Home page

How is the sterilization efficacy of a steam-pressure sterilizer verified?

Release time：2015-08-03

1. Experimental Materials

① Thermophilic Bacillus spore strips; Thermophilic Bacillus ATCC 7053, with a spore count of 5–10⁵ CFU per strip.

② Chemical indicator cards for 121°C steam sterilization; bromothymol purple peptone water medium, autoclaved at 116°C for 20 minutes and set aside for later use.

③ 0–150°C spot thermometer

2. Methods and Results

Place the thermophilic Bacillus spore test strips into sealed test tubes using sterile forceps. Place the chemical indicator cards and the thermal retention thermometer in open test tubes. Prepare 5–10 replicates of each type of tube, and position them at five locations: the steam outlet, the bottom exhaust port, the bottom water inlet, and the upper, lower, left, right, and central points. If the autoclave has two tiers, a total of 10 sampling points are required. Once the thermal retention thermometer has been properly calibrated, it may be used for validation testing. Prior to testing, the mercury column of the thermometer must be shaken down below 40°C. After each monitoring cycle, if the temperature difference recorded by the thermal retention thermometer remains within 1°C, this indicates that the temperature distribution inside the autoclave is uniform. The spore test strips should be placed, under strictly aseptic conditions, into bromothymol purple peptone broth. Incubate at 56–60°C for 24–48 hours and observe any color changes. If the medium turns yellow, it indicates that the thermophilic Bacillus spores on the test strip have not been completely inactivated; the bacteria can still grow in the medium, ferment glucose to produce acid, and cause the medium to turn yellow. If the medium retains its original purple color, it means the spores have been inactivated. At the same time, include unexposed test strips in the medium as a positive control, and use a blank medium without any test strips as a negative control. On the chemical indicator card, the indicator color block will change from pale yellow to black during autoclaving. By assessing the degree of color change and comparing it with the reference color, one can determine whether the sterilization performance meets the required standards. Chemical indicator cards should be stored in a dry place; exposure to moisture can cause discoloration and interfere with accurate observation of the results. The autoclave must ensure that steam enters the chamber smoothly, comes into contact with the articles being sterilized, and displaces the pre-existing cold air in order to achieve the desired sterilization effect. Both empty-load thermal distribution and full-load thermal penetration tests must be conducted (with the load not exceeding two-thirds of the total chamber volume). Each type of verification should be repeated three times, for a total of six tests. The results from the five sampling points across all six tests show that the temperature consistently reached 121°C, the chemical indicator cards turned black, the degree of color change matched the reference color, and the culture media remained unchanged in color, indicating that Autoclave The result is qualified.

The quality of sterilization equipment affects food quality.

Sterilization methods

+ More Products

2025-05-19

The 2025 Shanghai Pujiang International Intellectual Property Forum Concludes Successfully, with Jiangyin Binjiang Medical Equipment Co., Ltd.

Learn More →

2021-06-09

Solemn Statement

Recently, Jiangyin Binjiang Medical Equipment Co., Ltd. (hereinafter referred to as “our company”) discovered that information about our products and promotional materials are being posted on Taobao and various other online platforms. We hereby solemnly declare that, apart from our official website, our company has never registered any merchant accounts on any other online platforms, nor has it ever published product information or promotional materials on such platforms.

Learn More →

2020-11-25

How to Properly Use Electric Heating Equipment Such as Oven Dryers

The oven must be placed indoors in a dry, level location to prevent vibration and corrosion. Always ensure that the power supply is properly monitored: select a power switch and wiring that match the oven’s power consumption and capacity, and provide a reliable grounding connection.

Learn More →