Modified atmosphere preservation bag and application thereof in normal-temperature transportation of fresh chestnut kernels

Abstract

The invention relates to the technical field of food preservation, in particular to a modified atmosphere preservation bag and application of the modified atmosphere preservation bag in normal-temperature transportation of fresh chestnut kernels. Through the breathable film, the aerobic respiration speed of the fresh chestnut kernels can be slowed down, and meanwhile anaerobic respiration is avoided; the modified atmosphere fresh-keeping packaging prevents water loss, keeps the freshness of the fresh chestnut kernels, and reduces the mildew rate at the same time; in addition, the storage cavity is extruded through air pressure of the inflation cavity, so that the position of the fresh chestnut kernel is fixed, skin damage and oxidation caused by excessive friction of the chestnut kernel are prevented, and meanwhile anti-collision protection is provided for the raw chestnut kernel. Furthermore, the permeability difference between the sodium chloride solution and the chestnut kernel germs is utilized, so that the germinating ability of the germs is inhibited; an external control type deoxidizing agent and a drying agent are used for adjusting the oxygen concentration and humidity in the package and inhibiting oxidation and germination of the fresh chestnut kernels; and epsilon-polylysine hydrochloride and Vc improve the corrosion and mildew resistance of the chestnut kernels, so that the fresh-keeping period can be further prolonged, and the requirements of longer-time storage or shelf display are met.

Description

Technical Field

[0001] The present invention relates to the technical field of food preservation, and in particular to a modified atmosphere fresh-keeping bag and its application in the room-temperature transportation of fresh chestnut kernels. Background Art

[0002] Currently, the chestnut sales products on the market are mainly stir-fried chestnuts in shells and small packages of cooked chestnut kernels, and the market for fresh chestnut kernels is also growing rapidly. In applications such as making zongzi and stewing dishes with side ingredients, customers need raw chestnut kernels after shelling, and it is more convenient to directly cook with raw chestnut kernels that have already had their inner skins removed. Currently, the packaging of fresh chestnut kernels sold on the market, especially on e-commerce platforms, includes open packaging, semi-open packaging, and vacuum packaging. Open packaging is mainly the simple packaging of mesh bags. Such packaging easily causes the chestnut kernels to lose water. After losing water, the chestnut kernels are prone to becoming soft and cracking, with poor freshness. When the dehydrated chestnut kernels absorb water again, they are prone to mildew and spoilage. Moreover, the open packaging makes the chestnut kernels vulnerable to contamination during express delivery. Without protection and fixation, the chestnut kernels rub against each other and collide, resulting in damaged epidermis and oxidation spots, and the damaged parts are also prone to mildew. Semi-open packaging mainly includes perforated plastic bags, woven bags, etc. Such packaging slows down the water loss of fresh chestnut kernels, but the high humidity inside the packaging makes the chestnut kernels more likely to germinate. At the same time, the chestnut kernels are still not fixed and lack protection against bumps, and oxidation spots or even mildew spots are likely to appear on the surface of the chestnut kernels. Although vacuum packaging does not need to consider problems such as oxidation, mildew, and fixation protection of chestnut kernels, vacuum packaging is only suitable for cooked food. Fresh chestnut kernels still have vital activity. Using vacuum packaging will cause the chestnuts to undergo intense anaerobic respiration, losing flavor and nutrients at low temperatures, and the chestnut kernels will rot and emit pungent odors at high temperatures, with obvious strange odors when eaten. In the case where the product is raw chestnut kernels and cannot be sterilized at high temperatures, anaerobic bacteria in the anaerobic environment multiply rapidly, easily causing the vacuum-packed chestnut kernels to have bitter and rancid strange odors. E-commerce merchants often place an external control type fresh-keeping agent that absorbs carbon dioxide, alcohol, and ethylene in the vacuum packaging. This fresh-keeping agent only absorbs the products of anaerobic respiration and cannot prevent anaerobic respiration, and cannot solve problems such as a large amount of consumption of nutrients, obvious strange odors, and physiological diseases of chestnut kernels caused by anaerobic respiration. Due to the characteristics of a large number of retail sales on e-commerce platforms and the low unit price of chestnut kernels, expensive cold-chain transportation is not suitable for the e-commerce retail scenario of raw chestnut kernels.

[0003] Today, with the increasing development of e-commerce, there is an urgent need for a preservation method that enables e-commerce retail raw chestnut kernels to maintain freshness and taste characteristics, maintain a low softening rate, low breakage rate, low mildew rate, and low germination rate during 3 - 5 days of room-temperature transportation and 10 days of refrigeration, and avoid the occurrence of anaerobic respiration. Summary of the Invention

[0004] To solve the above problems, the present invention provides a modified atmosphere fresh-keeping bag and its application in the room-temperature transportation of fresh chestnut kernels. The modified atmosphere fresh-keeping bag provided by the present invention can meet the requirements of room-temperature transportation of fresh chestnut kernels, has the advantages of good fresh-keeping effect and low cost, and solves the problems of water loss, softening, germination, mildew and anaerobic respiration of chestnut kernels during the transportation of e-commerce fresh chestnut kernels.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention provides a modified atmosphere fresh-keeping bag, which includes a double-layer inflatable bag, an inflation port and a breathable film; the double-layer inflatable bag includes two outer films and two inner films, and an inflation cavity is formed between the adjacent outer film and inner film, and a storage cavity is formed between the two inner films; the storage cavity is a cavity with one end open and the rest of the edges closed before sealing; the inflation port connects the inflation cavity and the outside of the double-layer inflatable bag; at least one breathable hole is provided on the double-layer inflatable bag, the breathable hole penetrates through the adjacent inner film and outer film, and the inner film and outer film at the edge of the breathable hole are hermetically connected; the edge of the breathable hole is connected to the breathable film, and the area of the breathable film > the area of the breathable hole.

