 21-23 days after tasseling, with the husks still attached. At this time, the husks are green, the skin is firm, the corn is juicy, and the sugar content is high, resulting in the best flavor. The silks at the top of the ear are also preserved. After harvesting, the husks and silks are cleaned. The outermost layer of contaminated leaves is removed from the husks, and the dirty parts of the silks are removed. This process helps to remove bacteria and prevents the corn from providing a suitable environment for microbial growth during storage. (2) Spray cooling After harvesting, the fresh corn is sprayed and cooled for 15 minutes. The spray water temperature is 0-2℃. In order to prevent the corn quality from deteriorating, effectively clean the surface of the fresh corn, and lower the temperature of the fresh corn, this process should be carried out within 4 hours after harvesting. (3) Rapid cooling Immediately after spraying and cooling, the fresh corn is intermittently immersed in a 0-2℃ ice-water mixture for 3 minutes for further cooling. (4) Water control and heat preservation Remove the fresh corn and drain it for 3 hours at a temperature of 0-2℃. (5) After draining the fresh corn, soak it in a fresh corn preservative for 15 minutes, wherein, ①Preparation of basic preservative solution I A lysozyme solution was prepared by dissolving lysozyme with an enzyme activity of 15000 U / g in sterile double-distilled water. A chitosan solution was prepared by dissolving chitosan with a deacetylation degree ≥85% in 0.5% glacial acetic acid solution. The lysozyme solution and chitosan solution were mixed evenly to prepare a solution with a chitosan concentration of 1.6% and a lysozyme concentration of 0.3%. The pH was adjusted to 6.2, and the enzymatic hydrolysis reaction was carried out at 45℃ for 3 hours to prepare the basic preservation solution I. ②Preparation of basic preservative solution II Chitosan with a deacetylation degree ≥85% was dissolved in a 0.5% glacial acetic acid solution to prepare a chitosan solution. Corn pollen polysaccharide (an active polysaccharide isolated and purified from corn pollen with a mass percentage concentration of 18%), tea polyphenols, sorbitol, sodium diacetate, and potassium sorbate were dissolved in sterile double-distilled water, and the chitosan solution was added to prepare a basic preservation solution II with a chitosan mass percentage concentration of 2.0%, a corn pollen polysaccharide mass percentage concentration of 3.0%, a tea polyphenol mass percentage concentration of 0.6%, and a sorbitol mass percentage concentration of 6.0%. ③Preparation of basic preservative solution III Span-80, Tween-80 and edible soybean oil were added to sterile double-distilled water to prepare a mixture with a mass percentage concentration of 0.6% for Span-80, 2.4% for Tween-80 and 10.0% for edible soybean oil. After homogenization for 15 minutes, the mixture was allowed to stand for 40 minutes to prepare the basic preservation solution III. ④ Compound fresh corn preservative After mixing the basic preservative solution II and the basic preservative solution III at a volume ratio of 3:1, a composite solution of basic preservative solution II and III is obtained. Then, the composite solution of basic preservative solution II and III is mixed with the basic preservative solution I at a volume ratio of 2:1 to prepare a fresh corn preservative. The fresh corn preservative comprises the following components by weight: 6.5 parts corn pollen polysaccharide, 3 parts sodium diacetate, 1.8 parts lysozyme, 5 parts chitosan, 3 parts tea polyphenols, 7 parts sorbitol, 3 parts potassium sorbate, 0.8 parts Span-80, 2.5 parts Tween-80, and 12 parts edible soybean oil. (6) Remove and drain, and store under vacuum conditions of 10-50 Pa and temperature of 0-4℃; (7) Packing: Lay a layer of plastic film at the bottom of the box, place the fresh corn with the tips facing up on the plastic film in the box, lay a layer of slush between the fresh corn, and place two ice packs above the tips of the fresh corn. (8) Storage and transportation: Boxes of fresh corn can be stored and transported in the cold chain.

