Spring has returned to the earth, and it is the season when strawberries are on the market in large quantities. For foodies, spring without strawberries is incomplete. Whenever I encounter it in supermarkets and wet markets, the cells of my body are shouting: "Buy it!" ”
As the face of the fruit industry, strawberry has the reputation of "fruit queen", but it has also been trapped in the rumor of "unclean".
Are strawberries really dirty? "Life Times" (search for "LT0385" in WeChat to follow) invites authoritative experts to clarify the doubts about strawberries at one time, so that you can eat with peace of mind.
Experts interviewed
Liu Jingliang, director of Yantai Green Strawberry Research Institute and executive director of the Strawberry Branch of the Chinese Horticultural Society
Li Weimin, director of the Department of Clinical Nutrition, The First Affiliated Hospital of Xi'an Jiaotong University
Liao Xia, attending physician of the Department of Clinical Nutrition, The First Affiliated Hospital of Xi'an Jiaotong University
The author of this article 丨 Life Times reporter Li Zhenyu
This article was edited by Ren Linxian
Strawberries have been "wronged" for a long time
Rumors about strawberries being "dirty" are widely debated.
Some people think that strawberries are vines that grow along the land and are easily polluted; some people think that the skin of strawberries is potholed, not as smooth and solid as apples and pears, and it is easy to "store" dirty things: others think that the seeds on strawberry fruits are dirty and cannot be eaten...
Myth 1: Strawberries are the dirtiest vegetables and fruits?
In 2018, the American Environmental Work Organization released a list saying that strawberries became the "dirtiest vegetables and fruits" for the third consecutive year, with as many as 1/3 of the samples containing 10 or more pesticides, and one of the samples measured 22 pesticide residues.
This news was widely concerned by American consumers at the time, and many media in the mainland also reprinted it. But soon, the American Food Technology Association responded to the list, saying that the large number of pesticide residues does not mean harmful, the key is to look at the dose.
The 12 pesticide residues mentioned in the list with the highest frequency of use are far below the reference dose, and the residual dose of some pesticides is one of the lower limit of the harmful value of 800,000 to 6 million, so consumers do not have to worry.
Rumor two: there are a lot of pesticides in the planting process?
Recently, there has been a video on the Internet, claiming as a strawberry grower that strawberries will use a lot of pesticides and fertilizers in all aspects of production and planting, such as: herbicide fiefdom before the seedling period; in order to preserve roots and sterilization during the seedling period, 6 to 7 kinds of pesticides each time, "spraying up and down irrigation" 8 to 10 times; before sealing the mulch film, in order to deal with aphids, thrips, red spiders and other diseases and insect pests, to fight a variety of insecticides; after sealing the mulch, in order to increase the color and fragrance of the fruit, but also to use compound fertilizer, bulking agent, Veterinary antibiotics are even used to prevent root rot.
Such information was widely disseminated, with more than 20,000 likes on a single platform. "There are too many rumors in this video, and the impact on the industry is very large, and the real farmers are both angry and very worried." Liu Jingliang, director of the Yantai Green Strawberry Research Institute and executive director of the Strawberry Branch of the Chinese Horticultural Society, said.
In 2015, some media reported that strawberries were poisoned with herbicides, causing great panic among the public, resulting in a sharp decline in strawberry sales, and farmers could only pour strawberries into the ditch, and the strawberry planting industry in the country lost 1.6 billion yuan that year.
In fact, the pesticide test of strawberries in the mainland is very strict, including more than 70 kinds of dichlorvos, methamidophos, methamidophos, pyrimidine, cypermethrin, etc., including almost all pesticides commonly used in crop cultivation. "I can responsibly say that the test standard for mainland strawberries has objectively exceeded the American standard."
Strawberry cultivation is not so much "dangerous addition"
Liu Jingliang said that the public must first know that now highly toxic pesticides are not produced, it is difficult for farmers to buy them, and most of the low-concentration fertilizers or pesticides will naturally degrade in 37 to 45 days.
