The Spring Festival is over, and it's time to turn over the "New Year's Taste" rumors
Our reporter Chen Xi
refute the rumor
February coincides with the Spring Festival of the Year of the Tiger. When the family is reunited, the sumptuous food on the table and the lively fireworks are indispensable.
The rumors that emerged this month are closely related to the diet and customs of the Chinese New Year - "waxed apples are harmful to eat", "cold fireworks are low in temperature and safe to set off", "pre-prepared dishes contain preservatives", "eat more high-quality meals" Fiber foods can 'scrape oil'"…
Today, a reporter from Science and Technology Daily took stock of the "Nianweier" rumors that appeared last month one by one, to help you clear the fog and find the truth.
Are waxed apples harmful to eat?
The truth: Fruit wax is a food additive, non-toxic
When visiting relatives and friends during the Chinese New Year, many people will present fresh fruits, and apples are the choice of many people.
However, there is a saying on the Internet: If the skin of the apple is smooth, sticky to the touch, and there is powder after scraping, it means that it has been waxed and is poisonous!
Such rumors have been around for a long time, and they will pop up every once in a while to "scare" everyone.
What is the truth?
"Fruit waxing is a very common phenomenon. Not only apples, but also citrus fruits or perishable fruits will be waxed after picking." Wang Hao, a professor at the School of Food Science and Technology of Tianjin University of Science and Technology, introduced in an interview with a reporter from Science and Technology Daily. , Waxing is a routine operation. Waxing can reduce the water loss of the fruit, keep it fresh and high "look", and also prevent the invasion of microorganisms, thereby prolonging the storage time.
The fruit wax used in waxing is a food additive.
"Fruit wax is a food additive that is allowed to be used in many countries, and regular waxing will not cause harm to human health." Wang Hao said that it is clearly stipulated in my country's "Hygienic Standards for the Use of Food Additives" that it can be Morpholine fatty acid salts (also known as fruit wax), carnauba wax, etc. are used as coating agents to preserve freshness, polish and prevent water evaporation.
Although fruit wax is harmless, there are still consumers who worry that businesses use non-food additives - industrial wax for waxing, which will cause harm to the human body.
In this regard, Wang Hao said that the composition of industrial wax is relatively complex. If such wax is used when waxing fruit, it may indeed penetrate into the pulp of heavy metals such as lead and mercury, and excessive intake will cause harm to human health.
However, my country has carried out strict supervision on this, and some provinces and cities have conducted relevant spot checks before, and the content of fruit wax and residual heavy metals are all qualified.
"Industrial wax has a slight pungent odor, while food-grade fruit wax is colorless and odorless." Wang Hao suggested that consumers can smell apples when they buy them to see if they have a pungent smell.
When eating, the wax can be easily removed by peeling the skin.
You can also rub the surface of the apple slowly with fine salt, which will remove a lot of wax and dust.
The temperature of cold fireworks is low, and it is safe to discharge?
Truth: Cold Fireworks Are Not "Cold"
"Atmosphere-responsible" fireworks are naturally indispensable for the Chinese New Year, and cold fireworks have become popular in recent years because of their low ignition point, smoke-free, and more environmentally friendly than traditional fireworks.
"Cold fireworks, also known as cold light fireworks, refer to a type of pyrotechnic substance that emits extremely white light when ignited, produces less smoke and has less residual slag." Liu Mingyu, a member of the Starlight Science Popularization Group of the School of Chemistry, Nankai University, was interviewed by a reporter from Science and Technology Daily When introduced, common cold fireworks include fairy sticks, electronic fireworks and so on.
The cold fireworks currently on the market are basically assembled by mixing a certain particle size of single-base gunpowder (the main component is nitrocellulose), oxidant, metal powder (usually titanium powder or zirconium powder), etc. .
For example, when a hand-held cold fireworks is set off, the temperature of the flame (spark) drops rapidly after it is ejected. The temperature can drop to about 80 degrees Celsius at a distance of 20 cm from the injection port, and it can drop to about 40 degrees Celsius at a distance of 50 cm from the injection port. It gives people the illusion that "the flame temperature of cold fireworks is very low and there is no danger".
"Actually, cold fireworks are not 'cold'." Liu Mingyu said that when burning, the light emitted by cold fireworks is not the "cold light" that people usually think, but the light emitted by thermal radiation.
The temperature at the nozzle of the fireworks can be as high as 800 degrees Celsius or even thousands of degrees Celsius. At this time, as long as you are close enough to the fireworks, you will be burned and your clothes will be scorched.
In addition, the cold fireworks will produce jet-like sparks when they are set off, and some of the larger particles with higher temperature can also ignite the surrounding combustibles, which will cause fires in severe cases.
In addition, in order to save costs, some illegal enterprises will use inferior materials to manufacture cold fireworks, resulting in uneven quality of related products on the market and great potential safety hazards.
Liu Mingyu emphasized that cold fireworks, as fireworks and firecrackers, are inflammable and explosive dangerous goods, and this basic attribute has not changed.
"It is recommended that when you set off cold fireworks, you should strictly abide by the regulations on fireworks safety management, use qualified fireworks products, and set off at a safe distance from fireworks," she said.
