Packaged food and its sterilization method

Abstract

The present invention provides a packaged food and a sterilization method thereof, belonging to the technical field of packaged food processing. The packaged food sterilization method includes the steps of sterilizing the sealed packaged food; the outer packaging material of the packaged food is a deformable packaging material, and the packaged food has a top gap; the sterilization treatment includes: successively performing a heating treatment, a constant temperature treatment, and a cooling treatment; wherein, the temperature and pressure of the heating treatment gradually increase over time and become constant; in the constant temperature treatment, the temperature remains unchanged, and the pressure gradually increases over time to a predetermined value; and the temperature and pressure of the cooling treatment gradually decrease over time. The packaged food and the sterilization method thereof provided by the present invention can effectively sterilize the packaged food, while ensuring that the appearance and taste of the contents of the packaged food are good, and the packaging of the packaged food does not deform.

Description

Technical Field

[0001] The present invention relates to the technical field of packaged food processing, in particular to a packaged food and a sterilization method thereof. Background Art

[0002] In recent years, with increasing public demand for packaged foods, consumers are increasingly interested in the types and forms of packaged foods. Legumes and grains packaged in traditional iron cans are often used as porridge or side dishes. These foods contain large amounts of water, salt, and sugar, which compromise their natural flavor. Glass jars, on the other hand, are heavy, fragile, and inconvenient to carry, making them unsuitable for today's consumers.

[0003] As consumer demand shifts toward healthy, light meals, a wide variety of packaged foods, such as chicken breast and corn, are emerging. These packaged foods are mostly vacuum- or nitrogen-filled, with simple contents. Consumers often add additional ingredients to enhance the taste.

[0004] Convenience box packaging is a common method for nitrogen-filled flexible packaging. Specifically, bagged ingredients and toppings are placed inside the box. Consumers unpack the bags and mix them in the box before consuming, achieving a balanced nutritional profile and enhancing the taste. However, when food is unpacked and mixed, the box can become contaminated, posing a health hazard. Furthermore, the bagged ingredients and toppings are easily impacted and wrinkled within the box, causing the packaging to break and leak, leading to product spoilage.

[0005] Some packaged foods are packaged in bags, but consumers report that these are inconvenient to consume. While most bagged foods come with a spoon, the bagged format makes scooping difficult and often results in the spoon falling during distribution.

[0006] The current trend is to package food in lightweight cup-shaped or can-shaped containers. For example, ingredients are placed inside the cup-shaped container, and topping packets are attached to the outside of the cup. When ready to eat, the packets are opened and the toppings are poured into the container to mix with the ingredients. Because space must be reserved within the container to accommodate the toppings, the packaged food requires a large headroom.

[0007] However, the headspace of currently packaged foods is relatively small, typically less than 5%, which does not meet the demand for a larger headspace. If the headspace ratio of packaged foods were simply increased based on existing packaging formats, the packaged foods would be easily affected during the sterilization process, causing the outer packaging to deform, severely limiting their commercial application. Summary of the Invention

[0008] Technical problems solved by the present invention:

[0009] In the light food sector, dairy products offer the best benefits for consumer health and convenience. For example, yogurt can be stored in a cup-shaped container, with other ingredients placed on the lid. When ready to eat, simply pour the ingredients into the cup and mix. However, yogurt is sterilized and cold-filled, while most packaged foods made from solid foods require sterilization after filling, meaning the package must be sealed and sterilized.

[0010] The current difficulty lies in that when a larger headspace is required for packaged food, it is impossible to effectively sterilize the packaged food while ensuring that the appearance and taste of the contents of the packaged food are good and that the outer packaging of the packaged food, i.e., the packaging container, does not deform.

[0011] In particular, when the headspace volume of packaged food exceeds 5%, there are large voids within the container. After the container is sealed, it undergoes a high-temperature, high-pressure sterilization phase. During this sterilization phase, the temperature rise rate inside and outside the container differs significantly, making it difficult to balance the pressure. This can easily lead to outer packaging deformation during the sterilization process, such as localized dents and wrinkles in the cover film. Furthermore, some raw materials are sensitive to light and oxygen, placing higher demands on the outer packaging materials and sterilization processes.

[0012] Therefore, there is a need for a method that can effectively sterilize packaged food with a large headspace while ensuring that the outer packaging does not deform.

[0013] In response to at least some of the above-mentioned defects, the present invention provides a packaged food and a sterilization method thereof, which can effectively sterilize the packaged food while ensuring that the appearance and taste of the contents of the packaged food are good and the outer packaging of the packaged food is not deformed.

[0014] The technical solutions of the present invention are as follows:

[0015] 1. A method for sterilizing packaged food, comprising the steps of sterilizing the sealed packaged food;

[0016] The outer packaging material of the packaged food is a deformable packaging material, and the packaged food has a top gap;

[0017] The sterilization treatment includes: heating treatment, constant temperature treatment and cooling treatment in sequence;

[0018] Wherein, the temperature and pressure of the heating treatment are gradually increased over time and become constant;

[0019] During the constant temperature treatment, the temperature remains constant and the pressure gradually increases to a predetermined value over time;

[0020] The temperature and pressure of the cooling treatment are gradually reduced over time.

[0021] 2. The method for sterilizing packaged food as described in Article 1,

[0022] The temperature and pressure of the temperature-raising treatment are increased in stages over time; and / or

[0023] The pressure of the constant temperature treatment is increased in stages over time; and / or

[0024] The temperature and pressure of the cooling treatment are reduced in stages over time.

[0025] 3. The method for sterilizing packaged food according to item 1, wherein the temperature of the temperature-raising treatment is raised from the initial temperature to the sterilization temperature, and the pressure is raised from the initial pressure to the sterilization pressure;

[0026] Wherein, the sterilization temperature is 60-130°C, and the sterilization pressure is 0-0.3MPa.

[0027] 4. The packaged food sterilization method according to any one of items 1 to 3, wherein the temperature rise treatment comprises at least one temperature rise stage, and the temperature rise rate of each temperature rise stage is between 0.5°C and 1.7°C / min;

[0028] Preferably, as time changes, the heating rate of the latter heating stage is lower than the heating rate of the former heating stage.

[0029] 5. The method for sterilizing packaged food according to any one of items 1 to 4, wherein the constant temperature treatment comprises at least one constant temperature stage, the temperature of each constant temperature stage is controlled and maintained constant between 60°C and 130°C, and the pressure of each constant temperature stage increases over time at a rate of increase between 0.002 MPa / min and 0.008 MPa / min;

[0030] Preferably, as time changes, the pressure increase rate in the latter constant temperature stage is lower than the pressure increase rate in the former constant temperature stage;

[0031] Preferably, the endpoint pressure of the constant temperature treatment is the saturated vapor pressure corresponding to the temperature of the constant temperature treatment ±0.03 MPa.

[0032] 6. The packaged food sterilization method according to any one of items 1 to 5, wherein the cooling treatment comprises at least one cooling stage, and the cooling rate of each cooling stage is between 1-6°C / min;

[0033] Preferably, as time changes, the cooling rate of the first cooling stage is higher than the cooling rate of the second cooling stage.

