How to evaluate the anti-mold effect of leather anti-mold agent ?
The evaluation of the antifungal effect of the leather antifungal agent generally includes two aspects. On the one hand, the detection of the effectiveness of the antifungal agent, the main purpose of which is to determine whether the drug has the ability to inhibit or kill the mold.
Commonly used evaluation methods include: inhibition zone method, plate pour method, spot bacteria method, dilution culture method, diffusion method, determination of minimum inhibitory concentration (MIC), etc.; on the other hand, antifungal effect after adding mildew inhibitor to leather Commonly used laboratory evaluation methods include: inhibition zone method, natural exposure method, wet room suspension method, soil burying method, medium method, and the like.
At present, the laboratory evaluation methods frequently used by tanners are as follows.
(1) inhibition zone method
Using a round paper or a round skin (generally 2 to 4 cm in diameter), immersed or rotated in a certain concentration of the anti-mold agent solution for a period of time, and then attached to a culture of coating a certain amount of mold spore suspension Center the plate, then incubate for a period of time at a temperature of (28 ± 1) ° C, relative humidity ≥ 95%, observe the presence or absence of a transparent zone of inhibition around the round paper or round skin, or use a Vernier caliper to measure The diameter of the mushroom circle. The inhibition zone method is only a qualitative or semi-quantitative method, and the size of the zone of inhibition is affected by the ability of the mold inhibitor to spread on the agar plate (with the nature of the mold inhibitor, the solvent of the mold inhibitor dissolved in the mold inhibitor) The type, the composition of the medium, the distribution of the antifungal agent in the skin, and the culture conditions are all greatly affected, and thus the reference effect is limited. However, this method also has the advantages of simple operation, identifiable to the naked eye, good visuality, and the like, and is often used for the preliminary evaluation of the mildewproof effect of the mold inhibitor.
(2) Minimum inhibitory concentration (MIC) method
The test mildew inhibitor is formulated into a series of concentrations, and then 1 mL is taken out aseptically, added to the sterilized culture dish, and then 1 mL of the test bacterial suspension is injected into each culture dish (or by inoculation loop) The suspension of the test strain is streaked on the agar medium plate to which the fungicide is added and solidified, and finally, a predetermined 40° C. agar medium is injected into each of the culture dishes, and uniformly mixed and coagulated. It is placed in an environment with a temperature of (28 ± 1) ° C and a relative humidity of ≥ 95% for a period of time (generally 3 to 5 days), and the lowest concentration of the test species can be checked and compared. The MIC method is a quantitative method, which can better reflect the virulence of the anti-fungal agent and facilitate the comparison of the anti-mildew effects between different anti-fungal agents. It is one of the most commonly used virulence expression methods. However, there are many factors affecting the MIC value, such as the source of the test strain, the inoculum amount, the number of mold spores in the mold spore suspension, the medium, the solvent type in which the mold inhibitor is dissolved, the culture conditions, etc., so The MIC of the mold inhibitor should be carried out under the same conditions.
(3) Wet chamber suspension method
The anti-mold agent-treated skin (usually a long square of 2.5 cm × 5.0 cm) is sprayed on the surface of the skin with a spray of the mold for spore suspension, and then suspended in a constant temperature and humidity chamber. The temperature was (28 ± 1) ° C, relative humidity ≥ 95%] cultured for 28 days, and the mildew condition was observed regularly, and the mildew effect of the mildew inhibitor was judged by the long mildew condition of the skin.
The tested strains are generally Aspergillus niger, Aspergillus flavus, Penicillium citrinum, Penicillium fuliginea and Trichoderma. This method of measurement is an accelerated test simulating the natural environment. The sample mold resistance is 0 or 1 grade, and the others are unqualified. Each of these methods has its own advantages and disadvantages. For the same anti-mold agent, different evaluation methods may be used. The results may not be the same. Even if the same method is used, the results will be different due to different conditions such as time, place and tester. Differences. Therefore, the accelerating test methods of these laboratories only have certain reference value, and the real application performance of the antifungal agent must also be verified by practical application.
