Home > Guidelines for on-site low temperature disinfection evaluation of cold chain food packaging

Evaluation principle:

On site low temperature disinfection evaluation includes process evaluation and effect evaluation. Process evaluation shall be conducted for each low-temperature disinfection. Generally, the disinfection implementation unit shall conduct self inspection and self-evaluation. Relevant supervision departments can conduct random inspection on the disinfection process and self-examination and self-evaluation process to ensure the effectiveness of the disinfection process. The effect evaluation generally adopts the method of regular random inspection, and it is recommended to evaluate once every half a year. When the low-temperature disinfection method is changed, the disinfection effect shall be evaluated to prove that the low-temperature disinfection is effective before it can be put into use.

On site low temperature disinfection process evaluation:

During each disinfection process, the disinfection implementation unit shall make disinfection records and conduct self-evaluation to evaluate whether the whole disinfection operation is carried out according to the disinfection work plan, whether the low-temperature disinfection products used are legal and effective, whether the disinfection method matches the disinfection object and environment, whether the disinfection parts are fully covered, whether the use amount meets the requirements, and whether the disinfection action time is sufficient Whether the disinfection records are standardized, etc. The contents include but are not limited to disinfection day, disinfection place, disinfection scope, disinfection object, disinfection procedure, disinfectant preparation, disinfectant concentration and dosage, action time, disinfection method, disinfection equipment, personal protection, etc.

The low-temperature disinfection products used shall meet the requirements of relevant national health standards and specifications, and the health and safety evaluation shall be qualified. Disinfectant information includes disinfectant name, main active ingredients and their content, validity period, preparation method, application scope, application method, etc; Disinfection equipment information includes equipment name, main sterilization factors and their intensity, scope of use, method of use, etc.

Evaluation of disinfection effect of low temperature on site:

Evaluation objects and indicators:

The evaluation object of low-temperature disinfection effect is the object surface. Indicator microorganisms are selected according to the resistance of COVID-19 virus to disinfection factors, and the killing rate of indicator microorganisms is taken as the evaluation index. Indicates that the resistance of the microbe should be equivalent to or higher than that of the Novel Coronavirus, easy to cultivate and in compliance with laboratory biosafety and WS/T683 requirements. For chemical disinfection,  staphylococcus aureus (ATCC 6538) and Escherichia coli (8099) can be used. During physical disinfection, the indicator microorganism meeting the above requirements should be selected according to the characteristics of disinfection factors.

Evaluation method:

Prepare bacterial tablets for experiment according to GB / T 38502 (tryptone soybean broth medium is used as organic disruptor in the evaluation of low-temperature field disinfection effect), so that the number of recovered bacteria of each bacterial tablet is 1x106CFU / tablet ~ 5 x106CFU / tablet. Put the indicator microorganism tablet into the corresponding low-temperature environment, and at least ensure that the indicator microorganism reaches the same low temperature before the next operation.
Before disinfection: put the bacteria tablets on the site, and focus on the desktop, door handle, button, etc., with no less than 2 samples for each type of object; For the outer packaging of cold chain food, points shall be arranged on six sides of the outer packaging; The total number of test samples shall not be less than 30.

After disinfection: after the disinfection reaches the action time, use sterile tweezers to move the bacterial tablets into the test tube containing 5.0 ml of corresponding neutralizer, vibrate 80 times in the palm of the hand or mix evenly with a mixer and neutralize for 10 minutes. At the same time, a positive control group should be  established.

Laboratory culture: shake the sampling tube on the mixer for 20 s or shake it vigorously for 80 times, absorb 1.0 ml of the sample to be tested and inoculate it on sterile plates, inoculate two plates in parallel for each sample, add 15 ml ~ 18 ml of dissolved culture medium at 45 ℃ ~ 48 ℃, pour and shake it evenly, wait for agar to solidify, incubate at 36 ℃ ± 1 ℃ for 48 hours, count the number of colonies and calculate the killing rate.

Result judgment:

The average killing rate of indicator microorganisms on the object surface is ≥ 99.9%, and the number of samples with killing rate > 99.9% accounts for more than 90%, which is judged as qualified disinfection.

Matters needing attention:

Combined with the characteristics of the place, clarify the disinfection object, and carry out the disinfection work in strict accordance with the disinfection procedures and specifications.

The implementation unit of disinfection work shall have the ability of on-site disinfection. The operators shall receive professional disinfection training, master the basic knowledge of disinfection and personal protection, and be familiar with the use of disinfection equipment and the preparation of disinfectants.

All on-site disinfection shall be recorded and kept for at least 2 years, and self-monitoring shall be carried out at the same time. When conducting disinfection effect evaluation, attention should be paid to standardized operation, and harmless treatment of samples and relevant test materials should be done in strict accordance with biosafety requirements.

During on-site disinfection, personal protection shall be done well, and formal and effective personal protective equipment shall be selected according to the on-site conditions and relevant standards.

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