[0007] Preferably, the number of the inflation ports is 1, and the inflation cavities on both sides of the double-layer inflatable bag are communicated.

[0008] Preferably, the ratio of the O2 permeability to the CO2 permeability of the breathable film is 1:5-6, and based on the maximum mass of chestnuts stored in the storage cavity, the ratio of the total area of the breathable holes to the mass of the stored chestnuts is 2-6 cm 2 : 500 g.

[0009] Preferably, the number of the breathable holes is not less than 1, and the breathable holes penetrate through the outer film and the inner film.

[0010] The present invention provides an application of the modified atmosphere fresh-keeping bag described in the above technical solution in storing and / or transporting chestnut kernels.

[0011] Preferably, the chestnut kernels are fresh chestnut kernels; the transportation is room-temperature transportation, and the storage is refrigeration.

[0012] The present invention provides a method for preserving chestnut kernels by using the modified atmosphere fresh-keeping bag described in the above technical solution, including the following steps:

[0013] Put the chestnut kernels into the storage cavity, and perform an incomplete sealing treatment on the storage cavity;

[0014] Inflate the inflation cavity through the inflation port. After the inflation is completed, wait until the air pressure in the storage cavity is balanced with the external air pressure, and then seal the remaining unsealed position of the storage cavity.

[0015] Preferably, the chestnut kernels are fresh chestnut kernels; the chestnut kernels are pretreated before being loaded into the storage cavity; the pretreatment includes: soaking the chestnut kernels in a fresh-keeping solution for 20 - 30 minutes and then taking them out to remove the surface moisture; the fresh-keeping solution includes a sodium chloride solution of 75 - 100 g / L.

[0016] Preferably, the fresh-keeping solution further includes: 10 g / L of ε-polylysine hydrochloride and 10 g / L of vitamin C.

[0017] Preferably, a desiccant and a deoxidizer are also loaded into the storage cavity; the deoxidizer includes iron powder; the desiccant includes silica gel desiccant; the mass ratio of the silica gel desiccant to the chestnut kernels is 20:500; the mass ratio of the iron powder to the chestnut kernels is 2:500.

[0018] Beneficial effects:

[0019] The present invention provides a modified atmosphere fresh-keeping bag, which includes a double-layer inflatable bag, an inflation port and a breathable film; the double-layer inflatable bag includes two outer films and two inner films, and an inflation cavity is formed between the adjacent outer film and inner film, and a storage cavity is formed between the two inner films; the storage cavity is a cavity with one end open and the rest of the edges closed before sealing; the inflation port connects the inflation cavity and the outside of the double-layer inflatable bag; at least one breathable hole is provided on the double-layer inflatable bag, the breathable hole penetrates through the adjacent inner film and outer film, and the inner film and outer film at the edge of the breathable hole are hermetically connected; the edge of the breathable hole is connected to the breathable film, and the area of the breathable film > the area of the breathable hole. The modified atmosphere fresh-keeping bag provided by the present invention can adjust the oxygen concentration in the package to be 4% - 12% within 72 hours and 4% - 15% within 96 hours through the breathable film, slow down the aerobic respiration rate of fresh chestnut kernels and avoid anaerobic respiration at the same time; the modified atmosphere fresh-keeping packaging can also prevent moisture loss, maintain the freshness of fresh chestnut kernels and reduce the mildew rate at the same time; in addition, the present invention uses the air pressure in the inflation cavity to squeeze the storage cavity to fix the position of the fresh chestnut kernels, prevent the chestnut kernels from being damaged and oxidized due to excessive friction, and provide anti-collision protection for the fresh chestnut kernels at the same time.

[0020] Furthermore, the present invention also provides a method for preserving chestnut kernels using the modified atmosphere fresh-keeping bag. By using the osmotic pressure difference between the sodium chloride solution and the chestnut kernel germ, the germination ability of the germ is inhibited; ε-polylysine hydrochloride and Vc enhance the anti-corrosion and anti-mildew ability of the chestnut kernels; the externally controlled deoxidizer and desiccant adjust the oxygen concentration and humidity inside the package, inhibit the oxidation and mildew of fresh chestnut kernels, so as to further extend the preservation period and meet the requirements of long-term storage or long-term shelf display. Description of the Drawings

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments.

