Packed food and sterilization method therefor

Abstract

To provide a packed food and a sterilization method therefor, capable of effectively sterilizing a packed food and securing a desirable exterior appearance and a texture of the content of the packed food while curbing deformation of an outer package of the packed food.SOLUTION: A sterilization method for packed food includes a step of sterilizing a sealed packed food, where an outer package material of the packed food is a deformable package material, and a headspace is present in the packed food. The sterilization processing includes performing the following processes consecutively: a temperature raising process of gradually raising both temperature and pressure with time to be constant; a constant temperature process of gradually raising the pressure with time to a predetermined value while keeping the temperature at constant; and a temperature lowering process of gradually lowering both the temperature and the pressure with time.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention belongs to the field of packaged food processing, and in particular to a packaged food and a method for sterilizing the same. [Background technology]

[0002] In recent years, with the increasing demand for packaged foods, consumers are increasingly paying attention to the types and packaging forms of packaged foods. Conventional steel can packaged bean and grain packaged foods are often cooked and eaten as porridge or side dishes, but the packaged foods contain large amounts of water, salt, and sugar, which affects the original taste of the packaged foods. Meanwhile, packaged foods that use glass can packaging are heavy, easily broken, and inconvenient to carry, and do not currently meet consumer needs.

[0003] As healthy snacks have become a hotspot in consumption, various types of packaged snack foods such as chicken breast and corn are appearing one after another. Most of these packaged foods use vacuum or nitrogen-filled flexible packaging, which makes the product contents simple and enriches the texture, and when eaten, packaged foods generally contain some ingredients.

[0004] Convenient box packaging is a common packaging method for nitrogen-filled flexible packaging, specifically, food packs and ingredient packs are placed in a box, and after consumers remove the packs, they mix and eat in the box, which has the effect of improving nutritional balance and taste. However, when convenient box-packaged foods are removed and the contents are mixed, the box is easily contaminated, posing a hygiene risk, and the food packs and ingredient packs are easily wrinkled due to impact inside the box, which can cause the packaging to break and leak, leading to product deterioration.

[0005] Some packaged foods are packaged in pouches, but consumer feedback has shown that pouches are inconvenient to eat. Most pouched foods come with a spoon, but the pouch shape makes it difficult to scoop the food, and the spoon often falls off during distribution.

[0006] At present, the mainstream of prepackaged foods are those that use lightweight packaging containers such as cups or cans, in which, for example, raw ingredients are placed in a cup-shaped packaging container, an ingredient pack is attached to the outside of the cup-shaped packaging container, and when it is time to eat, the ingredient pack is opened, the ingredients are placed in the packaging container, and mixed with the raw ingredients.Since it is necessary to secure space in the packaging container to accommodate the ingredients, it is necessary to provide a large head space in the prepackaged food.

[0007] However, the head space of current packaged foods is relatively small, generally less than 5%, which does not meet the need for large head space. Simply increasing the head space ratio of packaged foods in traditional packaging formats will make the packaged foods more susceptible to sterilization and may cause deformation of the outer packaging, which will severely limit the commercialization of packaged foods. Summary of the Invention [Problem to be solved by the invention]

[0008] In the snack food sector, dairy product packaging is the best in terms of consumer health and ease of eating: for example, yogurt is stored in a cup-shaped container, other ingredients are placed on the top lid of the container, and when eating, the ingredients are mixed in the cup-shaped container. However, while yogurt is sterilized and then filled at low temperature under aseptic conditions, most packaged foods that use solid foods must be sterilized after filling, that is, sealed and then sterilized.

[0009] The current challenge is that when a packaged food requires a large headspace, it is not possible to effectively sterilize the packaged food and ensure a good appearance and texture of the contents of the packaged food while suppressing deformation of the outer packaging of the packaged food, i.e., the packaging container.

[0010] In particular, when the head space volume ratio of a packaged food exceeds 5%, a large gap is generated in the packaging container of the packaged food, and after the packaging container is sealed, a high-temperature and high-pressure sterilization stage must be performed, and during the temperature rise process in the sterilization stage, the difference in the temperature rise rate between the inside and outside of the packaging container is large, and the pressure is difficult to balance, so that deformation of the outer packaging, such as localized dents in the outer packaging and wrinkles in the cover film, is very likely to occur during sterilization. In addition, some raw food ingredients are sensitive to light and oxygen, so higher requirements are placed on the outer packaging material and sterilization process.

[0011] Therefore, there is a need for a method that can effectively sterilize packaged foods with a large head space while minimizing deformation of the outer packaging.

[0012] In consideration of at least some of the above problems, the present invention aims to provide a packaged food and a sterilization method thereof that can effectively sterilize the packaged food and ensure good appearance and texture of the contents of the packaged food while suppressing deformation of the outer packaging of the packaged food. [Means for solving the problem]

[0013] The gist of the present invention is as follows.

[0014] 1. A method for sterilizing a packaged food, comprising the steps of sterilizing a sealed packaged food, the outer packaging material of the packaged food is a deformable packaging material, and the packaged food has a head space; The sterilization process includes sequentially carrying out a temperature increase process in which both the temperature and pressure are gradually increased over time and then kept constant, a constant temperature process in which the pressure is gradually increased over time to a predetermined value while keeping the temperature constant, and a temperature decrease process in which both the temperature and pressure are gradually decreased over time. 2. The temperature and pressure of the heating treatment are increased stepwise over time, and / or The pressure of the isothermal treatment is increased stepwise over time, and / or 2. The method for sterilizing packaged foods according to claim 1, wherein the temperature and pressure of the temperature-lowering treatment are lowered stepwise over time. 3. The temperature of the temperature-raising treatment is increased from the initial temperature to a sterilization temperature of 60 to 130°C, and the pressure is increased from the initial pressure to a sterilization pressure of 0 to 0.3 MPa. 1. A method for sterilizing packaged food according to claim 1. 4. The temperature-raising treatment includes at least one temperature-raising stage, and the temperature-raising rate in each of the temperature-raising stages is in the range of 0.5 to 1.7 ° C. / min; The method for sterilizing packaged foods according to any one of claims 1 to 3, wherein the temperature increase rate in the subsequent temperature increase stage is preferably lower than the temperature increase rate in the previous temperature increase stage with time. 5. The constant temperature treatment includes at least one constant temperature stage, the temperature of each constant temperature stage is controlled and maintained constant in the range of 60 to 130°C, the pressure of each constant temperature stage is increased over time, and the pressure increase rate is in the range of 0.002 to 0.008 MPa / min; Preferably, with time, the pressure increase rate of the subsequent constant temperature stage is lower than the pressure increase rate of the previous constant temperature stage; 5. The method for sterilizing packaged foods according to any one of 1 to 4, wherein the end point pressure of the isothermal treatment is preferably within ±0.03 MPa of the saturated vapor pressure corresponding to the temperature of the isothermal treatment. 6. The temperature-lowering treatment includes at least one temperature-lowering stage, and the temperature-lowering rate in each of the temperature-lowering stages is in the range of 1 to 6 ° C. / min; The method for sterilizing packaged foods according to any one of claims 1 to 5, wherein, preferably, with time, the temperature decreasing rate in the temperature decreasing step in a previous stage is higher than the temperature decreasing rate in the temperature decreasing step in a subsequent stage. 7. The head space volume of the packaged food is 5% or more; Preferably, the headspace volume ratio of the packaged food is 20% to 60%, 7. The method for sterilizing a packaged food according to any one of items 1 to 6, wherein the volume percentage of solid matter in the packaged food is preferably 30% to 80%, and the volume percentage of juice is less than 10%. 8. The oxygen permeability of the outer packaging material of the packaged food is 0.5 cm 3 / (m 224h·0.1MPa), and preferably the oxygen permeability of the outer packaging material of the packaged food is less than 0.1 cm 3 / (m 2 ·24h·0.1MPa) The method for sterilizing a packaged food according to any one of claims 1 to 7, wherein the outer packaging material preferably contains at least one of polyvinylidene chloride, ethylene-vinyl alcohol copolymer, a nitrile resin, polyvinyl alcohol, polyethylene naphthalate, polyethylene terephthalate, polybutylene terephthalate, polyarylate, or polyamide. 9. Specifically, the method includes the steps of putting raw material ingredients into a packaging container made of an outer packaging material, evacuating the packaging container, filling it with a protective gas, and sealing it in order to obtain the packaged food, and then sterilizing the packaged food; Preferably, the raw food ingredients include at least one of corn, beef, oats, chickpeas, quinoa, and chicken breast, Preferably, the internal pressure of the packaging container after evacuation is −0.1 MPa or less, Preferably, the protective gas comprises at least one of nitrogen gas, carbon dioxide and an inert gas; 9. The method for sterilizing packaged food according to any one of claims 1 to 8, wherein the purity of the protective gas is preferably 99.99% or more, preferably 99.999% or more.

