How to kill E. coli in milk production Ask for specific operation steps Thank you!

Pasteurized milk is generally pasteurized, or UHT ultra-high temperature instantaneous sterilization, there is no moist heat sterilization method, pasteurized milk due to the low temperature (about 65 90 degrees, the general pathogenic bacteria at this temperature can be killed, except for some thermophilic and heat-resistant spores, the lower the temperature, the longer it takes), the taste and flavor are preserved better, and the ultra-high temperature is 135 140 like this, and the duration is about 4 seconds to 10 seconds, due to the relatively short time, Protein can still be preserved relatively well, and will not be denatured (not spoiled).

Coliform bacteria is one of the important indicators to evaluate the quality of food hygiene, and has been widely used in food hygiene inspection. Coliform bacteria are mostly found in warm-blooded animal feces, places where human activities are often carried out and places where feces are contaminated, and the number of coliform bacteria indicates the degree of contamination in food and food production processes.

Coliform Bacteria Test Strip (FilmplateTM

enumeration of coliformbe211) contains a selective medium, a chromogenic indicator of coliform bacteria-specific galactosidase, and a polymer hydroabsorbent gel, which is made into a one-time rapid test product using proprietary technology. Shenzhen Sanfangyuan products are suitable for counting coliform bacteria in food, drinking water and raw materials, and can also be used for hygienic testing on the surface of food processing equipment. Executive Standards:

National standards. Food microbiology test coliform count.

One is to heat the milk to 62 65 and hold it for 30 minutes. Using this method, it can kill all kinds of growth pathogenic bacteria in milk, and the sterilization efficiency can be reached, and only some thermophilic bacteria and heat-resistant bacteria and spores remain after disinfection, but most of these bacteria are lactic acid bacteria, and lactic acid bacteria are not only harmless to people but beneficial to health.

The second method heats the milk to 75 90 and keeps it warm for 15 16 seconds, which has a shorter sterilization time and higher work efficiency. However, the basic principle of sterilization is that the pathogenic bacteria can be killed, and if the temperature is too high, there will be more nutrient loss.

In addition, with the advancement of technology, ultra-high temperature sterilization (higher than 100 °C, but with a short heating time and less damage to nutrients) is also used to treat milk. Milk that has been processed in this way has a longer shelf life. Most of the kind of carton milk we see is packaged in this way.

Pasteurization and UHT sterilization.

UHT sterilization.

That is, the product is heated to 135 150 for 4 15 seconds, after which the milk is aseptically packaged to protect the product from exposure to light and oxygen in the air, so it can be stored at ambient temperature.

UHT technology is effective in destroying bacteria, but at the same time preserving the original nutrients of the milk. The study showed that UHT treatment had no effect on the nutritional value of fats, minerals and major proteins in milk, and that the nutritional value of essential amino acids and vitamins was only slightly changed. UHT milk needs to be fresh, high-quality milk.

After entering the production hall, the first step is to carry out the unique process of pre-treatment. The raw milk is heated to 75 degrees in a sealed pipe to activate the bacteria in the milk, which is subsequently enhanced by UHT sterilization. Because if milk is to be sterile, raw milk must ensure that the number of bacteria per milliliter does not exceed 30,000 before UHT sterilization, which is actually the standard for pasteurized drinking milk, but the standard for UHT milk is higher.

The pre-treated milk is then subjected to the UHT process, which is also carried out in a completely closed and sterile environment. The outside staff heated the milk in the closed pipe to 135 by heating it three times, and then cooled it quickly for a few seconds. In this way, not only can the bacteria in the milk be fully killed, but the nutrients in the milk will not be destroyed because the heating time is very short, only about 4 seconds.

The first method is E. coli MPN counting.

Procedure. Dilution of the sample.

Recently, E. coli has often appeared in the solid workshop of our factory, which not only causes the problem of unqualified bacterial testing, but also causes certain economic losses. In order to better improve the situation, we must all act together and adopt a series of effective countermeasures.