[0022] Figure 1 It is a front view of the modified atmosphere fresh-keeping bag;

[0023] Figure 2 It is a cross-sectional view of the modified atmosphere fresh-keeping bag after inflation; Figures 1 - 2 In the figure, 1 is a double-layer film; 2 is an inflation port; 4 is a ventilation hole; 5 is a ventilation film; 6 is a heat-sealing strip; 7 is an inner layer film; 8 is an outer layer film; 9 is an inflation cavity; 10 is a storage cavity;

[0024] Figure 3 It is a physical picture of the modified atmosphere fresh-keeping bag;

[0025] Figure 4 It is a physical picture of the modified atmosphere fresh-keeping bag after loading chestnuts and inflating and sealing;

[0026] Figure 5 It is the change situation of the oxygen concentration inside the modified atmosphere fresh-keeping bag prepared in Example 1 of Example 7 at different times when placed in an incubator;

[0027] Figure 6 It is the change situation of the oxygen concentration inside the modified atmosphere fresh-keeping bag prepared in Example 2 of Example 7 at different times when placed in an incubator;

[0028] Figure 7 It is the change situation of the oxygen concentration inside the modified atmosphere fresh-keeping bag prepared in Example 2 of Example 7 at different times when placed in a refrigerator;

[0029] Figure 8 It is the change situation of the oxygen concentration inside the modified atmosphere fresh-keeping bag prepared in Example 3 of Example 7 at different times when placed in a refrigerator. Detailed implementation manners

[0030] The present invention provides a modified atmosphere fresh-keeping bag, including a double-layer inflatable bag, an inflation port and a ventilation film; the double-layer inflatable bag includes two outer layer films and two inner layer films, and an inflation cavity is formed between the adjacent outer layer film and inner layer film, and a storage cavity is formed between the two inner layer films; the storage cavity is a cavity with one end open and the rest of the edges closed before sealing; the inflation port connects the inflation cavity and the outside of the double-layer inflatable bag; at least one ventilation hole is provided on the double-layer inflatable bag, the ventilation hole penetrates through the adjacent inner layer film and outer layer film, and the inner layer film and outer layer film at the edge of the ventilation hole are hermetically connected; the edge of the ventilation hole is connected to the ventilation film, and the area of the ventilation film > the area of the ventilation hole.

[0031] After the modified atmosphere fresh-keeping bag provided by the present invention is sealed and inflated, the inner film is extruded by the air pressure in the inflation cavity to squeeze the storage cavity, and the objects in the storage cavity are fixed. It breathes through the breathable film and can be applied to room-temperature transportation with the advantages of low cost and easy production, solving the problems of water loss, softening, germination, mildew and anaerobic respiration of chestnut kernels during the transportation of e-commerce fresh chestnut kernels.

[0032] As an embodiment, the materials of the outer film and the inner film can be a film formed by co-extruding a polyethylene film and a nylon film; as an embodiment, the thickness of the outer film and the inner film is 0.05 mm.

[0033] As an embodiment, the sealing method of the outer film and the inner film in the double-layer inflatable bag can be hot pressing.

[0034] As an embodiment, the number of the inflation ports is 1, and the inflation cavities on both sides of the double-layer inflatable bag are communicated.

[0035] As an embodiment, the ratio of the O2 permeability to the CO2 permeability of the breathable film is 1:5-6. Based on the maximum mass of chestnuts stored in the storage cavity, the ratio of the total area of the breathable holes to the mass of the stored chestnuts is 2-6 cm 2 : 500 g. As an embodiment, the breathable film can be a cloth-based silicone rubber film; as another embodiment, the thickness of the cloth-based silicone rubber film can be 0.3 mm. As an embodiment, the cloth-based silicone rubber film is purchased from the Jinan Fruit Research Institute of the All-China Federation of Supply and Marketing Cooperatives. By means of a suitable breathable film and in combination with a suitable total area of the breathable holes, the present invention can passively reduce the oxygen concentration in the bag, achieving the effect of modified atmosphere fresh-keeping, thereby effectively reducing the water loss rate, mildew rate, breakage rate and germination rate of chestnut kernels during room-temperature transportation, and at the same time avoiding the occurrence of anaerobic respiration and maintaining the flavor and freshness of fresh chestnut kernels.

[0036] As an embodiment, the number of the breathable holes is 2, and the breathable holes penetrate through two outer films and two inner films (see Figure 1 and Figure 2 ). By providing breathable holes that penetrate through two outer films and two inner films, the present invention can simplify the preparation method and reduce the preparation cost.

[0037] As an embodiment, the breathable film covers the breathable holes, the breathable film is welded to the edges of the breathable holes of the inner and outer films, and the storage cavity is separated from the outside by the breathable film.

[0038] As an embodiment, the double-layer inflatable bag is square, and each bag contains 500 g of chestnuts; as another embodiment, the length of the double-layer inflatable bag is 20 cm and the width is 20 cm.

[0039] Based on the above advantages, the present invention provides the application of the modified atmosphere fresh-keeping bag described in the above technical solution in storing and / or transporting chestnut kernels. As an implementation manner, the chestnut kernels are raw chestnut kernels; the transportation is at normal temperature, and the storage is refrigeration.

[0040] Based on the above advantages, the present invention provides a method for preserving chestnut kernels using the modified atmosphere fresh-keeping bag described in the above technical solution, including the following steps:

[0041] Put the chestnut kernels into the storage cavity and perform an incomplete sealing treatment on the storage cavity;

[0042] Inflate the inflation cavity through the inflation port. After the inflation is completed, wait for the air pressure in the storage cavity to balance with the outside, and then seal the remaining unsealed position of the storage cavity.

[0043] As an implementation manner, the chestnut kernels are raw chestnut kernels. As another implementation manner, the preparation method of the raw chestnut kernels includes: peeling off the chestnut shell and removing the inner skin, and screening the chestnut kernels without damage, water loss, mildew, internal rot and germination on the surface; as another implementation manner, the process of removing the inner skin should be completed quickly, and the chestnut kernels are placed in cold water during the subsequent waiting and transportation processes to prevent water loss, excessive friction and collision, and the water sealing time does not exceed 45 minutes to prevent obvious anaerobic respiration.