[0015] 10. A packaged food obtained by sterilization using the method for sterilizing a packaged food according to any one of claims 1 to 9. Effect of the Invention

[0016] The present invention has at least the following advantageous effects. According to the method for sterilizing packaged foods provided by the present invention, by performing temperature increase treatment, constant temperature treatment, and temperature decrease treatment in stages, it is possible to effectively sterilize the packaged foods while avoiding damage to the outer packaging of the packaged foods caused by sudden changes in sterilization temperature and pressure. By adopting the sterilization method of the present invention, even in the case of packaged foods with a large head space, the outer packaging does not deform during sterilization, and good appearance and texture of the contents of the packaged foods can be ensured. Therefore, the present invention provides a sterilization method that can effectively sterilize packaged foods with a large head space without causing deformation of the outer packaging, and is advantageous for large-scale commercialization of the packaged foods obtained by sterilization. [Brief description of the drawings]

[0017] In order to more clearly explain the specific embodiments of the present invention or the prior art, the drawings necessary for the description of the specific embodiments or the prior art will be briefly introduced below. However, the drawings in the following description show some embodiments of the present invention, and it is obvious that a person skilled in the art can obtain other drawings based on these drawings without any creative ingenuity.

[0018] [Figure 1] FIG. 1 shows packaged foods after sterilization in Examples 1, 5, and 6 of the present invention, where 1a and 1b are external views of the outer packaging, and 1c and 1d are external views of the contents. [Diagram 2] FIG. 2A is a diagram comparing a packaged food after sterilization in Comparative Example 1 of the present invention with a packaged food after sterilization in Example 1, in which FIGS. 2A and 2B are external views of the outer packaging of Example 1 and Comparative Example 1, respectively, and FIGS. 2C and 2D are external views of the contents of Example 1 and Comparative Example 1, respectively. [Diagram 3] FIG. 3 is a diagram comparing a sterilized packaged food in Comparative Example 2 of the present invention with a sterilized packaged food in Example 1, where 3a and 3b are external views of the contents of Example 1 and Comparative Example 1, respectively. [Figure 4] FIG. 4 is an external view of a packaged food after sterilization in Comparative Example 3 of the present invention, with 4a to 4d being external views of the outer packaging of Comparative Example 3 as viewed from different angles. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] It should be understood that the specific embodiments shown herein are for purposes of explanation to one of ordinary skill in the art and are exemplary only and not limiting. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention can be practiced without these specific details. In other instances, well-known processes or techniques have not been described in detail in order to avoid obscuring the present invention.

[0020] The terms used in this specification have the following meanings.

[0021] The term "packaged food" means food in which raw ingredients are placed in a packaging container and sealed. The packaging container may be cylindrical, cup-shaped, can-shaped, or may have the shape of a common commercially available can; in this specification, the packaging container is also referred to as the outer packaging. The term "deformable packaging material" refers to a material that has a certain deformation ability, which is deformed by the action of an external force, but the deformation form is not rigid crushing, wrinkling, bursting, etc. For example, the deformable packaging material may be a non-rigid material such as a tinplate-based rigid material, a flexible material, etc. The term "contents" refers to the raw food ingredients contained within the packaging container. The term "headspace volume" refers to the volume of the void space other than the space occupied by the raw ingredients in the packaging container after the raw ingredients are placed in the packaging container and sealed. The term "headspace volume ratio" refers to the ratio of the headspace volume to the internal volume of the packaging container. The term "solid matter" refers to the solid edible matter in the raw food material packed in the packaging container. The term "volume ratio of solid matter" refers to the volume ratio of solid matter in the packaging container to the internal volume of the packaging container. The term "juice" refers to the liquid edible matter in the raw food material packed in the packaging container. The term "juice volume ratio" refers to the ratio of the volume of the juice in the packaging container to the internal volume of the packaging container. The term "vacuuming" refers to a vacuuming process using a device such as a vacuum extractor to create a vacuum environment inside the packaging container. Furthermore, the internal pressure of the packaged food after vacuuming refers to the gauge pressure (relative pressure) inside the packaging container. The term "inert gas" refers to helium gas, neon gas, argon gas, krypton gas, xenon gas, radon gas, and oganesson, also known as rare gases. The term "shower-type sterilizing boiler" refers to a sterilizing device that sprays or jets boiling water onto packaged foods during sterilization, heats the raw ingredients inside the packaging container quickly and uniformly, and performs high-temperature sterilization. It also has a rotation function and uses boiling water as a heating medium. The term "shower / water bath dual-use sterilizing boiler" refers to a sterilizing device that uses boiling water as a heating medium, can freely switch between heating by a water bath and heating by a shower, and also has a rotation function. The term "high barrier plastic cup" refers to a plastic cup-shaped packaging container (hereinafter referred to as "cup") made of a high barrier material that has high barrier properties against gas and moisture and plays a role mainly in blocking oxygen. The term "high barrier film" refers to a film having properties such as low gas and moisture permeability, high barrier properties, and chemical resistance, and has a multilayer structure formed by simultaneously extruding a material with high gas barrier properties and a polyolefin with high heat sealability and moisture barrier properties. The term "aluminum blister high barrier film" refers to a high barrier film to which aluminum foil has been added. By adding aluminum foil, the hardness of the packaging container after packaging formation can be strengthened, making it less likely to deform.

[0022] Unless otherwise stated, all pressures in this specification refer to relative pressures, also known as gauge pressures.

[0023] The present invention will be described in detail below.

[0024] An embodiment of the present invention provides a method for sterilizing packaged foods, which includes a step of sterilizing sealed packaged foods, wherein an outer packaging material of the packaged foods is a deformable packaging material that has the advantage of imparting a certain degree of deformability to the outer packaging of the packaged foods and making them less likely to break, and a head space is present in the packaged foods, and the sterilization process includes sequentially carrying out a temperature increase process in which both the temperature and pressure are gradually increased over time and kept constant, a constant temperature process in which the pressure is gradually increased over time to a predetermined value while keeping the temperature constant, and a temperature decrease process in which both the temperature and pressure are gradually decreased over time.

