Canned packaging containers mainly use tin cans, thin-walled glass cans, cooking bags, empty metal cans and empty glass jars, can be purchased directly from the designated manufacturers, cooking bags can be purchased prefabricated bags or directly from the cannery production plant. Empty cans should be inspected prior to use, requiring tanks to be neat, welds uniform and uniform, with no gaps or deformations at the edges of the can and lid, and no rust and tin removal on the tin plate. Glass jars should be neatly shaped, smooth and non-notched, uniform in thickness, and free of bubbles and cracks in the glass. Some empty cans should be cleaned before loading, and should not be put back for a long time after cleaning to avoid re-pollution. ?
The production process of canned food varies according to varieties and raw materials, but the basic packaging process is generally: filling, exhaust, sealing, sterilization, cooling, and each process has the factors that cause canned food to deteriorate. The main influencing factors are analyzed as follows:
Filling process?
Filling is the loading of contents into empty cans. When filling, there must be a certain headspace in the can, and its size will directly affect the capacity of the food in the tank, the degree of vacuum and the deformation of the can after sterilization. If the headspace is too small, due to food expansion and pressure increase during pasteurization, it often causes the bottom lid of the can to protrude outwards until it cracks; if the headspace is too large, the pressure in the tank after sterilizing and cooling decreases greatly, often the can The body sags itself. In addition, due to the large headspace, there is more air in the tank, which can easily cause oxidative discoloration of the food. The size of the headspace is slightly different depending on the type of raw material, the shape of the tank, and the state of the raw materials. Generally, the top clearance is 6-8mm. Keep the edges of the cans clean and dry when canning and injecting salt solution. Do not stick raw material or salt solution to the cans and affect sealing. ?
Canned filling generally uses a rotary cup or drum type vibratory jar, both of which are volumetric. The reasons for the unqualified filling amount are: the capacity of the measuring cup is not adjusted correctly, the feeding of the hopper is too slow or unstable, the charging surface of the hopper is too low, the feeding tube is too small, the material flow is not cool, and the feeding tube and the measuring cup are different And so on will make the measuring cup dissatisfaction. If the operation speed of the machine is too fast, the speed at which the material is dropped by the hopper too quickly will cause the material to be recirculated so that the amount of filling will be too much; improper adjustment of the measuring cup telescopic mechanism will cause excessive backflow; if the container and feeding pipe are not concentric, the beat is not accurate. If the container is too small or the material sticks in the material pipe, the material will be damaged if the material is delayed. ?
Exhaust process?
Exhaust is to exclude the air contained in the canned food tissue as far as possible after filling the food, so that when the cans are heated and sterilized, the pressure inside the can is not caused due to the thermal expansion of the air, so that the can body is deformed or the can seam is cracked; At the same time, a certain degree of vacuum is formed in the tank, which can inhibit the activities of aerobic microorganisms remaining in the tank, reduce the oxidation corrosion of the tank wall and reduce the oxidation loss of nutrients (especially vitamin c), and better preserve the canned food. The color, smell and taste. It is generally required that the exhaust air reach the center of the sealed tank to a temperature of 70-80 degrees Celsius. ?
The tin cans are often vacuumed. The container and its contents are placed in a closed volume. The vacuum is used to vacuum the closed volume. The density of the air in the volume is reduced, the vacuum is obtained after sealing, or the steam injection method is used. The pressure steam jets the bottle mouth, after the seal steam condensation forms a certain vacuum. Glass bottles and cans are usually heated by a method of exhausting the gas—the container and contents are heated before sealing, so that the density of the air in the bottle is reduced, and the glass is sealed while hot and the vacuum is obtained after cooling. The cooking bag adopts the vacuum method. In order to effectively eliminate the air in the tank without affecting the quality of the contents, it should be noted that when exhausting, the type with slow thermal conductivity should be refilled before filling and hot-filled with boiling water. Re-exhaust and lengthen the exhaust time appropriately. The exhaust process must prevent the steam from dripping into the tank. When using the vacuum suction method, the degree of vacuuming should be controlled according to the shape of the pot, the variety, and the temperature of the added soup. With the variety of soup, the vacuum is too high, the soup is easily extracted, too low and often cause the vacuum inside the tank is not enough. General control vacuum 40-66.7kga is appropriate. ?
