Efficient dried longan preservation technology
Through an efficient longan dry preservation process including ultraviolet rays and microwave sterilization treatments, as well as nitrogen-filled packaging, the problem that longan dry is susceptible to factors such as humidity, temperature, and oxygen in the prior art is solved, and the effect of improving preparation efficiency, killing microorganisms, and extending the shelf life is achieved.
Patent Information
- Application Number
- CN202411767293.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-04
- Publication Date
- 2025-02-28
AI Technical Summary
The existing longan dry preservation process is easily affected by factors such as humidity, temperature, and oxygen, resulting in a decline in quality, mold, insect worms, and darker color, which seriously affects the edible value and commercial value.
An efficient dry preservation process for longan is adopted, including raw material selection, cleaning, shearing, soaking, overshaking, initial roasting, sterilization, re-roasting, thigh cutting, grading and nitrogen filling packaging. Through ultraviolet and microwave sterilization, microorganisms are killed and air in the packaging is eliminated by nitrogen-filled packaging to prevent oxidation and mold growth.
The process flow is optimized, the preparation efficiency of longan dry is improved, the microorganisms are effectively killed, the hygiene quality is improved, the shelf life is extended, and the process is simple and easy to use, suitable for large-scale production and application.
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of food processing, in particular to an efficient dry longan preservation process. Background Art
[0002] Longan is a delicious and nutritious fruit that is deeply loved by the public. In order to facilitate storage and extend the shelf life, people make it into dried longan. In the traditional production process of dried longan, sun drying is the main dehydration method, but in actual operation, it is found that if complete drying is pursued to reduce the risk of mold, the dried longan after sun drying will become dry, hard and astringent when eaten, which greatly affects the pleasure of eating. On the other hand, if the dried longan is not dried enough to ensure the ready-to-eat taste, although its taste is relatively good in a short time, the moisture content is still at a high level, which provides favorable conditions for the growth of microorganisms such as mold. During storage, these microorganisms will multiply rapidly, causing the dried longan to mold and deteriorate. Once moldy, the dried longan not only loses its edible value, but may also produce substances harmful to human health. Therefore, an efficient dried longan preservation process is particularly needed.
[0003] However, the existing dried longan preservation process is easily affected by factors such as humidity, temperature, and oxygen during the processing of dried longan, which leads to its quality degradation, mildew, insect infestation, darkening of color, and other problems, seriously affecting the edible value and commercial value of dried longan. Summary of the invention
[0004] The purpose of the present invention is to provide an efficient dried longan preservation process to solve the problems raised in the above background technology.
[0005] In order to solve the above technical problems, the present invention is solved by the following technical solutions: an efficient longan dried fresh-keeping process, comprising the following steps:
[0006] 1. An efficient longan dried fresh-keeping process, characterized in that it comprises the following steps:
[0007] S1. Raw material selection;
[0008] S2, cleaning, cutting, and soaking;
[0009] S3, over-shaking;
[0010] S4, initial roasting;
[0011] S5, sterilization;
[0012] S6, re-roasting;
[0013] S7, cutting and grading;
[0014] S8. Nitrogen-filled packaging.
[0015] Preferably, in S1, fresh, ripe, disease- and insect-free longan fruits are selected as raw materials.
[0016] Preferably, the specific methods of S2, cleaning, cutting and soaking are as follows:
[0017] S2-1. Put the longan fruit in clean water and gently scrub it with a soft brush to remove dust and impurities on the surface;
[0018] S2-2, cut the longan fruits from the clusters with scissors, leaving the stems at a length of 1.5 mm, and remove the broken fruits;
[0019] S2-3. Put the cut longan fruits into a bamboo basket and soak them in clean water for 5-10 minutes to wash off the dust.
[0020] Preferably, the specific method in the step S3, over-shaking, is as follows:
[0021] Pour the soaked longan fruits into a special shaking cage, with each cage holding about 35 kilograms. Sprinkle 250 grams of clean fine sand in the shaking cage, hang the shaking cage on a special wooden frame or a waist-high branch, and have two people hold the handles at both ends of the cage tightly, and shake it rapidly for 6-8 minutes to make the fruit roll and rub continuously in the cage. Wait until the shell turns brown and dry. Shaking with sand can make the shell thinner and smoother for easier drying, but the shell cannot be ground too thin, otherwise the shell will easily dent when dried.