[0025] According to the sterilization method for packaged food according to the embodiment of the present invention, the sterilization includes a temperature increase process, a constant temperature process, and a temperature decrease process. Specifically, in the temperature increase process, the temperature and pressure are controlled to increase gradually, and the temperature and pressure settings are not correlated with each other. That is, the temperature and pressure are only correlated with time. Next, in the constant temperature process, the temperature is controlled to be constant and the pressure is continuously increased, thereby maintaining constant temperature sterilization under high temperature and pressure conditions. Finally, in the temperature decrease process, both the temperature and pressure are controlled to decrease gradually with time to complete the sterilization operation, and the temperature and pressure settings are not correlated with each other. That is, the temperature and pressure are only correlated with time. In this way, effective sterilization is possible, and damage to the outer packaging of the packaged food caused by sudden changes in temperature and pressure can be avoided.

[0026] In particular, the method for sterilizing packaged foods according to an embodiment of the present invention can effectively sterilize packaged foods that have a larger head space than general packaged foods and whose outer packaging material is a deformable packaging material by selecting and discarding the sterilization treatment steps, thereby maintaining a good appearance and texture of the contents of the packaged food while minimizing deformation of the outer packaging of the packaged food.

[0027] In some optional embodiments, the temperature and pressure of the temperature-raising process are increased stepwise over time, and / or the pressure of the constant temperature process are increased stepwise over time, and / or the temperature and pressure of the temperature-reducing process are decreased stepwise over time. By controlling the temperature and pressure of the sterilization stepwise, it is possible to achieve effective sterilization while also obtaining a good effect of protecting the appearance of the outer packaging and contents of the packaged food.

[0028] In some optional embodiments, the temperature of the temperature-raising process is increased from the initial temperature to a sterilization temperature of 60 to 130°C, and the pressure is increased from the initial pressure to a sterilization pressure of 0 to 0.3 MPa. For example, the sterilization temperature may be 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, or any value in the range of 60 to 130°C, and the sterilization pressure may be 0MPa, 0.01MPa, 0.05MPa, 0.1MPa, 0.15MPa, 0.2MPa, 0.25MPa, 0.3MPa, or any value in the range of 0 to 0.3MPa. If the sterilization temperature and sterilization pressure are within the range of the present embodiment, the packaged food can be effectively sterilized and the commercial sterility requirements of the packaged food can be met, and the pressure and temperature can be controlled respectively to prevent the outer packaging of the packaged food from being damaged under the high temperature and high pressure conditions of the sterilization process.

[0029] In some optional embodiments, the temperature rise process includes at least one temperature rise stage, and the temperature rise rate of each temperature rise stage is in the range of 0.5 to 1.7° C. / min. For example, the temperature rise rate may be 0.5° C. / min, 0.6° C. / min, 0.7° C. / min, 0.8° C. / min, 0.9° C. / min, 1.0° C. / min, 1.1° C. / min, 1.2° C. / min, 1.3° C. / min, 1.4° C. / min, 1.5° C. / min, 1.6° C. / min, 1.7° C. / min, or any value in the range of 0.5 to 1.7° C. / min.

[0030] In some optional embodiments, the temperature-raising process includes one temperature-raising stage, i.e., a first temperature-raising stage in which the temperature is raised from an initial temperature to a temperature of 60-130°C required for sterilizing packaged foods, and the pressure is raised from the initial pressure to a pressure of 0-0.3 MPa required for sterilizing packaged foods. Here, the initial temperature and initial pressure refer to the temperature and pressure of the raw food material before the sterilization process. For example, when the initial temperature is 25°C, the temperature in the first temperature-raising stage is raised from 25°C to 60-130°C, and when the initial pressure is -0.1 MPa, the pressure in the first temperature-raising stage is raised from -0.1 MPa to 0-0.3 MPa.

[0031] In some optional embodiments, the temperature ramp process includes two ramp stages: a first ramp stage and a second ramp stage. The temperature and pressure in the first heating stage are both lower than those in the second heating stage, and the temperature is increased to a certain value at the end of the second heating stage to facilitate constant temperature treatment. Specifically, the temperature in the first heating stage is increased from the initial temperature to 105°C, and the pressure is increased from the initial pressure to 0.11 MPa, while the temperature in the second heating stage is 105-121°C, and the pressure is 0.11-0.185 MPa.

[0032] In some optional embodiments, the temperature ramp process includes three ramp stages: a first ramp stage, a second ramp stage, and a third ramp stage. The temperature and pressure in the first heating stage, the second heating stage and the third heating stage are successively increased, and the temperature is increased to a constant value at the end of the third heating stage to facilitate the isothermal treatment. Specifically, the temperature in the first heating stage is increased from the initial temperature to 70°C, and the pressure is increased from the initial pressure to 0.025MPa, the temperature in the second heating stage is 70-95°C and the pressure is 0.025-0.065MPa, and the temperature in the third heating stage is 95-116°C and the pressure is 0.065-0.17MPa.

[0033] In some optional embodiments, the temperature ramp process includes four ramp stages: a first ramp stage, a second ramp stage, a third ramp stage, and a fourth ramp stage. The temperature and pressure in the first, second, third and fourth heating stages are sequentially increased, and the temperature is increased to a constant value at the end of the fourth heating stage to facilitate constant temperature treatment. Specifically, the temperature in the first heating stage is increased from the initial temperature to 60°C, and the pressure is increased from the initial pressure to 0.02MPa, the temperature in the second heating stage is 60-90°C and the pressure is 0.02-0.06MPa, the temperature in the third heating stage is 90-105°C and the pressure is 0.06-0.11MPa, and the temperature in the fourth heating stage is 105-125°C and the pressure is 0.11-0.19MPa.

[0034] It should be appreciated that in any further embodiment, the temperature ramp process may further include multiple ramp stages, such as five, six, seven, etc. ramp stages.

[0035] In some optional embodiments, the heating rate of the later heating stage is lower than that of the earlier heating stage with time. The heating rate is controlled and gradually decreased to avoid the outer packaging being deformed due to the temperature change being too fast after heating to a high temperature.

[0036] In some optional embodiments, the isothermal treatment includes at least one isothermal stage, the temperature of each isothermal stage is controlled and maintained constant in the range of 60-130° C., the pressure of each isothermal stage is increased over time, and the pressure increase rate is in the range of 0.002-0.008 MPa / min. For example, the pressure increase rate may be 0.002 MPa / min, 0.003 MPa / min, 0.004 MPa / min, 0.005 MPa / min, 0.006 MPa / min, 0.007 MPa / min, 0.008 MPa / min, or any value in the range of 0.002-0.008 MPa / min.

[0037] In some optional embodiments, the end point pressure (predetermined value) of the constant temperature treatment is the saturated steam pressure corresponding to the temperature of the constant temperature treatment ±0.03 MPa. Within the temperature and pressure range of the constant temperature treatment according to the present embodiment, the packaged food can be effectively sterilized without damaging the outer packaging.

[0038] In some optional embodiments, the isothermal treatment includes one isothermal stage, i.e., a first isothermal stage, in which the temperature is kept constant and the pressure is gradually increased over time, specifically, the temperature of the first isothermal stage is 116° C., the duration is 25 minutes, and the pressure is increased from 0.17 MPa to 0.21 MPa.