When the exhaust gas is heated, if the temperature of the exhaust gas is too high, the material in the tank may be easily damaged and the net weight may be insufficient. If the exhaust gas is insufficient, the degree of vacuum in the tank is too low, which can easily cause corrosion of the canned lid, the swelled can, and the can. The inhibition of the growth of aerobic bacteria remaining in the tank is effectively suppressed, and the pressure difference in the tank during sterilizing and cooling of the can is also affected, and it also indirectly affects the leakage of the can during sterilization. The main reason is that the temperature of the steam or hot water used does not meet the requirements. ?
When the vacuum exhaust is used, the main cause of the shortage of vacuum is: the pumping rate of the vacuum pump drops; the air path is seriously leaking or the air pumping pipe is filled; the vacuum device fails; the rubber seal in the glass bottle cap is damaged. ?
Sealing process?
Sealing is to maintain the vacuum in the packaging container under the conditions of food and external environment is no longer isolated due to external air and microbial contamination caused by corruption, sealing quality does not meet the requirements will make food and air contact oxidation and deterioration. The tin can sealing method is a double crimping method, which uses two roll-sealing rollers with different groove shapes to crimp and hook the pre-laminated can body and the flange-like can lid inner periphery. Glass jars are mainly used for screw-type sealing - the use of jaws, friction wheel or friction belt, so that the metal bottle cap with claws and the glass bottle with a screw flange flange relative rotation and move it along the spiral axis to The top sealant is pressed tightly against the end of the bottle to form a seal. Soft cans are mainly sealed by heat sealing. Sealing quality issues have the following aspects:
(1) The reason why the double crimping is not strict:
Fake roll—the curling hook and the cover hook are not engaged. The problem is the flange damage caused during transportation and transportation of the can body, the shape of the can body flange is unqualified, and the round edge of the can lid is defective or damaged. The lid is not aligned with the can body. ?
Large collapse - When the tank is sealed, the can body or the lid edge is in serious contact with the lid, so that the can body and the can lid do not hook each other. At the lower edge of the curling, there is a visible can body flange, because the can body is transported. Damaged flanging caused by the conveying process. The shape of the flange of the can body is unqualified. The round edge of the can lid is damaged or the round edge is too large. When the lid is closed, the lid of the can is not aligned with the can body. ?
Skipping - Due to the thicker bead at the weld seam, the sealing roller skips over the can weld and fails to tighten the bead because the sealer is running too fast and the two sealing wheel buffer spring is too soft The seams of the can body are too thick. ?
Incomplete curling - partial crimping due to skidding of the can lid on the indenter or poor rotation of the sealing roller is not fully compacted, and is characterized by a normal thickness of the curled part and a super thick part. The reason is that the tray pressure is too small, the size or taper of the lid and the indenter is not suitable, the pressure head is worn, the height of the indenter shaft is improperly adjusted, the distance between the tray and the tray is too large, the tray spring is out of order, and the indenter or the tray has oil. Indenter axial movement, inaccurate positioning. ?
Curl "teeth" - cover hooks and hooks are not overlapped, V-shaped or protruding at the lower edge of the curl because of the sealing curve of a sealing wheel is not ideal, the pre-sealing machine or the head sealing roller is adjusted Too loose, the sealing wheel wears. The tight adjustment of the two sealing rollers will aggravate the defects of the teeth. The design of the can lid is not ideal. The can lid has wrinkles on the bearing surface. There is too much sealant in the curl or too much sealant in the lid. The tray pressure is too high. , Excessive amount of solid cans, sealing wheel bearings are not flexible and so on. ?
Crimping - cracks in the outer layer of the seam at the seam of the can body. The reason is that the second sealing wheel is too tightly adjusted, the lid material is defective, the lid has too many seals, and the curl is trapped inside. The head sealing wheel is too tight, causing the lid to fold too long. The tightness does not meet the requirements due to an unreasonable curve of the sealing wheel, improper adjustment of the sealing wheel, serious wear of the sealing wheel curve, irrational shape of the rubber-bearing surface of the can lid, or wrinkles on the rubber surface of the can lid, and the bearing of the sealing wheel is not running. Flexible and so on. ?
Hemming damage - The damage on the outer surface of the hemming part or the peeling off of the coating, due to the unreasonable curve of a sealing wheel, the low smoothness of the sealing surface of one or two sealing wheels or the tight adjustment of the wheel. ?
(2) The reasons for the lax sealing of the glass bottle: The gap between the bottle turntable and the bottle holder is not uniform or the whole machine action is inconsistent and the bottle is broken.æ“ Twist the belt with the speed over the mouth of the ambassador to crush or the speed is too small to seal the bottle tightly. ?