[0022] Example 3

[0023] A low-temperature vacuum dehydration and preservation process for fresh corn includes the following steps: (1) Harvesting and processing Sweet corn is harvested 21-23 days after tasseling, with the husks still attached. At this time, the husks are green, the skin is firm, the corn is juicy, and the sugar content is high, resulting in the best flavor. The silks at the top of the ear are also preserved. After harvesting, the husks and silks are cleaned. The outermost layer of contaminated leaves is removed from the husks, and the dirty parts of the silks are removed. This process helps to remove bacteria and prevents the corn from providing a suitable environment for microbial growth during storage. (2) Spray cooling After harvesting, the fresh corn is sprayed and cooled for 15 minutes. The spray water temperature is 1-3℃. In order to prevent the corn quality from declining, effectively clean the surface of the fresh corn, and lower the temperature of the fresh corn, this process should be carried out within 4 hours after harvesting. (3) Rapid cooling Immediately after spraying and cooling, the fresh corn is intermittently immersed in a 1-3℃ ice-water mixture for 3 minutes for further cooling. (4) Water control and heat preservation Remove the fresh corn and drain it for 3 hours at a temperature of 0-3℃. (5) After draining the fresh corn, soak it in a fresh corn preservative for 12 minutes, wherein, ①Preparation of basic preservative solution I A lysozyme solution was prepared by dissolving lysozyme with an enzyme activity of 12000 U / g in sterile double-distilled water. A chitosan solution was prepared by dissolving chitosan with a deacetylation degree ≥85% in 0.5% glacial acetic acid solution. The lysozyme solution and chitosan solution were mixed evenly to prepare a solution with a chitosan concentration of 1.6% and a lysozyme concentration of 0.3%. The pH was adjusted to 5.2, and the enzymatic hydrolysis reaction was carried out at 45℃ for 3 hours to prepare the basic preservation solution I. ②Preparation of basic preservative solution II Chitosan with a deacetylation degree ≥85% was dissolved in a 0.5% glacial acetic acid solution to prepare a chitosan solution. Corn pollen polysaccharide (an active polysaccharide isolated and purified from corn pollen with a mass percentage concentration of 18%), tea polyphenols, sorbitol, sodium diacetate, and potassium sorbate were dissolved in sterile double-distilled water, and the chitosan solution was added to prepare a basic preservation solution II with a chitosan mass percentage concentration of 2.0%, a corn pollen polysaccharide mass percentage concentration of 3.0%, a tea polyphenol mass percentage concentration of 0.6%, and a sorbitol mass percentage concentration of 6.0%. ③Preparation of basic preservative solution III Span-80, Tween-80 and edible soybean oil were added to sterile double-distilled water to prepare a mixture with a mass percentage concentration of 0.6% for Span-80, 2.4% for Tween-80 and 10.0% for edible soybean oil. After homogenization for 15 minutes, the mixture was allowed to stand for 40 minutes to prepare the basic preservation solution III. ④ Compound fresh corn preservative After mixing the basic preservative solution II and the basic preservative solution III at a volume ratio of 5:1, a composite solution of basic preservative solution II and III is obtained. Then, the composite solution of basic preservative solution II and III is mixed with the basic preservative solution I at a volume ratio of 1:2 to prepare a fresh corn preservative. The fresh corn preservative comprises the following components by weight: 7.1 parts corn pollen polysaccharide, 2.5 parts sodium diacetate, 1.6 parts lysozyme, 5 parts chitosan, 3 parts tea polyphenols, 8 parts sorbitol, 3 parts potassium sorbate, 0.9 parts Span-80, 2.8 parts Tween-80, and 12 parts edible soybean oil. (6) Remove and drain, and store under vacuum conditions of 10-50 Pa and temperature of 0-4℃; (7) Packing: Lay a layer of plastic film at the bottom of the box, place the fresh corn with the tips facing up on the plastic film in the box, lay a layer of slush between the fresh corn, and place two ice packs above the tips of the fresh corn. (8) Storage and transportation: Boxes of fresh corn can be stored and transported in the cold chain.