[0034] 7. The packaged food sterilization method according to any one of items 1 to 6, wherein the headspace volume of the packaged food accounts for greater than or equal to 5%;

[0035] Preferably, the headspace volume of the packaged food accounts for 20%-60%;

[0036] Preferably, the solid volume proportion of the packaged food is 30%-80%, and the soup volume proportion is less than 10%.

[0037] 8. The method for sterilizing packaged food according to any one of items 1 to 7, wherein the oxygen permeability of the outer packaging material of the packaged food is less than 0.5 cm 3 / (m 2 ·24h·0.1MPa); preferably, the oxygen permeability of the outer packaging material of the packaged food is <0.1cm 3 / (m 2 ·24h·0.1MPa);

[0038] 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 or polyamide.

[0039] 9. The packaged food sterilization method according to any one of items 1 to 8, wherein the method specifically comprises the following steps: placing the raw food ingredients into a packaging container formed of an outer packaging material, sequentially evacuating the packaging container, filling it with a protective gas, and sealing it to obtain the packaged food, and then sterilizing the packaged food;

[0040] Preferably, the raw material includes at least one of corn, beef, oats, chickpeas, quinoa and chicken breast;

[0041] Preferably, the internal pressure of the vacuum packaging container is not higher than -0.1 MPa;

[0042] Preferably, the protective gas comprises at least one of nitrogen, carbon dioxide and an inert gas;

[0043] Preferably, the purity of the protective gas is not less than 99.99%, preferably not less than 99.999%.

[0044] 10. A packaged food obtained by sterilizing the packaged food according to any one of items 1 to 9.

[0045] The present invention has at least the following beneficial effects:

[0046] The method for sterilizing packaged food provided by the present invention can achieve effective sterilization by performing a temperature increase treatment, a constant temperature treatment, and a temperature decrease treatment in stages, while avoiding damage to the outer packaging of the packaged food caused by sudden changes in temperature and pressure during sterilization. When the sterilization method provided by the present invention is adopted, even if the packaged food has a large headspace, deformation of the outer packaging will not occur during the sterilization process, and the appearance and taste of the contents of the packaged food can be ensured to be good. Therefore, the present invention provides a sterilization method that can achieve effective sterilization of packaged food with a large headspace while ensuring that the outer packaging does not deform, which is conducive to the large-scale commercial application of the sterilized packaged food. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0048] Figure 1 The packaged food after sterilization in Examples 1, 5, and 6 of the present invention is shown, wherein 1a and 1b are outer appearance drawings of the outer packaging, and 1c and 1d are outer appearance drawings of the contents;

[0049] Figure 2 2a and 2b are diagrams comparing the packaged food after sterilization in Comparative Example 1 of the present invention and the packaged food after sterilization in Example 1, wherein 2a and 2b are diagrams of the outer packaging of Example 1 and Comparative Example 1, respectively, and 2c and 2d are diagrams of the outer packaging of Example 1 and Comparative Example 1, respectively;

[0050] Figure 3 3a and 3b are diagrams comparing the packaged food after sterilization in Comparative Example 2 of the present invention and the packaged food after sterilization in Example 1, wherein 3a and 3b are diagrams of the outer appearance of the contents of Example 1 and Comparative Example 1, respectively;

[0051] Figure 4 4a-4d are the appearance diagrams of the packaged food after sterilization in Comparative Example 3 of the present invention, wherein 4a-4d are the appearance diagrams of the outer packaging of Comparative Example 3 at different angles. DETAILED DESCRIPTION

[0052] It should be understood that the specific embodiments given herein are for the purpose of explaining to those skilled in the art and are merely illustrative rather than restrictive.

[0053] In the following description, many specific details are set forth to provide a thorough understanding of the present invention. However, it will be apparent to one of ordinary skill in the art that it is not necessary to employ these specific details to practice the present invention. In other cases, well-known steps or operations are not described in detail to avoid obscuring the present invention.

[0054] It should be noted that in this article, the meanings of relevant terms are as follows:

[0055] The term "packaged food" refers to food formed by putting raw ingredients into a packaging container and sealing it. The packaging container can be in the shape of a cylinder, cup, can, or the shape of a can commonly found on the market. In this article, the packaging container is also called the outer packaging.

[0056] The term "deformable packaging material" refers to a material with a certain degree of deformation ability, which will deform under the action of an external force, but the form of deformation is not rigid crushing, wrinkling or fragmentation. For example, the deformable packaging material can be a rigid material such as tinplate, a flexible material or other non-rigid material.

[0057] The term "contents" refers to the raw materials and ingredients stored in the packaging container.

[0058] The term "headspace volume" refers to the volume of the empty space within a sealed packaging container, excluding the space occupied by the ingredients. The term "headspace volume ratio" refers to the ratio of the headspace volume to the internal volume of the packaging container.

[0059] The term "solids" refers to the solid edible substances in the raw materials and ingredients placed in the packaging container. The term "solids by volume" refers to the ratio of the solids volume in the packaging container to the internal volume of the packaging container.

[0060] The term "broth" refers to the liquid edible substance in the raw ingredients placed in the packaging container. The term "broth volume ratio" refers to the ratio of the volume of the broth in the packaging container to the internal volume of the packaging container.

[0061] The term "vacuuming" refers to the process of evacuating the interior of a packaging container using a vacuum extractor or other equipment, creating a near-vacuum environment. Furthermore, the internal pressure of a packaged food after evacuation refers to the gauge pressure (relative pressure) within the packaging container.

[0062] The term "inert gas" refers to helium, neon, argon, krypton, xenon, radon, and austenite, also known as rare gases.

[0063] The term "spray sterilizer" refers to a sterilization device that uses hot water as a heating medium and has a rotating function. During sterilization, the hot water is sprayed or injected onto the packaged food, so that the raw materials inside the packaging container are quickly and evenly heated, thereby performing high-temperature sterilization.

[0064] The term "spray water bath dual-purpose sterilizer" refers to a sterilization equipment that uses hot water as the heating medium and can freely switch between water bath heating and spray heating and has a rotating function.

[0065] The term "high-barrier plastic cup" refers to a plastic cup-shaped packaging container (hereinafter referred to as the cup) formed of a high-barrier material, wherein the high-barrier material has strong gas and moisture barrier properties and mainly plays the role of isolating oxygen.

[0066] The term "high-barrier film" refers to a multi-layer film made by simultaneously extruding a material with strong gas barrier properties and a polyolefin with strong heat-sealing and moisture barrier properties. It has the characteristics of low gas and moisture permeability, strong barrier properties and chemical resistance.

[0067] The term "aluminum-plastic high-barrier film" refers to a high-barrier film with added aluminum foil. By adding aluminum foil, the hardness of the packaging container after packaging can be enhanced, making it less likely to deform.

[0068] Unless otherwise specified, the pressure in this article refers to relative pressure, also known as gauge pressure.

[0069] The present invention will be described in detail below.

[0070] An embodiment of the present invention provides a method for sterilizing packaged food, comprising the steps of sterilizing the sealed packaged food; the outer packaging material of the packaged food is a deformable packaging material, so that the outer packaging of the packaged food has a certain deformation ability and is not easy to break, and the packaged food has a top gap; the sterilization treatment comprises: performing a heating treatment, a constant temperature treatment and a cooling treatment in sequence; wherein the temperature and pressure of the heating treatment gradually increase over time and become constant; during the constant temperature treatment process, the temperature remains unchanged and the pressure gradually increases over time to a predetermined value; and the temperature and pressure of the cooling treatment gradually decrease over time.