(3) The reason why the seal of the heat-sealing bag is not strong or the seal is burned or damaged is that the former is mainly due to the low sealing temperature or the insufficient sealing pressure and heat sealing time; the bag mouth has debris to make the sealing not secure; the heat sealer Bonding of the melted plastic; the shaper and the material do not center when making the bag, so that the edges of the bag seam are not aligned. The latter is mainly caused by the heat sealing time being too long or the temperature being too high or the pressure being too large. ?
Sterilization process?
The purpose of sterilizing canned food is to kill microorganisms that are detrimental to food and produce toxins. When sterilizing, it is necessary to preserve the original color, flavor, texture and nutritional value of the food. If the sterilization is not complete, the microorganisms in the cans will multiply when the conditions are suitable for growth, causing the food to be corrupted. ?
Canned sterilization often uses heat sterilization - the product is heated to a certain temperature for a certain period of time to kill the bacteria.
Most of the heat sources use steam or hot water. When sterilizing, each can must be in direct contact with the heat source. There are many factors that affect the bactericidal effect, mainly the following points: Improper canned sterilization formula (temperature or time can not meet the requirements); Steam sterilizing exhaust is not sufficient or the convection effect of hot water sterilization is not good, etc. With soup foods, too high a solids content can affect the convective heat transfer effect in the tank or the filling function in the tank is too full to make the head gap gas agitation function. If the initial temperature is too low, the time required for the can to reach the sterilization effect will be extended, making the sterilization formula inappropriate. The high temperature of canned sterilization will temporarily soften the bottom apron. When the inside of the can is cooled after the sterilization is completed, a small amount of cooling water may be sucked in, especially when the crimping quality is not good. The nature and chemical composition of foods are the environmental conditions for the presence of microorganisms during sterilization. The acids, sugars, proteins, oils, and salts of foods can affect the heat resistance of microorganisms. Other factors such as low ph value of the food, high salt concentration, and the presence of nitrites and organic acids can enhance the heat of sterilization. The high concentration of sugar liquid has a protective effect on bacterial spores, food block size, solids content, canning methods, etc. will affect the heat transfer within the tank. The microbial contamination in the tank during sterilization is high, and because the residual microbe in the tank after sterilization is proportional to the number of initial bacteria, after the same sterilization conditions, the bacteria content in the tank is high, and the remaining number is high, which will make the can not reach Commercial aseptic requirements.
Cooling process?
After the canned food is sterilized, it must be cooled quickly. Otherwise, the food in the can still maintain a fairly high temperature and continue cooking. This will change the color and flavor of the product and sometimes affect the structure of the product. Normal-pressure sterilized can of tinplate can be directly put into cold water. When the temperature of the can is cooled to about 40°C, it is taken out. The residual heat inside the can is used to evaporate the moisture attached to the can. If the cooling is excessive, the moisture attached to the can is not easy to evaporate. In particular, moisture in the can seam is difficult to evaporate, which can easily lead to corrosion of iron skin or recontamination of microorganisms. Glass bottles and cans due to poor thermal conductivity, sterilization can not be directly put into cold water cooling, or easy to cause rupture, should be sub-cooling. ?
Pressure-sterilized cans are sterilized. Because the food in the tank expands due to high temperature during sterilization, the pressure in the tank increases significantly. If the pressure is rapidly restored after sterilization, the internal pressure will be too large, which will cause deformation or rupture of the tank and affect the can. Sealing performance. Therefore, such cans should be pressurized and cooled, ie, back pressure cooling, so that the pressure in the sterilizer is slightly greater than the pressure in the tank. When the contents of the can are sufficiently cooled and the internal pressure is moderated, no expansion or rupture occurs. Pressurized cooling can use steam pressure cooling or use air pressure cooling or timely cold water into the sterilization pot cooling. ?
After heat sterilization, it will still be re-contaminated by microorganisms suspended in canned cooling water or on conveyor belts and on unclean surfaces of handling equipment. Water is the main carrier for microorganisms to cross the leakage path of the packaging container seal or damaged structure. In the post-cooling stage, when the contents of the tank are cooled, the pressure inside the tank will drop to form a partial vacuum. When this occurs, there will be a chance of leakage if the water contains enough water. A quantity of microorganisms can also cause re-contamination. ?