[0022] Preferably, the specific method in the S4, primary baking step is as follows:
[0023] Spread the fruits evenly on the roasting stove. Generally, the thickness at the front edge of the stove is 17 cm, and 11 cm at the back edge. 300-500 kg of longan can be roasted each time. Charcoal or dry branches can be used as fuel. Turn them over once 8 hours after spreading. Roast them in three layers: upper, middle and lower. Put the longan on the upper, middle and lower layers into bamboo baskets respectively, and then pour the longan on the upper layer into the roasting mat to flatten it, then pour it into the middle layer, and finally pour it into the lower layer. After 8 hours, turn it over for the second time, and the method is the same as the first time. After 3-5 hours of baking, it can be started roasting, and stored in baskets after heat dissipation.
[0024] Preferably, the specific method in the sterilization step S5 is as follows:
[0025] S5-1. Place the pre-baked dried longan in an ultraviolet sterilization room to ensure that each dried longan can be fully exposed to ultraviolet light to destroy the DNA structure of microorganisms and make them inactive. The exposure time is 10-20 minutes.
[0026] S5-2. Place the dried longan sterilized by ultraviolet light into a microwave sterilization device, set appropriate microwave power and time, and use the thermal and non-thermal effects of microwaves to kill the microorganisms in the dried longan in a short time. The microwave power is 500-1000W and the time is 2-5 minutes.
[0027] Preferably, the specific method in the step S6, re-baking, is as follows:
[0028] After 2-3 days of initial baking and sterilization, the moisture in the core and pulp of the dried longan gradually diffuses outward, and the moisture content on the surface of the pulp increases compared to when it is just out of baking. It needs to be baked again, and a low heat should be used for about 12 hours. The fruit should be turned over several times in the middle. When no juice flows out when pressed with fingers and the core is chestnut brown when cut open, it can be baked. After baking, it needs to be cooled for 24 hours.
[0029] Preferably, the specific methods in the step of S7, cutting the stems and grading are as follows:
[0030] S7-1. Use scissors to cut off the stems of longan;
[0031] S7-2, sieve the dried longan fruit particles and classify them according to size.
[0032] Preferably, the specific method in the step of S8, nitrogen filling and packaging is as follows:
[0033] S8-1. Use high-purity nitrogen to ensure that it does not contain moisture or other impurities;
[0034] S8-2. Choose packaging materials with good barrier properties, such as composite plastic films, aluminum foil bags, etc., to prevent the intrusion of oxygen, moisture and odor. The packaging materials should comply with food hygiene standards and be non-toxic, odorless and corrosion-resistant;
[0035] S8-3, put the graded dried longan into packaging materials, and then fill the package with nitrogen through the nitrogen filling system. During the nitrogen filling process, vacuum is drawn first, and then nitrogen is injected. Since the dried longan shell is relatively thick, the air inside the dried longan will penetrate through the shell. After the first vacuum is drawn and nitrogen is injected, it is necessary to wait for 5-6 hours before vacuuming again and injecting nitrogen again. This is repeated three times. Generally speaking, the nitrogen pressure in the package is 0.1-0.2MPa, which plays a role in preservation and protection.
[0036] S8-4. After nitrogen filling is completed, the package should be sealed immediately. Heat sealing, cold sealing or other sealing methods can be used to ensure good sealing of the package.
[0037] Compared with the prior art, the present invention has the following beneficial effects: the preservation process of the present invention can optimize the process flow, improve the preparation efficiency of dried longan, adopt ultraviolet and microwave sterilization treatment to effectively kill microorganisms in the dried longan, improve the sanitary quality of the dried longan, and nitrogen-filled packaging can remove the air in the packaging to prevent oxidation and mold growth, effectively extending the shelf life of the dried longan. The process of the present invention is simple and easy to implement, and is suitable for large-scale production and application. DETAILED DESCRIPTION
[0038] Unless the context clearly dictates otherwise, unmodified nouns and nouns modified by "the" include singular and plural referents.
[0039] As used in the specification and claims, the terms "comprises," "comprising," "having," "may," "containing," and variations thereof as used herein refer to open transitional phrases, terms, or words that require the presence of specified ingredients / steps and allow for the presence of other ingredients / steps. However, such descriptions should be interpreted as also describing compositions or methods as "consisting of" and "consisting essentially of" the recited ingredients / steps, which allows for the presence of only the specified ingredients / steps and any unavoidable impurities that may result therefrom, and excludes other ingredients / steps.
[0040] Numerical values in the specification and claims of this application should be understood to include the same numerical values when reduced to the same number of significant figures and numerical values that differ from the stated value by less than the experimental error of ordinary measurement techniques of the type described in this application for determining the stated value.
[0041] All ranges disclosed herein are inclusive of the indicated endpoints and are independently combinable (eg, the range of "2 grams to 10 grams" includes the endpoints 2 grams and 10 grams, and all intermediate values).