[0071] According to the packaged food sterilization method provided by an embodiment of the present invention, the sterilization process includes temperature rising treatment, constant temperature treatment and temperature cooling treatment. Specifically, first, in the temperature rising treatment process, the temperature and pressure are controlled to gradually rise, wherein the temperature and pressure settings are independent of each other, that is, the temperature and pressure are only related to time respectively; then, in the constant temperature treatment process, the temperature is controlled to remain unchanged while the pressure continues to rise, thereby maintaining constant temperature sterilization under high temperature and high pressure conditions; finally, in the temperature cooling treatment process, the temperature and pressure are controlled to gradually decrease over time to complete the sterilization operation, wherein the temperature and pressure settings are independent of each other, that is, the temperature and pressure are only related to time respectively. This can not only effectively sterilize, but also avoid damage to the outer packaging of the packaged food due to sudden changes in temperature and pressure.

[0072] In particular, due to the staged selection and trade-offs of the sterilization treatment, the packaged food sterilization method of the embodiment of the present invention can effectively sterilize packaged food with a larger top gap than that of general packaged food and an outer packaging material that is a deformable packaging material, while ensuring that the appearance and taste of the contents of the packaged food are good and the outer packaging of the packaged food is not deformed.

[0073] In some optional embodiments, the temperature and pressure of the heating treatment are increased in stages over time; and / or the pressure of the constant temperature treatment is increased in stages over time; and / or the temperature and pressure of the cooling treatment are decreased in stages over time. By regulating the sterilization temperature and pressure in stages, effective sterilization can be achieved while also effectively protecting the outer packaging and contents of the packaged food.

[0074] In some optional embodiments, the temperature of the heating treatment is increased from the initial temperature to the sterilization temperature, and the pressure is increased from the initial pressure to the sterilization pressure; wherein the sterilization temperature is 60-130°C, and the sterilization pressure is 0-0.3 MPa. For example, the sterilization temperature can 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 between 60-130°C; the sterilization pressure can be 0 MPa, 0.01 MPa, 0.05 MPa, 0.1 MPa, 0.15 MPa, 0.2 MPa, 0.25 MPa, 0.3 MPa, or any value between 0-0.3 MPa. Within the sterilization temperature and sterilization pressure range of this embodiment, packaged food can be effectively sterilized to ensure that the packaged food meets commercial sterility requirements. Moreover, by controlling the pressure and temperature separately, the high temperature and high pressure conditions of the sterilization process will not damage the outer packaging of the packaged food.

[0075] In some optional embodiments, the temperature rising treatment includes at least one temperature rising stage, and the temperature rising rate of each temperature rising stage is between 0.5-1.7°C / min. For example, the temperature rising rate can 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 between 0.5-1.7°C / min.

[0076] In some optional embodiments, the temperature rise treatment includes a temperature rise stage, namely a first temperature rise stage, in which the temperature in the first temperature rise stage is increased from the initial temperature to the sterilization temperature of 60-130°C required for the packaged food, and the pressure is increased from the initial pressure to the sterilization pressure of 0-0.3 MPa required for the packaged food. The initial temperature and initial pressure refer to the temperature and pressure of the raw food before the sterilization treatment. For example, when the initial temperature is 25°C, the temperature in the first temperature rise stage is increased from 25°C to 60-130°C, and when the initial pressure is -0.1 MPa, the pressure in the first temperature rise stage is increased from -0.1 MPa to 0-0.3 MPa.

[0077] In some optional embodiments, the temperature rising process includes two temperature rising stages, namely a first temperature rising stage and a second temperature rising stage.

[0078] The temperature and pressure in the first heating stage are lower than those in the second heating stage, and the temperature is raised to a constant level at the end of the second heating stage to facilitate constant temperature treatment. Specifically, the temperature in the first heating stage is raised from the initial temperature to 105°C, and the pressure is raised from the initial pressure to 0.11 MPa. The temperature in the second heating stage is 105-121°C, and the pressure is 0.11-0.185 MPa.

[0079] In some optional embodiments, the temperature rising process includes three temperature rising stages, namely a first temperature rising stage, a second temperature rising stage and a third temperature rising stage.

[0080] The temperature and pressure in the first, second, and third heating stages are increased sequentially, and the temperature is raised to a constant value at the end of the third heating stage to facilitate constant temperature 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 0.025 MPa. The temperature in the second heating stage is 70-95°C, and the pressure is 0.025-0.065 MPa. The temperature in the third heating stage is 95-116°C, and the pressure is 0.065-0.17 MPa.

[0081] In some optional embodiments, the temperature rising process includes four temperature rising stages, namely a first temperature rising stage, a second temperature rising stage, a third temperature rising stage and a fourth temperature rising stage.

[0082] The temperature and pressure of the first, second, third and fourth heating stages are increased in sequence, and the temperature is raised to a constant value at the end of the fourth heating stage to facilitate constant temperature treatment. Specifically, the temperature of the first heating stage is increased from the initial temperature to 60°C, and the pressure is increased from the initial pressure to 0.02 MPa, the temperature of the second heating stage is 60-90°C, and the pressure is 0.02-0.06 MPa, the temperature of the third heating stage is 90-105°C, and the pressure is 0.06-0.11 MPa, and the temperature of the fourth heating stage is 105-125°C, and the pressure is 0.11-0.19 MPa.

[0083] It can be understood that in other optional embodiments, the temperature rising process may further include more temperature rising stages, such as five, six, or seven temperature rising stages.

[0084] In some optional embodiments, the heating rate of the subsequent heating stage is lower than the heating rate of the previous heating stage over time. By controlling the heating rate to gradually decrease, it is possible to avoid the problem of outer packaging deformation caused by excessive temperature changes after heating to a higher temperature.

[0085] In some optional embodiments, the constant temperature treatment includes at least one constant temperature stage, the temperature of each constant temperature stage is controlled and maintained constant between 60-130° C., the pressure of each constant temperature stage increases over time, and the pressure increase rate is between 0.002-0.008 MPa / min. For example, the pressure increase rate can 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 between 0.002-0.008 MPa / min.

[0086] In some optional embodiments, the endpoint pressure (predetermined value) of the constant temperature treatment is the saturated vapor pressure corresponding to the constant temperature treatment temperature ± 0.03 MPa. Within the temperature and pressure range of the constant temperature treatment provided in this embodiment, effective sterilization can be achieved without damaging the outer packaging of the packaged food.

[0087] In some optional embodiments, the isothermal treatment includes a first isothermal treatment stage, wherein the temperature in the first isothermal treatment stage is kept constant while the pressure is continuously increased over time. Specifically, the temperature in the first isothermal treatment stage is 116° C., the treatment lasts for 25 minutes, and the pressure is increased from 0.17 MPa to 0.21 MPa.