[0044] As an implementation manner, when sealing, a thin strip of high-temperature resistant object (such as a silicone strip) is placed at the sealing position, and then sealed. At the same time, inflate through the inflation port, and the air in the storage cavity can quickly escape through the unsealed gap where the silicone strip is placed. After most of the air in the storage cavity is discharged, perform secondary sealing. Thus, the air in the storage cavity is discharged faster, and the chestnut kernels are fixed faster, avoiding the problem that some chestnut kernels continue to rub against each other during transportation due to the failure to fix the chestnut kernels, resulting in surface damage, oxidation and even mildew of the chestnut kernels.

[0045] As an implementation manner, the chestnut kernels are pretreated before being put into the storage cavity; the pretreatment includes: soaking the chestnut kernels in the preservation solution for 20 - 30 minutes and then taking them out to remove the surface moisture; the preservation solution includes a sodium chloride solution with a concentration of 75 - 100 g / L. The present invention can not only control the germination rate of chestnut kernels within 2% after high-temperature transportation through a suitable sodium chloride solution, and only be in a just germinated state with the germ not exceeding 2 mm exposed, meeting the requirements of the actual scenario, but also make only sodium chloride remain on the product surface without other additives, reducing customers' concerns about food safety.

[0046] As an implementation manner, the fresh-keeping solution further includes: 10 g / L of ε-polylysine hydrochloride and 10 g / L of vitamin C (Vc). For scenarios with long-term shelf display requirements, using a mixed solution of sodium chloride, ε-polylysine hydrochloride, and Vc as the fresh-keeping liquid can further extend the fresh-keeping period.

[0047] As an implementation manner, a desiccant and a deoxidizer are also loaded into the storage cavity; the deoxidizer includes iron powder; the desiccant includes silica gel desiccant; the mass ratio of the silica gel desiccant to the chestnut kernels is 20:500; the mass ratio of the iron powder to the chestnut kernels is 2:500. An appropriate desiccant can adjust the humidity inside the bag, and an appropriate deoxidizer can adjust the oxygen concentration inside the bag, thus being beneficial to inhibiting the germination of fresh chestnut kernels.

[0048] To further illustrate the present invention, the present invention provides a modified atmosphere fresh-keeping bag and its application in the ambient temperature transportation of fresh chestnut kernels will be described in detail below with reference to the accompanying drawings and embodiments, but they cannot be understood as limiting the protection scope of the present invention.

[0049] Example 1

[0050] A modified atmosphere fresh-keeping bag for the ambient temperature transportation of fresh chestnut kernels is prepared as follows:

[0051] As shown in Figure 1 and Figure 2 , the bottom of the double-layer film is hot-pressed, one layer of film is superimposed on each side, an air inlet is placed between the inner and outer layers of the film, the top of the inner and outer layers of the film is hot-pressed, and the four layers of film at the bottom and both sides are hot-pressed to form a double-layer inflatable bag. The hot-pressed seal position at the bottom of the double-layer film of the storage cavity is higher than the hot-pressed seal of the four layers of film, so that the inflatable cavities on both sides of the inflatable bag are connected through the bottom. The size of the double-layer inflatable bag is 20 cm × 20 cm; the material of the double-layer film 1 is a polyethylene nylon composite film; a circular ventilation hole 4 is cut out on each of the front and back sides of the double-layer inflatable bag, and the total area of the ventilation holes 4 is 6 cm 2 .

[0052] A square ventilation film 5 with a side length greater than 3 cm is cut out; the ventilation film 5 is a cloth-based silicone rubber film purchased from the Jinan Fruit Research Institute of the All-China Federation of Supply and Marketing Cooperatives.

[0053] One side of the cloth-based silicone rubber film is relatively smooth and the other side is relatively rough. The smooth surfaces are difficult to be hot-melt bonded to the film. The two cloth-based silicone rubber films are placed with their smooth surfaces facing each other. After being superimposed, the two are placed together at the position of the ventilation hole 4 inside the double-layer inflatable bag and cover the ventilation hole 4. A circular heating head with a diameter of 3 cm is used to hot-press the film edge and the cloth-based silicone rubber film part on both sides of the double-layer inflatable bag, and the hot-melt temperature is maintained at 175 - 200 °C to obtain the modified atmosphere fresh-keeping bag (see Figure 3 ).

[0054] The usage method is as follows:

[0055] Prepare a silica gel strip with a diameter of 1 - 2 mm. After loading the chestnut kernels into the modified atmosphere fresh-keeping bag, place the silica gel strip at the outermost side of the sealing position, that is, the upper left corner or the upper right corner of the modified atmosphere fresh-keeping bag. After heat-sealing, about 2 mm of the silica gel strip part will remain unsealed to form a ventilation hole.

[0056] Inflate through the air inlet 2. Most of the air in the internal storage cavity will quickly escape through the unsealed ventilation hole. Subsequently, seal the unsealed ventilation hole at the upper left corner or the upper right corner of the modified atmosphere fresh-keeping bag to form a heat-sealed strip 6 (see Figure 1 and Figure 4 ). A space that only breathes through the breathable film, namely the storage cavity 10, is formed inside the modified atmosphere fresh-keeping bag (see Figure 2 and Figure 4 ).

[0057] Example 2

[0058] A modified atmosphere fresh-keeping bag similar to that in Example 1, the difference is that the total area of the ventilation holes 4 is 4 cm 2 .