[0042] The terms "about" and "approximately" can be used to include any numerical value that can be varied without changing the basic function of the value. When used with a range, "about" and "approximately" also disclose the range defined by the absolute values of the two endpoints, for example, "about 2 to about 4" also discloses a range of "2 to 4". Generally, the terms "about" and "approximately" can refer to ±10% of the indicated number. However, for temperature, the term "approximately" refers to ±1°C.
[0043] Unless expressly stated otherwise, the percentages of elements are to be considered as percentages by weight of the alloy in question.
[0044] The present disclosure may refer to the temperature of certain method steps. It should be noted that these specifications generally refer to the temperature set by the heat source (such as a furnace), and not necessarily the temperature that the heated material must reach.
[0045] S1. Raw material selection;
[0046] Choose fresh, ripe, disease- and insect-free longan fruits as raw materials.
[0047] S2, cleaning, cutting, and soaking;
[0048] S2-1. Put the longan fruit in clean water and gently scrub it with a soft brush to remove dust and impurities on the surface;
[0049] S2-2, cut the longan fruits from the clusters with scissors, leaving the stems at a length of 1.5 mm, and remove the broken fruits;
[0050] S2-3. Put the cut longan fruits into a bamboo basket and soak them in clean water for 5-10 minutes to wash off the dust.
[0051] S3, over-shaking;
[0052] Pour the soaked longan fruits into a special shaking cage, with each cage holding about 35 kilograms. Sprinkle 250 grams of clean fine sand in the shaking cage, hang the shaking cage on a special wooden frame or a waist-high branch, and have two people hold the handles at both ends of the cage tightly, and shake it rapidly for 6-8 minutes to make the fruit roll and rub continuously in the cage. Wait until the shell turns brown and dry. Shaking with sand can make the shell thinner and smoother for easier drying, but the shell cannot be ground too thin, otherwise the shell will easily dent when dried.
[0053] S4, initial roasting;
[0054] Spread the fruits evenly on the roasting stove. Generally, the thickness at the front edge of the stove is 17 cm, and 11 cm at the back edge. 300-500 kg of longan can be roasted each time. Charcoal or dry branches can be used as fuel. Turn them over once 8 hours after spreading. Roast them in three layers: upper, middle and lower. Put the longan on the upper, middle and lower layers into bamboo baskets respectively, and then pour the longan on the upper layer into the roasting mat to flatten it, then pour it into the middle layer, and finally pour it into the lower layer. After 8 hours, turn it over for the second time, and the method is the same as the first time. After 3-5 hours of baking, it can be started roasting, and stored in baskets after heat dissipation.
[0055] S5, sterilization;
[0056] S5-1. Place the pre-baked dried longan in an ultraviolet sterilization room to ensure that each dried longan can be fully exposed to ultraviolet light to destroy the DNA structure of microorganisms and make them inactive. The exposure time is 10-20 minutes.
[0057] S5-2. Place the dried longan sterilized by ultraviolet light into a microwave sterilization device, set appropriate microwave power and time, and use the thermal and non-thermal effects of microwaves to kill the microorganisms in the dried longan in a short time. The microwave power is 500-1000W and the time is 2-5 minutes.
[0058] S6, re-roasting;
[0059] After 2-3 days of initial baking and sterilization, the moisture in the core and pulp of the dried longan gradually diffuses outward, and the moisture content on the surface of the pulp increases compared to when it is just out of baking. It needs to be baked again, and a low heat should be used for about 12 hours. The fruit should be turned over several times in the middle. When no juice flows out when pressed with fingers and the core is chestnut brown when cut open, it can be baked. After baking, it needs to be cooled for 24 hours.
[0060] S7, cutting and grading;
[0061] S7-1. Use scissors to cut off the stems of longan;
[0062] S7-2, sieve the dried longan fruit particles and classify them according to size.
[0063] S8, nitrogen-filled packaging;
[0064] S8-1. Use high-purity nitrogen to ensure that it does not contain moisture or other impurities;
[0065] S8-2. Choose packaging materials with good barrier properties, such as composite plastic films, aluminum foil bags, etc., to prevent the intrusion of oxygen, moisture and odor. The packaging materials should comply with food hygiene standards and be non-toxic, odorless and corrosion-resistant;
[0066] S8-3, put the graded dried longan into packaging materials, and then fill the package with nitrogen through the nitrogen filling system. During the nitrogen filling process, vacuum is drawn first, and then nitrogen is injected. Since the dried longan shell is relatively thick, the air inside the dried longan will penetrate through the shell. After the first vacuum is drawn and nitrogen is injected, it is necessary to wait for 5-6 hours before vacuuming again and injecting nitrogen again. This is repeated three times. Generally speaking, the nitrogen pressure in the package is 0.1-0.2MPa, which plays a role in preservation and protection.