[0088] In some optional embodiments, the isothermal treatment includes two isothermal stages: a first isothermal stage and a second isothermal stage. The temperatures in the first and second isothermal stages are the same and remain constant, while the pressure increases continuously over time. Specifically, the first isothermal stage is at a temperature of 116°C for 8 minutes, with the pressure increasing from 0.17 MPa to 0.195 MPa. The second isothermal stage is at a temperature of 116°C for 12 minutes, with the pressure increasing from 0.195 MPa to 0.205 MPa.

[0089] In some optional embodiments, the constant temperature treatment includes three constant temperature stages, namely a first constant temperature stage, a second constant temperature stage, and a third constant temperature stage. The temperatures in the first constant temperature stage, the second constant temperature stage, and the third constant temperature stage are the same and remain constant, while the pressure increases continuously over time. Specifically, the temperature in the first constant temperature stage is 116°C, the time is 4 minutes, and the pressure increases from 0.17 MPa to 0.185 MPa; the temperature in the second constant temperature stage is 116°C, the time is 6 minutes, and the pressure increases from 0.185 MPa to 0.195 MPa; the temperature in the third constant temperature stage is 116°C, the time is 8 minutes, and the pressure increases from 0.195 MPa to 0.205 MPa.

[0090] In some optional embodiments, the pressure increase rate during the subsequent constant temperature phase is lower than the pressure increase rate during the previous constant temperature phase over time. As pressure increases, the likelihood of outer packaging deformation increases. In this embodiment, by gradually reducing the pressure increase rate, deformation of the outer packaging caused by excessive pressure changes can be effectively avoided.

[0091] It can be understood that in other optional embodiments, the constant temperature treatment can also include more constant temperature stages, such as four, five, six, seven constant temperature stages, etc.

[0092] In some optional embodiments, the cooling treatment includes at least one cooling stage, and the cooling rate of each cooling stage is between 1-6°C / min, for example, 1, 2, 3, 4, 5, 6°C / min.

[0093] In some optional embodiments, the cooling treatment includes a cooling stage, namely the first cooling stage, the temperature of the first cooling stage is reduced from the temperature of the constant temperature treatment to 20°C, and the pressure is reduced from the end pressure of the constant temperature treatment to 0.015-0.005MPa.

[0094] In some optional embodiments, the cooling treatment includes two cooling stages, namely a first cooling stage and a second cooling stage. The temperature in the first cooling stage is reduced from the constant temperature treatment temperature to 60-40°C, and the end pressure of the first cooling stage is 0.05-0.03MPa; the end temperature of the second cooling stage is 30-20°C, and the end pressure is 0.02-0.01MPa.

[0095] In some optional embodiments, the cooling treatment includes three cooling stages, namely the first cooling stage, the second cooling stage and the third cooling stage. The temperature in the first cooling stage is reduced from the constant temperature treatment temperature to 60°C, and the terminal pressure of the first cooling stage is 0.05-0.04MPa; the temperature in the second cooling stage is 60-40°C, and the pressure is 0.04-0.025MPa; the temperature in the third cooling stage is 40-20°C, and the pressure is 0.025-0.01MPa.

[0096] It is understandable that in other optional embodiments, the cooling process may further include more cooling stages, such as four, five, six, seven cooling stages, etc.

[0097] In some optional embodiments, the cooling rate in the first cooling stage is higher than the cooling rate in the second cooling stage over time. In this embodiment, a higher cooling rate is used in the cooling stage with a higher temperature, which facilitates rapid cooling, thereby minimizing the impact of high temperature on the outer packaging and avoiding deformation of the outer packaging.

[0098] From the constant temperature treatment process to the cooling treatment process, the packaged food does not experience huge environmental differences due to the changes in temperature and pressure as well as the staged selection; and the process selection of heating treatment, constant temperature treatment and cooling treatment all takes into special consideration the top gap ratio and the matching of common deformable outer packaging materials, thereby achieving multiple effects such as effective sterilization, preservation of food color and sensory properties, and non-deformation.

[0099] In some optional embodiments, the temperature and pressure of the sterilization process are linearly related to time, and the temperature and pressure are independent of each other. That is, the sterilization temperature first increases, then remains constant, and then decreases over time, while the sterilization pressure first increases, then decreases over time, and the corresponding relationship between temperature and pressure during the heating process is different from the corresponding relationship between temperature and pressure during the cooling process.

[0100] For example, during the heating treatment process, when the temperature rises to 85°C and the pressure is 0.1MPa, then during the cooling treatment process, when the temperature drops to 85°C, the pressure is 0.8MPa, 0.9MPa, 0.11MPa, etc., except 0.1MPa; for another example, during the heating treatment process, when the temperature rises to 100°C and the pressure is 0.18MPa, then during the cooling treatment process, when the temperature drops to 100°C, the pressure is 0.16MPa, 0.17MPa, 0.19MPa, etc., except 0.18MPa.

[0101] In this embodiment, multi-stage sterilization is employed, with temperature and pressure set in parallel with time. Specifically, the sterilization process requires that temperature and pressure are independent of each other, but rather linearly correlated with time. Furthermore, the pressure can be varied over time within the constant temperature sterilization stage. By gradually reducing the sterilization temperature and pressure, effective sterilization is achieved while also effectively protecting the sensory properties of the packaged food packaging and contents.

[0102] In some optional embodiments, the headspace volume of the packaged food is greater than or equal to 5%, preferably between 20% and 60%. In prior art, the headspace volume of packaged food is generally less than 5%. If the headspace is too large, the temperature rise rate inside and outside the packaging container will differ significantly during the sterilization process, making it difficult to balance the pressure and easily causing the outer packaging to deform. However, in this embodiment, the volume of the contents of the packaging container is much smaller than the volume of the packaging container. In particular, when the headspace volume accounts for 20% to 60%, the outer packaging will not deform during the sterilization process.

[0103] For example, in this embodiment, the headspace volume proportion of the packaged food can be 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 99.9% or any value between 5% and 100% (excluding 100%).

[0104] In some optional embodiments, the solids volume percentage of the packaged food is 30%-80%, and the broth volume percentage is less than 10%. In this embodiment, the packaged food has a high solids content and can be sterilized without adding broth or with a small amount of broth. This method is particularly suitable for processing various solid meat and vegetable fresh ingredients used as packaged food ingredients.

[0105] For example, the solid volume percentage of the packaged food can be 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80% or any value between 40% and 80%; the soup volume percentage can be 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or any value between 0-10%.

[0106] In some optional embodiments, the oxygen transmission rate of the outer packaging material of the packaged food is less than 0.5 cm 3 / (m 2 ·24h·0.1MPa), preferably oxygen permeability <0.1cm 3 / (m 2 ·24h·0.1MPa). The “oxygen permeability” refers to the amount of oxygen that passes through an area of 1m2 within 24 hours under the condition of an oxygen pressure of 0.1MPa. 2In this embodiment, a high barrier material with extremely low oxygen permeability is used for packaging, which can effectively isolate oxygen and other gases and moisture, preventing oxygen from penetrating into the packaged food and causing damage to the raw materials.

[0107] Preferably, the outer packaging material includes 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 effectively shields the food from light and air, preventing oxidation of the contents during the sterilization process. This helps reduce nutritional loss and maintains the freshness of the packaged food.

