How Hot Air Sterilization Can Ensure Food Packaging Is Bacteria Free

This vapor is sprayed into the containers and settles at the inner surfaces of the container. Important for this method is a full coverage without any blind spots to be able to kill all spoiling organisms inside the container. In bottle decontamination systems the surfaces above the neck ring are exposed to the vapour as well.

This process is necessary to ensure complete sterilization of all surfaces that will be in contact with the product. After approximately 4 seconds, the H₂O₂ residuals are dried out with hot air to ensure a maximum residual level of less than 0.5 ppm H₂O₂. This so-called “dry sterilization” offers some advantages: Dry aseptic is cost efficient, has a small footprint in the aseptic filling machine, generates zero waste, and doesn’t need sterile water rinsing.

To assess such systems, sterility tests are performed at every new installation using H₂O₂, peracetic acid, or steam in accordance to various equipment testing standards. To make sure the sterilization process is efficient, test germs like Bacillus atrophaeus and Bacillus subtilis SA 22 are used. For steam, the test germ is Geobacillus stearothermophilus NCA 1518. All surfaces of the packaging material in contact with product will be exposed to the test germs. The contaminated packaging material is then exposed to the sterilization systems of a filling machine using H₂O₂, peracetic acid, or steam. After the decontamination is completed, the log reduction rate has to be at least 10-5 for aseptic systems.

Even though there are many dry sterilization systems in use today, there are alternative sterilization solutions that can be implemented with hot air. While the beverage carton industry is dominated by dry sterilization systems, the majority of aseptic bottle filling systems in the market utilize peracetic acid (wet aseptic) to sterilise the inside and outside of the bottle.

Steam sterilization is mainly used for bottling applications that involve glass packaging. One side effect of this sterilization method is the moisture generated on the surface of the bottle. Not removing this residual moisture can lead to issues with coding, labeling, and bacteria growth. In order to remove this moisture, manufacturers locate hot air products and high-volume blowers on bottling lines before coding and labeling in order to achieve a dry surface on the outside of the bottle; it can also be used to dry the inside of the bottles as well. This method is referred to as a hot air knife.

With the hot air knife process, bottlers mount high pressure blowers and air heaters directly on the manufacturing line. In order to concentrate the airflow to the surface of the bottle, a special type of nozzle is utilized to direct airflow. This nozzle blows a curtain of air, which provides a level of evaporation as the bottles run down the line. Since the high-pressure blower and air heater can be regulated from a control system, this allows for a repeatable process that provides a clean, dry bottle, and can be documented for validation purposes.

The use of air heaters and blowers for the sterilization process provides many benefits for the end user. The air heaters and blowers can be integrated into sterilization equipment with ease by simply sending a signal to obtain the desired output temperature. This allows for repeatability for the end user that can help remove pathogens, improve product quality, and minimize waste. The repeatability also assists in the validation process of the sterilization system. With these added benefits incorporated into the process, manufacturers can have confidence in knowing that they have removed harmful bacteria from their end products.

For food packaging processes, it is essential to take the necessary precautions to ensure that packaging has been thoroughly sterilized. Whether a bottling application or food packaging process, hot air can be used as the driver for the sterilization process to deliver a quality product that is consumer friendly. The end result is a product that is produced in an efficient manner that is safe for consumption.