[0067] S8-4. After nitrogen filling is completed, the package should be sealed immediately. Heat sealing, cold sealing or other sealing methods can be used to ensure good sealing of the package.
[0068] Specific steps: select fresh, ripe, disease-free and insect-free longan fruits as raw materials, put the longan fruits in clean water, brush them gently with a soft brush to remove dust and impurities on the surface, cut the longan fruits from the fruit clusters with scissors, leaving a stem length of 1.5 mm, remove broken fruits, put the cut longan fruits in a bamboo basket, and soak them in clean water for 5-10 minutes together with the bamboo basket to wash off the dust, pour the soaked longan fruits into a special shaking cage, each cage can hold about 35 kilograms, sprinkle 250 grams of clean fine sand in the shaking cage, hang the shaking cage on a special wooden frame or a waist-high branch, have two people hold the cage handles tightly, and shake rapidly for 6-8 minutes to make the fruit roll and rub continuously in the cage, and wait until the shell turns brown and dry. Sand shaking can make the shell thinner and smoother, For drying, but the shell cannot be ground too thin, otherwise the shell will easily sag when drying. Spread the fruit evenly on the baking stove. Generally, the thickness of the front edge of the stove is 17 cm and the back edge is 11 cm. 300-500 kg of longan can be baked each time. Charcoal or dry branches can be used as fuel. Turn it over once every 8 hours after spreading. Start baking in three layers: upper, middle and lower. Put the longan on the upper, middle and lower layers into bamboo baskets respectively, and then pour the longan on the upper layer into the baking mat to level it, then pour it into the middle layer, and finally pour it into the lower layer. After 8 hours, turn it over for the second time, and the method is the same as the first time. After 3-5 hours of baking, it can be started baking. After heat dissipation, put it into the basket for storage. Put the dried longan after the initial baking in the ultraviolet sterilization room to ensure that each dried longan can fully receive ultraviolet radiation to destroy microorganisms. DNA structure to make it lose its activity. The irradiation time is 10-20 minutes. Put the dried longan sterilized by ultraviolet light into the microwave sterilization device, set the appropriate microwave power and time, and use the thermal effect and non-thermal effect of microwave to kill the microorganisms in the dried longan in a short time. The microwave power is 500-1000W, and the time is 2-5 minutes. After 2-3 days of initial baking and sterilization, the moisture in the core and pulp of the dried longan gradually diffuses outward, and the moisture content on the surface of the pulp increases compared with when it is just baked. It needs to be baked again. When baking again, a low heat must be used for about 12 hours, and it is turned over several times in the middle. When no juice flows out when pressing the fruit with fingers and the core is chestnut brown when it is cut open, it can be baked. After baking, it needs to dissipate heat for 24 hours. Cut off the fruit stalks of the dried longan with scissors, and put the dried longan into the dried longan. The longan fruit particles are screened and graded by size. High-purity nitrogen is used to ensure that the nitrogen does not contain moisture and other impurities. Packaging materials with good barrier properties, such as composite plastic films, aluminum foil bags, etc., are selected to prevent the invasion of oxygen, moisture and odor. The packaging materials should meet food hygiene standards and be non-toxic, odorless and corrosion-resistant. The graded longan dried fruits are packed into packaging materials, and then nitrogen is filled into the package through the nitrogen filling system. During the nitrogen filling process, vacuum is first drawn, and then nitrogen is injected after vacuum is drawn. Since the longan dried fruit shell is relatively thick, the air inside the longan dried fruit shell will penetrate through the fruit shell. After the first vacuum is drawn and nitrogen is injected, it is necessary to wait for 5-6 hours before vacuuming again and injecting nitrogen again. Repeat three times. Generally speaking, the nitrogen pressure in the package is 0.1-0.2MPa, plays a role in preservation and protection. After the nitrogen filling is completed, the package is sealed immediately. Heat sealing, cold sealing or other sealing methods can be used to ensure good sealing of the package.
[0069] Embodiment 1:
[0070] S1. Raw material selection;
[0071] Choose fresh, ripe, disease- and insect-free longan fruits as raw materials.
[0072] S2, cleaning, cutting, and soaking;
[0073] S2-1. Put the longan fruit in clean water and gently scrub it with a soft brush to remove dust and impurities on the surface;
[0074] S2-2, cut the longan fruits from the clusters with scissors, leaving the stems at a length of 1.5 mm, and remove the broken fruits;
[0075] S2-3. Put the cut longan fruits into a bamboo basket and soak them in clean water for 8 minutes to wash off the dust.
