Strain produced by milk spoilage Urgent!!

When milk is contaminated with microorganisms, it can cause spoilage and spoilage. If the contaminating microorganisms multiply and produce gas in the product, the appearance of the product is swollen (i.e., swollen); If the contaminating microorganisms will multiply in the product but do not produce gas, the product will have an intact appearance package type (i.e., a flat acid package); If the contaminating microorganisms break down the protein into bitter peptide fragments in the product, the product tastes bitter. The main reasons are:

Effect of raw milk or excipients. If the raw milk or excipients contain more spores or heat-resistant bacillus, after UHT sterilization, there will be more spores or heat-resistant spores left in the corresponding product, so that the number of bad packages of the product will increase.

The sterilization efficiency did not meet the requirements. Sterilization efficiency depends on the combination of sterilization temperature and sterilization time, and is also affected by the degree of fouling on the inner surface (one side of the product) of the sterilizer (for indirect heating).

If the sterilization efficiency does not meet the requirements, there will be more residual microorganisms (especially spores or heat-resistant spores) in the sterilized products, and the packaged products will be bad.

However, the concept of metamorphism is also a process in which miscellaneous bacteria enter the substance, slowly grow, and change from quantity to quality. If you do it at home, it is impossible to be completely sterile, so it should be said that the temperature is a bit low in the twenties that have been infected with miscellaneous bacteria, but if the milk has been heated and covered after heating, it should not deteriorate, because most bacteria do not grow very quickly in the twenties.

The slowing of milk and the dust is caused by the reproduction of microorganisms, among which thermophilic bacteria are the mainstay. When milk is processed into milk powder or cheese, if it is not stored properly, nutrients such as protein and fat will be decomposed, thus reducing the nutritional value of these nutrients. In addition, there is a bacterium called Clostridium butyricum that produces an enzyme that converts lactose into lactic acid in milk, thus destroying the nutrients in milk.

In order to prevent milk from spoiling, in addition to requiring the raw materials to be fresh, non-toxic and harmless, suitable storage conditions and methods must also be adopted. At present, the commonly used methods of disturbing Zen are: low-temperature storage; Short-term storage at high temperatures; UHT instantaneous sterilization; Pasteurization.

Hello dear, I am happy to answer for you: How does the bacterial phase of milk change during the preservation process Answer: Hello dear, Because raw milk is rich in nutrients, high water content, and pH value is close to neutral, all kinds of microorganisms can grow and multiply in it.

Raw milk contains a large number of microorganisms, which are mainly divided into three categories: pathogenic microorganisms, harmful microorganisms and beneficial microorganisms. When there are pathogenic bacteria in milk, as long as the storage is not reasonable, it will grow and multiply rapidly, and will metabolize and produce a large number of toxins, although it can kill pathogenic bacteria in the later processing process, but the toxins are still active, so that poisoning occurs after disturbing the ants and humans to drink. Common pathogens include Salmonella, Cholerae arc burial, Staphylococcus, Streptococcus agalactiae, Shigella, Brucella, Mycobacterium tuberculosis and Sakazakii.

Harmful microorganisms are often called spoilage bacteria, the most common of which are psychrophiles. In the process of low-temperature storage of raw milk, this kind of bacteria can also grow, and the lipase and protease secreted by it can still be active through high-temperature sterilization, which can decompose the fat and protein of milk, and seriously affect the production of dairy industry. The most common examples of this type of bacteria are Pseudomonas, Alcaligenes, and Flavobacterium.

Lactic acid bacteria are the main beneficial microorganisms in raw milk, including Streptococcus, Lactobacillus and Leuconostoc. Control methods: Dairy farms and breeders should carry out regular health inspections, quarantine and veterinary health care, and formulate a reasonable disease prevention system and inspection and quarantine system.