[0024] Example 4

[0025] A low-temperature vacuum dehydration and preservation process for fresh corn includes the following steps: (1) Harvesting and processing Sweet corn is harvested 21-23 days after tasseling, with the husks still attached. At this time, the husks are green, the skin is firm, the corn is juicy, and the sugar content is high, resulting in the best flavor. The silks at the top of the ear are also preserved. After harvesting, the husks and silks are cleaned. The outermost layer of contaminated leaves is removed from the husks, and the dirty parts of the silks are removed. This process helps to remove bacteria and prevents the corn from providing a suitable environment for microbial growth during storage. (2) Spray cooling After harvesting, the fresh corn is sprayed and cooled for 15 minutes. The spray water temperature is 2-3℃. In order to prevent the corn quality from deteriorating, effectively clean the surface of the fresh corn, and lower the temperature of the fresh corn, this process should be carried out within 4 hours after harvesting. (3) Rapid cooling Immediately after spraying and cooling, the fresh corn is intermittently immersed in a 2-3℃ ice-water mixture for 3 minutes for further cooling. (4) Water control and heat preservation Remove the fresh corn and drain it for 3 hours at a temperature of 3-4℃. (5) After draining the fresh corn, soak it in a fresh corn preservative for 15 minutes, wherein, ①Preparation of basic preservative solution I A lysozyme solution was prepared by dissolving lysozyme with an enzyme activity of 13000 U / g in sterile double-distilled water. A chitosan solution was prepared by dissolving chitosan with a deacetylation degree ≥85% in 0.5% glacial acetic acid solution. The lysozyme solution and chitosan solution were mixed evenly to prepare a solution with a chitosan concentration of 1.6% and a lysozyme concentration of 0.3%. The pH was adjusted to 5.2, and the enzymatic hydrolysis reaction was carried out at 45℃ for 3 hours to prepare the basic preservation solution I. ②Preparation of basic preservative solution II Chitosan with a deacetylation degree ≥85% was dissolved in a 0.5% glacial acetic acid solution to prepare a chitosan solution. Corn pollen polysaccharide (an active polysaccharide isolated and purified from corn pollen with a mass percentage concentration of 18%), tea polyphenols, sorbitol, sodium diacetate, and potassium sorbate were dissolved in sterile double-distilled water, and the chitosan solution was added to prepare a basic preservation solution II with a chitosan mass percentage concentration of 2.0%, a corn pollen polysaccharide mass percentage concentration of 3.0%, a tea polyphenol mass percentage concentration of 0.6%, and a sorbitol mass percentage concentration of 6.0%. ③Preparation of basic preservative solution III Span-80, Tween-80 and edible soybean oil were added to sterile double-distilled water to prepare a mixture with a mass percentage concentration of 0.6% for Span-80, 2.4% for Tween-80 and 10.0% for edible soybean oil. After homogenization for 15 minutes, the mixture was allowed to stand for 40 minutes to prepare the basic preservation solution III. ④ Compound fresh corn preservative After mixing the basic preservative solution II and the basic preservative solution III at a volume ratio of 2:1, a composite solution of basic preservative solution II and III is obtained. Then, the composite solution of basic preservative solution II and III is mixed with the basic preservative solution I at a volume ratio of 2:1 to prepare a fresh corn preservative. The fresh corn preservative comprises the following components by weight: 7.4 parts corn pollen polysaccharide, 2.8 parts sodium diacetate, 2.0 parts lysozyme, 6 parts chitosan, 2.5 parts tea polyphenols, 8 parts sorbitol, 3 parts potassium sorbate, 0.9 parts Span-80, 3.6 parts Tween-80, and 13 parts edible soybean oil. (6) Remove and drain, and store under vacuum conditions of 10-50 Pa and temperature of 0-4℃; (7) Packing: Lay a layer of plastic film at the bottom of the box, place the fresh corn with the tips facing up on the plastic film in the box, lay a layer of slush between the fresh corn, and place two ice packs above the tips of the fresh corn. (8) Storage and transportation: Boxes of fresh corn can be stored and transported in the cold chain.