[0076] S3, over-shaking;
[0077] Pour the soaked longan fruits into a special shaking cage, with each cage holding about 35 kilograms. Sprinkle 250 grams of clean fine sand in the shaking cage, hang the shaking cage on a special wooden frame or a waist-high branch, and have two people hold the handles at both ends of the cage tightly, and shake it rapidly for 7 minutes to make the fruit roll and rub continuously in the cage. Wait until the shell turns brown and dry. Shaking with sand can make the shell thinner and smoother for easier drying, but the shell cannot be ground too thin, otherwise the shell will easily dent when dried.
[0078] S4, initial roasting;
[0079] Spread the fruits evenly on the roasting stove. Generally, the thickness at the front edge of the stove is 17 cm, and 11 cm at the back edge. 400 kg of longan can be roasted each time. Charcoal or dry branches can be used as fuel. Turn them over once every 8 hours after spreading. Roast them in three layers: upper, middle and lower. Put the longan on the upper, middle and lower layers into bamboo baskets respectively, and then pour the longan on the upper layer into the roasting mat to flatten it, then pour it into the middle layer, and finally pour it into the lower layer. After 8 hours, turn it over for the second time, and the method is the same as the first time. After 4 hours of baking, it can be started roasting, and put into baskets for storage after heat dissipation.
[0080] S5, sterilization;
[0081] S5-1. Place the pre-baked dried longan in an ultraviolet sterilization chamber to ensure that each dried longan can be fully exposed to ultraviolet light to destroy the DNA structure of microorganisms and inactivate them. The exposure time is 15 minutes.
[0082] S5-2. Place the dried longan sterilized by ultraviolet light into a microwave sterilization device, set appropriate microwave power and time, and use the thermal and non-thermal effects of microwaves to kill the microorganisms in the dried longan in a short time. The microwave power is 800W and the time is 3 minutes.
[0083] S6, re-roasting;
[0084] After 2 days of initial baking and sterilization, the moisture in the core and pulp of the dried longan gradually diffuses outward, and the moisture content on the surface of the pulp increases compared to when it is just out of baking. It needs to be baked again, and a low fire should be used for about 12 hours. The fruit should be turned over several times in the middle. When no juice flows out when pressed with fingers and the core is chestnut brown when cut open, it can be baked. After baking, it needs to be cooled for 24 hours.
[0085] S7, cutting and grading;
[0086] S7-1. Use scissors to cut off the stems of longan;
[0087] S7-2, sieve the dried longan fruit particles and classify them according to size.
[0088] S8, nitrogen-filled packaging;
[0089] S8-1. Use high-purity nitrogen;
[0090] S8-2, select composite plastic film as packaging material;
[0091] S8-3, the graded dried longan is put into packaging materials, and then nitrogen is filled into the package through a nitrogen filling system. During the nitrogen filling process, vacuum is drawn first, and then nitrogen is injected. After the first vacuum is drawn and nitrogen is injected, it is necessary to wait for 5 hours before vacuuming again and then injecting nitrogen. This is repeated three times, and the nitrogen pressure in the package is 0.15MPa;
[0092] S8-4. Seal the package by heat sealing.