[0059] Example 3

[0060] A modified atmosphere fresh-keeping bag similar to that in Example 1, the difference is that the total area of the ventilation holes 4 is 2 cm 2 .

[0061] Example 4

[0062] The experimental materials were Qianxi chestnuts stored in a cold storage for 9 months. After shelling, the inner skin was removed, and the air-dried, mildewed, internally decayed, germinated, and damaged chestnut kernels were removed. They were divided into 6 groups of experimental samples, with 2 portions in each group and 55 - 65 chestnuts in each portion, so that the net content of each portion was close to 500 g and consistent with the weight of common commercially available packaging styles. The treatment of different groups of samples was as follows:

[0063] 1) Sample group 1 was packaged using an open mesh bag.

[0064] 2) Sample group 2 was packaged using a perforated plastic film.

[0065] 3) Sample group 3 was vacuum packaged and 50 g of a fresh-keeping agent (a composite product that absorbs carbon dioxide, ethylene, and water, purchased from Jiangsu Zhongben Desiccant Co., Ltd., product number X50) was placed inside.

[0066] 4) Sample group 4 used the modified atmosphere fresh-keeping bag in Example 1 and was inflated after sealing.

[0067] 5) Sample group 5: First, soak chestnuts in a 75 g / L sodium chloride solution for 20 min. After taking them out, remove the surface moisture, put them into the modified atmosphere fresh-keeping bag in Example 1, and inflate after sealing.

[0068] 6) Sample group 6: Soak in a 75 g / L sodium chloride solution for 20 min. After taking them out, remove the surface moisture, put them into the modified atmosphere fresh-keeping bag in Example 1, and at the same time put 20 g of silica gel desiccant, and inflate after sealing.

[0069] All samples are packed into a breathable cardboard box and mailed from Qianxi County, Tangshan City to Guangzhou by express logistics, and then mailed back to Qianxi County from Guangzhou. After receiving, put them into the refrigerator's fresh-keeping compartment and refrigerate at 0°C - 5°C for one week.

[0070] Measure the weight loss rate, mildew rate, germination rate, softening rate, and soluble solid content (SSC) of chestnuts in all sample groups after refrigerating for one week, and at the same time determine whether there is an obvious peculiar smell.

[0071] Weight loss rate = (weight before experiment - weight after experiment) / weight before experiment;

[0072] Mildew / spoilage rate = number of mildewed and spoiled ones after experiment / total number of samples in the sample group;

[0073] Germination rate = number of germinated ones / total number of samples in the sample group;

[0074] Softening rate = number of softened ones / total number of samples in the sample group. Chestnuts become soft mostly due to excessive water loss, and it is difficult to guarantee the original taste and flavor after the chestnuts become soft.

[0075] Whether there is a peculiar smell: Determine whether chestnuts have undergone anaerobic respiration for a long time by whether an obvious peculiar smell is smelled. Chestnuts undergoing anaerobic respiration for a long time will produce a pungent peculiar smell and alcohol smell.

[0076] The soluble solid content is mainly the content of substances such as soluble sugars, acids, and vitamins that determine the flavor of chestnuts. The measurement method is as follows:

[0077] Randomly weigh 100 - 150 g of chestnuts from each group of samples, add 4 times the weight of water at a ratio of 1:4, put them into a tissue homogenizer and homogenize for 3 - 5 min, let it stand for 5 min, take the upper solution and filter to obtain a clear liquid, drop it into a soluble solid content measuring instrument with a minimum scale of 0.1% and an accuracy of 0.2% to obtain the measured concentration, and multiply the measured concentration by 5 to get the soluble solid content (SSC) of the sample group. The accuracy is 1%, and a difference of 1% or less is regarded as the same content. The measurement results are shown in Table 1.

[0078] Table 1 Results of the comparative experiment on the normal-temperature transportation of chestnuts

[0079] Category Weight loss rate (%) Mildew / rot rate (%) Germination rate (%) Softening rate (%) SSC (%) Whether there is peculiar smell Sample group 1 11.00 12.20 6.50 69.11 21 No Sample group 2 6.78 6.56 10.66 46.72 22 No Sample group 3 3.01 1 0 0 15 Yes Sample group 4 1.51 1.68 22.69 0 21.5 No Sample group 5 1.55 1.60 5.60 0 22 No Sample group 6 1.80 0 1.56 1.56 21.5 No

[0080] The chestnuts were mailed from Qianxi, Hebei to Guangzhou and then returned to Qianxi, Hebei for 6 days at normal temperature. The highest temperature in the box was 36.7℃, and the average temperature in the box was 29.4℃.

[0081] As shown in Table 1, the vacuum packaging (sample group 3) had obvious anaerobic respiration, and the six-day normal temperature transportation in summer caused all of them to decay. The SSC content of sample groups 4, 5, and 6 using modified atmosphere fresh-keeping packaging remained unchanged within the error range compared with the common packaging on the market, and the SSC of vacuum packaging dropped sharply. Compared with sample group 4, sample group 1 and sample group 2 showed obvious improvement in the fresh-keeping effect of modified atmosphere fresh-keeping packaging in terms of weight loss rate, mildew / corruption rate and softening rate, and the germination rate also increased significantly. Sample group 5 was soaked in sodium chloride solution, and the germination rate was significantly controlled; sample group 6 was soaked in sodium chloride solution and accompanied by desiccant, and the germination rate was reduced to the lowest level, and the chestnut kernel softened. Therefore, it is a better choice to use modified atmosphere fresh-keeping packaging, soak in sodium chloride solution, adjust the amount of desiccant, maintain low weight loss rate and mildew / corruption rate, and balance the germination rate and softening rate.

