Curling damage - curling part of the appearance of the damage or coating off, because a sealing wheel curve is not reasonable, one or two sealing wheel curling surface smoothness is low or tighter wheel adjustment.

 

(2) Reasons for poor sealing of glass bottles: uneven size of the gap between the turntable and the bottle protector or inconsistent operation of the whole machine, resulting in broken bottles; rubbing and twisting the belt speed too fast to break the bottle mouth or too small to seal the bottle cap tightly and so on.

 

(3) Reasons for unstable sealing or burning or breakage at the sealing of hot-sealed bags: the former is mainly due to low sealing temperature or insufficient sealing pressure or time; the bags have sundries that make the sealing unstable; the hot-sealers are bonded and melted plastic; the shapers and materials are not aligned so that the seams of the bags are not aligned; It is mainly caused by excessive heat sealing time, excessive temperature or excessive pressure.

 

4, sterilization process

 

The purpose of canned food sterilization is to kill the microorganisms which can destroy the food and produce poison. The original color, flavor, texture and nutritional value of canned food should be preserved as much as possible. If the sterilization is not thorough, the microorganisms in the cans will multiply in large numbers and spoil the food when the conditions are suitable for growth.

 

Canning sterilization is usually done by heating the product to a certain temperature and holding it for a certain period of time to kill bacteria. The heat source is mostly steam or hot water. When sterilizing, each can must be directly in contact with the heat source. There are many factors affecting the germicidal efficacy, mainly as follows: inappropriate sterilization formula (temperature or time can not meet the requirements); inadequate steam sterilization exhaust or hot water sterilization convection effect and other reasons for the cold spots in the sterilization pot; soup food, solid content is too high will affect the convective heat transfer efficiency in the pot. The stirring function of the top gap gas is affected by the filling of the fruit or the cans too full; the initial temperature too low will prolong the time needed for the cans to achieve sterilization effect and make the sterilization formula inappropriate; the high temperature of the cans sterilization will make the bottom cover apron temporarily soften, and when the cans are cooled to form a vacuum after sterilization, a small amount of cooling water may be sucked in, especially. When the quality of curling edge is not good, there will be micro-leakage; the nature and chemical composition of food are the environmental conditions for microorganisms to exist when sterilizing; the acid, sugar, protein, oil, salt and other factors can affect the microbial heat resistance; other factors such as low pH value of food, high salt concentration, nitrite and organic acid exist. High concentration of sugar solution can protect bacterial spores. The size of food blocks, the content of solids and the way of canning all affect the heat transfer in the cans. After the condition of bacteria, the content of bacteria in the cans is high, and the number of remaining bacteria is high, which will make the cans not up to the commercial aseptic requirements.

 

5. Cooling process

 

Canned food must be cooled quickly after sterilization. Otherwise, the food in the cans will continue to be cooked at a high temperature, which will change the color and flavor of the products, and sometimes the structure of the products will be affected. Horse tin cans which have been sterilized under atmospheric pressure are directly put into cold water and taken out when the temperature of the cans is cooled to about 40 degrees Celsius. The water attached to the outside of the cans is evaporated by the waste heat in the cans. If the cooling is excessive, the water attached to the outside of the cans is not easy to evaporate, especially the water in the cracks of the cans is difficult to evaporate, and it is easy to cause rust of the iron sheet Contamination; glass bottles and tanks due to poor thermal conductivity, sterilization can not be directly put into cold water to cool, otherwise easy to cause rupture, should be cooled by stages.

 

Because of the expansion of food in the cans due to high temperature during sterilization, the pressure in the cans increases significantly. If the cans restore to normal pressure quickly after sterilization, the internal pressure will be too high and cause the deformation or breakage of the cans, which will affect the sealing performance of the cans. Therefore, pressure cooling, i.e. reverse pressure cooling, should be adopted for this kind of cans. The pressure in the sterilizing pot is slightly greater than the pressure in the pot. When the contents of the pot are fully cooled and the internal pressure is relaxed, there will be no expansion or rupture. The pressurized cooling can be cooled by steam pressurization or air pressurization or cold water is injected into the sterilizing pot.

After thermal sterilization, it is contaminated again by microorganisms suspended in the cooling water of cans, conveyor belts or unclean surfaces of transport equipment. Water is the main carrier for microorganisms to pass through leakage channels such as sealing or damaged structures of packaging containers. In the later stage of cooling, when the contents of the container are cooled down to form a partial vacuum, leakage opportunities occur. If there are enough microorganisms in the water, it will cause re-contamination.

 

The main reasons are: structural defects - by improper sealing structure or excessive mechanical handling of the tank deformation or damage, damage to the integrity of the can, the cooling process of the tank capillary cracks in the microorganisms into the tank and cause re-pollution; unclean cooling water. The main cause of the damage is impact or pressure. When the speed of the cans on the conveyor belt slows down or the direction of the conveyor changes, the impact on the cans will occur because of the collision with other cans or other parts on the conveyor belt. When the cans are conveyed on the conveyor, the forward movement of the cans is blocked while the conveyor belt is still moving. The head is damaged by extrusion.

 

In order to ensure the quality of canned food and the health of the people, it is necessary to do things according to the regulations in the packaging process and the storage and transportation process, so as to avoid canned food in the