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1.Scope of application
It is suitable for sampling and testing environmental microorganisms such as the number of air bacteria in the food production workshop, the equipment surface of the product contact surface (direct or indirect), the inner packaging material, and the surface of the human hand.
References
GB 14881-2013 National Food Safety Standard General hygienic specifications for food production.
GB 15979-2002 Hygienic Standard for Disposable Hygiene Products.
gb 4789.1-2016 National Food Safety Standard Food Microbiology Inspection General Provisions.
gb 4789.2-2022 National Food Safety Standard Food Microbiology Test Colony Count Determination.
gb 4789.3-2016 National Food Safety Standard Food Microbiology Test Coliform Count.
Equipment & Materials
Incubator: 36 1;
Refrigerator 0-4 ;
Thermostatic water bath 46 1 ;
Electric furnace: debuggable;
Flat dish: the diameter of the bottom of the dish is 9cm;
Pipette: 10 ml, marked with 0Scale in 1 ml units;
Pipette: 5 ml, marked with 0Scale in 1 ml units;
Test tube; test tube racks; sterilized cotton swabs;
Timer; Pipette: capacity is 10ml;
The inner diameter of the sterilization specification plate is (10cm 10cm);
Alcohol burner; Lighter;
alcohol cotton balls; glass crayons;
Tray. Nutrient agar medium; lactose bile salt medium; Eosin Melan agar medium;
Normal saline, quantitatively aliquoted in glass bottles and test tubes, sterilized.
Procedure
4.1. Sampling and culture of bacterial colonies in the air of the production workshop.
4.1.1. Before sampling, the prepared nutrient agar medium 36 1 was incubated for 24 hours, and the polluted medium was removed to check whether there was contamination.
4.1.2. When sampling, place the dish containing nutrient agar medium (9cm in diameter) at the sampling point (about the height of the table), open the lid of the plate, and expose the dish to the air for more than 5min. The specific requirements are as follows:
4.1.2.1. The room temperature area in the indoor air shall not exceed 30m, and two points shall be set on the diagonal, and the two points shall be 1m away from the wall;
4.1.2.2. The indoor area is more than 30m, with three points inside, middle and outside, and the surrounding three points are 1m away from the wall.
4.1.3. Send the collected medium to the laboratory, let it be incubated for 36 1 for 48 h, observe the results, and count the number of colonies on the plate.
.2. Sampling and detection of contact surfaces
.2.1. The surface of the equipment and the surface of the inner packaging material:
Place a sterilized plate with an inner diameter of 5 cm 5 cm (or other sampling method of at least 25 cm2) on the surface of the object to be tested, apply a cotton swab soaked in sterilized saline solution 10 times, then cut off the part of the cotton swab that touches the hand, and put the cotton swab into a sampling tube containing 10 ml of sterilized saline.
4.2.2 manpower:
The examinee put his fingers together, rubbed 1010 ml back and forth from the tip of his finger to the surface of his right finger with a cotton swab soaked in normal saline
4.2.3. Total number of colonies assay:
In aseptic operation, 1ml of sample solution was taken after each sample tube that has been collected was fully mixed, put it into a sterilized dish, nutrient agar medium was poured, two plates of each sample were inoculated in parallel, and 36 1 was incubated for 48 hours, and the number of bacterial colonies on the plate was counted.
4.2.4. Coliform count detection
4.2.4.1. Initial fermentation experiment.
After fully mixing the sample solution of each type of sample bottle collected, inoculated 3 tubes of lauryl sulfate tryptone (LST) broth, each tube was inoculated with 1ml, placed in 36 1 culture for 24 h, and three samples were made in parallel;
4.2.4.1.1. For gas producers, the first fermentation experiment is carried out.
4.2.4.1.2. If there is no gas production, continue to culture until 48 2 hours, if gas is produced, carry out ** fermentation experiment; If gas is not produced, E. coliform enteric negative is reported;
4.2.4.2**Fermentation experiment.
1 ring of the culture was taken from the gas-producing LST broth tube with an inoculation loop, and transplanted into a brilliant green lactose bile salt broth (BGLB) tube, and incubated at 36°C at 1°C for 48h for 2h to observe the gas production. Gas-producing people are counted as coliform positive tubes.
4.2.4.3 reports of the most probable number of coliforms (MPN).
Press 42.4.2 confirmed the number of BCLB positive tubes for coliform bacteria, and retrieved the MPN table (see Appendix B) to report the MPN value of coliform bacteria per g (ml) sample.
5 Report the results
Query the Most Probable Number of Coliform Bacteria (MPN) search table.
Where: Y1 – the total number of colonies in the air, CFU M3
Y2 – Total number of colonies on the surface of the food contact surface, CFU cm
Y3 – Total number of colonies on the surface of the human hand cfu per hand.
Y4 - Coliform bacteria on the surface of food contact surface (MPN M2), coliform bacteria on the surface of human hands MPN hands.
a - Average number of colonies on a plate.
s1 – slab area.
s2 – sampling area cm
.Production environmental hygiene indicators
7.Record