[0039] In some optional embodiments, the isothermal treatment includes two isothermal stages, a first isothermal stage and a second isothermal stage, the temperatures of the first isothermal stage and the second isothermal stage are kept constant and the pressure is gradually increased with time, specifically, the temperature of the first isothermal stage is 116°C, the time is 8 minutes, and the pressure is increased from 0.17 MPa to 0.195 MPa, and the temperature of the second isothermal stage is 116°C, the time is 12 minutes, and the pressure is increased from 0.195 MPa to 0.205 MPa.

[0040] In some optional embodiments, the isothermal treatment includes three isothermal stages, the first isothermal stage, the second isothermal stage, and the third isothermal stage, in which the temperatures of the first isothermal stage, the second isothermal stage, and the third isothermal stage are kept constant and the pressure is gradually increased with time. Specifically, the temperature of the first isothermal stage is 116°C, the time is 4 minutes, and the pressure is increased from 0.17MPa to 0.185MPa, the temperature of the second isothermal stage is 116°C, the time is 6 minutes, and the pressure is increased from 0.185MPa to 0.195MPa, and the temperature of the third isothermal stage is 116°C, the time is 8 minutes, and the pressure is increased from 0.195MPa to 0.205MPa.

[0041] In some optional embodiments, the pressure rise rate of the later isothermal stage is lower than that of the earlier isothermal stage with time. As the pressure rises, the possibility of deformation of the outer packaging increases. In this embodiment, the pressure rise rate is controlled to gradually decrease, so that the deformation of the outer packaging due to the excessive pressure change can be avoided.

[0042] It should be appreciated that in any further embodiment, the isothermal treatment may further include multiple isothermal stages, such as four, five, six, seven, etc. isothermal stages.

[0043] In some optional embodiments, the temperature-reducing treatment includes at least one temperature-reducing step, and the temperature-reducing rate in each step is in the range of 1 to 6° C. / min, for example, 1, 2, 3, 4, 5, or 6° C. / min.

[0044] In some optional embodiments, the temperature reduction process includes one temperature reduction stage, i.e., a first temperature reduction stage, in which the temperature is reduced from the temperature of the isothermal process to 20° C., and the pressure is reduced from the end pressure of the isothermal process to 0.015-0.005 MPa.

[0045] In some optional embodiments, the temperature reduction process includes two temperature reduction stages, a first temperature reduction stage and a second temperature reduction stage, in which the temperature in the first temperature reduction stage is reduced from the temperature of the constant temperature process to 60-40°C, the end point pressure of the first temperature reduction stage is 0.05-0.03 MPa, and the end point temperature of the second temperature reduction stage is 30-20°C, and the end point pressure is 0.02-0.01 MPa.

[0046] In some optional embodiments, the temperature reduction process includes three temperature reduction stages, namely, a first temperature reduction stage, a second temperature reduction stage, and a third temperature reduction stage, in which the temperature in the first temperature reduction stage is reduced from the temperature of the constant temperature process to 60°C, the end point pressure of the first temperature reduction stage is 0.05 to 0.04 MPa, the temperature in the second temperature reduction stage is 60 to 40°C and the pressure is 0.04 to 0.025 MPa, and the temperature in the third temperature reduction stage is 40 to 20°C and the pressure is 0.025 to 0.01 MPa. It should be appreciated that in another optional embodiment, the cooling process may further include multiple cooling steps, such as four, five, six, seven, etc. cooling steps.

[0047] In some optional embodiments, the temperature drop rate of the early stage temperature drop stage is higher than that of the later stage temperature drop stage with time. In this embodiment, the relatively high temperature drop rate is adopted in the higher temperature drop stage, which is advantageous for rapid temperature drop, and can minimize the impact of high temperature on the outer packaging and avoid deformation of the outer packaging.

[0048] From the constant temperature treatment process to the cooling treatment process, the temperature and pressure are changed and selected stepwise, so that the packaged food does not experience a large environmental change, and the selection of the temperature increase treatment, constant temperature treatment and cooling treatment all takes into consideration the head space ratio and the compatibility with normal deformable outer packaging materials, thereby achieving multiple effects such as effective sterilization, maintaining the color and sensory properties of the food, and preventing deformation.

[0049] In some optional embodiments, the temperature and pressure of the sterilization process are linearly correlated with time, and the temperature and pressure are not correlated with each other, i.e., the temperature of sterilization increases with time, then remains constant, and then decreases, and the pressure of sterilization increases with time, then decreases, and the corresponding relationship between the temperature and pressure during the temperature increase process is different from the corresponding relationship between the temperature and pressure during the temperature decrease process. For example, in the temperature-raising process, when the temperature rises to 85° C., the pressure is 0.1 MPa, whereas in the temperature-lowering process, when the temperature falls to 85° C., the pressure is a value other than 0.1 MPa, such as 0.8 MPa, 0.9 MPa, 0.11 MPa, etc. Also, for example, in the temperature-raising process, when the temperature rises to 100° C., the pressure is 0.18 MPa, whereas in the temperature-lowering process, when the temperature falls to 100° C., the pressure is a value other than 0.18 MPa, such as 0.16 MPa, 0.17 MPa, 0.19 MPa, etc.

[0050] In this embodiment, multi-stage sterilization is adopted during sterilization, and the temperature and pressure are set according to time. Specifically, it is required to control the temperature and pressure during sterilization so that they are not correlated with each other, but are linearly correlated with time. This can ensure that the pressure in the constant temperature stage of sterilization changes with time. By gradually decreasing the temperature and pressure of sterilization, it is possible to achieve effective sterilization while exerting a good protective effect on the sensory properties of the outer packaging and contents of the packaged food.

[0051] In some optional embodiments, the headspace volume ratio of the packaged food is 5% or more, preferably 20%-60%. In conventional technology, the headspace volume ratio of the packaged food is generally less than 5%, and if the headspace is too large, the difference in the temperature rise rate between the inside and outside of the packaging container during the temperature rise sterilization process is large, making it difficult to balance the pressure, and the outer packaging is easily deformed. However, in this embodiment, the volume of the contents of the packaging container is much smaller than the volume of the packaging container, and in particular, even if the headspace volume ratio is as high as 20%-60%, no deformation of the outer packaging occurs during sterilization. For example, the headspace volume percentage of the packaged food in this embodiment may be 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 99.9%, or any value in the range of 5% to 100% (excluding 100%).

[0052] In some optional embodiments, the volume percentage of solids in the packaged food is 30%-80%, and the volume percentage of liquid is less than 10%. In this embodiment, since the solid content of the packaged food is high, no liquid or only a small amount of liquid can be added, so that effective sterilization can be achieved without destroying the outer packaging, and is particularly applicable to various kinds of solid meats and vegetables suitable for processing as raw ingredients of packaged foods. For example, the volume percentage of solids in the packaged food may be 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, or any number in the range of 40% to 80%, and the volume percentage of juice may be 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or any number in the range of 0 to 10%.

[0053] In some optional embodiments, the oxygen permeability of the outer packaging of the packaged food is 0.5 cm 3 / (m 2 24h 0.1MPa), and preferably the oxygen permeability is 0.1cm 3 / (m 2 Here, the "oxygen permeability" is defined as the oxygen permeability of the packaging material per unit area of ​​1 m under an oxygen pressure of 0.1 MPa.2 This refers to the volume of oxygen that passes through per 24 hours per unit of food. In this embodiment, by packaging using a high-barrier material with extremely low oxygen permeability, gases such as oxygen and moisture can be effectively blocked, preventing oxygen from penetrating the packaged food and damaging the raw ingredients.