[0082] Example 5

[0083] The primary purpose of the preservation solution is to reduce the germination rate of chestnut kernels. Therefore, when there is no need for long-term preservation (more than 20 days), only sodium chloride solution can be used to control the germination rate. For example, in an e-commerce scenario, it only takes 3 to 5 days at room temperature + 15 days of refrigeration to keep fresh. Soaking fresh chestnut kernels in sodium chloride solution can reduce the amount of additives in the chestnut kernels and reduce customers' concerns about food additives. The experimental steps are as follows:

[0084] Qianxi chestnuts were shelled and the inner skin was removed. The air-dried, moldy, rotten, sprouted and damaged chestnut kernels were removed and divided into 22 groups of experimental samples, with two portions in each group. The weight of each portion of chestnut kernels was 495-505g and the number of chestnut kernels was 55-65.

[0085] The samples were soaked in 25g / L, 50g / L, 75g / L, 100g / L, and 125g / L sodium chloride solutions, and the chestnuts were soaked for 10min, 20min, 30min, and 40min in each concentration; two control groups were added, one was soaked in 0g / L sodium chloride solution, i.e., water without sodium chloride, for 10min, and the other was not soaked. The specific grouping is shown in Table 2. After taking out, the surface moisture was removed, and the chestnuts were placed in the atmosphere-controlled fresh-keeping bag prepared in Example 1, sealed and inflated, and placed in a well-ventilated carton.

[0086] All samples were stored at room temperature for 4 days, and then the germination rates were calculated. The results are shown in Table 2.

[0087] Table 2 Effects of different concentrations of sodium chloride solution on the germination rate of fresh chestnut kernels in modified atmosphere packaging

[0088] Number Sodium chloride concentration (g / L) Soaking time (min) Germination rate (%) 1 25 10 15.25 2 25 20 7.69 3 25 30 6.11 4 25 40 4.92 5 50 10 6.61 6 50 20 3.94 7 50 30 5.04 8 50 40 3.28 9 75 10 6.31 10 75 20 4.58 11 75 30 1.64 12 75 40 1.80 13 100 10 3.25 14 100 20 1.75 15 100 30 0 16 100 40 0 17 125 10 1.60 18 125 20 0 19 125 30 0.81 20 125 40 0 21 0 0 22.14 22 0 10 25.58

[0089] Correlation analysis was performed on the data, and the results are shown in Table 3.

[0090] Table 3 Correlation analysis of sodium chloride concentration, soaking time and germination rate

[0091]

[0092]

[0093] As can be seen from Table 3, the correlation coefficient between sodium chloride concentration and germination rate is -0.788, and the correlation coefficient between soaking time and germination rate is -0.599, both showing significance at the 0.01 level. Therefore, it shows that both sodium chloride concentration and soaking time have a significant negative correlation with germination rate.

[0094] As can be seen from Table 2, without adding external control additives such as desiccants and oxygen absorbers, the effects of soaking in 125 g / L sodium chloride solution for 10 - 40 min, 100 g / L sodium chloride solution for 20 - 40 min, and 75 g / L sodium chloride solution for 30 - 40 min are the same, with a germination rate lower than 2%, and the number of germinated chestnut kernels per 500 g is no more than 2 on average. After soaking chestnut kernels in 125 g / L sodium chloride solution, the chestnut kernels will have an obvious salty taste and there may be salt stains on the surface of the chestnut kernels. Therefore, choosing a 75 - 100 g / L sodium chloride solution is the best choice. Due to the different states of chestnuts in different seasons and the differences in chestnut varieties, it is difficult to draw a conclusion to ensure that chestnut kernels do not germinate at all. In this example, a germination rate lower than 2% and a germ less than 2 mm already meet the requirements of the actual scenario.

[0095] Example 6

[0096] In the scenario of supermarket shelf display and sales, a certain amount of inventory and display time are required, and fresh chestnut kernels need a relatively long shelf life (more than 20 days). According to customer needs, additives can be used to enhance the anti-corrosion and anti-mildew of fresh chestnut kernels. Fresh chestnut kernels belong to processed nuts (shelled). According to the Food Additive Use Standard GB2760-2024, ε-polylysine hydrochloride and Vc are allowed to be used for the anti-corrosion and preservation of fresh chestnut kernels. Chestnuts with longer storage time are in a worse state, have a shorter product shelf life, and have higher requirements for preservation measures. In this example, chestnuts stored for 11 months are used as raw materials. From the perspective of the storage period, these are the chestnuts with the greatest preservation challenges, in order to obtain test results on the shelf life of safe fresh chestnut kernels.

[0097] The specific steps are as follows:

[0098] (1) Qianxi chestnuts stored for 11 months were shelled and the inner skin was removed. The chestnut kernels that were air-dried, moldy, rotten, sprouted, and damaged were removed and divided into 4 groups of experimental samples, each group had two portions, each portion weighed 495-505 g, and each portion contained 55-65 chestnuts.