[0093] Specific steps: select fresh, ripe, disease-free and insect-free longan fruits as raw materials, put the longan fruits in clean water, brush them gently with a soft brush to remove dust and impurities on the surface, cut the longan fruits from the fruit clusters with scissors, leaving a stem length of 1.5 mm, remove broken fruits, put the cut longan fruits in a bamboo basket, soak them in clean water for 8 minutes together with the bamboo basket, wash off the dust, pour the soaked longan fruits into a special shaking cage, each cage can hold about 35 kilograms, sprinkle 250 grams of clean fine sand in the shaking cage, hang the shaking cage on a special wooden frame or a waist-high branch, have two people hold the cage handles tightly, and shake it rapidly for 7 minutes to make the fruit roll and rub continuously in the cage, and wait for the shell to When it turns brown and is dry, it is ready. Shaking the fruit shell can make it thinner and smoother for drying, but the fruit shell cannot be ground too thin, otherwise the fruit shell will easily sag when it is dried. Spread the fruit evenly on the roasting stove. Generally, the thickness of the front edge of the stove is 17 cm and the back edge is 11 cm. 400 kg of longan can be roasted each time. Charcoal or dry branches can be used as fuel. Turn it over once every 8 hours after spreading. Roasting is divided into three layers: upper, middle and lower. Put the longan on the upper, middle and lower layers into bamboo baskets respectively, and then pour the longan on the upper layer into the roasting mat to level it, then pour it into the middle layer, and finally pour it into the lower layer. After 8 hours, turn it over for the second time, and the method is the same as the first time. After another 4 hours of baking, it can be started to roast, and after heat dissipation, it can be put into baskets for storage , Place the dried longan after initial baking in the ultraviolet sterilization room to ensure that each dried longan can be fully exposed to ultraviolet radiation to destroy the DNA structure of microorganisms and make them inactive. The irradiation time is 15 minutes. Put the dried longan after ultraviolet sterilization into the microwave sterilization device, set the appropriate microwave power and time, and use the thermal effect and non-thermal effect of microwaves to kill the microorganisms in the dried longan in a short time. The microwave power is 800W and the time is 3 minutes. After 2 days of initial baking and sterilization, the moisture in the core and pulp of the dried longan gradually diffuses outward, and the moisture content on the surface of the pulp increases compared to when it is just baked. It needs to be baked again. When baking again, it must be baked with a low fire for about 12 hours. In the middle Turn the fruit over several times. When no juice flows out when pressing the fruit with fingers and the core is chestnut brown when cut open, it can be baked. After baking, it needs to be cooled for 24 hours. Use scissors to cut off the fruit stalks of the dried longan, sieve the dried longan fruit, and grade them by size. Use high-purity nitrogen and composite plastic film as packaging materials. Put the graded dried longan into the packaging materials, and then fill the package with nitrogen through the nitrogen filling system. During the nitrogen filling process, vacuum is drawn first, and then nitrogen is injected after vacuum is drawn. After the first vacuum is drawn and nitrogen is injected, it is necessary to wait for 5 hours before vacuuming again and injecting nitrogen again. Repeat three times. The nitrogen pressure in the package is 0.15MPa, and the package is sealed by heat sealing.
[0094] Embodiment 2:
[0095] S1. Raw material selection;
[0096] Choose fresh, ripe, disease- and insect-free longan fruits as raw materials.
[0097] S2, cleaning, cutting, and soaking;
[0098] S2-1. Put the longan fruit in clean water and gently scrub it with a soft brush to remove dust and impurities on the surface;
[0099] S2-2, cut the longan fruits from the clusters with scissors, leaving the stems at a length of 1.5 mm, and remove the broken fruits;
[0100] S2-3. Put the cut longan fruits into a bamboo basket and soak them in clean water for 10 minutes to wash off the dust.
[0101] S3, over-shaking;
[0102] Pour the soaked longan fruits into a special shaking cage, with each cage holding about 35 kilograms. Sprinkle 250 grams of clean fine sand in the shaking cage, hang the shaking cage on a special wooden frame or a waist-high branch, and have two people hold the handles at both ends of the cage tightly, and shake it rapidly for 8 minutes to make the fruit roll and rub continuously in the cage. Wait until the shell turns brown and dry. Shaking with sand can make the shell thinner and smoother for easier drying, but the shell cannot be ground too thin, otherwise the shell will easily dent when dried.
[0103] S4, initial roasting;
[0104] Spread the fruits evenly on the roasting stove. Generally, the thickness at the front edge of the stove is 17 cm, and 11 cm at the back edge. 500 kg of longan can be roasted each time. Charcoal or dry branches can be used as fuel. Turn them over once every 8 hours after spreading. Roast them in three layers: upper, middle and lower. Put the longan on the upper, middle and lower layers into bamboo baskets respectively, and then pour the longan on the upper layer into the roasting mat to flatten it, then pour it into the middle layer, and finally pour it into the lower layer. After 8 hours, turn it over for the second time, and the method is the same as the first time. After 5 hours of baking, it can be started roasting, and put into baskets for storage after heat dissipation.
[0105] S5, sterilization;
[0106] S5-1. Place the pre-baked dried longan in an ultraviolet sterilization chamber to ensure that each dried longan can be fully exposed to ultraviolet light to destroy the DNA structure of microorganisms and inactivate them. The exposure time is 20 minutes.
[0107] S5-2. Place the dried longan sterilized by ultraviolet light into a microwave sterilization device, set appropriate microwave power and time, and utilize the thermal and non-thermal effects of microwaves to kill the microorganisms in the dried longan in a short time. The microwave power is 1000W and the time is 5 minutes.
[0108] S6, re-roasting;
[0109] After 3 days of initial baking and sterilization, the moisture in the core and pulp of the dried longan gradually diffuses outward, and the moisture content on the surface of the pulp increases compared to when it is just out of baking. It needs to be baked again, and a low fire should be used for about 12 hours. The fruit should be turned over several times in the middle. When no juice flows out when pressed with fingers and the core is chestnut brown when cut open, it can be baked. After baking, it needs to be cooled for 24 hours.