[0026] Example 5

[0027] A low-temperature vacuum dehydration and preservation process for fresh corn includes the following steps: (1) Harvesting and processing Sweet corn is harvested 21-23 days after tasseling, with the husks still attached. At this time, the husks are green, the skin is firm, the corn is juicy, and the sugar content is high, resulting in the best flavor. The silks at the top of the ear are also preserved. After harvesting, the husks and silks are cleaned. The outermost layer of contaminated leaves is removed from the husks, and the dirty parts of the silks are removed. This process helps to remove bacteria and prevents the corn from providing a suitable environment for microbial growth during storage. (2) Spray cooling After harvesting, the fresh corn is sprayed and cooled for 15 minutes. The spray water temperature is 2-3℃. In order to prevent the corn quality from deteriorating, effectively clean the surface of the fresh corn, and lower the temperature of the fresh corn, this process should be carried out within 4 hours after harvesting. (3) Rapid cooling Immediately after spraying and cooling, the fresh corn is intermittently immersed in a 2-3℃ ice-water mixture for 3 minutes for further cooling. (4) Water control and heat preservation Remove the fresh corn and drain it for 3 hours at a temperature of 2-4℃. (5) After draining the fresh corn, soak it in a fresh corn preservative for 15 minutes, wherein, ①Preparation of basic preservative solution I A lysozyme solution was prepared by dissolving lysozyme with an enzyme activity of 18000 U / g in sterile double-distilled water. A chitosan solution was prepared by dissolving chitosan with a deacetylation degree ≥85% in 0.5% glacial acetic acid solution. The lysozyme solution and chitosan solution were mixed evenly to prepare a solution with a chitosan concentration of 1.6% and a lysozyme concentration of 0.3%. The pH was adjusted to 5.2, and the enzymatic hydrolysis reaction was carried out at 45℃ for 3 hours to prepare the basic preservation solution I. ②Preparation of basic preservative solution II Chitosan with a deacetylation degree ≥80% was dissolved in a 0.5% glacial acetic acid solution to prepare a chitosan solution. Corn pollen polysaccharide (an active polysaccharide isolated and purified from corn pollen with a mass percentage concentration of 18%), tea polyphenols, sorbitol, sodium diacetate, and potassium sorbate were dissolved in sterile double-distilled water, and the chitosan solution was added to prepare a basic preservation solution II with a chitosan mass percentage concentration of 2.0%, a corn pollen polysaccharide mass percentage concentration of 3.0%, a tea polyphenol mass percentage concentration of 0.6%, and a sorbitol mass percentage concentration of 6.0%. ③Preparation of basic preservative solution III Span-80, Tween-80 and edible soybean oil were added to sterile double-distilled water to prepare a mixture with a mass percentage concentration of 0.6% for Span-80, 2.4% for Tween-80 and 10.0% for edible soybean oil. After homogenization for 15 minutes, the mixture was allowed to stand for 40 minutes to prepare the basic preservation solution III. ④ Compound fresh corn preservative After mixing the basic preservative solution II and basic preservative solution III at a volume ratio of 3:1, a composite solution of basic preservative solution II and III is obtained. Then, the composite solution of basic preservative solution II and III is mixed with basic preservative solution I at a volume ratio of 2:1 to prepare a fresh corn preservative. The fresh corn preservative comprises the following components by weight: 6.8 parts corn pollen polysaccharide, 2.3 parts sodium diacetate, 2.1 parts lysozyme, 7 parts chitosan, 2.5 parts tea polyphenols, 9 parts sorbitol, 2.5 parts potassium sorbate, 0.7 parts Span-80, 3.2 parts Tween-80, and 11 parts edible soybean oil. (6) Remove and drain, and store under vacuum conditions of 10-50 Pa and temperature of 0-4℃; (7) Packing: Lay a layer of plastic film at the bottom of the box, place the fresh corn with the tips facing up on the plastic film in the box, lay a layer of slush between the fresh corn, and place two ice packs above the tips of the fresh corn. (8) Storage and transportation: Boxes of fresh corn can be stored and transported in the cold chain.