[0054] Preferably, the outer packaging material comprises at least one of polyvinylidene chloride, ethylene-vinyl alcohol copolymer, nitrile resin, polyvinyl alcohol, polyethylene naphthalate, polyethylene terephthalate, polybutylene terephthalate, polyarylate, and polyamide. In this case, the outer packaging of the packaged food can effectively avoid light and block ventilation, and can prevent the oxidation of the contents of the packaged food during the sterilization process, which is favorable for reducing nutritional loss and maintaining the taste of the packaged food.

[0055] In some optional embodiments, the sterilization method includes the steps of placing the raw food ingredients in a packaging container made of an outer packaging material, vacuuming the packaging container, filling it with a protective gas, sealing it, obtaining a packaged food, and further sterilizing the packaged food. In this embodiment, the temperature of the raw food ingredients before filling may be low temperature, room temperature (25°C), or high temperature (over 60°C), or frozen raw materials may be directly filled. The packaged food may adopt a gas replacement packaging method, for example, a gas replacement packaging machine may be used to evacuate the packaging container after filling it with the raw materials, and then a protective gas may be filled to effectively preserve the freshness of the packaged raw food ingredients, and then the container may be sealed. By filling the protective gas after evacuating it, the oxygen content in the packaged food may be reduced, and the problem of oxidative deterioration of the raw food ingredients may be avoided. In addition, when the outer packaging material of the above embodiment is adopted and the gas replacement packaging method of the present embodiment is adopted, the influence of oxygen on the ingredients may be further reduced, and the method is particularly suitable for packaging and sterilization of low-acid packaged foods.

[0056] In some optional embodiments, the raw food ingredients include at least one of corn, beef, oats, chickpeas, quinoa, and chicken breast. When the raw food ingredients are sterilized by the sterilization method of the present embodiment, good color and quality of the raw food ingredients can be ensured, which helps to ensure the quality of the packaged food.

[0057] In some optional embodiments, the internal pressure of the packaging container after evacuation is -0.1 MPa or less, which is advantageous for ensuring that as much air as possible is removed from the packaged food, and is also advantageous for filling a sufficient amount of protective gas into the packaged food.

[0058] In some optional embodiments, the protective gas comprises at least one of nitrogen gas, carbon dioxide and an inert gas. The properties of nitrogen gas, carbon dioxide and / or inert gas are stable and do not react with the raw food material in the packaging container, so that the original air in the packaging container can be replaced with nitrogen gas, carbon dioxide and / or inert gas to prevent the oxygen in the original air from reacting with the raw food material and destroying the raw food material.

[0059] In some optional embodiments, the purity of the protective gas is 99.99% or more (by volume fraction), preferably 99.999% or more, in order to minimize residual oxygen in the packaged food and prevent oxygen from reacting with the raw ingredients and spoiling the packaged food.

[0060] In some optional embodiments, the sterilization kettle includes a shower sterilization kettle or a shower / water bath dual-use sterilization kettle, and these two types of sterilization kettles may have a rotation function. Both the shower sterilization method and the water bath sterilization method use high-temperature and high-pressure hot water as a heating medium to sterilize the sealed and molded packaged food. When the shower sterilization method is adopted, the contents of the packaged food can be heated quickly and uniformly by spraying or injecting hot water at a high speed onto the outer packaging of the packaged food, and when the water bath sterilization method is adopted, the packaged food can be immersed entirely in hot water to achieve a relatively uniform heat distribution. In addition, since the sterilization kettle has a rotation function, the uniformity of the package heating can be further ensured. Thus, by adopting the above sterilization method, the heating time can be greatly shortened, high-temperature sterilization and sterilization can be performed in a short time, and the good color and quality of the contents of the packaged food can be maintained, and the quality of the packaged food can be ensured.

[0061] Another embodiment of the present invention provides a packaged food obtained by sterilization using the method for sterilizing a packaged food of the above embodiment.

[0062] In order to make the objectives, technical configurations and advantageous effects of the present invention more comprehensible, the present invention will be described in more detail with reference to specific examples below. However, the following specific examples are merely for the purpose of illustrating the present invention and are not intended to limit the present invention.

[0063] Example 1 A method for sterilizing fresh kernel corn cups is provided, the specific steps of which are as follows: 1.Product raw material: quick-frozen kernel corn. 2. Outer packaging: High-barrier plastic cup and aluminum blister high-barrier film. The oxygen permeability of the cup and aluminum blister high-barrier film is 0.1 cm 3 / (m 2 ·24h·0.1MPa). 3. Filling with raw materials: The volume of the quick-frozen kernel corn to be filled is 40% of the cup volume, no juice is added, the filling temperature is less than -10°C, and after filling, the cup is evacuated until the internal pressure is -0.1MPa. Then, 99.999% pure nitrogen gas is filled into the cup until the cover film sealed with a sealing film is slightly concave. 4. Sterilization: A sterilization boiler that can be used for both shower and water bath was used. 4.1. Temperature increase treatment: First heating stage: A water bath was selected to heat the sealed cup, the water bath temperature was 70°C, and the temperature was maintained for 30 minutes, and the pressure in the sterilization vessel was increased from 0.008MPa to 0.025MPa. The hot water from the lower tank was then recovered and shower sterilization was switched to. Second heating stage: the temperature was increased from 70° C. to 95° C. for 20 minutes, and the pressure in the sterilization vessel was increased from 0.025 MPa to 0.065 MPa. Third heating stage: the temperature was increased from 95°C to 116°C, the time was 25 minutes, and the pressure in the sterilization vessel was increased from 0.065MPa to 0.17MPa. 4.2. Constant temperature treatment: The temperature was kept at 116°C for 25 minutes, and the pressure in the sterilization vessel was increased from 0.17 MPa to 0.21 MPa. 4.3. Cooling treatment: First cooling stage: The temperature was reduced from 116°C to 40°C, the time was set to 20 minutes, and the pressure in the sterilization vessel was reduced from 0.021 MPa to 0.03 MPa. Second cooling stage: The temperature was reduced from 40° C. to 25° C. for 15 minutes, and the pressure in the sterilization vessel was reduced from 0.03 MPa to 0.01 MPa. 5. Sterilization result: As shown in Figure 1, after the above sterilization steps are completed, the high-barrier plastic cup is torn open and it is found that the kernel corn has bright color, crisp texture and sweet taste, the cup body is intact, and the cover film is slightly bulging, which means the product meets commercial aseptic standards.

