Frequently Asked Questions

Microorganisms have different levels of resistance. To kill all germs, the item being sterilized is heated in steam at 121°C at a pressure of two bar for 20 minutes, or at 134°C at 3 bar for 5 minutes. To destroy prions, it is heated to 134°C at 3 bar for 18 minutes.

The F0 value is a time specification in minutes and is a measure of the effectiveness of the sterilization process with moist heat. The F0 value depends on the z-value; each microbe species has a different z-value. The z-value is the thermal resistance constant of a microorganism and is given as a temperature difference in K or °C to 121.1°C. To ensure that all known microbes are reliably killed, the z-value for the sterilization of medical devices with moist heat was set at 10°C. The formula for calculating the F0 value is: F0 = Δt[minutes] × 10^((T−121)/z). This formula results in a sterilization time of 20 minutes at 121.1°C, which is mandatory for medical devices.

Sterilization is carried out all over the world, which is why an internationally valid regulation was wanted. The calculation for the sterilization rules in Fahrenheit results in a value of 250°F for 20 minutes. 250°F corresponds to 121.1°C, which is why you sometimes see this temperature specification.

Spices and dried herbs can be contaminated with microorganisms such as salmonella or molds during cultivation, harvesting, and processing. Sterilization significantly reduces these germs and ensures that the products meet applicable food and hygiene standards.

Imtech-Steri relies on vacuum steam batch sterilization. Saturated steam is used under controlled process conditions to effectively reduce microorganisms. This method is considered particularly effective and, at the same time, gentle on the product.

Modern steam sterilization processes are designed to preserve organoleptic properties -taste, smell, and texture -as much as possible. Precise control of temperature, pressure, and time achieves a balance between microbiological safety and product quality.

The processes aim to significantly reduce pathogenic germs such as salmonella, enterobacteria, or molds. The specific log reduction depends on the product and the defined process parameters.

There is no general explicit obligation to sterilize. However, food manufacturers are legally required to place safe products on the market. In many markets, validated microbial reduction is practically a prerequisite for compliance.

Imtech-Steri supports customers with process validation and documentation. Relevant parameters such as temperature and pressure are monitored and documented, ensuring traceability.

The process is particularly suitable for dry food ingredients such as spices, herbs, seeds, nuts, or flours. Specific suitability is assessed through technical review and consultation.

Yes. In addition to engineering solutions, Imtech-Steri offers sterilization as a service for batch processing. Companies can have their products treated externally or integrate customized system solutions.

Within the framework of quality assurance, validation is to be divided into three stages: Installation Qualification (IQ), Functional Qualification (OQ) and Performance Qualification (PQ), as defined by Swiss Good Practice for the Reprocessing of Medical Devices.

IQ covers: testing of water/steam quality; testing of the sterilizer installation; structural and technical requirements; testing of the manufacturer's documentation; description of the programs; description of the process parameters and tolerances; description of the product family(s) that can be sterilized and their limitations regarding size and/or weight; description of the reference load, sterilizer loading plan and list of instruments. The IQ and OQ are each part of the installation of a new system.

OQ covers: calibration of the system pressure/temperature; testing for air leaks (checking the cycle parameters and the test); steam penetration test (B&D test, checking the cycle parameters and the test); steam penetration test with hollow-body systems (Process Challenge Device, PCD) according to SN EN 285.

PQ covers: thermometric testing of a minimum load; thermometric testing of three reference loads per program; interpretation of physical parameters (time, temperature, pressure, theoretical temperatures); assessment of the dryness of the reference load; visual inspection of the integrity of packaging and sterilized medical devices.

Following the detailed validation, requalification must be carried out annually. It consists of the IQ, OQ and PQ qualification stages, as defined by Swiss Good Practice for the Reprocessing of Medical Devices.

Testing the quality of the water and steam condensate.

Calibration of the system (pressure/temperature); testing of the safety and fault-detection systems; air-leakage testing; steam penetration testing (B&D test); steam penetration testing with hollow-body systems (Process Challenge Device, PCD) according to SN EN 285. We perform the IQ and OQ revalidation as part of our annual maintenance.

Thermometric testing of a minimum load; thermometric testing of one reference load per program; testing of the reproducibility and interpretation of the physical parameters (time, temperature, pressure, theoretical temperatures) compared to the previous validation; assessment of the dryness of the load; visual inspection of the integrity of the packaging and the sterilized goods.

Non-condensable gases (NCG) in the sterilizing steam, such as air and/or CO2, can seriously jeopardize the efficiency of steam sterilization processes under certain conditions. These gases enter the steam for various reasons. Small quantities of NCGs are not critical, as long as the steam or water can mix with them and this mixture reaches all surfaces to be sterilized. The critical NCG quantity depends on the goods. For example, a 7 kg Bowie-Dick test pack reveals errors via an inserted indicator sheet or the growth of inserted biological indicators; this detects whether 150–200 ml of air has accumulated inside the pack. Due to the high steam consumption when heating the load from room temperature to sterilization temperature, even a low NCG concentration can accumulate to quantities that compromise sterilization safety. The NCG content is therefore an important quality characteristic of sterilizing steam. The limit value for NCGs in DIN EN 285 of 3.5% is used to assess the performance of sterilization processes for standardized loads. Tolerable NCG quantities in practice must be determined during process validation.