[0108] In some optional embodiments, the sterilization method specifically includes the following steps: loading the raw food into a packaging container formed by an outer packaging material, vacuuming the packaging container, filling it with protective gas, and sealing it to obtain packaged food, and then sterilizing the packaged food. In this embodiment, the temperature of the raw food before loading can be low temperature, room temperature (25°C), high temperature (>60°C), or frozen raw materials can be directly loaded. The packaged food can be packaged in a modified atmosphere packaging method, for example, the air in the packaging container after loading is vacuumed by a modified atmosphere fresh-keeping packaging machine, and then filled with protective gas to effectively preserve the packaged raw food, and then sealed. By vacuuming and then filling it with protective gas, the oxygen content in the packaged food can be reduced, thereby avoiding the problem of oxidation and deterioration of the raw food. Moreover, when the outer packaging material in the above embodiment is used, the modified atmosphere packaging method in this embodiment is also used, which can further reduce the impact of oxygen on the food, and is particularly suitable for the packaging and sterilization of low-acid packaged foods.

[0109] In some optional embodiments, the raw material includes at least one of corn, beef, oats, chickpeas, quinoa, and chicken breast. When the sterilization method of this embodiment is used to sterilize the above raw materials, the raw materials can maintain good color and quality, which is conducive to ensuring the quality of the packaged food.

[0110] In some optional embodiments, the internal pressure of the packaging container after vacuuming is no higher than -0.1 MPa; this is beneficial to ensure that the air inside the packaged food is exhausted as much as possible, and is also beneficial to fill the packaged food with a sufficient amount of protective gas.

[0111] In some optional embodiments, the protective gas includes at least one of nitrogen, carbon dioxide, and an inert gas. Because nitrogen, carbon dioxide, and / or inert gases are stable and do not react with the raw materials and food ingredients within the packaging container, replacing the existing air within the packaging container with nitrogen, carbon dioxide, and / or inert gas can prevent the reaction of oxygen in the existing air with the raw materials and food ingredients, thereby preventing damage to the raw materials and food ingredients.

[0112] In some optional embodiments, the purity of the protective gas (by volume fraction) is not less than 99.99%, preferably not less than 99.999%. In this case, the addition of the protective gas can minimize the amount of residual oxygen in the packaged food, thereby preventing the reaction of oxygen with the raw materials and causing the packaged food to deteriorate.

[0113] In some optional embodiments, the retort includes a spray retort or a dual-purpose spray-water bath retort, both of which may have a rotation function. Both the spray and water bath sterilization methods can use high-temperature, high-pressure hot water as the heating medium to sterilize sealed, packaged foods. When using the spray sterilization method, the hot water is sprayed or jetted onto the outer packaging of the packaged food at high speed, allowing the contents of the packaged food to be quickly and evenly heated. When using the water bath sterilization method, the entire packaged food is immersed in the hot water, which also allows for more uniform heat distribution. Furthermore, the retort's rotation function further ensures uniform heating of the package. Thus, using these sterilization methods can significantly shorten the heating time, allowing for high-temperature, short-term sterilization or disinfection. This allows the contents of the packaged food to maintain excellent color and quality, thus ensuring the quality of the packaged food.

[0114] Another embodiment of the present invention provides a packaged food obtained by sterilizing the packaged food sterilization method according to the above embodiment.

[0115] In order to make the purpose, technical solutions and beneficial effects of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments. However, the specific embodiments described are only used to explain the present invention and are not intended to limit the present invention.

[0116] Example 1

[0117] A method for sterilizing fresh corn kernel cups is provided, and the specific steps are as follows:

[0118] 1.Ingredients: quick-frozen corn kernels.

[0119] 2. Outer packaging materials: high barrier plastic cups and aluminum-plastic high barrier films. The oxygen transmission rate of the cups and aluminum-plastic high barrier films is less than 0.1cm 3 / (m 2 ·24h·0.1MPa).

[0120] 3. Raw material charging: The volume of the quick-frozen corn kernels charged is 40% of the volume of the cup. No soup is added. The charging temperature is less than -10°C. After charging, vacuum the cup to a pressure of -0.1 MPa. Then, fill the cup with 99.999% pure nitrogen until the cover film is slightly concave after sealing.

[0121] 4. Sterilization: Use spray water bath dual-purpose sterilizer

[0122] 4.1. Heating treatment:

[0123] The first heating stage: select a water bath to heat the sealed cup, the water bath temperature is 70 ° C, keep warm for 30 minutes, and the pressure in the autoclave is increased from 0.008 MPa to 0.025 MPa;

[0124] Then recycle the hot water in the lower tank and switch to spray sterilization;

[0125] Second heating stage: set the temperature from 70℃ to 95℃, the time is 20min, and the pressure in the autoclave increases from 0.025MPa to 0.065MPa;

[0126] The third heating stage: set the temperature from 95 ° C to 116 ° C, the time is 25 minutes, and the pressure in the sterilizer is increased from 0.065 MPa to 0.17 MPa.

[0127] 4.2. Constant temperature treatment: Set the temperature to 116℃ for 25 minutes, and increase the pressure in the autoclave from 0.17MPa to 0.21MPa.

[0128] 4.3. Cooling treatment:

[0129] The first cooling stage: the temperature is set to drop from 116°C to 40°C for 20 minutes, and the pressure in the autoclave is reduced from 0.021MPa to 0.03MPa;

[0130] The second cooling stage: set the temperature from 40℃ to 25℃, the time is 15min, and the pressure in the sterilizer is reduced from 0.03MPa to 0.01MPa.

[0131] 5. Sterilization results: refer to Figure 1 As shown, after the sterilization steps above are completed, the high-barrier plastic cup is torn open and it is found that the corn kernels are bright in color and have a crisp and sweet taste; the cup body is intact and the cover film is slightly bulging; the product meets the commercial sterility requirements.

[0132] Example 2

[0133] A method for sterilizing an instant beef granules and oatmeal mixed cup is provided, and the specific steps are as follows:

[0134] 1. Product ingredients: small pieces of raw marinated beef and soaked pre-cooked oatmeal.

[0135] 2. Outer packaging materials: high barrier plastic cup and transparent easy-to-tear high barrier film. The oxygen transmission rate of the cup and high barrier film is <0.5cm 3 / (m 2 ·24h·0.1MPa).

[0136] 3. Raw material loading: The volume of the raw marinated small pieces of beef and soaked pre-cooked oatmeal should be 60% of the volume of the cup. No soup should be added. The loading temperature should be less than 5-10℃. After loading, vacuum the cup to a pressure of -0.1MPa. Then, fill the cup with 99.99% pure nitrogen until the cover film is slightly concave after sealing.

[0137] 4. Sterilization: Use spray sterilizer

[0138] 4.1. Heating treatment:

[0139] The first heating stage: the temperature is set to rise from room temperature to 105 ° C, the time is 30 minutes, and the pressure in the autoclave is increased from 0.003 MPa to 0.11 MPa;

[0140] The second heating stage: the temperature is set from 105 ° C to 121 ° C, the time is 10 min, and the pressure in the sterilizer is increased from 0.11 MPa to 0.185 MPa.

[0141] 4.2. Constant temperature treatment: Set the temperature to 121℃ for 20 minutes, and increase the pressure in the autoclave from 0.185MPa to 0.23MPa.