The main reasons are: Structural defects - Deformation and damage to the cans caused by incorrectly sealed structures or over-mechanized handling damage the integrity of the cans. During the cooling process, the cooling water is not clean and the micro-organisms in the can seams enter the tank. It causes re-contamination. The main cause of can damage is impact or pressure. When the can speed on the conveyor belt is slowed or the conveying direction changes, it will impact the can because it collides with other cans or other parts on the conveyor belt. When transported on a conveyor, its forward movement is hindered while the conveyor belt is still moving and the cans are squeezed and damaged.
The production process of canned food varies according to varieties and raw materials, but the basic packaging process is generally: filling, exhaust, sealing, sterilization, cooling, and each process has the factors that cause canned food to deteriorate. The main influencing factors are analyzed as follows:
Filling process?
Filling is the loading of contents into empty cans. When filling, there must be a certain headspace in the can, and its size will directly affect the capacity of the food in the tank, the degree of vacuum and the deformation of the can after sterilization. If the headspace is too small, due to food expansion and pressure increase during pasteurization, it often causes the bottom lid of the can to protrude outwards until it cracks; if the headspace is too large, the pressure in the tank after sterilizing and cooling decreases greatly, often the can The body sags itself. In addition, due to the large headspace, there is more air in the tank, which can easily cause oxidative discoloration of the food. The size of the headspace is slightly different depending on the type of raw material, the shape of the tank, and the state of the raw materials. Generally, the top clearance is 6-8mm. Keep the edges of the cans clean and dry when canning and injecting salt solution. Do not stick raw material or salt solution to the cans and affect sealing. ?
Canned filling generally uses a rotary cup or drum type vibratory jar, both of which are volumetric. The reasons for the unqualified filling amount are: the capacity of the measuring cup is not adjusted correctly, the feeding of the hopper is too slow or unstable, the charging surface of the hopper is too low, the feeding tube is too small, the material flow is not cool, and the feeding tube and the measuring cup are different And so on will make the measuring cup dissatisfaction. If the operation speed of the machine is too fast, the speed at which the material is dropped by the hopper too quickly will cause the material to be recirculated so that the amount of filling will be too much; improper adjustment of the measuring cup telescopic mechanism will cause excessive backflow; if the container and feeding pipe are not concentric, the beat is not accurate. If the container is too small or the material sticks in the material pipe, the material will be damaged if the material is delayed. ?
Exhaust process?
Exhaust is to exclude the air contained in the canned food tissue as far as possible after filling the food, so that when the cans are heated and sterilized, the pressure inside the can is not caused due to the thermal expansion of the air, so that the can body is deformed or the can seam is cracked; At the same time, a certain degree of vacuum is formed in the tank, which can inhibit the activities of aerobic microorganisms remaining in the tank, reduce the oxidation corrosion of the tank wall and reduce the oxidation loss of nutrients (especially vitamin c), and better preserve the canned food. The color, smell and taste. It is generally required that the exhaust air reach the center of the sealed tank to a temperature of 70-80 degrees Celsius. ?
The tin cans are often vacuumed. The container and its contents are placed in a closed volume. The vacuum is used to vacuum the closed volume. The density of the air in the volume is reduced, the vacuum is obtained after sealing, or the steam injection method is used. The pressure steam jets the bottle mouth, after the seal steam condensation forms a certain vacuum. Glass bottles and cans are usually heated by a method of exhausting the gas—the container and contents are heated before sealing, so that the density of the air in the bottle is reduced, and the glass is sealed while hot and the vacuum is obtained after cooling. The cooking bag adopts the vacuum method. In order to effectively eliminate the air in the tank without affecting the quality of the contents, it should be noted that when exhausting, the type with slow thermal conductivity should be refilled before filling and hot-filled with boiling water. Re-exhaust and lengthen the exhaust time appropriately. The exhaust process must prevent the steam from dripping into the tank. When using the vacuum suction method, the degree of vacuuming should be controlled according to the shape of the pot, the variety, and the temperature of the added soup. With the variety of soup, the vacuum is too high, the soup is easily extracted, too low and often cause the vacuum inside the tank is not enough. General control vacuum 40-66.7kga is appropriate. ?
When the exhaust gas is heated, if the temperature of the exhaust gas is too high, the material in the tank may be easily damaged and the net weight may be insufficient. If the exhaust gas is insufficient, the degree of vacuum in the tank is too low, which can easily cause corrosion of the canned lid, the swelled can, and the can. The inhibition of the growth of aerobic bacteria remaining in the tank is effectively suppressed, and the pressure difference in the tank during sterilizing and cooling of the can is also affected, and it also indirectly affects the leakage of the can during sterilization. The main reason is that the temperature of the steam or hot water used does not meet the requirements. ?