[0028] Example 6

[0029] A low-temperature vacuum dehydration and preservation process for fresh corn includes the following steps: (1) Harvesting and processing Sweet corn is harvested 21-23 days after tasseling, with the husks still attached. At this time, the husks are green, the skin is firm, the corn is juicy, and the sugar content is high, resulting in the best flavor. The silks at the top of the ear are also preserved. After harvesting, the husks and silks are cleaned. The outermost layer of contaminated leaves is removed from the husks, and the dirty parts of the silks are removed. This process helps to remove bacteria and prevents the corn from providing a suitable environment for microbial growth during storage. (2) Spray cooling After harvesting, the fresh corn is sprayed and cooled for 15 minutes. The spray water temperature is 1-3℃. In order to prevent the corn quality from declining, effectively clean the surface of the fresh corn, and lower the temperature of the fresh corn, this process should be carried out within 4 hours after harvesting. (3) Rapid cooling Immediately after spraying and cooling, the fresh corn is intermittently immersed in a 1-3℃ ice-water mixture for 3 minutes for further cooling. (4) Water control and heat preservation Remove the fresh corn and drain it for 3 hours at a temperature of 1-4℃. (5) After draining the fresh corn, soak it in a fresh corn preservative for 15 minutes, wherein, ①Preparation of basic preservative solution I A lysozyme solution was prepared by dissolving lysozyme with an enzyme activity of 15000 U / g in sterile double-distilled water. A chitosan solution was prepared by dissolving chitosan with a deacetylation degree ≥85% in 0.5% glacial acetic acid solution. The lysozyme solution and chitosan solution were mixed evenly to prepare a solution with a chitosan concentration of 1.6% and a lysozyme concentration of 0.3%. The pH was adjusted to 5.2, and the enzymatic hydrolysis reaction was carried out at 45℃ for 3 hours to prepare the basic preservation solution I. ②Preparation of basic preservative solution II Chitosan with a deacetylation degree ≥85% was dissolved in a 0.5% glacial acetic acid solution to prepare a chitosan solution. Corn pollen polysaccharide (an active polysaccharide isolated and purified from corn pollen with a mass percentage concentration of 18%), tea polyphenols, sorbitol, sodium diacetate, and potassium sorbate were dissolved in sterile double-distilled water, and the chitosan solution was added to prepare a basic preservation solution II with a chitosan mass percentage concentration of 2.0%, a corn pollen polysaccharide mass percentage concentration of 3.0%, a tea polyphenol mass percentage concentration of 0.6%, and a sorbitol mass percentage concentration of 6.0%. ③Preparation of basic preservative solution III Span-80, Tween-80 and edible soybean oil were added to sterile double-distilled water to prepare a mixture with a mass percentage concentration of 0.6% for Span-80, 2.4% for Tween-80 and 10.0% for edible soybean oil. After homogenization for 15 minutes, the mixture was allowed to stand for 40 minutes to prepare the basic preservation solution III. ④ Compound fresh corn preservative After mixing the basic preservative solution II and basic preservative solution III at a volume ratio of 5:1, a composite solution of basic preservative solution II and III is obtained. Then, the composite solution of basic preservative solution II and III is mixed with basic preservative solution I at a volume ratio of 2:1 to prepare a fresh corn preservative. The fresh corn preservative comprises the following components by weight: 7.8 parts corn pollen polysaccharide, 2.2 parts sodium diacetate, 1.9 parts lysozyme, 6.2 parts chitosan, 2.8 parts tea polyphenols, 7.5 parts sorbitol, 3.1 parts potassium sorbate, 1.0 parts Span-80, 2.8 parts Tween-80, and 12.5 parts edible soybean oil. (6) Remove and drain, and store under vacuum conditions of 10-50 Pa and temperature of 0-4℃; (7) Packing: Lay a layer of plastic film at the bottom of the box, place the fresh corn with the tips facing up on the plastic film in the box, lay a layer of slush between the fresh corn, and place two ice packs above the tips of the fresh corn. (8) Storage and transportation: Boxes of fresh corn can be stored and transported in the cold chain.