[0142] 4.3. Cooling treatment:

[0143] The first cooling stage: the temperature is set to drop from 121°C to 60°C for 15 minutes, and the pressure in the autoclave is reduced from 0.23MPa to 0.04MPa;

[0144] Second cooling stage: set the temperature to drop from 60℃ to 40℃ for 10 minutes, and the pressure in the autoclave drops from 0.04MPa to 0.025MPa;

[0145] The third cooling stage: set the temperature from 40℃ to 25℃, the time is 10min, and the pressure in the sterilizer is reduced from 0.025MPa to 0.01MPa.

[0146] 5. Sterilization results: After the sterilization steps above were completed, the high-barrier plastic cup was torn open and it was found that the beef cubes were well cooked, the oatmeal grains were intact and elastic when chewed; the cup body was intact and the cover film was flat; the product met the requirements of commercial sterility.

[0147] Example 3

[0148] Provided is a method for sterilizing instant chickpea quinoa cups, the specific steps being as follows:

[0149] 1. Ingredients: soak and precook chickpeas and precook quinoa.

[0150] 2. Outer packaging materials: high barrier plastic cup and transparent easy-to-tear high barrier film. The oxygen transmission rate of the cup and high barrier film is <0.5cm 3 / (m 2 ·24h·0.1MPa).

[0151] 3. Raw material charging: The volume of soaked pre-cooked chickpeas and pre-cooked quinoa charged is 70% of the volume of the cup, and the volume of added soup is 10% of the volume of the cup. The charging temperature is 70-80°C. After charging, vacuum the cup to a pressure of -0.1MPa. Then, fill the cup with 99.99% pure nitrogen until the film is sealed and the cover film is slightly inflated.

[0152] 4. Sterilization: Use spray sterilizer

[0153] 4.1. Heating treatment:

[0154] The first heating stage: set the temperature from 70℃ to 121℃, the time is 25min, and the pressure in the sterilizer increases from 0.003MPa to 0.19MPa.

[0155] 4.2. Constant temperature treatment: Set the temperature to 121℃ for 20 minutes, and increase the pressure in the autoclave from 0.19MPa to 0.23MPa.

[0156] 4.3. Cooling treatment:

[0157] The first cooling stage: the temperature is set to drop from 121°C to 60°C for 15 minutes, and the pressure in the autoclave is reduced from 0.23MPa to 0.04MPa;

[0158] Second cooling stage: set the temperature to drop from 60℃ to 40℃ for 10 minutes, and the pressure in the autoclave drops from 0.04MPa to 0.025MPa;

[0159] The third cooling stage: set the temperature from 40℃ to 20℃, the time is 10min, and the pressure in the sterilizer is reduced from 0.025MPa to 0.01MPa.

[0160] 5. Sterilization results: After the sterilization steps above were completed, the high-barrier plastic cup was torn open, revealing that the chickpea and quinoa were intact in appearance, had a non-powdery texture, and were highly palatable. The cup was intact, with a slightly concave cover film. The product met the requirements for commercial sterility.

[0161] Example 4

[0162] A method for sterilizing a ready-to-eat chicken breast and corn mixed cup is provided, and the specific steps are as follows:

[0163] 1. Product ingredients: a mixture of small pieces of raw marinated chicken breast and quick-frozen sweet corn kernels.

[0164] 2. Outer packaging materials: high barrier plastic cups and aluminum-plastic high barrier films. The oxygen transmission rate of the cups and aluminum-plastic high barrier films is less than 0.1cm 3 / (m 2 ·24h·0.1MPa).

[0165] 3. Raw material loading: The volume of the raw marinated chicken breast cubes and quick-frozen sweet corn kernels is 60% of the volume of the cup. No soup is added. The loading temperature is 0-5°C. After loading, vacuum the cup to a pressure of -0.1MPa. Then, fill the cup with 99.99% pure nitrogen until the cover film is slightly concave after sealing.

[0166] 4. Sterilization: Use spray water bath dual-purpose sterilizer

[0167] 4.1. Heating treatment:

[0168] The first heating stage: the sealed cup is heated in a water bath at 60°C for 40 minutes, and the pressure in the autoclave is increased from 0.008 MPa to 0.025 MPa.

[0169] Then recycle the hot water in the lower tank and switch to spray sterilization;

[0170] The second heating stage: the temperature is set to rise from 60°C to 90°C for 20 minutes, and the pressure in the autoclave is increased from 0.025MPa to 0.06MPa;

[0171] The third heating stage: the temperature is set to rise from 90℃ to 105℃, the time is 12min, and the pressure in the autoclave is increased from 0.06MPa to 0.11MPa;

[0172] The fourth heating stage: the temperature is set from 105 ° C to 125 ° C, the time is 12 min, and the pressure in the sterilizer is increased from 0.11 MPa to 0.19 MPa.

[0173] 4.2. Constant temperature treatment: Set the temperature to 125℃ for 5 minutes, and increase the pressure in the autoclave from 0.19MPa to 0.21MPa.

[0174] 4.3. Cooling treatment:

[0175] The first cooling stage: the temperature is set to drop from 125°C to 40°C for 20 minutes, and the pressure in the autoclave is reduced from 0.21MPa to 0.035MPa;

[0176] The second cooling stage: set the temperature from 40℃ to 25℃, the time is 15min, and the pressure in the sterilizer is reduced from 0.035MPa to 0.01MPa.

[0177] 5. Sterilization results: After the sterilization steps above were completed, the high-barrier plastic cup was torn open and it was found that the chicken pieces were well cooked, the corn kernels were intact and elastic when chewed; the cup body was intact and the cover film was flat; the product met the commercial sterility requirements.

[0178] Example 5

[0179] A method for sterilizing fresh corn kernel cups is provided, and the specific steps are as follows:

[0180] 1.Ingredients: quick-frozen corn kernels.

[0181] 2. Outer packaging materials: high barrier plastic cups and aluminum-plastic high barrier films. The oxygen transmission rate of the cups and aluminum-plastic high barrier films is less than 0.1cm 3 / (m 2 ·24h·0.1MPa).

[0182] 3. Raw material loading: The volume of the quick-frozen corn kernels loaded is 60% of the volume of the cup. No soup is added. The raw material temperature is less than -10°C. After loading, vacuum the cup until the internal pressure is -0.1MPa. Then fill the cup with 99.999% pure nitrogen until the cover film is slightly concave after sealing.

[0183] 4. Sterilization: Use spray sterilizer

[0184] 4.1. Heating treatment:

[0185] The first heating stage: the spray sterilizer is used to heat the sealed cups. The spray temperature is raised from 20°C to 116°C over a heating time of 80 minutes. The pressure in the sterilizer is raised from 0 to 0.17 MPa.

[0186] 4.2. Constant temperature treatment:

[0187] The first constant temperature stage: the temperature is set to maintain at 116 ° C for 8 minutes, and the pressure in the autoclave increases from 0.17 MPa to 0.195 MPa.

[0188] The second constant temperature stage: the temperature is set to maintain at 116 ° C for 12 minutes, and the pressure in the sterilizer increases from 0.195 MPa to 0.205 MPa.

