Look at the canned food packaging process (below)

Look at the canned food packaging process (below)

Crimping "teeth" - the hook and the body hook are not overlapped, and the V-shape or protrusion formed at the lower edge of the bead is because the sealing curve of a sealing wheel is not ideal, and the pre-sealing machine or the head sealing roller is adjusted. Too loose, the sealing wheel is worn. If the two sealing rings are adjusted too tightly, the dental defects will be aggravated, the design of the can lid is not ideal, the can lid has wrinkles on the rubberized surface, the inclusions in the curling edge or the sealing rubber in the can lid is too much, and the tray pressure is too high. The actual tank canned capacity is too large, and the sealing wheel bearing is not flexible. ?

Crimping of the curling edge - the outer layer of the iron sheet is broken at the seam of the can body. The reason is that the two sealing rings are adjusted too tightly, the material of the can lid is defective, the inside of the cap is too tightly sealed, and the inside of the crimping is pinched with debris due to The head sealing wheel was adjusted too tightly, causing the can lid to be too long. The tightness does not meet the requirements. The reason is that the curve of a sealing wheel is unreasonable, the adjustment of the sealing wheel is not suitable, the curve of a sealing wheel is seriously worn, the shape of the rubber surface of the can lid is unreasonable or the surface of the can end is wrinkled, and the sealing wheel bearing does not operate. Flexible and so on.

Crimping damage - damage to the outer surface of the crimped part or peeling of the coating, because the curve of a sealing wheel is unreasonable, the smoothness of the curved surface of one or two sealing rings is low or the wheel is tightly adjusted. ?

(2) The reason why the sealing of the glass bottle is not strict: the gap between the bottle turning plate and the bottle holder is not uniform or the movement of the whole machine is uncoordinated, which causes the bottle to break. When the speed of the belt is too large, the bottle mouth is broken or the belt speed is too small, so that the bottle cap is not tightly sealed. ?

(3) The reason why the heat-sealed bag mouth is not tightly sealed or the seal is burnt or damaged: the former is mainly because the sealing temperature is too low or the sealing pressure and heat sealing time are not enough; the bag mouth has debris to make the sealing not firm; the heat sealer Bonding the melted plastic; the shaper is not centered with the material during bag making, so that the seam edges of the bag are not aligned. The latter is mainly caused by excessive heat sealing time or excessive temperature or excessive pressure. ?

Sterilization process?

The purpose of sterilization of canned food is to kill microorganisms that cause damage to food and produce poison. When sterilizing, try 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, and the food will be spoiled. ?

Canned sterilization is often carried out by heat sterilization - heating the product to a certain temperature for a certain period of time to kill the bacteria.

The heat source is mostly steam or hot water, and each can can be directly in contact with the heat source during sterilization. There are many factors affecting the bactericidal effect, mainly the following: improper canning sterilization formula (temperature or time can not meet the requirements); steam sterilization and exhaustion is not sufficient or hot water sterilization convection is not good, etc., causing cold spots in the sterilization pot In the case of soup containing food, the high solid content will affect the convective heat transfer effect in the tank or the filling in the tank will be too full to affect the stirring function of the headspace gas. If the initial temperature is too low, it will prolong the time required for the can to achieve the sterilization effect, making the sterilization formula inappropriate. The high temperature of canned sterilization will temporarily soften the rubber cap of the bottom cover. When the can is cooled to form a vacuum after the sterilization is completed, it is possible to suck in a small amount of cooling water, especially when the quality of the curling is not good, micro-leakage occurs. The nature and chemical composition of foods are the environmental conditions in which microorganisms are present during sterilization. The acid, sugar, protein, oil, and salt of foods can affect the heat resistance of microorganisms. Other factors such as low pH of food, high salt concentration, and the presence of nitrite and organic acids enhance the thermal effect of sterilization. The high concentration of sugar liquid has a protective effect on bacterial spores. The size of the food block, the high solid content, and the filling method will affect the heat transfer inside the tank. When the sterilization, the degree of microbial contamination in the tank is high, and the amount of microbial residues in the tank after sterilization is proportional to the initial number of bacteria. After the same sterilization condition, the bacteria content in the tank is high, and the residual amount is also high, so that the can is not reached. Commercial sterility requirements.

Cooling process

After the canning is completed, it must be cooled rapidly. Otherwise, the food in the can still maintains a relatively high temperature and continues to cook, which will change the color and flavor of the product, and sometimes the structure will be affected. The tinplate canned after atmospheric pressure sterilization is directly put into cold water, and is taken out when the tank temperature is cooled to about 40 ° C. The residual heat in the tank is used to evaporate the water attached to the outside of the tank. If the cooling is excessive, the moisture attached to the tank is not easily evaporated. In particular, it is difficult to evaporate water in the tank, which may cause corrosion of the iron or re-contamination of microorganisms. Due to the poor thermal conductivity of glass bottles, they cannot be directly cooled into cold water after sterilization, otherwise they may cause cracking and should be cooled in stages.

After very sterilized cans, the food in the cans expands due to high temperature during sterilization, and the pressure inside the cans increases remarkably. If the normal pressure is quickly restored after sterilization, the internal pressure will be too large and the cans will be deformed or broken, affecting the cans. Sealing performance. Therefore, pressurized cooling is required for such cans, that is, back pressure cooling, so that the pressure in the sterilization pot is slightly larger than the pressure inside the tank, and when the contents of the can are sufficiently cooled, the internal pressure is relaxed, and expansion or cracking does not occur. Pressurization cooling may be performed by steam pressure cooling or by air pressure cooling or by timely cooling the cold water into a sterilization pot. ?

After thermal sterilization, it will still be re-contaminated by microorganisms suspended in canned cooling water or conveyor belts and unclean surfaces of handling equipment. Water is the main carrier for microorganisms to pass through the leakage channel of the packaging container seal or damaged structure. In the post-cooling stage, when the contents are cooled and the pressure inside the tank drops to form a partial vacuum, there will be a chance of leakage if the water contains enough The amount of microorganisms can also cause re-contamination. ?

The main reason is: structural defects - the deformation and damage of the tank after improperly sealed structure or excessive mechanical handling, destroying the integrity of the can, the cooling water is not clean during the cooling process, and the microorganisms in the capillary of the tank enter the tank Internally caused re-contamination. The main cause of can damage is impact or pressure. When the speed of the can on the conveyor belt is slowed down or the direction of conveyance is changed, the impact on the can occurs when it collides with other cans or other parts on the conveyor belt. When transported on the conveyor, its forward movement is blocked and the conveyor belt is still moving, and the can is crushed and damaged. ?

In order to ensure the quality of food canned food and protect the health of the people, it is necessary to follow the rules in the packaging process and in the process of storage and transportation to avoid the corruption of canned food during storage.