First, staple food. Staple food is divided into two categories according to the water content. There are steamed bread, bread and moon cakes with more water, and biscuits with less water. The shelf life of bread is usually 3~7 days. After the shelf life, if it is only dry, it can be made into bread crumbs. If it is moldy and sour, it can't be eaten. The situation of steamed bread is similar to that of bread. If it is moldy and has gray spots, it should be discarded. Depending on the packaging, the shelf life of moon cakes ranges from a few days to 90 days. Because of the high fat content, once the shelf life has passed, it will be spicy and can't be eaten. Cookies contain less water. If it is sealed, the shelf life is generally more than one year. As long as it is not airtight and damp, it can be eaten even after the shelf life, as long as the taste has not changed.
Second, canned food. Canned food is sealed and isolated from the air, so the shelf life is long, and some can reach more than two years. Be careful not to buy expansion tanks when buying. If the canned food swells after the shelf life, it is often that the food is contaminated by bacteria, and the canned food must be thrown away. If it doesn't swell, open it and smell it If it tastes sour and smelly, you can't eat it. If there is rust in the can, you shouldn't eat it. In addition, after the shelf life, even if it is not unpalatable, it should be heated before eating.
Third, milk and dairy products. The shelf life of milk varies from 48 hours to 7 days, depending on technology and packaging. If the milk that has passed the shelf life is in the form of a thick and uneven solution, or has clots or flocs, it should be thrown away. In summer, even if it looks normal, try to cook it. If boiled, it will produce blood clots, indicating that bacteria exceed the standard and cannot be drunk. Milk powder has no moisture, long shelf life and short expiration time. As long as there is no color darkening, impurities or foreign bodies can be seen by the naked eye, and they can be eaten with bad taste, musty taste and spicy taste. After the milk powder is washed with boiling water, if white clots are found, water and milk are separated, or free fat floats, it will not work. If it is only slightly caked, it can be used to make snacks or cook, that is, heating can be used continuously. Expired yogurt, if there are bubbles or whey precipitation, does not mean toxic and harmful, only that the lactic acid bacteria inside acidify the remaining lactulose. If it smells of alcohol, corruption, mildew, etc. It means that it is contaminated by other bacteria and cannot be drunk.
Fourth, meat products such as sausages. If it is vacuum packed and stored under dry and frozen conditions, the nutrition will become worse and the shelf life can reach 3 years. Sausage itself is not a healthy food, so it should be eaten as soon as possible when the shelf life is approaching. After the shelf life, if there is spicy taste or sticky casing, it means that microorganisms are breeding and must not be eaten.
5. drinks. It's usually sealed. Such as no obvious change in appearance, fading, turbidity, precipitation, etc. After the shelf life, the taste shall prevail. You can't drink it if it smells bad.
Sixth, edible oil. Many people buy a big barrel of oil at a time and eat it slowly in order to save money. Although the oil does not change color and taste, the peroxide value of the oil will gradually increase after the cover comes into contact with oxygen. Eating such oil for a long time may increase the degree of oxidation in the body and increase the risk of cardiovascular and cerebrovascular diseases and cancer. Therefore, Fan Zhihong stressed that the opened oil must be used up within three months; The oil poured into the oil pan must be consumed within 1 week.
Seven, dried fruit. The shelf life of vacuum-packed dried fruits is six months to one year, but once the package is opened, problems are likely to occur during the shelf life. So this kind of food should be thrown away as long as it smells bad and tastes bitter and sour. If the taste is not crisp, it means that it will quickly deteriorate, mildew and oxidative rancidity after water absorption, and it cannot be used.