[0064] Example 2 A method for sterilizing a ready-to-eat beef cubes and oatmeal mixed cup is provided, the specific steps of which are as follows: 1. Product ingredients: Marinated raw beef cubes mixed with soaked and boiled oatmeal. 2. Outer packaging: High-barrier plastic cup and transparent, easily torn high-barrier film. The oxygen permeability of both the cup and the high-barrier film is 0.5 cm 3 / (m 2 ·24h·0.1MPa). 3. Filling with ingredients: The volume of the marinated raw beef cubes and soaked and boiled oatmeal to be filled is 60% of the cup volume, no liquid is added, the filling temperature is less than 5-10°C, after filling, a vacuum is drawn until the internal pressure of the cup is -0.1MPa, and then 99.99% pure nitrogen gas is filled into the cup until the cover film sealed with a sealing film is slightly concave. 4. Sterilization: A shower-type sterilization boiler was used. 4.1. Temperature increase treatment: First heating stage: The temperature was raised from room temperature to 105° C. for 30 minutes, and the pressure in the sterilization vessel was raised from 0.003 MPa to 0.11 MPa. Second heating stage: the temperature was increased from 105° C. to 121° C. for 10 minutes, and the pressure in the sterilization vessel was increased from 0.11 MPa to 0.185 MPa. 4.2. Constant temperature treatment: The temperature was kept at 121°C for 20 minutes, and the pressure in the sterilization vessel was increased from 0.185 MPa to 0.23 MPa. 4.3. Cooling treatment: First cooling stage: The temperature was reduced from 121°C to 60°C for 15 minutes, and the pressure in the sterilization vessel was reduced from 0.23 MPa to 0.04 MPa. Second cooling stage: The temperature was reduced from 60°C to 40°C for 10 minutes, and the pressure in the sterilization vessel was reduced from 0.04MPa to 0.025MPa. Third cooling stage: The temperature was reduced from 40° C. to 25° C. for 10 minutes, and the pressure in the sterilization vessel was reduced from 0.025 MPa to 0.01 MPa. 5. Sterilization result: After the above sterilization steps are completed, the high-barrier plastic cup is torn open and found that the beef cubes are well ripened, the oatmeal has high integrity and chewy texture, the cup body is intact, the cover film is flat, and the product meets commercial sterility.

[0065] Example 3 A method for sterilizing ready-to-eat chickpea quinoa cups is provided, the specific steps of which are as follows: 1. Product ingredients: soaked and boiled chickpeas, boiled quinoa. 2. Outer packaging: High-barrier plastic cup and transparent, easily torn high-barrier film. The oxygen permeability of both the cup and the high-barrier film is 0.5 cm 3 / (m 2 ·24h·0.1MPa). 3. Filling with ingredients: The volume of the soaked and boiled chickpeas and boiled quinoa to be filled was 70% of the cup volume, and the volume of the added liquid was 10% of the cup volume. The filling temperature was 70-80°C, and after filling, the cup was evacuated until the internal pressure was -0.1MPa. After that, 99.99% pure nitrogen gas was filled into the cup until the cover film sealed with a sealing film swelled slightly. 4. Sterilization: A shower-type sterilization boiler was used. 4.1. Temperature increase treatment: First heating stage: the temperature was increased from 70° C. to 121° C. for 25 minutes, and the pressure in the sterilization vessel was increased from 0.003 MPa to 0.19 MPa. 4.2. Constant temperature treatment: The temperature was kept at 121°C for 20 minutes, and the pressure in the sterilization vessel was increased from 0.19 MPa to 0.23 MPa. 4.3. Temperature reduction treatment: First cooling stage: The temperature was reduced from 121°C to 60°C for 15 minutes, and the pressure in the sterilization vessel was reduced from 0.23 MPa to 0.04 MPa. Second cooling stage: The temperature was reduced from 60°C to 40°C for 10 minutes, and the pressure in the sterilization vessel was reduced from 0.04MPa to 0.025MPa. Third cooling stage: The temperature was reduced from 40°C to 20°C, the time was set to 10 minutes, and the pressure in the sterilization vessel was reduced from 0.025 MPa to 0.01 MPa. 5. Sterilization result: After the above sterilization steps are completed, the high-barrier plastic cup is torn open, and it is found that the chickpea quinoa has an intact appearance, the texture is not powdery, the palatability is good, the cup body is intact, and the cover film is slightly dented, and the product meets the commercial aseptic standard.

[0066] Example 4 A method for sterilizing ready-to-eat chicken breast and corn mixed cups is provided, the specific steps of which are as follows: 1.Product ingredients: Marinated raw chicken breast cubes mixed with quick-frozen sweet kernel corn. 2. Outer packaging: High-barrier plastic cup and aluminum blister high-barrier film. The oxygen permeability of the cup and aluminum blister high-barrier film is 0.1 cm 3 / (m 2 ·24h·0.1MPa). 3. Filling with raw materials: The volume of the marinated raw chicken breast cubes and flash-frozen sweet kernel corn to be filled is 60% of the cup volume, no juice is added, the filling temperature is 0~5℃, after filling, the cup is evacuated until the internal pressure is -0.1MPa, and then 99.99% pure nitrogen gas is filled into the cup until the cover film sealed with a sealing film is slightly concave. 4. Sterilization: A sterilization boiler that can be used for both shower and water bath was used. 4.1. Temperature increase treatment: First heating stage: A water bath was selected to heat the sealed cup, the water bath temperature was 60°C, and the temperature was maintained for 40 minutes, and the pressure in the sterilization vessel was increased from 0.008MPa to 0.025MPa. The hot water from the lower tank was then recovered and shower sterilization was switched to. Second heating stage: the temperature was increased from 60° C. to 90° C. for 20 minutes, and the pressure in the sterilization vessel was increased from 0.025 MPa to 0.06 MPa. Third heating stage: the temperature was increased from 90°C to 105°C, the time was 12 minutes, and the pressure in the sterilization vessel was increased from 0.06 MPa to 0.11 MPa. Fourth heating stage: the temperature was increased from 105°C to 125°C for 12 minutes, and the pressure in the sterilization vessel was increased from 0.11 MPa to 0.19 MPa. 4.2. Constant temperature treatment: The temperature was kept at 125°C for 5 minutes, and the pressure in the sterilization vessel was increased from 0.19 MPa to 0.21 MPa. 4.3. Cooling treatment: First cooling stage: The temperature was reduced from 125°C to 40°C for 20 minutes, and the pressure in the sterilization vessel was reduced from 0.21 MPa to 0.035 MPa. Second cooling stage: The temperature was reduced from 40° C. to 25° C. for 15 minutes, and the pressure in the sterilization vessel was reduced from 0.035 MPa to 0.01 MPa. 5. Sterilization result: After the above sterilization steps are completed, the high-barrier plastic cup is torn open and found that the chicken cubes are well ripe, the kernel corn has high integrity and chewy texture, the cup body is intact, the cover film is flat, and the product meets commercial sterility.

[0067] Example 5 A method for sterilizing fresh kernel corn cups is provided, the specific steps of which are as follows: 1.Product raw material: quick-frozen kernel corn. 2. Outer packaging: High-barrier plastic cup and aluminum blister high-barrier film. The oxygen permeability of the cup and aluminum blister high-barrier film is 0.1 cm 3 / (m 2 ·24h·0.1MPa). 3. Filling with raw materials: The volume of the quick-frozen kernel corn to be filled is 60% of the cup volume, no juice is added, the raw material temperature is less than -10°C, and after filling, the cup is evacuated until the internal pressure is -0.1MPa. Then, 99.999% pure nitrogen gas is filled into the cup until the cover film sealed with a sealing film is slightly concave. 4. Sterilization: A shower-type sterilization boiler was used. 4.1. Temperature increase treatment: First heating stage: A shower-type sterilization pot was selected to heat the sealed cups, the shower temperature was increased from 20°C to 116°C, the heating time was 80 minutes, and the pressure in the sterilization pot was increased from 0 to 0.17Mpa. 4.2. Temperature treatment: First constant temperature stage: the temperature was kept at 116°C for 8 minutes, and the pressure in the sterilization vessel was increased from 0.17 MPa to 0.195 MPa. Second constant temperature stage: the temperature was kept at 116°C for 12 minutes, and the pressure in the sterilizer was increased from 0.195 MPa to 0.205 MPa. 4.3. Cooling treatment: First cooling stage: The temperature was reduced from 116°C to 20°C, the time was set to 30 minutes, and the pressure in the sterilization vessel was reduced from 0.205 MPa to 0.015 MPa. 5. Sterilization result: As shown in Figure 1, after the above sterilization steps are completed, the high-barrier plastic cup is torn open and it is found that the kernel corn has bright color, crisp texture and sweet taste, the cup body is intact, and the cover film is slightly bulging, which means the product meets commercial aseptic standards.