[0189] 4.3. Cooling treatment:

[0190] The first cooling stage: the temperature is set to drop from 116°C to 20°C for 30 minutes, and the pressure in the autoclave is reduced from 0.205MPa to 0.015MPa;

[0191] 5. Sterilization results: refer to Figure 1 As shown, after the sterilization steps above are completed, the high-barrier plastic cup is torn open and it is found that the corn kernels are bright in color and have a crisp and sweet taste; the cup body is intact and the cover film is slightly bulging; the product meets the commercial sterility requirements.

[0192] Example 6

[0193] A method for sterilizing fresh corn kernel cups is provided, and the specific steps are as follows:

[0194] 1.Ingredients: quick-frozen corn kernels.

[0195] 2. Outer packaging materials: high barrier plastic cups and aluminum-plastic high barrier films. The oxygen transmission rate of the cups and aluminum-plastic high barrier films is less than 0.1cm 3 / (m 2 ·24h·0.1MPa).

[0196] 3. Raw material charging: The volume of the quick-frozen corn kernels charged is 40% of the volume of the cup. No soup is added. The charging temperature is less than -10°C. After charging, vacuum the cup to a pressure of -0.1 MPa. Then, fill the cup with 99.999% pure nitrogen until the cover film is slightly concave after sealing.

[0197] 4. Sterilization: Use spray sterilizer

[0198] 4.1. Heating treatment:

[0199] The first heating stage: a spray sterilizer with a rotating function is selected to heat the sealed cups. The spray temperature is 60°C, the temperature is kept for 25 minutes, and the pressure in the sterilizer is 0.02MPa.

[0200] The second heating stage: the temperature is set to rise from 60°C to 90°C for 20 minutes, and the pressure in the autoclave is increased from 0.02MPa to 0.06MPa;

[0201] The third heating stage: set the temperature from 90℃ to 105℃, the time is 10min, and the pressure in the sterilizer increases from 0.06MPa to 0.11MPa.

[0202] The fourth heating stage: the temperature is set to rise from 105°C to 116°C, the time is 8 minutes, and the pressure in the sterilizer is increased from 0.11MPa to 0.17MPa.

[0203] 4.2. Constant temperature treatment

[0204] The first constant temperature stage: the temperature is set to maintain at 116 ° C, the time is 4 minutes, and the pressure in the autoclave increases from 0.17 MPa to 0.185 MPa.

[0205] The second constant temperature stage: the temperature is set to maintain at 116 ° C, the time is 6 minutes, and the pressure in the autoclave increases from 0.185 MPa to 0.195 MPa.

[0206] The third constant temperature stage: the temperature is set to maintain at 116 ° C for 8 minutes, and the pressure in the sterilizer increases from 0.195 MPa to 0.205 MPa.

[0207] 4.3. Cooling treatment:

[0208] The first cooling stage: the temperature is set to drop from 116°C to 40°C for 18 minutes, and the pressure in the autoclave is reduced from 0.205MPa to 0.03MPa;

[0209] The second cooling stage: set the temperature from 40℃ to 20℃, the time is 10min, and the pressure in the sterilizer is reduced from 0.03MPa to 0.01MPa.

[0210] 5. Sterilization results: refer to Figure 1 As shown, after the sterilization steps above are completed, the high-barrier plastic cup is torn open and it is found that the corn kernels are bright in color and have a crisp and sweet taste; the cup body is intact and the cover film is slightly bulging; the product meets the commercial sterility requirements.

[0211] Table 1 shows the sterilization parameters and sterilization results in Examples 1-6

[0212]

[0213]

[0214] Figure 1 The figures show the packaged food after sterilization in Examples 1, 5 and 6 of the present invention, wherein 1a and 1b are outer appearance drawings of the outer packaging, and 1c and 1d are outer appearance drawings of the contents.

[0215] according to Figure 1 As shown in Table 1, after sterilization, the packaged foods in Examples 1-6 retained their original appearance intact, with no signs of damage. After tasting, they tasted good and showed no signs of deterioration. This demonstrates that the outer packaging materials, loading, and sterilization methods selected in the present embodiments effectively protect the sensory properties of the packaged food contents. Furthermore, in Examples 1-6, even when the headspace volume of the packaged foods accounted for significantly more than 5%, the outer packaging remained intact after sterilization, exhibiting no deformation. This demonstrates that the present embodiments also effectively protect the outer packaging of packaged foods, demonstrating that the sterilization method of the present invention can meet the sterilization requirements of foods packaged with very large headspaces.

[0216] Comparative Example 1

[0217] The difference from Example 1 is that the packaging cover film is not made of high barrier material, and the other conditions are the same as Example 1. The specific differences are as follows:

[0218] The packaging materials in this comparative example are high barrier plastic cup and ordinary cover film, and the oxygen transmission rate of the cup is <0.1cm 3 / (m 2 ·24h·0.1MPa), oxygen transmission rate of cover film>25cm 3 / (m 2 ·24h·0.1MPa).

[0219] Comparative Example 2

[0220] The difference from Example 1 is that no deoxygenation is performed after loading, and the other conditions are the same as those in Example 1. The specific differences are as follows:

[0221] In this comparative example, the raw material loading is as follows: the volume of the quick-frozen corn kernels loaded is 40% of the volume of the cup, no soup is added, the loading temperature is less than -10°C, and after loading, the vacuum is applied until the cover film is slightly concave after the film is sealed. During vacuuming, the air inside the cup is not completely extracted, and nitrogen is not filled into the cup.

[0222] Comparative Example 3

[0223] The difference from Example 1 is that the sterilization temperature and pressure correspond to each other (the same temperature corresponds to the same pressure), and the other conditions are the same as Example 1. The specific differences are as follows:

[0224] Sterilization in this comparative example: using a spray water bath dual-purpose sterilizer

[0225] Heating treatment:

[0226] The first heating stage: select a water bath to heat the sealed cup, the water bath temperature is 70 ° C, keep warm for 30 minutes, and the pressure in the autoclave is increased from 0.008 MPa to 0.025 MPa;

[0227] Then recycle the hot water in the lower tank and switch to spray sterilization;

[0228] The second heating stage: set the temperature from 70℃ to 116℃, time 45min.

[0229] Constant temperature treatment: set the temperature to 116℃ for 25 minutes.

[0230] Cooling treatment:

[0231] First cooling stage: set the temperature to cool from 116°C to 40°C for 20 minutes;

[0232] Second cooling stage: set the temperature from 40℃ to 25℃, time 15min.

[0233] Among them, the corresponding relationship between the pressure and temperature of the sterilizer is shown in Table 2 below:

[0234] Table 2 shows the corresponding relationship between sterilization temperature and pressure of Comparative Example 3

[0235]

[0236] Figure 2 2a and 2b are diagrams comparing the packaged food after sterilization in Comparative Example 1 of the present invention and the packaged food after sterilization in Example 1, wherein 2a and 2b are diagrams of the outer packaging of Example 1 and Comparative Example 1, respectively, and 2c and 2d are diagrams of the outer packaging of Example 1 and Comparative Example 1, respectively; Figure 3 3a and 3b are diagrams comparing the packaged food after sterilization in Comparative Example 2 of the present invention and the packaged food after sterilization in Example 1, wherein 3a and 3b are diagrams of the outer appearance of the contents of Example 1 and Comparative Example 1, respectively; Figure 4 4a-4d are the appearance diagrams of the packaged food after sterilization in Comparative Example 3 of the present invention, wherein 4a-4d are the appearance diagrams of the outer packaging of Comparative Example 3 at different angles.

