What is the difference between shelf life and shelf life
The soon-to-be-eaten food can not be eaten. First of all, this "phase" should be clearly distinguished. One is called the shelf life, also known as the best period of consumption, called the shelf life abroad. Refers to the time period for which the food is maintained in quality under the storage conditions indicated on the label. Under proper storage conditions, foods that exceed the shelf life may still be edible within a certain period of time if they do not change color, smell and taste. The other is called the shelf life, which is the final date when the product is edible. He Jiguo pointed out that after the storage period, the food may undergo quality changes, no longer have the desired quality characteristics of the consumer, cannot be eaten, and even cannot be used for sale.
Saving conditions are important
"Shelf life is just a relative concept." Experts said that under normal circumstances, the food within the shelf life will not deteriorate, but if the storage environment does not meet the requirements, the food taste, smell and appearance will change very quickly, it may also cause The shelf life expires prematurely. Here are some common foods to illustrate.
Dairy products: Dairy products are very prone to spoilage, and if exposed to room temperature, they deteriorate within a few hours. For special yoghurts in the supermarket that are already near their shelf life, if you simply can't finish this period, don't buy it.
Edible oil: Usually the shelf life of edible oil is 18 months, but this is based on the unopened package. Fatty acids in edible oils undergo chemical changes as storage time increases, and the nutritional value also decreases. Therefore, it is very important to buy oil to see the date of production. The fresher the better. The edible oil is exposed to the air after being opened and the shelf life will be shortened accordingly. Even if it is not finished, it should be changed at least once every three months.
Rice noodles: The shelf life of rice noodles ranges from 6 to 12 months at room temperature. If it is in the north, as long as it is not placed in a hot and humid place, the storage conditions are normal and can be extended to 24 months. However, if the rice surface becomes moldy, it must not be eaten.
Bakery and pastries: There are different shelf life depending on the season, generally 7 days in winter, 3 to 5 days in spring and autumn, and 1 to 2 days in summer. However, if the bread is not properly preserved, it is usually possible to grow the fungus the next day. At this time, even if it does not expire, it must be resolutely thrown away.
Eggs: There is no fixed shelf life, and it is generally no problem to eat within 3 to 5 weeks after purchase. Usually the quality of an egg will fall by one grade every week, but it is still edible.
The refrigerator is not a safe
It is unscientific for foods to be stored at room temperature because many microorganisms have a suitable temperature range of 4°C to 60°C. For perishable foods, refrigerate them immediately after you buy them home. If you do not eat them immediately, they should be frozen immediately. To know that their own home refrigerator is not the factory's quick-frozen production line, most of them can only be "slowly frozen." In the process of slow freezing, the nutrition and flavor of food will be changed, and the taste quality of cooking will also be significantly reduced. After food is put into the refrigerator, eat it as soon as possible.
Roughness Measuring Instrument
Roughness meter, also known as surface roughness meter, surface smoothness meter, surface roughness tester, roughness measurement meter, roughness tester, and other names. It has the characteristics of high measurement accuracy, wide measurement range, easy operation, portability, and stable operation. It can be widely used for the detection of various metal and non-metal processing surfaces. This instrument is a pocket instrument that integrates sensors and hosts, with handheld characteristics, making it more suitable for use in production sites. The exterior design is sturdy and durable, with significant resistance to electromagnetic interference, in line with current design trends.
The application fields of roughness meters include:
1. Mechanical processing and manufacturing industry, mainly metal processing and manufacturing. Roughness meters were originally developed to detect the surface roughness of machined parts. Especially, stylus type roughness measuring instruments are more suitable for detecting hard metal surfaces. For example, the automotive parts processing and manufacturing industry, the mechanical parts processing and manufacturing industry, and so on. As long as these processing and manufacturing industries involve the surface quality of workpieces, the detection application of roughness meters is essential.
2. In the non-metallic processing and manufacturing industry, with the progress and development of technology, more and more new materials are applied to processing processes, such as ceramics, plastics, polyethylene, etc. Some bearings are now made of special ceramic materials, and pump valves are made of polyethylene materials. These materials have a hard texture, and some applications can replace metal materials to make workpieces. During production and processing, their surface roughness also needs to be tested.
3. With the continuous strengthening and improvement of the technology and functions of roughness meters, as well as their in-depth promotion and application, more and more industries have been found to require roughness detection. In addition to mechanical processing and manufacturing, roughness evaluation is also required in the production and processing of power, communication, electronics, such as couplings on switches, integrated circuit semiconductors, and even stationery, tableware, and other products used in people's daily lives The surface roughness of human teeth needs to be tested.
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