Cooling is cooling, food heating and sterilization after the end should be quickly cooled, because in spite of the end of the heating sterilization, but the tank is still in the high temperature state, if not cooling immediately, the quality of the food color, fragrance, taste, tissue will be affected, even lose the product value; if the cooling rate is slow, the product is within the product. The retention time between 50 and 60 centigrade is too long, which may promote the reproduction and activity of thermophilic bacteria, cause the food to deteriorate and corrupt, and the high acid food will accelerate the corrosion of the inner wall of the tank, so the food sterilization should be cooled immediately, and the temperature of the food center after the thermal sterilization is quickly reduced to 40 or below. The faster the cooling, the better the quality of the content.

 

1. Quality of cooling water

 

In the cooling process, the cooling water is in full contact with the canned water, so the cooling water must be colorless, tasteless, clear and transparent. The pH value, hardness, sulfur content and microorganism of the cooling water must be strictly controlled. This is because the temperature of the packaged food is very high, when the cooling water is in contact with the canned water, especially when it is just beginning to cold. In a flash, the high temperature packaging food meets the low temperature water, such as the double curling edge and sealant of the sealed food of the tank, and the sealant will shrink suddenly and produce a trace of the loose gap. It may cause the cooling water to be penetrated into the container, which causes the micro water molecules or microbes to infiltrate into the container, causing the food to be re polluted after sterilization. In severe cases, the contents are corrupted and spoiled. This is the "two pollution" that is customary. So the bacterial content in the cooling water must be strictly controlled, such as 20 drops per litre of water, 100 bacteria per milliliter of cooling water, 5 bacteria per drop of cooling water, and 1/5 of each drop in the seal. However, if there are one million bacteria per milliliter of cooling water, there are fifty thousand per drop of water. Bacteria, in this content, the best sealing conditions are also impossible to prevent microorganisms from penetrating the double edges of the container into the food.

 

Therefore, the cooling water must conform to the hygienic standard of GB5749 drinking water, the total coliform group must not be detected, the total number of colonies (CFU/Ml) < 100, sulphate (mg/L) < 250, the total hardness (CaCO3, mg/L) < 450. The cooling water used as packaged food is safe, and the cooling water discharged at the end of cooling at the end of the cooling water is more and more safe. The sampling test showed that the coliform group was not detected and the colony number was less than 1. The test data is sufficient to show that the product is safe and the quality of the product is guaranteed by using the water which is in accordance with the national standard GB5749 "sanitary standard for drinking water" as the sterilization and cooling water of the packaged food.

 

Two, chlorination treatment of cooling water

 

Whether the water for the supply of sterilization and cooling should be added to chlorine or by other methods, the criterion is the hygienic condition of cooling water cooling water before entering the sterilizing pot, and the potential harm to the product will be cooled by the water, and the possibility of contamination before the water enters the sterilization pot. If the sanitary condition of the cooling water is poor, the potential harm to the safety of the product or the possibility of the water being polluted in the middle part, it is necessary to add chlorine or other methods before the cooling water enters the sterilizing pot. It is best to chlorination 20 minutes before the use of the cooling water so that the chlorine of the cooling water can be effectively sterilized. Function to ensure the hygienic indicator of cooling water. The cooling water should not be added with chlorine, which is related to the way of cooling water supply and the use of cooling water, so the problem of chlorine adding can not be cut in one knife, and the specific analysis should be carried out scientifically.

 

There are two ways to use cooling water directly and indirectly.

 

Direct water supply: cooling water directly from the urban water supply network to the sterilization pot.

 

Cooling water directly comes from the urban water supply and distribution network, without any intermediate link, there is no possibility of any pollution. Since the water quality of the city can meet the requirements of the national standard GB5749, the majority of the water source in the user terminal still contains the residual chlorine 0.2-0.8 mg/L, which can ensure the cooling of the sterilization pot. The direct cooling of packaged food with this water is not necessary for further chlorination. See Figure 2-8 for water supply.

 

But many enterprises also found that the water supply of the urban pipe network is sometimes unstable, especially the smaller County, which is limited to the facilities and technical forces of the water plant, and the water supply chlorine is unstable, sometimes high, and sometimes zero. Many food enterprises are distributed in counties and towns, so experience tells us that enterprises still need to have their own independent water chlorination system.

 

Indirect water supply: the indirect use is to use the factory ground water or the water supplied by the urban water supply and distribution network to enter the tank, tower, trough and other intermediate links and then enter the sterilizing pot for cooling water.

 

Although the water of urban water supply is in accordance with the requirements of the national standard GB5749, the possibility of water pollution in the process of water storage in the middle link, such as pool, tower and trough, will cause the water quality to be polluted. While strengthening management, facilities and equipment should also be chlorinated or treated with other methods. Of course, the filtration of the underground water must be chlorinated to ensure the quality of the cooling water. The chlorination standard is better than 0.5 ppm of the free residual chlorine in the cooling water discharged from the end of the cooling terminal.