[0237] according to Figure 2-Figure 4 It can be seen that the sterilization results of Example 1 and Comparative Examples 1-3 are compared as follows:

[0238] Table 3 shows the comparison of the sterilization results of Example 1 and Comparative Examples 1-3

[0239]

[0240] According to the comparison between Example 1 and Comparative Example 1, the packaging cover film in Comparative Example 1 does not use high barrier material, and the oxygen transmission rate of the cover film is greater than 25cm 3 / (m 2 ·24h·0.1MPa), at this time, the color of the sterilized corn kernels is dark, which shows that the quality of the corn kernels in Comparative Example 1 is significantly lower than that in Example 1. Compared with Comparative Example 1, Example 1 uses high barrier material for packaging, and the oxygen permeability of the cover film is <0.1cm 3 / (m 2 ·24h·0.1MPa), which can effectively prevent oxygen from entering the interior of the corn kernel cup and causing the corn kernels to oxidize and deteriorate.

[0241] According to the comparison between Example 1 and Comparative Example 2, in Comparative Example 2, the oxygen in the corn kernel cup was not completely removed after loading. Specifically, the air inside the cup was not completely extracted during vacuuming, and nitrogen was not filled into the cup. At this time, the color of the sterilized corn kernels became darker. It can be seen that the quality of the corn kernels in Comparative Example 2 is significantly lower than that of the corn kernels in Example 1.

[0242] Compared with Comparative Example 2, in Example 1, after loading, the interior of the corn kernel cup is vacuumed to a pressure of -0.1 MPa, and nitrogen is filled into the corn kernel cup for protection. This can effectively avoid the problem of oxygen inside the corn kernel cup and corn kernels oxidizing and causing deterioration.

[0243] According to the comparison between Example 1 and Comparative Example 3, the temperature and pressure during sterilization in Comparative Example 3 are set accordingly. Specifically, during the whole process of heating treatment, constant temperature treatment and cooling treatment, each temperature corresponds to a specific pressure value. For example, when the temperature of heating treatment is 100°C, the pressure is 0.1MPa, and when the temperature of cooling treatment is 100°C, the pressure is also 0.1MPa; and when the temperature of constant temperature treatment is maintained at 116°C, the pressure is always maintained at 0.17MPa. Figure 4 At this point, the appearance of the sterilized corn kernel cup is severely deformed and is no longer suitable for commercial use. Compared to Comparative Example 3, Example 1 controls the temperature and pressure separately during sterilization, effectively preventing the problem of packaging deformation of the corn kernel cup. Even when the headspace volume of the corn kernel cup accounts for as much as 60%, the appearance of the corn kernel cup can still remain intact.

[0244] It can be seen that the packaging materials, loading and sterilization methods selected in the present invention have a good protective effect on the appearance of packaged food and the sensory properties of the contents, and can meet the sterilization requirements of low-acidity, large headspace packaged foods that need to be shielded from light and oxygen.

[0245] The various technical features described above can be combined arbitrarily. Although not all possible combinations of these technical features are described, any combination of these technical features should be considered to be covered by this specification as long as such combination does not conflict.

[0246] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for sterilizing packaged food, characterized in that: include: The raw food ingredients are placed in a packaging container formed by an outer packaging material, the packaging container is vacuumed, filled with protective gas, and sealed in sequence to obtain the packaged food, and the packaged food is sterilized; The outer packaging material of the packaged food is a deformable packaging material, and the packaged food has a top gap; The sterilization treatment includes: heating treatment, constant temperature treatment and cooling treatment in sequence; Wherein, the temperature and pressure of the heating treatment are gradually increased over time and become constant; During the constant temperature treatment, the temperature remains constant and the pressure gradually increases to a predetermined value over time; The temperature and pressure of the cooling treatment are gradually reduced over time; The heating treatment includes at least one heating stage, and the heating rate of each heating stage is between 0.5-1.7°C / min; The constant temperature treatment includes at least one constant temperature stage, the temperature of each constant temperature stage is controlled between 60-130°C and maintained constant, the pressure of each constant temperature stage increases with time, and the pressure increase rate is between 0.002-0.008 MPa / min; the endpoint pressure of the constant temperature treatment is the saturated vapor pressure corresponding to the constant temperature treatment temperature ±0.03 MPa; The cooling process includes at least one cooling stage, and the cooling rate of each cooling stage is between 1-6°C / min; The headspace volume of the packaged food is greater than or equal to 5%, and the oxygen permeability of the outer packaging material of the packaged food is less than 0.5 cm 3 / (m 2 ·24h·0.1MPa), wherein the protective gas comprises at least one of nitrogen, carbon dioxide and an inert gas.

2. The method for sterilizing packaged food according to claim 1, wherein: The temperature and pressure of the temperature-raising treatment are increased in stages over time, and the heating rate of the latter heating stage is lower than the heating rate of the former heating stage; and / or The pressure of the constant temperature treatment increases in stages over time, with the pressure increase rate in the latter constant temperature stage being lower than the pressure increase rate in the former constant temperature stage; and / or The temperature and pressure of the cooling treatment are reduced in stages over time, and the cooling rate in the first cooling stage is higher than the cooling rate in the second cooling stage.

3. The method for sterilizing packaged food according to claim 1, wherein: The temperature of the heating treatment is increased from the initial temperature to the sterilization temperature, and the pressure is increased from the initial pressure to the sterilization pressure; Wherein, the sterilization temperature is 60-130°C, and the sterilization pressure is 0.1-0.3MPa.

4. The method for sterilizing packaged food according to any one of claims 1 to 3, characterized in that: The headspace volume of the packaged food accounts for 20%-60%.

5. The method for sterilizing packaged food according to any one of claims 1 to 3, characterized in that: The solid volume of the packaged food accounts for 30%-80%, and the soup volume accounts for less than 10%.

6. The method for sterilizing packaged food according to any one of claims 1 to 3, characterized in that: The oxygen transmission rate of the outer packaging material of the packaged food is less than 0.1cm 3 / (m 2 ·24h·0.1MPa).

7. The method for sterilizing packaged food according to any one of claims 1 to 3, characterized in that: The outer packaging material includes at least one of polyvinylidene chloride, ethylene-vinyl alcohol copolymer, polyvinyl alcohol, polyethylene naphthalate, polyethylene terephthalate, polybutylene terephthalate, polyarylate or polyamide.

8. The method for sterilizing packaged food according to any one of claims 1 to 3, characterized in that: The raw material ingredients include at least one of corn, beef, oats, chickpeas, quinoa and chicken breast.

9. The method for sterilizing packaged food according to any one of claims 1 to 3, characterized in that: The internal pressure of the vacuum packaging container is no higher than -0.1 MPa.

10. The method for sterilizing packaged food according to any one of claims 1 to 3, characterized in that: The purity of the protective gas is not less than 99.99%.

11. The method for sterilizing packaged food according to any one of claims 1 to 3, characterized in that: The purity of the protective gas is not less than 99.999%.

12. A packaged food, characterized in that: Obtained by sterilization according to the packaged food sterilization method according to any one of claims 1 to 11.

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