Preserved dishes contain preservatives?
The truth: Freshness is mainly depended on rapid freezing
I want to make a big meal for my family, but I can't master my cooking skills, and the process of preparing the New Year's Eve dinner is cumbersome, what should I do?
Pre-made dishes solve these problems, and the price is cheaper than restaurants.
It is very convenient to make and can be eaten with only heating or simple cooking. Even a "little white" in the kitchen can "make" hard dishes with complex production processes such as Buddha Jumping over the Wall, Sichuan pepper chicken, boiled beef, and pickled fish.
However, the quietly popular pre-made dishes have also raised some doubts: the shelf life of pre-made dishes can be as long as one year, and preservatives must be added to them.
Is it really the truth?
"Generally speaking, the purpose of adding preservatives is to prolong the shelf life and inhibit the growth of pathogenic microorganisms." Wang Hao said, but the preservation of prefabricated vegetables does not depend on adding preservatives.
First of all, pre-made dishes are almost all cooked food. After a long period of high-temperature cooking, it is equivalent to sterilization; secondly, with the progress of preservation technology, the dishes are generally stored by rapid freezing technology (minus 18 degrees Celsius) after cooking. The low-temperature preservation method can ensure that the moisture in the food is not lost as much as possible without using any preservatives or other additives, maximize the preservation of the nutrition of the food, and at the same time inhibit the reproduction of microorganisms.
Regarding the use of additives, Wang Hao said that everyone should not be overly nervous.
"There are some additives that we often encounter in our daily life and are also used in home cooking." Wang Hao gave an example. For example, many oyster sauces contain sodium glutamate, potassium sorbate, and hydroxypropyl distarch phosphate. , citric acid, etc., these are additives.
As long as the content of additives is within the standard range set by the state, consumers will not cause harm to the human body when they eat them.
Eating more high-fiber foods can "scrape oil"?
The truth: neither absorbs oil nor accelerates fat dissolution
As the saying goes, every festive season, you gain 3 pounds.
After the Spring Festival every year, losing weight will become a topic of concern for many people.
This year, it is widely rumored on the Internet that dietary fiber can absorb fat in the small intestine, and then excrete it with the feces, so as to achieve the purpose of "scraping oil" and achieve weight loss.
Is this statement plausible?
"According to solubility, dietary fiber can be divided into two types: soluble dietary fiber and insoluble dietary fiber. Such as pectin, gum, seaweed polysaccharide, fructooligosaccharide, etc. are soluble dietary fiber, their water capacity is large, can be dispersed in water to form High-viscosity solution. While wheat bran and vegetable fiber (higher content of leafy vegetables) have a smaller water capacity than soluble dietary fiber, they belong to insoluble dietary fiber." Tan Guijun, chief physician of the Department of Nutrition, Tianjin First Central Hospital, accepted In an interview, a reporter from Science and Technology Daily said that these two kinds of dietary fibers will not be integrated with fat, nor have the function of absorbing fat, and will not speed up the decomposition of fat. Therefore, eating more foods with high dietary fiber content can "scrape oil". Inaccurate.
However, for people who need to control their weight and "three highs", eating foods high in dietary fiber will indeed help a lot.
"Insoluble dietary fiber can accelerate the excretion of stool by stimulating the contraction and peristalsis of the intestinal tract; soluble dietary fiber has strong water absorption. At the same time, the volume and weight of the fecal mass after water absorption increases, which can stimulate the contraction and peristalsis of the intestinal tract, and accelerate the excretion of stool, thereby improving constipation and accelerating the discharge of toxic substances in the intestinal contents. "Tan Guijun said.
In addition, most soluble dietary fiber can be combined with bile acid and excreted from the body, thereby expelling cholesterol and reducing cholesterol.
Soluble dietary fiber can also delay gastric emptying time, thereby reducing the magnitude of postprandial blood sugar rises.
Soluble dietary fiber can be completely lysed by bacteria in the large intestine to produce short-chain fatty acids, which are the source of nutrients for intestinal probiotics, and can provide very good "living conditions" for probiotics, thereby regulating the environment of intestinal flora.
These short-chain fatty acids can also stimulate colon cells to release active factors, reduce sugar intake, increase insulin secretion, and play a role in controlling blood sugar.
"Although dietary fiber has many benefits for the human body, it is not that the more you eat, the better." Tan Guijun said that excessive intake of dietary fiber may cause abdominal discomfort and affect the body's absorption of protein, vitamins and trace elements, but it will cause the body to produce Negative Effects.
For different groups of people, dietary fiber can be consumed under the guidance of nutritionists according to the recommendations of the Chinese Nutrition Society and other authoritative guidelines.
The Chinese Nutrition Society released the reference intake of dietary nutrients for Chinese residents on October 15, 2017. The recommended intake of dietary fiber is 25 to 30 grams per day.
The Chinese guidelines for the diagnosis and treatment of chronic constipation recommend that patients with constipation should increase the intake of dietary fiber and water, and recommend a daily intake of 25 to 35 grams of dietary fiber.