When the vacuum exhaust is used, the main cause of the shortage of vacuum is: the pumping rate of the vacuum pump drops; the air path is seriously leaking or the air pumping pipe is filled; the vacuum device fails; the rubber seal in the glass bottle cap is damaged. ?
Sealing process?
Sealing is to maintain the vacuum in the packaging container under the conditions of food and external environment is no longer isolated due to external air and microbial contamination caused by corruption, sealing quality does not meet the requirements will make food and air contact oxidation and deterioration. The tin can sealing method is a double crimping method, which uses two roll-sealing rollers with different groove shapes to crimp and hook the pre-laminated can body and the flange-like can lid inner periphery. Glass jars are mainly used for screw-type sealing - the use of jaws, friction wheel or friction belt, so that the metal bottle cap with claws and the glass bottle with a screw flange flange relative rotation and move it along the spiral axis to The top sealant is pressed tightly against the end of the bottle to form a seal. Soft cans are mainly sealed by heat sealing. Sealing quality issues have the following aspects:
(1) The reason why the double crimping is not strict:
Fake roll—the curling hook and the cover hook are not engaged. The problem is the flange damage caused during transportation and transportation of the can body, the shape of the can body flange is unqualified, and the round edge of the can lid is defective or damaged. The lid is not aligned with the can body. ?
Large collapse - When the tank is sealed, the can body or the lid edge is in serious contact with the lid, so that the can body and the can lid do not hook each other. At the lower edge of the curling, there is a visible can body flange, because the can body is transported. Damaged flanging caused by the conveying process. The shape of the flange of the can body is unqualified. The round edge of the can lid is damaged or the round edge is too large. When the lid is closed, the lid of the can is not aligned with the can body. ?
Skipping - Due to the thicker bead at the weld seam, the sealing roller skips over the can weld and fails to tighten the bead because the sealer is running too fast and the two sealing wheel buffer spring is too soft The seams of the can body are too thick. ?
Incomplete curling - partial crimping due to skidding of the can lid on the indenter or poor rotation of the sealing roller is not fully compacted, and is characterized by a normal thickness of the curled part and a super thick part. The reason is that the tray pressure is too small, the size or taper of the lid and the indenter is not suitable, the pressure head is worn, the height of the indenter shaft is improperly adjusted, the distance between the tray and the tray is too large, the tray spring is out of order, and the indenter or the tray has oil. Indenter axial movement, inaccurate positioning. ?
Curl "teeth" - cover hooks and hooks are not overlapped, V-shaped or protruding at the lower edge of the curl because of the sealing curve of a sealing wheel is not ideal, the pre-sealing machine or the head sealing roller is adjusted Too loose, the sealing wheel wears. The tight adjustment of the two sealing rollers will aggravate the defects of the teeth. The design of the can lid is not ideal. The can lid has wrinkles on the bearing surface. There is too much sealant in the curl or too much sealant in the lid. The tray pressure is too high. , Excessive amount of solid cans, sealing wheel bearings are not flexible and so on. ?
Crimping - cracks in the outer layer of the seam at the seam of the can body. The reason is that the second sealing wheel is too tightly adjusted, the lid material is defective, the lid has too many seals, and the curl is trapped inside. The head sealing wheel is too tight, causing the lid to fold too long. The tightness does not meet the requirements due to an unreasonable curve of the sealing wheel, improper adjustment of the sealing wheel, serious wear of the sealing wheel curve, irrational shape of the rubber-bearing surface of the can lid, or wrinkles on the rubber surface of the can lid, and the bearing of the sealing wheel is not running. Flexible and so on. ?
Hemming damage - The damage on the outer surface of the hemming part or the peeling off of the coating, due to the unreasonable curve of a sealing wheel, the low smoothness of the sealing surface of one or two sealing wheels or the tight adjustment of the wheel. ?
(2) The reasons for the lax sealing of the glass bottle: The gap between the bottle turntable and the bottle holder is not uniform or the whole machine action is inconsistent and the bottle is broken.æ“ Twist the belt with the speed over the mouth of the ambassador to crush or the speed is too small to seal the bottle tightly. ?
(3) The reason why the seal of the heat-sealing bag is not strong or the seal is burned or damaged is that the former is mainly due to the low sealing temperature or the insufficient sealing pressure and heat sealing time; the bag mouth has debris to make the sealing not secure; the heat sealer Bonding of the melted plastic; the shaper and the material do not center when making the bag, so that the edges of the bag seam are not aligned. The latter is mainly caused by the heat sealing time being too long or the temperature being too high or the pressure being too large. ?
