For food after heat treatment, the integrity of the container is very important. To ensure the integrity of the container, manufacturing containers should ensure that won't let clostridium botulinum and other pathogens invade after heat treatment of food again. This article introduces for food after heat treatment of metal and glass containers and the important characteristics of the retort pouch.
Metal containers
Metal containers can be made from two or three pieces of metal chips: make two piece cans, through moulded metal stretching into seamless body composed of side wall and bottom. Tank lid with body by double edge joint. Three cans made: three pieces of sheet metal cans, tank bottom and the tank cover. Most three cans have a side of welding seam, tank bottom and the lid with body by double edge joint.
Double edge
In the process of machining double edge:
The top flange to the outer edge of body. The curved part of the tank body hook. The cover edge bending down, then buckle up into the flange. The bending part form can cover the hook. Tank cover edge of the sealant (a kind of rubber sealing material) can realize the sealing effect. In most cases, the canned manufacturers are under carefully controlled conditions, making three cans of side seam and double edge at the tank bottom. However, food manufacturers processing of these two kinds of metal cans tank cover The double edge, processing chamber conditions are not very ideal. So, the problem of control mainly concentrated on the edge of the pot cover double roll.
The evaluation of double edge
Can check include laminated cover clasps and bottom, edge width, thickness, edge tightness and countersunk degrees (the distance from the edge at the top to the bottom tank), the measured value to judge the quality of the double edge. By examining these measurements, plus other evaluation criteria (e.g., degree of pressure ridges and folds), which can determine the quality of the sealed container. These assessments shall be carried out under the guiding principle of the container manufacturers. If the edge devices Has not been maintained, or did not follow the principle of edge guide, edge defects may occur.
Quality assurance
External processing personnel should be visual double edge, check to see if its defects. Suggest at least once every 30 minutes to perform visual inspection; The following circumstances shall be immediately visual analysis: can sealing machine. Closing machine adjustment. After downtime for a long time to boot.
In addition, should also be tested to teardown, to verify compliance with all edge guiding principles. During teardown detection, edge indicators should be measured and recorded. Suggest at least once every four hours to perform teardown detection.
Edge defects
If the processing personnel not carefully, may appear the following edge defects:
Drop the lip: lip is refers to the double edge appear below its normal edge smooth suspension parts. If the lip is too large, then cover the hook is too short or not, which makes it impossible to form a laminated.
Edge residual food: sometimes, in the process of edge, food will be involved in the seal.
Sharp edge: edge sealing the sharp edge of the medial upper will split sheet metal, that is the sharp edge.
False: edge part of a complete decoupling and cover on the outer body hook, hook pressure that is false. Visual sometimes cannot detect this kind of defect.
Wrinkles: detect cover hook with and without wrinkles. If the edge in the operation pressure is not enough, can't pressed cover hook, so there are wrinkles in the hook. Wrinkles degrees (or close) test is to ensure the integrity of the container is a very important link.
Glass containers
Glass containers are normally used for holding low acidity and acidic foods, made up of two separate parts: glass jar and metal cover. The two parts is the key to form a good air tightness.
Glass jar: top of the jar and cap on threaded or flanged joint. Glass jars with metal cover seal at the top of the edge.
Metal cover: metal cover of rubber or plastic sol (a kind of soft heated plastic) gasket. Sealing washer and the top of the jar edge joint, a sealing device. , with metal cover or flanged or threaded screw into the jar, fixed in position.
Vacuum forming
Glass container seal is through internal vacuum sealing edge of the jar and metal cover gasket joint tightly together. Vacuum forming is the key to ensure the integrity of the glass container. The following factors affect the formation of a vacuum:
At the top of the space: in order to be able to absorb enough steam vacuum, also in order to be able to accommodate the expansion of the food, food in jars above must leave enough space.
Food temperature: seal food when the temperature is higher, the higher vacuum degree.
Residual gas: food stored up in the air, the more the lower vacuum.
Equipment operation: vacuum equipment must be able to work efficiently, produce enough vacuum.
The quality control of glass containers
Suggest to control the quality of glass containers should include visual and qualitative measurement according to the following factors: vacuum degree. Pull away from. Security.
Glass container inspection and measurement
Cock of visual: should check whether the sealing of the container and if there are other obvious defects. After sealing on correctly twist, sealing surface of the glass jar will block in the uniform imprint on the washer.
Qualitative measurements: vacuum degree: after processing measure the vacuum degree is an important control program. Many large cap there is a button, after the formation of vacuum bottle, ambient pressure will press the button, and whenever the jars to keep appropriate vacuum degree, will keep the pressure state.
Pull away from: from refers to a mouth mould seam and the distance between the flange of the front end recently. Supporting jar/bottle design shall ensure that: correctly after the screw on cap, the distance value remains the same. Glass jar or bottle manufacturers to provide the correct distance limit.
Safety: to measure safety, first of all, in a glass jar and metal tag line on the intersection point, and then the kaifeng to tighten the bottle cap, until the gasket and seal face just joint. At this time, remember line of bottle cap shall be located right on the jar tag line, which means that the gland equipment enough torque for cap, sealing effect. Glass jar or bottle manufacturers to provide the correct security restrictions.
Retort pouch
Retort pouch is a kind of flexibility, can be heat sealed and relatively flat container, able to withstand the high temperature low acidity food to meet the need of pressure processing. Retort pouch sealing is usually through heating cooking bags on both sides of the membrane fusion together. For multilayer packaging bags, such as containing metal foil layer or layers of paper bags, simply fusion lining.
The quality control
Even the best container sealing effect, leakage may occur. Therefore, please be sure to follow the container manufacturer's recommendations, to ensure the seal integrity. In the cooling process, when the container is from stress state to a vacuum inside, the biggest risk of leakage. Vacuum suction easily outside of the pollutants. Preventive measures during cooling
Air-cooled: if the container to be air cooling after cooking, so, should be avoided during the cooling process external contaminants into the container. For example, should be avoided in easy contact with the rain, birds, rodents and staff clothing.
Water: if the container must carry on the water, then the cooling water should be contained residual chlorine or other disinfectant, in order to reduce the risk of pollution.
Seal strength test
Recommended by test to verify seal strength. Common test include:
Burst test: burst test is used to ensure security one of the most important test of retort pouch sealing. The trials will continue to put pressure on until the seal failure. Seal strength should comply with the container manufacturer's specifications.
Tensile strength test: through the shearing section of seal, then ripping the seals in mechanical way, can test the seal of the tensile strength. This test is a useful complement to burst test, but only a small part of the inspection seal.
Visual: for each container, after processing should be visual analysis, to ensure complete sealing.