[0110] S7, cutting and grading;
[0111] S7-1. Use scissors to cut off the stems of longan;
[0112] S7-2, sieve the dried longan fruit particles and classify them according to size.
[0113] S8, nitrogen-filled packaging;
[0114] S8-1. Use high-purity nitrogen;
[0115] S8-2, select aluminum foil bag as packaging material;
[0116] S8-3, the graded dried longan is put into packaging materials, and then nitrogen is filled into the package through a nitrogen filling system. During the nitrogen filling process, vacuum is drawn first, and then nitrogen is injected. After the first vacuum is drawn and nitrogen is injected, it is necessary to wait for 6 hours before vacuuming again and then injecting nitrogen. This is repeated three times, and the nitrogen pressure in the package is 0.2MPa;
[0117] S8-4. Use cold sealing method to seal the package.
[0118] Specific steps: select fresh, ripe, disease-free and insect-free longan fruits as raw materials, put the longan fruits in clean water, brush them gently with a soft brush to remove dust and impurities on the surface, cut the longan fruits from the fruit clusters with scissors, leaving a stem length of 1.5 mm, remove broken fruits, put the cut longan fruits in a bamboo basket, soak them in clean water for 10 minutes together with the bamboo basket, wash off the dust, pour the soaked longan fruits into a special shaking cage, each cage can hold about 35 kilograms, sprinkle 250 grams of clean fine sand in the shaking cage, hang the shaking cage on a special wooden frame or a waist-high branch, have two people hold the handles at the cage end tightly, and shake it rapidly for 8 minutes to make the fruit roll and rub continuously in the cage, and wait for it to The fruit shell is ready when it turns brown and is dry. Sand shaking can make the fruit shell thinner and smoother for easy drying, but the fruit shell cannot be ground too thin, otherwise the fruit shell will easily sag when drying. Spread the fruit evenly on the baking stove. Generally, the thickness of the front edge of the stove is 17 cm and the back edge is 11 cm. 500 kg of longan can be baked each time. Charcoal or dry branches can be used as fuel. Turn it over once every 8 hours after spreading. Roasting is divided into three layers: upper, middle and lower. Put the longan on the upper, middle and lower layers into the bamboo basket respectively, and then pour the longan on the upper layer into the baking mat to level it, then pour it into the middle layer, and finally pour it into the lower layer. After 8 hours, turn it over for the second time, and the method is the same as the first time. After 5 hours of baking, it can be started to bake, and put it into the basket after heat dissipation. The dried longan after initial baking is placed in an ultraviolet sterilization room to ensure that each dried longan can be fully exposed to ultraviolet radiation to destroy the DNA structure of microorganisms and make them inactive. The irradiation time is 20 minutes. The dried longan after ultraviolet sterilization is placed in a microwave sterilization device, and appropriate microwave power and time are set. The thermal effect and non-thermal effect of microwaves are used to kill the microorganisms in the dried longan in a short time. The microwave power is 1000W and the time is 5 minutes. After 3 days of initial baking and sterilization, the moisture in the core and pulp of the dried longan gradually diffuses outward, and the moisture content on the surface of the pulp increases compared to when it is just baked. It needs to be baked again. When baking again, a low fire must be used for about 12 minutes. After baking, it needs to be cooled for 24 hours. Use scissors to cut off the stalks of the dried longan, sieve the dried longan fruit, grade them by size, use high-purity nitrogen, choose aluminum foil bags as packaging materials, put the graded dried longan into the packaging materials, and then fill the package with nitrogen through the nitrogen filling system. During the nitrogen filling process, vacuum is drawn first, and then nitrogen is injected after vacuum is drawn. After the first vacuum is drawn and nitrogen is injected, it needs to wait for 6 hours before vacuuming again and injecting nitrogen again. Repeat three times. The nitrogen pressure in the package is 0.2MPa, and the package is sealed by cold sealing.
[0119] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.
Claims
1. An efficient longan dried fresh-keeping process, characterized in that: The following steps are involved: S1. Raw material selection; S2, cleaning, cutting, and soaking; S3, over-shaking; S4, initial roasting; S5, sterilization; S6, re-roasting; S7, cutting and grading; S8. Packaging with nitrogen.
2. The high-efficiency dried longan preservation process according to claim 1, characterized in that: In the S1, fresh, ripe, disease- and insect-free longan fruits are selected as raw materials.
