The recent news of a business selling food nearing its expiration date has sparked widespread concern, and the previous report of “shelf life is set by the manufacturers themselves” has also sparked a lot of spit. People often ask: after the shelf life of the food, can still eat? Before answering this question, let’s talk about what is meant by “food spoilage”. Each food has a variety of attributes, such as appearance, color, taste, flavor, safety and so on. When we say that a food is “qualified”, we mean that it meets our requirements in all aspects. Or, in other words, it meets the promises made by the food producer to the consumer. In modern society, it is difficult to insist on “ready-to-eat” food. Especially for processed food, from production to consumption, it has to go through transportation, distribution and other steps. Therefore, the preservation of food is inevitable. In the preservation of any food, the aforementioned aspects will change at a certain rate. In different foods, the fastest changing kind of properties are not the same. For example, milk, eggs, meat and other raw foods, often bacterial growth occurs first, before changes in smell and other aspects. Cookies, generally softened by moisture, are the first to change in taste. Instant noodles, on the other hand, may be the first to oxidize the oil and produce an odor. Bacterial growth and oxidation of oil produce harmful substances, while food that becomes soft with moisture just doesn’t taste good anymore. In the food industry, these are considered “food spoilage”. Generally speaking, the “shelf life” refers to the period in which no significant changes in any aspect of the food have occurred. In other words, this is a promise from the manufacturer – in this period, the flavor, taste, safety aspects of the food will be guaranteed. If something goes wrong, the manufacturer needs to be responsible. And just because it’s past its shelf life doesn’t mean it’s bad, it’s just that the manufacturer no longer guarantees it. Sometimes, food that is past its expiration date may just not look as appealing or taste as good …… Such food can still be eaten. The problem, though, is that it’s also entirely possible that the number of disease-causing bacteria is much higher and the likelihood of getting sick from eating it has increased. Moreover, you can’t tell what changes have occurred to it. So, the answer to the question “Can I eat expired food?” is that eating it does not necessarily cause problems, but the likelihood of problems increases. For example, within the shelf life, there is a rare 1 in 10,000 safety problems, so you can claim from the manufacturer. And after the shelf life, there may be 99 out of 100 is no problem, just if you run into the other one, you have to accept the bet. Obviously, the deterioration of food is a continuous process of gradual change. Food ingredients or bacteria, will not watch the shelf life in accordance with our instructions to change – it will not be like many people think: before the shelf life, honestly stay; after the shelf life, all of a sudden became a poison. This change process, in turn, is influenced by the production process and preservation conditions. For example, the use of pasteurized milk, refrigerated for two weeks, the general bacteria will not exceed the standard; and ultra-high temperature sterilization, at room temperature for several months or even years will not grow bacteria. Even for the same kind of food, such as pasteurized milk, the process control conditions of different manufacturers will make the change process faster or slower. Therefore, it is very common and normal for the same food to have a longer shelf life for manufacturers with good technology. China has a uniform national shelf life for many foods, but in fact, it is not reasonable – in the national permit shelf life, production control of poor food may also go bad. Thus, a national “shelf life standard” of food, may be spoiled. For those who work to improve the production process to extend the shelf life of the manufacturers, the national standards have played a role in combating the positive. As to whether the manufacturers will mark the shelf life, the need is to monitor whether the food within its shelf life is qualified. Unqualified to be heavily punished, resulting in consumer victimization, the need for compensation. Under strict supervision, no manufacturers will dare to label. It should be noted that “no spoilage within the shelf life” needs to follow the manufacturer’s preservation requirements to achieve. Otherwise, the food may deteriorate during the shelf life, and the manufacturer is not responsible. For example, the shelf life of fresh milk is two weeks, which means that the premise is not opened and refrigerated. If it has been opened, or left at room temperature, it may spoil quickly, and the manufacturer is not responsible for this. Another example is cookies, which can remain crispy if the bag is not opened during the shelf life. But if the bag is opened, and the environment is more humid, it will soon become soft and damp, very difficult to eat. In this case, the manufacturer can not be held responsible. Shelf life or expiration date or not, are only a control standard. For longer shelf life (such as several weeks or even months) of food, the day before the expiration date and the day after will not be much different. This is like our male 22 years old can get married, but the day before and the day after the 22nd birthday, a person at least in the physical will not have any difference.