The sealing of most glass bottle cans is mainly determined by the degree of vacuum in the bottle, rather than relying on the buckling of the claw and the thread. The function of the claw is only to ensure the closure of the cap and the thread during the sterilization process, as well as repeated capping and sterilization. The sealing after cooling is mainly ensured by the vacuum in the bottle. Usually the standard bottle cap is matched with the standard glass bottle, and the cover claw enters 1/3-1/2 of the screw thread of the bottle mouth when the cap is sealed, which is an ideal fit.
Excessive capping can easily cause deformation of the claws, rusting of the claws, chronic air leakage, sterilization and cap skipping.
Therefore, proper capping torque should be paid attention to when capping.
So the harder the can is to open, the better the seal is?
Bottle caps must be opened on the basis of ensuring sealing, easy to seal and easy to open, so that they can be used by end consumers. The sealing of most cans mainly depends on the degree of vacuum in the can, and has nothing to do with the opening of the bottle cap.
Therefore, a good bottle and cap should be able to ensure that the can is both well sealed and easy to open.
Does the safety button mean that the vacuum is good?
The safety button can be sucked down when a certain vacuum is formed in the can, but the suction of the safety button does not fully prove that the vacuum degree in the can meets the requirements. When the canned food is transported from low altitude to high altitude area, when the outside air pressure decreases or the outside temperature becomes higher, the vacuum degree in the tank will become lower. If the vacuum in the tank cannot be guaranteed during the capping process, it may cause the vacuum button to rebound. .
All kinds of safety button covers require corresponding vacuum degree requirements in the tank.
The capping of glass bottles is an extremely important two link in food processing. Improper control during the capping process will greatly increase the scrap rate, greatly reduce the efficiency, and increase the production cost; pay attention to the quality of the capping and improve
Cost advantage is a concern of every food manufacturer.
(1) Closing theory: For most canned food products, a certain degree of vacuum is required in the bottle. The claw-type unscrewing cap is matched with the claw mouth bottle. The contact surface of the rubber gasket and the bottle mouth forms a sealing surface. The thread with the bottle mouth plays a role in guiding the cap and preventing cap skipping and repeated capping by consumers during the sterilization process. The sealing effect of the finished can is mainly guaranteed by the sufficient vacuum in the bottle rather than the cap claw and the bottle thread. The degree of vacuum is equal to the outside air pressure minus the actual air pressure in the bottle.
(2) Claw-type unscrewing caps are often referred to as easy-spinning caps. A qualified unscrewing cap must be easy to close and open, so as to solve the problem that the can is delicious and difficult to open.
(3) Enough vacuum in the bottle should be ensured as much as possible when capping, with a good capping bottle, and the size of the vacuum degree should be determined after capping. Any leakage in the bottle due to excessive internal pressure during the sterilization process The resulting vacuum should not be promoted.
The formation of vacuum:
After capping, a closed space is formed in the bottle. Under this condition, the cooling volume of the contents is reduced, the steam in the headspace is condensed into water, and the cooling air pressure of the hot air in the headspace is reduced, forming the final vacuum in the bottle.
How to obtain vacuum:
In view of the vacuum forming mechanism, different response methods can be adopted to increase the vacuum in the bottle: 1) Maintain a proper head gap, use hot steam to replace the air, commonly used steam jet capping machine capping or steam exhaust tunnel plus manual instant capping to achieve 2) Maintain proper head clearance, use mechanical vacuum to reduce the air in the head clearance, and obtain vacuum 3) Increasing and ensuring the filling temperature is also a way to increase the vacuum degree
(4) The standard claw type unscrewing cap is matched with the GPI (or FD) standard bottle mouth. For glass bottles with stop, the cover claw should be sealed to the stop position of the glass bottle. For glass bottles without stop Bottle, usually the cover claw enters the bottle mouth thread 1/3—1/2 to achieve a more ideal fit, as shown in the figure below:
(5) The capping safety distance must be a positive value. If the safety distance is 0 or negative, it means that the capping is excessive
(6) In order to obtain a good, safe, hygienic and stable capping effect, machine capping should be the first choice, and manual capping should be considered when machine capping is not available. For manual capping, attention must be paid to the control of the capping torque to avoid Excessive capping affects the capping effect. Commonly used capping machines are generally divided into steam jet linear capping machines with vacuuming effect, mechanical vacuuming rotary capping machines, and linear or rotary capping machines without vacuuming effect.
1. Sterilization of canned food in glass bottles
After the cap is closed, the products that need to be further sterilized must be sterilized. Different content uses different sterilization formulas. The following are the issues related to the use of bottle caps that should be paid attention to.
(1) When the sterilization temperature exceeds 100°C, try to use a diameter greater than 53mm to unscrew the cap. Otherwise, please contact the cap manufacturer in advance to determine the applicable processing conditions and strictly control the specific operation.
(2) During high temperature sterilization, the external pressure should be greater than the internal pressure 0.2, but the external pressure should not exceed 2.1kg/cm2.
(3) During any heating process and transportation process, a soft porous rubber pad (with a thickness of not less than 4mm) must be laid between the bottom of each overlapping layer of bottle and the bottle cap, and the edge of the cap may be touched on the edge of the turnover basket. At the place, it is also necessary to increase the soft wrapper.
(4) The high temperature sterilization temperature should not exceed 121.1℃ under normal circumstances. If it needs to exceed, please contact the supplier in advance to determine the applicable processing conditions and strictly control the specific operation.
2. Cooling of canned food in glass bottles
(1) Adopt graded cooling to avoid bottle bursting or cap skipping caused by sudden changes in temperature and pressure.
(2) When the autoclave is cooled, ensure the stability of the back pressure to avoid sudden depressurization when the temperature in the bottle is high and the temperature of the autoclave is low, which may cause cap skipping.
(3) The cooling termination temperature should not be lower than 40℃, which is beneficial to the evaporation of water attached to the bottle neck and bottle cap, and avoids the cap from rusting.
(4) After cooling, if a compressed air nozzle is used to dry the water in the gap between the bottle cap and the bottle mouth, and a drying device is added, it can effectively prevent the claw paint film scratches caused by the cap from causing rust.
3. Storage and transportation of glass cans
(1) Avoid storing in a humid environment.
(2) During transportation, rubber cushions or other soft cushions must be laid between the bottom and the cap of each overlapping layer.
(3) For the canned products transported from low altitude to high altitude area, it should be noted that due to the decrease of external pressure, if the vacuum degree in the bottle is insufficient, it may cause safety button drum cover.