The area around the barn should also be cleaned frequently, so that the excrement is cleaned every day, the bedding is changed frequently, and the cattle farm should be cleaned with an effective disinfectant. The expressed raw milk is immediately cooled to around 4, due to the very low fecundity of microorganisms at this temperature, and it is also the most effective way to ensure that the milk does not spoil. The storage tank must be strictly cleaned and sterilized before each use, and can only be used to store milk after cooling.

Raw milk is not allowed to be transported in direct sunlight, and is often transported by covering it with a damp cloth to prevent the temperature of the milk from rising or slowing down, and with an awning truck. Thank you for your patience. The above is my full reply, if you are satisfied with my service, please give a thumbs up, and I wish you all the best!

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Summary. Based on the above results, we can see that all the milk that has just been opened meets the standard, and when several samples are left in the air for 2 days, the total number of colonies increases significantly, and the total number of colonies of several samples all exceeds the standard. It can be concluded that when pure milk is placed in the air, because the milk itself is very nutritious and is a natural medium, the bacteria in the milk multiply in large numbers during this period, and the growth of the total number of colonies in just a few days has reached an uncountable exceedance, and finally the --- boiling experiments have seen that after high temperature heating, the total number of colonies has been greatly reduced, and even has reached the standard.

It can be seen that heating has a good sterilization effect on contaminated milk. Therefore, milk should not be left open in the air in daily life, and the milk that has been put aside for a period of time can be safely eaten after boiling, but if it is processed many times, its nutrients and flavor will also be greatly deducted, and it will lose its original value. Therefore, it is recommended not to expose pure cow milk to the air as much as possible, and drink it immediately after opening the bag.

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I would like to ask you what kind of environment it is stored in, whether it is boiled or directly exposed to the air.

It is exposed to air.

Based on the above results, we can see that all the milk that has just been opened meets the standard, and when several samples are left in the air for 2 days, the total number of colonies increases significantly, and the total number of colonies of several samples exceeds the standard. It can be concluded that when pure milk is placed in the air, because the milk itself is very nutritious and is a natural medium, the bacteria in the milk multiply in large numbers during this period, and the growth of the total number of colonies in just a few days has reached an uncountable exceedance, and the last --- boiling experiments have seen that after high temperature and silver heating, the total number of colonies has been greatly reduced, and even has reached the standard. It can be seen that heating has a good sterilization effect on contaminated milk.

Therefore, milk should not be left open in the air in daily life, and the milk that has been put aside for a period of time can be safely eaten after boiling, but if it is processed many times, its nutrients and flavor will also be greatly deducted, and it will lose its original value. Therefore, it is recommended not to expose pure cow milk to the air as much as possible, and drink it immediately after opening the bag.

This is the conclusion of the relevant experiment I found, I hope it will be helpful to you.

Guess the reason why the milk spoiled:

1.There is no seal (dust from the air falls into the milk in large quantities, spoiling the milk; Bacteria and fungi that fall in the milk grow and multiply, making the milk coarse and coarse).

2.It is not fresh milk, and additives added when processing milk spoils the milk.

3.The high summer heat spoils the milk.

4.The air is too humid or too dry.

So do the following four experiments to verify the guess:

a) It is related to whether it is sealed or not.

Take two equal cups of processed milk, one sealed and one in the air, and place in the same place for observation.

b) Letters related to whether or not it is fresh milk.

Take two equal cups of milk, one processed milk and one fresh milk, and place them in the same place for observation.

3) It is related to whether it is high temperature.

Take two equal cups of processed milk, one in the incubator and one in the room (room temperature), and observe.

4) It is related to whether it is damp or not.

Take two equal cups of processed milk, one in a damp bin and one in a dry bin, and observe.

Experimental results: 1) Unsealed milk spoils first.

b) Fresh milk spoils first.

c) The temperature is high and the first thing to deteriorate.

d) Moisture spoils first.

Conclusion: The causes of milk residue deterioration are related to tightness, freshness, temperature and humidity. Therefore, when we store milk, we should choose a cool, dry place to seal and store the milk. But be sure to drink the milk before the expiration date.

in the air or in utensils.