After the reform and opening up, the development of China's beverage industry has been very rapid. The varieties of beverages have gradually developed from simple carbonated beverages in the past to mineral water, fruit juice, fruit and vegetable juice beverages and functional beverages; the filling method has also developed from cold filling to the current hot filling, medium temperature filling, aseptic cold filling, etc.; the packaging form has also changed from a single glass bottle to the current aluminum cans, PET bottles, etc.
After the microorganisms are irradiated by ultraviolet light, their proteins and nucleic acids absorb the energy of the ultraviolet spectrum, which will cause protein denaturation and cause the death of microorganisms.
In the beverage filling production equipment, the capping machine is a capping machine or a capping machine to convey the bottle caps. Ultraviolet sterilization lamps are installed on the upper part of the storage bin of the capping machine or the upper part of the conveyor belt. The bottle caps are exposed to ultraviolet rays during the conveying process, and the places where the ultraviolet rays are irradiated can achieve better sterilization effects. Due to the poor light transmittance of the bottle caps, ultraviolet rays cannot penetrate the bottle caps to irradiate the other side of the bottle caps. Therefore, the bottle cap can only be partially sterilized, and the sterilized surface is random. In order to sterilize the bottle cap surface in a targeted manner, an ultraviolet sterilization lamp is installed on the lower slide of the bottle cap of the capping machine or the capping machine. The bottle caps passing through here have been arranged in the same direction. The side irradiated by ultraviolet light is the side of the bottle cap in contact with the beverage, which effectively improves the sterilization effect.
Ultraviolet sterilization equipment is simple, does not require supporting equipment, has low cost, is easy to operate and manage, and is widely used. Due to the structural characteristics of the slide and the ultraviolet killing characteristics of microorganisms, ultraviolet sterilization is generally suitable for the following types of beverage filling bottle caps:
Carbonated beverages：Carbonated beverages contain CO2, which is acidic and can inhibit the growth of microorganisms. Therefore, the use of ultraviolet sterilization for carbonated beverage bottle caps can meet the needs. During production, the new bottle caps are poured into the storage bin of the capping machine, and the bottle caps are sterilized by ultraviolet radiation in the storage bin of the capping machine or on the conveyor belt. Ultraviolet sterilization lamps can also be set on the lower cap slide of the capping machine to sterilize the inner surface of the bottle caps by ultraviolet radiation, and then directly transported to the capping machine after sterilization.
Mineral water beverages：The state has formulated relatively strict regulations on the production of mineral water, among which the total colony count, mold count and E. coli count of mineral water are strictly limited to zero. Regardless of whether the mineral water has been filtered and sterilized, its total bacteria count, mold count and E. coli count must meet national standards. Since mineral water contains only inorganic salts, no microbial nutrient sources, and lacks nutrients for microbial production and development, ultraviolet sterilization can also be used for its bottle caps.
Tea drinks and fruit juice drinks filled at high temperature：There are various microorganisms (bacteria, molds and yeasts, etc.) in tea drinks and fruit juice drinks. The sterilization of beverages is to kill these microorganisms. At present, high-temperature short-time sterilization method, also known as instantaneous sterilization method, is generally used. High-temperature filling is to cool the beverage after instantaneous sterilization to a temperature range between 85℃ and 92℃ for filling. The beverage bottle uses a crystal heat-resistant hot filling bottle, and the bottle cap uses a heat-resistant bottle cap that can withstand 85℃. The filling method uses full bottle filling. After filling and capping (or screwing the cap), a bottle inversion device is added: the bottle body is tilted 90°~180°, and the high temperature of the beverage itself is used to sterilize the inside of the bottle cap. Therefore, ultraviolet sterilization can also be used for the preliminary treatment of the bottle cap.
Heating sterilization is one of the most traditional methods of food preservation. If microbial cells are heated to a certain temperature, the physiologically active substances in the cells (such as enzyme proteins, nuclear proteins, deoxyribonucleic acid, etc.) will denature and passivate, thus losing their activity and dying. The heating temperature and time for killing microorganisms vary significantly according to the type of microorganism, the physiological state of the cells, the cell concentration, etc. For killing a specific species of bacteria, increasing the sterilization temperature can shorten the heating time, and lowering the temperature requires extending the heating time. If the temperature is too low, it will not have a sterilizing effect on certain heat-resistant bacteria.