Although E. coli is almost ubiquitous in the natural environment, as long as we cut off the source of E. coli, I believe that in the near future we will say goodbye to "E. coli".

Personally, I think that E. coli appears frequently in the workshop, which may be due to the following reasons: poor sanitary conditions, unsatisfactory ventilation equipment, and poor management. Although disinfection can temporarily solve the problem of the "large intestine", we must be clear about the important purpose of disinfection, one of which is to create a good environment for the survival and reproduction of disease-causing microorganisms through disinfection

The second is to kill and inhibit the pathogenic microorganisms that have been generated, so as to reduce the chance of cross-infection. On the basis of the above, it is particularly necessary to pay attention to strengthening the awareness of management: understanding——— obeying ——— implementing ——— supervision.

In the workshop production, several aspects should be noted: 1. The water source and purified water must be qualified. 2. Regular inspection and measurement.

3. Avoid cross-contamination. 4. Pay special attention to places that are difficult to clean (such as return air outlets, dead corners, etc.). 5. Change the disinfectant from time to time.

6. Always remind yourself and consciously execute.

Therefore, we must always remind ourselves to prevent E. coli and strive to do our job well: do a good job in management, and eliminate all external causes as much as possible: do a good job and manage environmental hygiene, disinfect regularly, and change disinfectants from time to time.

Maybe we can easily solve this problem now, but if we don't raise our awareness and strengthen management, it may always be a constant topic.

I don't think it's an edible food, so it won't contain too much! You can process it at high temperature before eating it, and drink some liquor at the end. There shouldn't be a problem.

Recently, E. coli has often appeared in the solid workshop of our factory.

Escherichia coli, also known as Escherichia coli, was discovered by Escherich.

Methods and specific steps for raising E. coli:

1. Fermentation method, this method is mainly to culture E. coli on the lower medium, which contains fluorescent substrate and needs to be cultured for 24 h.

The fluorescent substrate is then released, which requires glucuronic acid to allow the medium to fluoresce under UV light. The main steps include fermentation, separation and culture, secondary fermentation, microscopic observation, etc.

2. The main process of the filter membrane method: add about 10 ml of sterile water to the filter, then add some sterile water to clean the inner wall of the filter, and then filter, put the filter membrane in M-FC medium, there can be no bubbles between the two, and then seal, store at a temperature of about 24 h, until the flora of E. coli turns blue or blue-green.

(1) Make a medium (containing carbon source, nitrogen source, growth factors, no base salts) (2) Sterilize the medium (very important).

3) Vaccination. 4) Culture.

1.Serve a bottle of LB and sterilize.

2.The preserved bacteria were coated or picked on a solid medium and incubated at 37 degrees.

3.The grown bacteria were picked and dropped into the sterilized LB at about 200 revolutions per minute at 37 degrees shaking and cultured.

Resuscitation: Prepare LB solid baii nutrient base, autoclave sterilization, and pour plates.

Pick the strain DAO and draw a line on the cultivation base.

37 Incubate for 24 hours until it grows.

Colonies. Shake bacteria to prepare LB liquid medium. Autoclaving.

Add 3 ml of LB medium to the sterile test tube, pick a single colony and add it to the medium, shake the bacteria at 37, 200 rpm overnight.

Expand the culture: Prepare LB liquid medium. Autoclaving.

Add 50ml of liquid LB medium to the triangular flask, add 1ml of bacterial solution, 37, and shake the bacteria at 200 rpm to the desired OD value.

Note: Antibiotics resistant to the strain should be added to the medium.

Tools: clean bench, alcohol lamp, inoculation needle, test tube, autoclave, petri dish, etc.

Pay attention to aseptic procedures.

Penicillin, cephalosporin and other antibiotics.

Homes can be sterilized at low temperatures. Bring the milk to 60 degrees, stop the heat, let it sit for a few hours, and cook again to 60.

There are two main methods of sterilization of milk: pasteurization and UHT.

