Sterilization of packaged items

There are two kinds of sterilization technologies commonly used in packaged goods. One is the ultra-high temperature short-time sterilization technology. It is mainly used to treat dairy products such as fresh milk, compound milk, concentrated milk, flavored milk drinks, butter, etc. Sterilization of food. The other is pasteurization technology, which is widely used in various acidic foods, such as juice, yogurt, fruit drinks and other products.
First, ultra-high temperature and short-term sterilization technology Ultra-high temperature short-term sterilization technology is to fill and seal food in the packaging bag made of composite film packaging materials, so that it can maintain a high temperature of about 130 °C in a short time to kill Bacteria inside the container. Using this technology can not only protect the quality of food, but also greatly improve production efficiency.
There are many kinds of foods, and the performance of various foods are different from each other. The causes of deterioration of foods are also inconsistent. However, the main factor in the deterioration of foods is the growth and reproduction of microorganisms in foods. Among all the microorganisms, the most heat-resistant is bacterial spores. When it is at an environmental temperature above 100°C, the higher the temperature, the faster the death of the spores, that is, the shorter the time required for sterilization, Table 7-2. The relationship between the death time and temperature of Clostridium botulinum spores in neutral phosphate buffer solution.
Table 7-2 Relationship between death time and temperature of botulinum spores

Foods are usually scented, pigmented, and contain various vitamins. When foods are heated for a certain temperature and time, they change to varying degrees. But the dependence of this change on temperature is relatively smaller than that of killing bacterial spores, but the dependence on time is great. The shorter the heating time, the smaller the chemical change, and the longer the heating time, the greater the chemical change. As can be seen from Table 7-2, the time for killing bacteria at a heating temperature of 130° C. or more is significantly shortened. Therefore, ultra-high temperature and short-term sterilization packaging technology can be used to kill the bacteria while maintaining the umami taste, nutritional value and pigment of the food.
Second, the pasteurization technology pasteurization technology is to fill and seal the food in the packaging container, in a certain period of time to maintain the temperature below 100 °C, kill the bacteria in the packaging container. Pasteurization can kill most pathogenic bacteria, and the killing capacity of non-pathogenic spoilage organisms and their spores is not enough. If pasteurization is combined with other storage methods, such as refrigeration, freezing, deoxygenation, packaging, etc. , can reach a certain period of preservation requirements.
The pasteurization technology is mainly used for the sterilization of citrus and apple juice beverage foods because the pH of the juice food is below 4.5, no microorganisms grow, and the sterilization objects are yeast, mold, and lactobacillus. In addition, pasteurization is also used for the sterilization of jams, canned fruits, beer, pickled vegetables, and pickles. Pasteurization has reliable acid resistance to sealed acidic foods. For those low-acid foods that are not resistant to high humidity, as long as they do not affect the consumption habits, the pH is often decreased by adding acid or by means of microbial fermentation. In the range of acidic foods, low-temperature sterilization can be used to preserve the quality of foods and resist the purpose of hiding.