[0099] (2) The samples were immersed in a composite solution consisting of ε-polylysine hydrochloride with a concentration of 5 g / L, 10 g / L, and 20 g / L, respectively, and sodium chloride with a concentration of 75 g / L and Vc with a concentration of 10 g / L. Another sample was taken and immersed in a solution containing only 75 g / L sodium chloride. All samples were immersed for 20 min, and after being taken out, surface moisture was removed, and the samples were placed in the atmosphere-controlled fresh-keeping bag prepared in Example 1, which was sealed and inflated.

[0100] (3) All samples were first stored at room temperature for 5 days, and then refrigerated for 15 days, 30 days, and 45 days. The number of mold and germination of different samples was measured. The results are shown in Table 4.

[0101] Table 4 Effects of different concentrations of ε-polylysine hydrochloride solution on fresh chestnut kernels in modified atmosphere packaging

[0102]

[0103] The correlation analysis between the ε-polylysine hydrochloride concentration in Table 4 and the mildew rate and germination rate is shown in Table 5.

[0104] Table 5 Correlation analysis between ε-polylysine hydrochloride concentration and mold number

[0105]

[0106] As shown in Table 5, the correlation coefficient between the concentration of ε-polylysine hydrochloride and the number of mold and mildew is -0.725, showing a significance level of 0.01, indicating that there is a significant negative correlation between the concentration of ε-polylysine hydrochloride and the number of mold and mildew.

[0107] The correlation coefficient between the concentration of ε-polylysine hydrochloride and the number of moldy seeds was -0.846, showing a significance level of 0.01, indicating that there was a significant negative correlation between the concentration of ε-polylysine hydrochloride and the number of moldy seeds. The reason why the ε-polylysine hydrochloride solution can inhibit the germination of chestnut kernels is the same as that of the sodium chloride solution, both of which inhibit germination by causing the embryo to lose water through the osmotic effect between the cell sap and the preservative solution, and the mixed solution of multiple substances superimposes the osmotic pressure, enhances the osmotic effect, and strengthens the germination inhibition.

[0108] As can be seen from Table 4, soaking chestnut kernels in a mixed fresh-keeping solution containing 10 g / L ε-polylysine hydrochloride, 10 g / L Vc, and 75 g / L sodium chloride for 20 min, combined with modified atmosphere fresh-keeping packaging and fresh-keeping methods, can make the moldy change number of chestnut kernels be 0 after storing at room temperature for 5 days and then refrigerating for 45 days, and the germination rate is lower than 2%. The effects of inhibiting mildew and germination are obvious, and it is applied to scenarios with a long-term fresh-keeping requirement for chestnut kernels.

[0109] Example 7

[0110] The change of oxygen concentration in the modified atmosphere fresh-keeping bag with different breathable hole areas is as follows:

[0111] (1) Take Qianxi chestnuts stored for 11 - 12 months, shell them and remove the inner skin, and remove the air-dried, moldy, internally rotten, germinated, and damaged chestnut kernels. Divide them into 4 groups of experimental samples, with each group being 495 - 505 g.

[0112] (2) Soak each group of samples in 75 g / L sodium chloride solution for 20 min, take them out and remove the surface moisture, then put them into modified atmosphere fresh-keeping bags with different breathable hole areas. At the same time, put 20 g of silica gel desiccant and 2 g of iron powder, seal the bags and inflate them, and divide them into 4 groups, specifically as follows:

[0113] 1) Use the modified atmosphere fresh-keeping bag of Example 1, put it into an incubator, set the temperature to 33 - 39 °C, and set it to 45 °C high temperature in some periods to simulate extreme environments such as short-term exposure to the sun in summer;

[0114] 2) Similar to 1), the difference is that use the modified atmosphere fresh-keeping bag of Example 2;

[0115] 3) Use the modified atmosphere fresh-keeping bag of Example 2, put it into the refrigerator to simulate the transportation environment when the temperature is relatively low in autumn and winter;

[0116] 4) Similar to 3), the difference is that use the modified atmosphere fresh-keeping bag of Example 3.

[0117] Measure the oxygen concentration and temperature in the modified atmosphere fresh-keeping bags of different groups at different times respectively, and the results are shown in Figures 5 - 8 .

[0118] The results show that the oxygen concentration in the bag is always lower than the oxygen concentration in the air. The smaller the breathable area of the cloth-based silicone rubber membrane, the lower the oxygen concentration in the bag, and the higher the temperature, the lower the oxygen concentration in the bag. The volume of express transportation is large, the operation of personnel is rough, and there are many uncontrollable factors during transportation. The package may be jolted, pressed, and stacked, etc., resulting in poor air permeability. The space in the bag is small, which is likely to cause poor air exchange in some positions, and there is a risk that chestnut kernels may face anaerobic respiration. Therefore, we cannot blindly pursue a lower oxygen concentration in the bag and leave a safe space for the oxygen concentration to drop for chestnut kernels. According to the test results, select a total breathable area of 4 - 6 cm in the high-temperature period of summer 2The mass ratio of the silicone rubber film to the chestnut kernels per 500 g of chestnuts. During the low-temperature period, select a total gas permeable area of 2 - 4 cm 2 The mass ratio of the silicone rubber film to the chestnut kernels per 500 g of chestnuts, combined with 2 g of iron powder deoxidizer, can keep the oxygen concentration in the bag within the range of 4% - 15% within 96 hours and within the range of 4% - 12% within 72 hours. Compared with the oxygen concentration in the environment, the oxygen concentration in the bag is reduced by 28.5% - 80%, improving the preservation effect of the chestnut kernels. The express delivery time is usually no longer than 96 hours. After the customers receive the chestnut kernels, they need to be refrigerated. The refrigeration temperature is close to the low-temperature test temperature in this embodiment. The oxygen concentration during refrigeration can refer to the oxygen concentration balance period of the low-temperature test samples in this embodiment later.