The common practice of the former is to heat the raw milk to 72-80 degrees Celsius for 3-15 minutes, so as to kill the harmful microorganisms in the raw milk as much as possible and preserve the taste and nutritional value of the milk to the greatest extent.

The latter uses special equipment to heat the raw milk to 135-140 degrees Celsius for 1-3 seconds to completely eliminate all microorganisms in the raw milk

70-80 degrees is fine, not too long

1. Seed inoculation: Seeds in lyophilized tubes or glycerin tubes are inoculated into LB medium shake flasks for activation, and antibiotics corresponding to resistance labels can generally be added. Then shake the bed and incubate at constant temperature.

2. Preparation of fermentation medium: If you shake the bottle, it is easy to say, and the sterilizer will do. In the case of fermenters, the tanks should be cleaned first, then the ingredients should be batched, and then sterilized.

3. The cultivated seed liquid is connected to the fermentation medium according to a certain inoculation amount. If it is a shake flask fermentation, there is generally no central control, and the time is up to put the bottle. In the case of fermentation in fermenters, the intermediate process needs to be fed, the pH value adjusted, the dissolved oxygen speed controlled, and so on.

It is necessary to pay attention to the tightness of the sample solution when sampling, if the sample solution is scattered everywhere, it is easy to lead to phage contamination.

4. Whether it is enzyme production, protein, amino acids or anything else, the amount of product must be detected.

5. After putting the tank, it is also necessary to pay attention to the collection, use and inactivation of the material solution to prevent phage contamination.

The following is the inspection method of baked food enterprises, and the inspection methods of enterprises and schools are different. It is in accordance with national standards.

E. coli assay – Gram stain.

First, the basic principle:

Gram staining is an important differentiating stain widely used in bacteriology. It was founded in 1884 by the Danish physician Gram. This method can divide bacteria into two categories: gram-negative bacteria and gram-positive bacteria.

The mechanism of Gram staining is mainly based on the differences in cell wall composition and structure between the two types of bacteria. Gram-negative bacteria have more lipids in their cell walls and less in peptidoglycan. When decolorized with alcohol or pyruvate, the lipids are dissolved, which increases the permeability of the cell wall, making the complex of crystal violet and iodine easy to exude after the initial staining, as a result, the cells are decolorized, and after counterstaining, they are stained with the color of the counterstaining solution.

However, the content of peptidoglycan in the cell wall of gram-positive bacteria is large, the degree of cross-linking is large, and the content of lipids is small, and after elution by ethanol or acetone, the pore size of the peptidoglycan layer becomes smaller, and the permeability is reduced, so the cells still retain the color of the initial stain.

Second, the basic steps:

The smear was fixed on the flame, crystal violet dyeing solution was added dropwise, dyed for 1min, and washed with water; Add Gram iodine solution dropwise, effect for 1min, wash with water; Add 95% ethanol dropwise for about 15 30s until the staining solution is washed off, do not decolorize excessively, wash with water;

Add saffronin counterstaining solution, counterstain for 1min, wash, wait to dry, and microscopic. Results: Gram-positive bacteria were purple and Gram-negative bacteria were red.

Here's what took a lot of effort to get up, I hope it helps:

Experiment 1: Construction and use of an ordinary light microscope.

Experiment 2: Simple staining and Gram staining of bacteria.

Experiment 3: Observation of yeast morphology.

Experiment 5: Dry heat sterilization and autoclave sterilization.

Experiment 6 Isolation, inoculation and purification of microorganisms.

Experiment 7 Plate colony counting method for microorganisms.

Experiment 8 Mold Counting.

Experiment 10 Preservation methods of commonly used strains.

Experiment 11 Microbiological examination of food contact surfaces.

Experiment 12 Fermented milk experiment.

Comprehensive training for the detection of microorganisms in water.

1. Determination of the total number of bacterial colonies.

It's too much, more than 1w words. Take a look at the references.