Hot water spray sterilization is to use nozzles to spray hot water on the bottle caps in multiple directions, while sterilizing and removing dust on the inner and outer surfaces of the bottle caps. In this method, the bottle caps after capping move in the same direction in the bottle cap channel, and multiple groups of nozzles are set above and below the channel. The nozzles spray hot water in multiple directions on the advancing bottle caps. The temperature of the hot water is the sterilization temperature, and the time of receiving the spray is the sterilization time.
Due to its high temperature resistance, the temperature of the hot water sprayed on the metal cap can exceed 85℃, and the spraying time can be reduced as the hot water temperature increases; for plastic bottle caps, the temperature of the hot water sprayed is generally controlled at 85℃. After hot water sterilization, the bottle cap needs to be sprayed with sterile air to promote the drying of the bottle cap.
Hot water spray sterilization requires hot water and sterile air, and requires corresponding supporting equipment. It consumes heat energy and a small amount of water resources during production, and is equipped with commonly used general equipment. Hot water spray sterilization can be used for the treatment of bottle caps of high-temperature filled tea beverages and juice beverages, and can also be used for the sterilization of mineral water bottle caps.
Ozone has a very strong oxidizing property, which can directly destroy the RNA or DNA of the virus and kill it. Ozone can also damage the cell membrane of bacteria and mold microorganisms, inhibit their growth, and further penetrate and destroy the tissue inside the membrane until the bacteria and mold microorganisms die. Ozone is dissolved in water and has a very good sterilization effect in a humid environment. Ozone water can also be used to sterilize bottle caps. Ozone water sterilization will be discussed later. The higher the ozone concentration, the better the sterilization effect. When the ozone concentration is 4.0mg/m3, the sterilization time generally takes 45 minutes to 1 hour.
Since ozone sterilization takes a long time, for an automated beverage production line with a certain production capacity, if the sterilization effect is to be met and the bottle cap sterilization process is to be completed continuously in the sterilization equipment, the sterilization equipment needs to be very large. In the actual production process, bottle cap ozone sterilization is to place a certain amount of bottle caps in a larger sealed space on an automated beverage production line with a certain production capacity, and then fill the space where the bottle caps are located with a certain concentration of ozone and keep it for a period of time. The number of bottle caps placed is determined by the number of bottle caps required to maintain production. The longer the sterilized bottle caps are stored, the greater the risk of contamination, so the storage time is generally not more than one week. The sterilized bottle caps need to be isolated from the outside world and sent to the cap conveyor when the cap conveyor needs them.
At present, independent equipment that directly uses ozone sterilization is mostly seen in small cabinet-type bottle cap sterilizers. This type of bottle cap sterilizer has a small sterilization space, small production capacity, interval production, and is non-automatic. When using this ozone sterilizer, it is necessary to manually move the sterilized bottle caps out of the sterilizer and put them into the cap conveyor, which is easy to cause secondary contamination of the bottle caps. Therefore, ozone sterilization is only suitable for non-automated production lines or small production lines that have certain sterilization requirements for bottle caps.
There are unstable elements in sterilizing water, which will decompose by themselves. Sterilizing with sterilizing water is to use this decomposition process (oxidation process) to oxidize the microorganisms on the surface of the object, thereby achieving the purpose of sterilization.
Common substances with strong oxidizing properties are: peracetic acid, ozone water and chlorine water. The instantaneous sterilization properties of ozone are better than chlorine. At present, the sterilizing water for sterilizing beverage bottle caps is basically peracetic acid and ozone water, most of which are peracetic acid. The higher the concentration of the sterilizing water, the shorter the sterilization time required. For 65℃2000PPM peracetic acid, the bottle cap can meet the commercial sterility requirements by sterilizing for 30 seconds to 60 seconds. Due to the short sterilization time and good sterilization effect of sterilizing water, it is widely used in the sterilization of bottles and caps of fruit and vegetable juice beverages. The main ways to sterilize beverage bottle caps with sterilizing water are spraying and immersion.
