The main reason for the excessive coliform bacteria in food is secondary pollution. The number of coliforms indicates the degree of fecal pollution and the degree of harm to human health, so the main reason for coliforms exceeding the standard is secondary pollution. If the processing equipment is not cleaned and disinfected regularly, the operator will not wash his hands thoroughly after going to the toilet, and his personal hygiene will not meet the standard, which will directly affect the hygiene of the final product.
Extended data:
Precautions:
1. Pay attention to aseptic operation during sample inspection.
2. Diluent used for dilution can be phosphate buffer or physiological saline. Inoculation is carried out by nine-tube method, and three gradients are set, namely, 0. 1g/mL, 0.0 1g/mL and 0.00 1g/mL, and each dilution tube should be fully mixed.
3. Each experiment needs a negative control.
4. When preparing a small inverted tube culture medium, in order to remove bubbles, don't cover the test tube too tightly during sterilization, and pay attention to observe whether the gas in the inverted tube is completely discharged after sterilization.
5. After autoclaving, when the pressure gauge of the autoclave reaches 0, take out the culture medium and put it in the refrigerator for cooling, and the effect will be better.
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