3. The high-efficiency dried longan preservation process according to claim 1, characterized in that: The specific methods of S2, cleaning, pelletizing and soaking are as follows: S2-1. Put the longan fruit in clean water and gently scrub it with a soft brush to remove dust and impurities on the surface; S2-2, cut the longan fruits from the clusters with scissors, leaving the stems at a length of 1.5 mm, and remove the broken fruits; S2-3. Put the cut longan fruits into a bamboo basket and soak them in clean water for 5-10 minutes to wash off the dust.
4. The high-efficiency dried longan preservation process according to claim 1, characterized in that: The specific method in the step S3, over-shaking, is as follows: Pour the soaked longan fruits into a special shaking cage, with each cage holding about 35 kilograms. Sprinkle 250 grams of clean fine sand in the shaking cage, hang the shaking cage on a special wooden frame or a waist-high branch, and have two people hold the handles at both ends of the cage tightly, and shake it rapidly for 6-8 minutes to make the fruit roll and rub continuously in the cage. Wait until the shell turns brown and dry. Shaking with sand can make the shell thinner and smoother for easier drying, but the shell cannot be ground too thin, otherwise the shell will easily dent when dried.
5. The high-efficiency dried longan preservation process according to claim 1, characterized in that: The specific method in the S4, primary baking step is as follows; Spread the fruits evenly on the roasting stove. Generally, the thickness at the front edge of the stove is 17 cm, and 11 cm at the back edge. 300-500 kg of longan can be roasted each time. Charcoal or dry branches can be used as fuel. Turn them over once 8 hours after spreading. Roast them in three layers: upper, middle and lower. Put the longan on the upper, middle and lower layers into bamboo baskets respectively, and then pour the longan on the upper layer into the roasting mat to flatten it, then pour it into the middle layer, and finally pour it into the lower layer. After 8 hours, turn it over for the second time, and the method is the same as the first time. After 3-5 hours of baking, it can be started roasting, and stored in baskets after heat dissipation.
6. The high-efficiency dried longan preservation process according to claim 1, characterized in that: The specific method in the sterilization step S5 is as follows; S5-1. Place the pre-baked dried longan in an ultraviolet sterilization room to ensure that each dried longan can be fully exposed to ultraviolet rays to destroy the DNA structure of microorganisms and make them inactive. The exposure time is 10-20 minutes. S5-2. Place the dried longan sterilized by ultraviolet light into a microwave sterilization device, set appropriate microwave power and time, and use the thermal and non-thermal effects of microwaves to kill the microorganisms in the dried longan in a short time. The microwave power is 500-1000W and the time is 2-5 minutes.
7. The high-efficiency dried longan preservation process according to claim 1, characterized in that: The specific method in the step S6, re-baking is as follows; After 2-3 days of initial baking and sterilization, the moisture in the core and pulp of the dried longan gradually diffuses outward, and the moisture content on the surface of the pulp increases compared to when it is just out of baking. It needs to be baked again, and a low heat should be used for about 12 hours. The fruit should be turned over several times in the middle. When no juice flows out when pressed with fingers and the core is chestnut brown when cut open, it can be baked. After baking, it needs to be cooled for 24 hours.
8. The high-efficiency dried longan preservation process according to claim 1, characterized in that: The specific methods in the step of S7, cutting the stems and grading are as follows; S7-1. Use scissors to cut off the stems of longan; S7-2, sieve the dried longan fruit particles and classify them according to size.
9. The high-efficiency dried longan preservation process according to claim 1, characterized in that: The specific method in the step of S8, nitrogen filling and packaging is as follows; S8-1. Use high-purity nitrogen to ensure that it does not contain moisture or other impurities; S8-2. Choose packaging materials with good barrier properties, such as composite plastic films, aluminum foil bags, etc., to prevent the intrusion of oxygen, moisture and odor. The packaging materials should comply with food hygiene standards and be non-toxic, odorless and corrosion-resistant; S8-3, put the graded dried longan into packaging materials, and then fill the package with nitrogen through the nitrogen filling system. During the nitrogen filling process, vacuum is drawn first, and then nitrogen is injected. Since the dried longan shell is relatively thick, the air inside the dried longan will penetrate through the shell. After the first vacuum is drawn and nitrogen is injected, it is necessary to wait for 5-6 hours before vacuuming again and injecting nitrogen again. This is repeated three times. Generally speaking, the nitrogen pressure in the package is 0.1-0.2MPa, which plays a role in preservation and protection. S8-4. After nitrogen filling is completed, the package should be sealed immediately. Heat sealing, cold sealing or other sealing methods can be used to ensure good sealing of the package.