1. Spraying is to use multiple groups of nozzles to spray sterilizing water in multiple directions of the bottle cap to sterilize the surface of the bottle cap. The time for the bottle cap to be sprayed should ensure that the microorganisms can be completely killed. The specific method is: the bottle caps after capping enter the bottle cap track in the same direction. There are multiple groups of nozzles above and below the track. Each group of nozzles can spray sterilizing water on the bottle caps from different angles. The sprayed sterilizing water sterilizes the bottle caps and pushes the bottle caps along the track.
When peracetic acid is used as sterilizing water, the bottle caps sprayed with sterilizing water need to be rinsed with sterile water to remove the residual peracetic acid on the bottle caps, so that the residual amount is lower than the relevant standard; after rinsing with sterile water, the bottle caps are blown dry with sterile air.
When ozone water is used as sterilizing water, since the products of ozone water decomposition are water and oxygen, there are no harmful residual substances. In theory, there is no need to process the bottle caps again. However, in the actual production process, the outlet of the bottle cap sterilizer is very close to the capping machine, and the residual ozone cannot be completely decomposed. Therefore, the bottle caps need to be rinsed with sterile water and blown dry with sterile air after ozone water sterilization.
Due to the linearity of the spray water, sterile water spray sterilization can be used to sterilize mineral water bottle caps, and can also be used to sterilize bottle caps during hot filling of tea beverages and juice beverages. Hot filling adopts full bottle filling, and after filling and capping, the bottle is turned upside down and heated for internal sterilization.
2. Immersion type is to completely immerse the beverage bottle caps in sterilizing water so that all the inner and outer surfaces of the bottle caps are sterilized by sterilizing water. The immersion time should meet the time requirements for complete sterilization of the bottle caps. One method is: the bottle caps with the same direction are fixed on the bottle cap rack, and the bottle cap rack is connected to the chain. The movement of the chain drives the bottle cap rack into the sterilization pool filled with sterilizing water and completely immerses the bottle caps in the sterilizing water. The immersion time should meet the time requirements for complete sterilization. Like the spray sterilization method, the bottle caps after being soaked in sterilizing water also need to be sprayed with sterile water and sprayed with sterile air to make the bottle caps dry and sterile.
When sterile water is used for sterilization, the sterilizing water, sterile water and sterile air need to be produced and processed. There are many peripheral supporting equipment, high supporting costs, high consumption costs and high management requirements. Therefore, this sterilization process is generally used for aseptic cold filling of fruit juice beverages.
Electrolysis is the use of inert electrodes to pass electricity in the liquid, and the anode undergoes oxidation reaction and the cathode undergoes reduction reaction. At present, relevant foreign personnel have studied the use of completely desalinated drinking water and sodium chloride dilute solution to produce an electrochemical reaction, and obtain a sterilizing solution in the anode area with a better sterilization effect than traditional sterilizing water. If the electrolysis principle is directly used for bottle cap sterilization, it can greatly reduce transportation and storage costs, save time and effort, and be safe and effective.
Summary
Analyzing the various bottle cap sterilization methods mentioned above, different cap sterilization processes can be selected according to the ingredient characteristics and quality requirements of different beverages, as shown in the table:
| Bottle cap sterilization method | Applicable beverages for sterilized bottle caps | Environmental requirements for sterilized bottle caps | Remarks |
| Ultraviolet sterilization | Carbonated beverages, mineral water | 10,000-grade aseptic | |
| Hot water spray sterilization | Mineral water, juice drinks and tea drinks in hot filling state | 1,000-grade aseptic or 10,000-grade aseptic | |
| Ozone sterilization | 1. Use a large sealed space to place the bottle cap to fill the ozone sterilization method: mineral water, fruit juice drinks and tea drinks in hot filling state | 1,000-grade aseptic or 10,000-grade aseptic | Not applicable to metal bottle cap sterilization |
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2. Use ozone sterilization cabinet for sterilization: small production capacity semi-automatic Non-sterile cold-filled beverages |
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| Sterilized water sterilization | 1. Spray type: Mineral water, fruit juice drinks and tea drinks in hot filling state | ||
| 2. Immersion type: can be used for all beverages, more suitable for all beverages in aseptic cold filling state | 100-level aseptic | Not suitable for metal bottle cap sterilization | |
| Electrolytic sterilization | Can be used for all beverages, more suitable for all beverages in aseptic cold filling state | 100-level aseptic | Not suitable for metal bottle cap sterilization |