[0068] Example 6 A method for sterilizing fresh kernel corn cups is provided, the specific steps of which are as follows: 1.Product raw material: quick-frozen kernel corn. 2. Outer packaging: High-barrier plastic cup and aluminum blister high-barrier film. The oxygen permeability of the cup and aluminum blister high-barrier film is 0.1 cm 3 / (m 2 ·24h·0.1MPa). 3. Filling with raw materials: The volume of the quick-frozen kernel corn to be filled is 40% of the cup volume, no juice is added, the filling temperature is less than -10°C, and after filling, the cup is evacuated until the internal pressure is -0.1MPa. Then, 99.999% pure nitrogen gas is filled into the cup until the cover film sealed with a sealing film is slightly concave. 4. Sterilization: A shower-type sterilization boiler was used. 4.1. Temperature increase treatment: First heating stage: A shower-type sterilizing kettle with a rotation function was selected to heat the sealed cups, the shower temperature was set to 60°C, the temperature was maintained for 25 minutes, and the pressure inside the sterilizing kettle was set to 0.02MPa. Second heating stage: the temperature was increased from 60° C. to 90° C. for 20 minutes, and the pressure in the sterilization vessel was increased from 0.02 MPa to 0.06 MPa. Third heating stage: the temperature was increased from 90° C. to 105° C. for 10 minutes, and the pressure in the sterilization vessel was increased from 0.06 MPa to 0.11 MPa. Fourth heating stage: the temperature was increased from 105°C to 116°C, the time was 8 minutes, and the pressure in the sterilization vessel was increased from 0.11 MPa to 0.17 MPa. 4.2. Constant temperature treatment First constant temperature stage: the temperature was kept at 116°C for 4 minutes, and the pressure in the sterilization vessel was increased from 0.17 MPa to 0.185 MPa. Second constant temperature stage: the temperature was kept at 116°C for 6 minutes, and the pressure in the sterilizer was increased from 0.185 MPa to 0.195 MPa. Third constant temperature stage: the temperature was kept at 116°C for 8 minutes, and the pressure in the sterilizer was increased from 0.195 MPa to 0.205 MPa. 4.3. Temperature reduction treatment: First cooling stage: The temperature was reduced from 116°C to 40°C, the time was set to 18 minutes, and the pressure in the sterilization vessel was reduced from 0.205 MPa to 0.03 MPa. Second cooling stage: The temperature was reduced from 40° C. to 20° C. for 10 minutes, and the pressure in the sterilization vessel was reduced from 0.03 MPa to 0.01 MPa. 5. Sterilization result: As shown in Figure 1, after the above sterilization steps are completed, the high-barrier plastic cup is torn open and it is found that the kernel corn has bright color, crisp texture and sweet taste, the cup body is intact, and the cover film is slightly bulging, which means the product meets commercial aseptic standards.

[0069] Table 1 shows the sterilization parameters and sterilization results in Examples 1 to 6.

[0070] [Table 1]

[0071] FIG. 1 shows packaged foods after sterilization in Examples 1, 5, and 6 of the present invention, where 1a and 1b are external views of the outer packaging, and 1c and 1d are external views of the contents.

[0072] As is clear from FIG. 1 and Table 1, the packaged foods of Examples 1 to 6 completely retained the appearance of the raw ingredients even after sterilization, and the appearance was not damaged, and the texture was good even after tasting, and there was no deterioration. It was found that the outer packaging material, filling and sterilization method according to the embodiment of the present invention had a good protective effect on the sensory properties of the contents of the packaged food. It was also found that when the headspace volume ratio of the packaged foods of Examples 1 to 6 greatly exceeded 5%, the shape of the outer packaging after sterilization was maintained and no deformation occurred. It was found that the embodiment of the present invention also had an excellent protective effect on the outer packaging of the packaged food. It was found that the sterilization method of the present invention can meet the sterilization requirements of packaged foods with very large headspaces.

[0073] Comparative Example 1 The difference from Example 1 is that a high barrier material was not selected as the packaging cover film, and other conditions were the same as those of Example 1. The specific differences are as follows. Packaging materials in this comparison: High barrier plastic cup and general cover film. The oxygen permeability of the cup is 0.1 cm 3 / (m 2 24h 0.1MPa) and the oxygen permeability of the cover film is 25cm 3 / (m 2 ·24h·0.1MPa).

[0074] Comparative Example 2 The difference from Example 1 is that oxygen was not removed after filling, and other conditions were the same as those of Example 1. The specific differences are as follows. Filling of raw materials in this comparative example: The volume of the quick-frozen kernel corn to be filled is 40% of the cup volume, no juice is added, the filling temperature is less than -10°C, and after filling, a vacuum is drawn until the cover film sealed with a sealing film is slightly concave. When drawing a vacuum, the air in the cup is not completely removed, and nitrogen is not filled into the cup.

[0075] Comparative Example 3 The difference from Example 1 is that the sterilization temperature corresponds to the pressure (the same temperature corresponds to the same pressure), and other conditions are the same as those of Example 1. The specific differences are as follows. Sterilization in this Comparative Example: A shower / bath sterilization kettle was used. Heat treatment: First heating stage: A water bath was selected to heat the sealed cup, the water bath temperature was 70°C, and the temperature was maintained for 30 minutes, and the pressure in the sterilization vessel was increased from 0.008MPa to 0.025MPa. The hot water from the lower tank was then recovered and shower sterilization was switched to. Second heat-up stage: the temperature was increased from 70° C. to 116° C. for a duration of 45 minutes. Thermostatic treatment: The temperature was held at 116° C. for 25 minutes. Cooling treatment: First cooling step: The temperature was reduced from 116° C. to 40° C. for 20 minutes. Second cooling step: the temperature was reduced from 40° C. to 25° C. for 15 minutes. Here, the corresponding relationship between the pressure and temperature in the sterilization vessel was controlled as shown in Table 2 below.

[0076] Table 2 shows the relationship between the sterilization temperature and pressure in Comparative Example 3.

[0077] [Table 2]

[0078] Fig. 2 is a diagram comparing a packaged food after sterilization in Comparative Example 1 of the present invention with a packaged food after sterilization in Example 1, where 2a and 2b are external views of the outer packaging of Example 1 and Comparative Example 1, respectively, and 2c and 2d are external views of the contents of Example 1 and Comparative Example 1, respectively. Fig. 3 is a diagram comparing a packaged food after sterilization in Comparative Example 2 of the present invention with a packaged food after sterilization in Example 1, where 3a and 3b are external views of the contents of Example 1 and Comparative Example 1, respectively. Fig. 4 is an external view of a packaged food after sterilization in Comparative Example 3 of the present invention, where 4a to 4d are external views of the outer packaging of Comparative Example 3 viewed from different angles.

[0079] 2 to 4, the sterilization results of Example 1 and Comparative Examples 1 to 3 are compared as follows.

[0080] Table 3 shows a comparison of the sterilization results of Example 1 and Comparative Examples 1 to 3.

