Application of back pressure technology of autoclave in food industry
The sterilizer backpressure operation involves applying an artificial pressure slightly higher than the internal pressure of the packaging container to the inside of the sterilizer during the sterilization process. This practice is usually achieved by introducing compressed air and is called "backpressure". Its main purpose is to prevent the packaging container from deforming or rupturing due to uneven internal and external pressure caused by temperature changes during the sterilization and cooling stages. Specifically:
During the sterilization stage: As the sterilizer heats up, the temperature inside the packaging container rises, causing the internal pressure to increase. Without backpressure measures, the internal pressure of the can may exceed the external pressure, causing deformation or bulging of the lid. By introducing compressed air, the pressure is raised to slightly higher than or equal to the internal pressure of the product, which effectively prevents deformation.
During the cooling phase: After sterilization, the product needs to be cooled. At this time, the temperature and pressure in the sterilizer will drop, especially when rapid cooling is required, the pressure may drop sharply, and the temperature and pressure inside the product fail to drop synchronously, resulting in excessive internal pressure, which may cause the package to deform or rupture. By continuously applying back pressure during the cooling process, the pressure can be kept stable to avoid damage to the product due to excessive pressure differences.
Back pressure technology is essential to ensure the integrity and safety of packaging containers during sterilization and cooling, preventing deformation or rupture caused by pressure fluctuations. This technology is widely used in the food industry for thermal sterilization of canned foods, flexible packaging, glass bottles, plastic boxes and bowls. By precisely controlling the back pressure, not only can the integrity of the product packaging be maintained, but also the excessive expansion of the gas inside the food can be limited, reducing the pressure on the food tissue, helping to maintain the sensory quality and nutritional content of the food, and preventing damage to the food structure, loss of juice or significant changes in color.
Methods for implementing backpressure include:
Air backpressure: Most high-temperature sterilization technologies use compressed air to regulate pressure. During the heating phase, the right amount of compressed air is injected according to a precise calculation. This method is applicable to many types of sterilizers.
Steam backpressure: For steam sterilizers, the overall gas pressure is increased by injecting the right amount of steam to achieve the required backpressure level. Steam here plays both a heating and a pressurizing role.
Cooling backpressure: Backpressure technology is also important during the cooling phase after sterilization. In order to prevent a vacuum from forming inside the package and causing the container to collapse, backpressure needs to continue to be applied during the cooling process, which is usually achieved by continuously injecting compressed air or steam.