Plastic wrap packaging technology course, plastic wrap is one of the tools used more and more by modern people, which is generally used to keep vegetables, fruits or leftovers fresh. Most people think that as long as it is wrapped with plastic wrap, the bacteria outside can be eliminated, but many people may not use plastic wrap. Here is a tutorial on plastic wrap packaging technology for everyone. Come and have a look.
Plastic wrap packaging technology course 1 tools/raw materials
Tear-resistant plastic packaging
Methods/steps
Open the box.
Press into the locking positions on both sides to fix the inner winding core.
Take out the plastic wrap as shown in the figure.
Seal the food, close the lid at the same time, keep the sawtooth close to the plastic wrap, press the plastic wrap with your left hand, and tear the box easily with your right hand.
As shown in the picture, the food is finally sealed and can be put into the refrigerator.
Plastic wrap packaging technology course 2 tools/raw materials
packing film
A container for holding things.
Methods/steps
Buy packaging film, packaging film can generally be bought from the supermarket, or online group purchase (this is more affordable)
Pay attention to the precautions of checking the packaging film when buying, and do not use microwave oven to heat it.
Usage: put the fruit in a suitable container-wrap one end of the packaging film around the edge of the container-then pull the packaging film until it completely wraps the mouth of the container-tear off the packaging film and roll it to the bottom of the container.
When using plastic wrap to package food containing oil and meat, avoid direct contact between plastic wrap and food. This is because in the case of contact with oil, substances harmful to human health such as plasticizers in plastic wrap are dissolved in oil.
Plastic wrap packaging tutorial 3 Nowadays, people rely more and more on plastic wrap, whether it is vegetables, fruits or leftovers, as long as you cover it, your heart will be much more practical. But the use of plastic wrap is also taboo. Let's take a look at the correct use of plastic wrap.
In the case of plastic wrap, the cold and hot degree of dishes and the presence or absence of plastic wrap have different effects on nutritional components.
First of all, the hot dishes have not completely cooled down. Covering with plastic wrap can not only protect vitamin C in vegetables, but also increase the loss of vitamin C. It should be stored in the refrigerator after the dishes are cooled.
Secondly, dishes should be preserved with plastic wrap during storage, which can protect vitamin C. According to experts' determination, if they are stored for 6 hours and covered with plastic wrap, the preserved vitamin C is equivalent to eating an extra pear. In addition, the protective effect of different vegetables covered with plastic wrap on vitamin C varies from dish to dish.
Taking100g of vegetables as an example, the pickled leeks covered with plastic wrap have more1.33mg of vitamin C and more1.92mg of lettuce leaves than those covered with plastic wrap. However, after 24 hours of storage with plastic wrap, vitamin C of concanavalis decreased by 65438±0.5mg, radish decreased by 3.4 mg, and cucumber decreased most obviously.
Of course, vitamin C is only one of the nutrients that the human body needs, and the results of this study can't be pushed to others, but it at least shows a problem: plastic wrap is particular.
Selection of plastic packaging
When shopping, you must choose plastic wrap or plastic bag according to the actual use. When buying, you should read the logo on the package carefully.
In addition, polyethylene cling film is generally poor in viscosity and transparency, and it is easy to open after being rubbed by hand, while PVC cling film is good in transparency and viscosity, and it is not easy to spread and stick to hands after being rubbed by hand;
After the polyethylene plastic wrap is ignited by fire, the flame is yellow and will not go out when leaving the fire source, with oil droplets and no pungent smell.
Qualified fresh-keeping bags are milky white, translucent or colorless, transparent, elastic, lubricated by hand, and the surface seems to have wax. The poisonous fresh-keeping bag is turbid in color and feels bloated. Grab one end of the fresh-keeping bag by hand and shake it vigorously. The crisp sound is non-toxic and the dull sound is of poor quality.