[0081] [Table 3]

[0082] As is clear from the comparison between Example 1 and Comparative Example 1, in Comparative Example 1, a high barrier material was not selected as the packaging cover film, and the oxygen permeability of the cover film was 25 cm 3 / (m 2 1·24h·0.1MPa), the color of the kernel corn after sterilization was dark, and it was found that the quality of the kernel corn in Comparative Example 1 was far inferior to that of Example 1. In Example 1, compared with Comparative Example 1, the kernel corn was packaged using a high barrier material and the oxygen permeability of the cover film was 0.1 cm 3 / (m 2 ·24h·0.1MPa), it can effectively prevent oxygen from penetrating into the inside of the kernel corn cup and causing the kernel corn to deteriorate due to oxidation.

[0083] Comparing Example 1 with Comparative Example 2, it was found that in Comparative Example 2, the oxygen in the kernel corn cup was not completely removed after filling, specifically, the air in the cup was not completely removed when vacuuming, and nitrogen gas was not filled into the cup, so the color of the kernel corn after sterilization was dark, and the quality of the kernel corn in Comparative Example 2 was far inferior to that of Example 1.

[0084] In Example 1, compared with Comparative Example 2, after filling, the inside of the kernel cone cup is evacuated until the pressure becomes -0.1 MPa, and the kernel cone cup is filled with nitrogen gas to protect it, which can effectively prevent the oxygen inside the kernel cone cup and the kernel cone from being oxidized and deteriorated.

[0085] From the comparison between Example 1 and Comparative Example 3, in Comparative Example 3, the temperature and pressure during sterilization are set correspondingly, specifically, in the whole process of the temperature rise treatment, constant temperature treatment and temperature drop treatment, the specific pressure value corresponds to each temperature, for example, if the temperature of the temperature rise treatment is 100 ° C, the pressure is 0.1 MPa, and if the temperature of the temperature drop treatment is 100 ° C, the pressure is also 0.1 MPa. In addition, when the temperature of the constant temperature treatment is kept at 116 ° C, the pressure is always kept at 0.17 MPa. Referring to FIG. 4, in this case, the appearance of the kernel corn cup after sterilization is greatly deformed, making it unsuitable for commercial application. In Example 1, compared with Comparative Example 3, the temperature and pressure during sterilization can be controlled respectively to effectively avoid the problem of the packaging deformation of the kernel corn cup, and even if the volume ratio of the head space of the kernel corn cup is as high as 60%, the appearance of the kernel corn cup can be maintained.

[0086] As described above, it can be seen that the packaging material, filling and sterilization method according to the present invention has an excellent protective effect on the appearance of the packaged food and the sensory properties of the contents, and can meet the sterilization requirements of low-acid, large-headspace packaged foods that need to be blocked from light and oxygen.

[0087] The components of the above-described embodiments may be combined in any manner. Although not all possible combinations of the components of the above-described embodiments are described, combinations of these components should be considered within the scope of this specification as long as they are not inconsistent.

[0088] It should be noted that the above embodiments are merely for illustrating the technical solutions of the present invention and are not limiting. The present invention has been described in detail with reference to the above embodiments. However, it should be understood by those skilled in the art that the technical solutions described in the above embodiments may be modified or some or all of the components may be replaced with equivalents, and such modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope described in the embodiments of the present invention.

Claims

1. 1. A method for sterilizing a packaged food, comprising the steps of sterilizing a sealed packaged food, the outer packaging material of the packaged food is a deformable packaging material, and the packaged food has a head space; The sterilization method for packaged foods is characterized in that the sterilization treatment includes sequentially carrying out a temperature increase treatment in which both the temperature and pressure are gradually increased over time and kept constant, a constant temperature treatment in which the pressure is gradually increased over time to a predetermined value while keeping the temperature constant, and a temperature decrease treatment in which both the temperature and pressure are gradually decreased over time.

2. The temperature and pressure of the temperature increase treatment are increased stepwise over time, and / or The pressure of the isothermal treatment is increased stepwise over time, and / or 2. The method for sterilizing packaged foods according to claim 1, wherein the temperature and pressure of the temperature-lowering treatment are lowered stepwise over time.

3. 2. The method for sterilizing packaged foods according to claim 1, wherein the temperature of the temperature-raising treatment is increased from an initial temperature to a sterilization temperature of 60 to 130° C., and the pressure is increased from the initial pressure to a sterilization pressure of 0 to 0.3 MPa.

4. The temperature rise treatment includes at least one temperature rise stage, and the temperature rise rate of each of the temperature rise stages is in the range of 0.5 to 1.7 ° C. / min; 2. The method for sterilizing packaged foods according to claim 1, wherein the temperature increase rate of the subsequent temperature increase stage is preferably lower than the temperature increase rate of the previous temperature increase stage with time.

5. The isothermal treatment includes at least one isothermal stage, the temperature of each isothermal stage is controlled and maintained constant in the range of 60 to 130° C., the pressure of each isothermal stage is increased over time, and the pressure increase rate is in the range of 0.002 to 0.008 MPa / min; Preferably, with time, the pressure increase rate of the subsequent constant temperature stage is lower than the pressure increase rate of the previous constant temperature stage; The method for sterilizing packaged foods according to claim 1, characterized in that the end point pressure of the constant temperature treatment is preferably within ±0.03 MPa of the saturated vapor pressure corresponding to the temperature of the constant temperature treatment.

6. The temperature-reducing treatment includes at least one temperature-reducing stage, and the temperature-reducing rate of each of the temperature-reducing stages is in the range of 1 to 6 ° C. / min; 2. The method for sterilizing packaged foods according to claim 1, wherein the temperature decreasing rate in the earlier temperature decreasing step is preferably higher than the temperature decreasing rate in the later temperature decreasing step with time.

7. The head space volume ratio of the packaged food is 5% or more, Preferably, the headspace volume percentage of the packaged food is between 20% and 60%, The method for sterilizing packaged food according to claim 1, wherein the volume percentage of solid matter in the packaged food is preferably 30% to 80%, and the volume percentage of juice is less than 10%.

8. The oxygen permeability of the outer packaging material of the packaged food is 0.5 cm ３ / (m ２ 24h-0.1MPa), and preferably the oxygen permeability of the outer packaging material of the packaged food is less than 0.1 cm ３ / (m ２ ・24h・0.1MPa) or less, The method for sterilizing packaged foods according to claim 1, characterized in that the outer packaging material preferably contains at least one of polyvinylidene chloride, ethylene-vinyl alcohol copolymer, nitrile resin, polyvinyl alcohol, polyethylene naphthalate, polyethylene terephthalate, polybutylene terephthalate, polyarylate, or polyamide.

9. Specifically, the method includes the steps of placing raw food ingredients in a packaging container made of an outer packaging material, evacuating the packaging container, filling the packaging container with a protective gas, and sealing the packaging container in order to obtain the packaged food, and then sterilizing the packaged food. Preferably, the raw food ingredients include at least one of corn, beef, oats, chickpeas, quinoa, and chicken breast, Preferably, the internal pressure of the packaging container after evacuation is −0.1 MPa or less, Preferably, the protective gas comprises at least one of nitrogen gas, carbon dioxide and an inert gas; A method for sterilizing packaged food according to claim 1, characterized in that the purity of the protective gas is preferably greater than or equal to 99.99%, preferably greater than or equal to 99.999%.

10. A packaged food obtained by sterilization using the method for sterilizing a packaged food according to claim 1.

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