[0030] Example 7

[0031] A low-temperature vacuum dehydration and preservation process for fresh corn includes the following steps: (1) Harvesting and processing Sweet corn is harvested 21-23 days after tasseling, with the husks still attached. At this time, the husks are green, the skin is firm, the corn is juicy, and the sugar content is high, resulting in the best flavor. The silks at the top of the ear are also preserved. After harvesting, the husks and silks are cleaned. The outermost layer of contaminated leaves is removed from the husks, and the dirty parts of the silks are removed. This process helps to remove bacteria and prevents the corn from providing a suitable environment for microbial growth during storage. (2) Spray cooling After harvesting, the fresh corn is sprayed and cooled for 15 minutes. The spray water temperature is 0-2℃. In order to prevent the corn quality from deteriorating, effectively clean the surface of the fresh corn, and lower the temperature of the fresh corn, this process should be carried out within 4 hours after harvesting. (3) Rapid cooling Immediately after spraying and cooling, the fresh corn is intermittently immersed in a 0-2℃ ice-water mixture for 3 minutes for further cooling. (4) Water control and heat preservation Remove the fresh corn and drain it for 3 hours at a temperature of 0-2℃. (5) After draining the fresh corn, soak it in a fresh corn preservative for 10 minutes, wherein, ①Preparation of basic preservative solution I A lysozyme solution was prepared by dissolving lysozyme with an enzyme activity of 16000 U / g in sterile double-distilled water. A chitosan solution was prepared by dissolving chitosan with a deacetylation degree ≥85% in 0.5% glacial acetic acid solution. The lysozyme solution and chitosan solution were mixed evenly to prepare a solution with a chitosan concentration of 1.6% and a lysozyme concentration of 0.3%. The pH was adjusted to 5.2, and the enzymatic hydrolysis reaction was carried out at 45℃ for 3 hours to prepare the basic preservation solution I. ②Preparation of basic preservative solution II Chitosan with a deacetylation degree ≥85% was dissolved in a 0.5% glacial acetic acid solution to prepare a chitosan solution. Corn pollen polysaccharide (an active polysaccharide isolated and purified from corn pollen with a mass percentage concentration of 18%), tea polyphenols, sorbitol, sodium diacetate, and potassium sorbate were dissolved in sterile double-distilled water, and the chitosan solution was added to prepare a basic preservation solution II with a chitosan mass percentage concentration of 2.0%, a corn pollen polysaccharide mass percentage concentration of 3.0%, a tea polyphenol mass percentage concentration of 0.6%, and a sorbitol mass percentage concentration of 6.0%. ③Preparation of basic preservative solution III Span-80, Tween-80 and edible soybean oil were added to sterile double-distilled water to prepare a mixture with a mass percentage concentration of 0.6% for Span-80, 2.4% for Tween-80 and 10.0% for edible soybean oil. After homogenization for 15 minutes, the mixture was allowed to stand for 40 minutes to prepare the basic preservation solution III. ④ Compound fresh corn preservative After mixing the basic preservative solution II and basic preservative solution III at a volume ratio of 3:2, a composite solution of basic preservative solution II and III is obtained. Then, the composite solution of basic preservative solution II and III is mixed with basic preservative solution I at a volume ratio of 1:3 to prepare a fresh corn preservative. The fresh corn preservative comprises the following components by weight: 8.0 parts corn pollen polysaccharide, 4.5 parts sodium diacetate, 2.3 parts lysozyme, 10 parts chitosan, 3 parts tea polyphenols, 15 parts sorbitol, 3 parts potassium sorbate, 0.9 parts Span-80, 3.8 parts Tween-80, and 13 parts edible soybean oil. (6) Remove and drain, and store under vacuum conditions of 10-50 Pa and temperature of 0-4℃; (7) Packing: Lay a layer of plastic film at the bottom of the box, place the fresh corn with the tips facing up on the plastic film in the box, lay a layer of slush between the fresh corn, and place two ice packs above the tips of the fresh corn. (8) Storage and transportation: Boxes of fresh corn can be stored and transported in the cold chain.