[0119] Example 8

[0120] Take Qianxi chestnuts stored for 10 months, shell them and remove the inner skin, and remove the air-dried, moldy, internally rotten, germinated and damaged chestnut kernels. Divide them into 4 groups of experimental samples, with 2 portions in each group, and each portion is 495 - 505 g.

[0121] The samples are soaked in 75 g / L sodium chloride solution for 20 min, taken out and the surface moisture is removed, then put into the modified atmosphere fresh-keeping bags prepared in Example 1, and 10 g, 20 g, 50 g and 100 g of silica gel desiccant are respectively placed with the chestnut kernels, and then sealed and inflated.

[0122] All samples are stored at room temperature for 4 days, and then the germination rate, mildew rate and softening rate are calculated. The results are shown in Table 6.

[0123] Table 6 Effects of desiccants with different weights on chestnut kernels

[0124] Desiccant weight Mildew rate (%) Germination rate (%) Softening rate (%) 10g 1.64 3.23 0 20g 0 1.61 1.61 50g 0 1.59 9.94 100g 0 0 14.3

[0125] The results show that the greater the amount of desiccant used, the lower the mildew rate and the germination rate, but the softening rate of the chestnut kernels also increases. In Example 5, fresh chestnut kernels are soaked in 75 g / L sodium chloride solution for 30 min, and the germination rate after being stored at room temperature for 4 days is 1.64%. In Example 8, under the condition of adding 20 g of desiccant, fresh chestnut kernels are soaked in 75 g / L sodium chloride solution for 20 min, and the germination rate is 1.61%. The germination rates of the two groups of samples before and after are at the same level, both lower than 2%, meeting the requirements. Considering the softening rate index, using 20 g of silica gel desiccant, with a sodium chloride solution concentration of 75 g / L and soaking for 20 min, both the germination rate and the softening rate are lower than 2%, and the germination inhibition and preservation effects of fresh chestnut kernels that meet the conditions can be obtained.

[0126] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, rather than all embodiments. People can also obtain other embodiments based on this embodiment without creative efforts, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A modified atmosphere fresh-keeping bag, characterized in that: It comprises a double-layer inflatable bag, an inflation port and a breathable film; the double-layer inflatable bag comprises two outer films and two inner films, an inflation cavity is formed between adjacent outer films and inner films, and a storage cavity is formed between the two inner films; the storage cavity is a cavity with one end open and the other edges closed before sealing; the inflation port connects the inflation cavity and the outside of the double-layer inflatable bag; the double-layer inflatable bag is provided with at least one air hole, the air hole passes through adjacent inner films and outer films, and the inner film and outer film at the edge of the air hole are sealed and connected; the edge of the air hole is connected to the air permeable membrane, and the area of ​​the air permeable membrane is greater than the area of ​​the air hole.

2. The modified atmosphere fresh-keeping bag according to claim 1, characterized in that: The number of the inflation port is one, and the inflation cavities on both sides of the double-layer inflatable bag are connected.

3. The modified atmosphere fresh-keeping bag according to claim 1, characterized in that: The ratio of the O2 to CO2 permeability of the breathable membrane is 1:5-6. Based on the maximum mass of chestnuts stored in the storage cavity, the ratio of the total area of ​​the breathable holes to the mass of the stored chestnuts is 2-6 cm 2 : 500g.

4. The modified atmosphere fresh-keeping bag according to claim 1 or 3, characterized in that: The number of the ventilation holes is not less than one, and the ventilation holes penetrate the outer film and the inner film.

5. Use of the modified atmosphere fresh-keeping bag according to any one of claims 1 to 4 in storing and / or transporting chestnut kernels.

6. The use according to claim 5, characterized in that: The chestnut kernels are raw chestnut kernels; the transportation is room temperature transportation, and the storage is refrigerated.

7. A method for preserving chestnut kernels using the modified atmosphere fresh-keeping bag according to any one of claims 1 to 4, characterized in that: The following steps are involved: Putting chestnut kernels into the storage cavity and performing an incomplete sealing process on the storage cavity; The inflation cavity is inflated through the inflation port, and after the inflation is completed, the remaining unsealed position of the storage cavity is sealed until the air pressure in the storage cavity is balanced with the outside.

8. The method according to claim 7, characterized in that The chestnut kernels are raw chestnut kernels; the chestnut kernels are pretreated before being loaded into the storage cavity; the pretreatment comprises: soaking the chestnut kernels in a fresh-keeping solution for 20 to 30 minutes, then taking them out and removing surface moisture; the fresh-keeping solution comprises 75 to 100 g / L sodium chloride solution.

9. The method according to claim 8, characterized in that The fresh-keeping solution also includes: 10 g / L of ε-polylysine hydrochloride and 10 g / L of vitamin C.

10. The method according to any one of claims 7 to 9, characterized in that: The storage cavity is also filled with a desiccant and a deoxidizer; the deoxidizer includes iron powder; the desiccant includes silica gel desiccant; the mass ratio of the silica gel desiccant to the chestnut kernel is 20:500; the mass ratio of the iron powder to the chestnut kernel is 2:500.

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