Sterilization process?
The purpose of sterilizing canned food is to kill microorganisms that are detrimental to food and produce toxins. When sterilizing, it is necessary to preserve the original color, flavor, texture and nutritional value of the food. If the sterilization is not complete, the microorganisms in the cans will multiply when the conditions are suitable for growth, causing the food to be corrupted. ?
Canned sterilization often uses heat sterilization - the product is heated to a certain temperature for a certain period of time to kill the bacteria.
Most of the heat sources use steam or hot water. When sterilizing, each can must be in direct contact with the heat source. There are many factors that affect the bactericidal effect, mainly the following points: Improper canned sterilization formula (temperature or time can not meet the requirements); Steam sterilizing exhaust is not sufficient or the convection effect of hot water sterilization is not good, etc. With soup foods, too high a solids content can affect the convective heat transfer effect in the tank or the filling function in the tank is too full to make the head gap gas agitation function. If the initial temperature is too low, the time required for the can to reach the sterilization effect will be extended, making the sterilization formula inappropriate. The high temperature of canned sterilization will temporarily soften the bottom apron. When the inside of the can is cooled after the sterilization is completed, a small amount of cooling water may be sucked in, especially when the crimping quality is not good. The nature and chemical composition of foods are the environmental conditions for the presence of microorganisms during sterilization. The acids, sugars, proteins, oils, and salts of foods can affect the heat resistance of microorganisms. Other factors such as low ph value of the food, high salt concentration, and the presence of nitrites and organic acids can enhance the heat of sterilization. The high concentration of sugar liquid has a protective effect on bacterial spores, food block size, solids content, canning methods, etc. will affect the heat transfer within the tank. The microbial contamination in the tank during sterilization is high, and because the residual microbe in the tank after sterilization is proportional to the number of initial bacteria, after the same sterilization conditions, the bacteria content in the tank is high, and the remaining number is high, which will make the can not reach Commercial aseptic requirements.
Cooling process?
After the canned food is sterilized, it must be cooled quickly. Otherwise, the food in the can still maintain a fairly high temperature and continue cooking. This will change the color and flavor of the product and sometimes affect the structure of the product. Normal-pressure sterilized can of tinplate can be directly put into cold water. When the temperature of the can is cooled to about 40°C, it is taken out. The residual heat inside the can is used to evaporate the moisture attached to the can. If the cooling is excessive, the moisture attached to the can is not easy to evaporate. In particular, moisture in the can seam is difficult to evaporate, which can easily lead to corrosion of iron skin or recontamination of microorganisms. Glass bottles and cans due to poor thermal conductivity, sterilization can not be directly put into cold water cooling, or easy to cause rupture, should be sub-cooling. ?
Pressure-sterilized cans are sterilized. Because the food in the tank expands due to high temperature during sterilization, the pressure in the tank increases significantly. If the pressure is rapidly restored after sterilization, the internal pressure will be too large, which will cause deformation or rupture of the tank and affect the can. Sealing performance. Therefore, such cans should be pressurized and cooled, ie, back pressure cooling, so that the pressure in the sterilizer is slightly greater than the pressure in the tank. When the contents of the can are sufficiently cooled and the internal pressure is moderated, no expansion or rupture occurs. Pressurized cooling can use steam pressure cooling or use air pressure cooling or timely cold water into the sterilization pot cooling. ?
After heat sterilization, it will still be re-contaminated by microorganisms suspended in canned cooling water or on conveyor belts and on unclean surfaces of handling equipment. Water is the main carrier for microorganisms to cross the leakage path of the packaging container seal or damaged structure. In the post-cooling stage, when the contents of the tank are cooled, the pressure inside the tank will drop to form a partial vacuum. When this occurs, there will be a chance of leakage if the water contains enough water. A quantity of microorganisms can also cause re-contamination. ?
The main reasons are: Structural defects - Deformation and damage to the cans caused by incorrectly sealed structures or over-mechanized handling damage the integrity of the cans. During the cooling process, the cooling water is not clean and the micro-organisms in the can seams enter the tank. It causes re-contamination. The main cause of can damage is impact or pressure. When the can speed on the conveyor belt is slowed or the conveying direction changes, it will impact the can because it collides with other cans or other parts on the conveyor belt. When transported on a conveyor, its forward movement is hindered while the conveyor belt is still moving and the cans are squeezed and damaged.