[0032] Example 8

[0033] A low-temperature vacuum dehydration and preservation process for fresh corn includes the following steps: (1) Harvesting and processing Sweet corn is harvested 21-23 days after tasseling, with the husks still attached. At this time, the husks are green, the skin is firm, the corn is juicy, and the sugar content is high, resulting in the best flavor. The silks at the top of the ear are also preserved. After harvesting, the husks and silks are cleaned. The outermost layer of contaminated leaves is removed from the husks, and the dirty parts of the silks are removed. This process helps to remove bacteria and prevents the corn from providing a suitable environment for microbial growth during storage. (2) Spray cooling After harvesting, the fresh corn is sprayed and cooled for 15 minutes. The spray water temperature is 0-1℃. In order to prevent the corn quality from deteriorating, effectively clean the surface of the fresh corn, and lower the temperature of the fresh corn, this process should be carried out within 4 hours after harvesting. (3) Rapid cooling Immediately after spraying and cooling, the fresh corn is intermittently immersed in a 0-1℃ ice-water mixture for 3 minutes for further cooling. (4) Water control and heat preservation Remove the fresh corn and drain it for 3 hours at a temperature of 0-1℃. (5) After draining the fresh corn, soak it in a fresh corn preservative for 10 minutes, wherein, ①Preparation of basic preservative solution I A lysozyme solution was prepared by dissolving lysozyme with an enzyme activity of 13000 U / g in sterile double-distilled water. A chitosan solution was prepared by dissolving chitosan with a deacetylation degree ≥85% in 0.5% glacial acetic acid solution. The lysozyme solution and chitosan solution were mixed evenly to prepare a solution with a chitosan concentration of 1.6% and a lysozyme concentration of 0.3%. The pH was adjusted to 5.2, and the enzymatic hydrolysis reaction was carried out at 45℃ for 3 hours to prepare the basic preservation solution I. ②Preparation of basic preservative solution II Chitosan with a deacetylation degree ≥85% was dissolved in a 0.5% glacial acetic acid solution to prepare a chitosan solution. Corn pollen polysaccharide (an active polysaccharide isolated and purified from corn pollen with a mass percentage concentration of 18%), tea polyphenols, sorbitol, sodium diacetate, and potassium sorbate were dissolved in sterile double-distilled water, and the chitosan solution was added to prepare a basic preservation solution II with a chitosan mass percentage concentration of 2.0%, a corn pollen polysaccharide mass percentage concentration of 3.0%, a tea polyphenol mass percentage concentration of 0.6%, and a sorbitol mass percentage concentration of 6.0%. ③Preparation of basic preservative solution III Span-80, Tween-80 and edible soybean oil were added to sterile double-distilled water to prepare a mixture with a mass percentage concentration of 0.6% for Span-80, 2.4% for Tween-80 and 10.0% for edible soybean oil. After homogenization for 15 minutes, the mixture was allowed to stand for 40 minutes to prepare the basic preservation solution III. ④ Compound fresh corn preservative Basic preservative solution II and basic preservative solution III are mixed evenly at a volume ratio of 5:1 to obtain a composite solution of basic preservative solution II and III. The composite solution of basic preservative solution II and III is then mixed evenly with basic preservative solution I at a volume ratio of 3:1 to prepare a fresh corn preservative. The fresh corn preservative comprises the following components by weight: 8.2 parts corn pollen polysaccharide, 5 parts sodium diacetate, 2.5 parts lysozyme, 12 parts chitosan, 4 parts tea polyphenols, 18 parts sorbitol, 4 parts potassium sorbate, 1.2 parts Span-80, 5.6 parts Tween-80, and 15 parts edible soybean oil. (6) Remove and drain, and store under vacuum conditions of 10-50 Pa and temperature of 0-4℃; (7) Packing: Lay a layer of plastic film at the bottom of the box, place the fresh corn with the tips facing up on the plastic film in the box, lay a layer of slush between the fresh corn, and place two ice packs above the tips of the fresh corn. (8) Storage and transportation: Boxes of fresh corn can be stored and transported in the cold chain.

[0034] Comparative Example 1 (1) Harvest fresh sweet corn 21-23 days after the ears have emerged, and remove the husks and silks from the harvested fresh sweet corn; (2) Spray the harvested fresh corn with water to cool it for 15 minutes. The water temperature should be 0-3℃. This process should be carried out within 4 hours after harvesting. (3) Immediately after spraying and cooling, the fresh corn is intermittently immersed in a mixture of ice water at 0-5℃ for 3 minutes for further cooling. (4) After cooling, take out the fresh corn and drain it for 3 hours in an environment of 0-4℃; (5) Lay a layer of plastic film at the bottom of the box, place the fresh corn with the tips facing up on the plastic film in the box, lay a layer of slush between the fresh corn, and place two ice packs above the tips of the fresh corn. The plastic film has two round holes evenly distributed near the middle. (6) Boxes of fresh corn can be stored and transported in cold storage, refrigerated storage and other cold chain facilities. The pre-cooling temperature of the cold chain is -3 to 5℃ and the relative humidity is maintained at 90 to 95%.

[0035] Comparative Example 2 Same as Example 1, except that no preservative was added.

[0036] Comparative Example 3 Same as Example 2, except that the water control and heat preservation in step (4) were not performed.

[0037] Table 1. Shelf life of fresh corn in Examples 1-8 and Comparative Examples 1-3

[0038] As shown in Table 1, the fresh corn preservation process in this embodiment has a long release period and can effectively maintain the fresh quality of the corn. This indicates that the compound formulation combines antibacterial, antioxidant, and film-forming properties, inhibiting microbial growth and oxidation reactions from multiple angles, delaying quality deterioration. The preservative can inhibit moisture loss, reducing the moisture loss rate by up to 18.6% and the quality loss rate by 19.9%, thereby maintaining the fresh and tender taste of the corn. The core advantage of the preservative lies in the synergistic effect of corn pollen polysaccharides, chitosan, and tea polyphenols, supplemented by the auxiliary functions of sorbitol, potassium sorbate, Span-80, and Tween-80, which can effectively extend shelf life and maintain quality.

[0039] The above description is merely an exemplary embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A process for the preservation of fresh corn by low temperature vacuum dehydration, characterized in that, It comprises the following steps: (1) harvesting treatment: fresh corn is harvested at 21-23 days after tasseling with bract leaves, and the harvested fresh corn is arranged with leaf wrapping silk, the outermost contaminated leaves are removed from the bract leaves, and the dirty and messy parts are removed from the silk; (2) spraying cooling: the harvested fresh corn is sprayed and cooled for 15-30 minutes, and the spraying water temperature is 0-3℃; (3) rapid cooling: after spraying and cooling, the fresh corn is immediately immersed in 0-3℃ ice water mixture for 3-10 minutes; (4) water control and heat preservation: the fresh corn is taken out and drained for 2-3 hours, and the draining temperature is 0-4℃; (5) after draining, the fresh corn is soaked in the fresh corn preservative for 10-15 minutes; The fresh corn preservative comprises, by weight: corn pollen polysaccharide 5.5-8.2 parts, sodium diacetate 2-5 parts, lysozyme 1.5-2.5 parts, chitosan 4-12 parts, tea polyphenol 2-4 parts, sorbitol 6-18 parts, potassium sorbate 2-4 parts, Span-800 0.6-1.2 parts, Tween-80 2.2-5.6 parts, and edible soybean oil 10-15 parts; (6) take out and drain, store under the conditions of vacuum degree 10-50 Pa and temperature 0-4℃; (7) boxing: a layer of plastic film is laid at the bottom of the box, the fresh corn is vertically placed on the plastic film in the box with the tip part upward, a layer of sand ice is laid between the fresh corn, and two ice bags are placed above the tip part of the fresh corn; (8) storage and transportation: the boxed fresh corn can enter the cold chain for storage and transportation.

2. The process for low temperature vacuum dehydration of fresh corn as claimed in claim 1 wherein, The fresh corn preservative comprises, by weight: corn pollen polysaccharide 6.5-8.0 parts, sodium diacetate 2-3 parts, lysozyme 2.0-2.5 parts, chitosan 6-8 parts, tea polyphenol 3-4 parts, sorbitol 8-12 parts, potassium sorbate 2-3 parts, Span-800 0.8-1.2 parts, Tween-80 2.5-4.0 parts, and edible soybean oil 12-15 parts.

3. The process for low temperature vacuum dehydration of fresh corn as claimed in claim 1 wherein, The (2) should be completed within 4 hours after picking.

4. The process for preservation of fresh corns by low temperature vacuum dehydration as claimed in claim 1 wherein, The degree of deacetylation of the chitosan is ≥85%.

5. The process for preservation of fresh corns by low temperature vacuum dehydration as claimed in claim 1 wherein, The enzyme activity of the lysozyme is 10000-20000 U / g.

6. The process for preservation of fresh corns by low temperature vacuum dehydration as claimed in claim 1 wherein, The corn pollen polysaccharide is an active polysaccharide with a mass percentage concentration of 15-20% separated and purified from corn silk.

7. The process for preservation of fresh corns by low temperature vacuum dehydration as claimed in claim 1 wherein, In the (6), the storage humidity is 80-85% during storage.

8. The process for preservation of fresh corns by low temperature vacuum dehydration as claimed in claim 1 wherein, In the (8), the precooling temperature of the cold chain is -3-5℃, and the relative humidity is kept at 90-95%.

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