As early as 2007, in order to solve the problem of pesticide residues in vegetables, fruits, tea and other agricultural products from the source, the Ministry of Agriculture and Rural Affairs of the People's Republic of China successively banned 39 kinds of highly toxic and high-risk pesticides and eliminated 22 kinds of highly toxic pesticides.
At the end of 2017, the Ministry of Agriculture and Rural Affairs issued another announcement to ban all highly toxic pesticides within 5 years. Now the technical staff guides the farmers to use plant-derived and biological-derived pesticides instead of chemical pesticides at the seedling stage, and will use pesticides to sterilize twice in the early stage of planting, and use two kinds of bacteria to treat diseases after entering the greenhouse, and basically do not use them at other times.
In response to the video mentioned that "all aspects of strawberry planting will use pesticides", Liu Jingliang gave an explanation and clarification.
01
Highly toxic pesticides have long been eliminated for insecticidal sterilization
Pollution-free methods such as natural enemies or probiotics are now used to deal with pests and diseases. Strawberries are mainly pests and diseases of red spiders and aphids, and most farmers know to use California predator mites and ladybugs to deal with them separately.
The common diseases of strawberries are powdery mildew and gray mold, which are mainly controlled by Em bacteria (containing a variety of beneficial bacteria and microorganisms) and Trichoderma Harz, and will not be like the rumors " 6 to 7 drugs at a time, but also 8 to 10 times." ”
02
Herbicides are rarely used on strawberries
Strawberry seedlings should be weeded when breeding to prevent the phenomenon of "grass barren eating seedlings", but the use of herbicides can easily lead to yellowing or even death of seedlings.
Therefore, during the seedling period, generally no herbicide is used, but a black grass film (mulch film is added to the black masterbatch or selective chemical herbicide, which has the function of weeding), or the substrate seedling is used, without weeding.
03
Bulking agents are used less and are generally non-toxic
The scientific name of the bulking agent is plant growth regulator, which is a hormone. Only in the winter low temperature, strawberry endogenous hormones are not enough to support its growth and development, only need exogenous regulator supplementation, generally in the allowable dose range with bulking agent, will not be toxic.
04
The use of fertilizers is mainly organic fertilizers
In the seedling stage, some compound fertilizers, such as nitrogen, phosphorus, potassium, etc., will be used, and the fruit stage is basically not used.
With the advancement of technology, many farmers directly add shrimp bran, sea oyster skin, grass charcoal soil and so on to the soil as nutrient raw materials. "It's like people eating, meat, eggs, and milk should be matched with the right amount, eating too much is not OK, strawberry fertilizer can not be used more." Liu Jingliang said.
05
Dwarfs are generally not used
Strawberries are herbaceous plants, if there is too much fertilizer during the nursery period, the seedlings are not densely packed, sometimes the short and strong pigment is used to control the prosperity, so that the seedlings are strong. However, chlorpyrin is only used occasionally at the seedling stage and is not used at all after greenhouse colonization.
06
Root rot prevention and control never use antibiotics
Root rot is known as the "cancer of strawberries," and once sick, any antibiotics are useless. So the key is prevention, such as choosing detoxification seedlings (virus-free seedlings) or properly disinfecting the soil.
4 big questions about strawberry consumption
The nutritional value of strawberries is very high, the content of vitamin C is 7 to 10 times higher than that of apples and grapes, and eating half a kilogram of strawberries can make up for the amount of vitamin C needed for a day; malic acid, citric acid, vitamin B1, vitamin B2, and the content of carotene, calcium, phosphorus, and iron is also 3 to 4 times higher than that of apples, pears, and grapes.
Li Weimin, director of the Clinical Nutrition Department of the First Affiliated Hospital of Xi'an Jiaotong University, said that giving up eating strawberries because of fear of unwarranted pesticide residues was a bit more than worth the loss.
Consumers also have doubts about the shape of some strawberries on the market, and experts answer them one by one.
No.1
Is strawberry seeds protruding or dented?
The first thing to be clear is that strawberry seeds are edible. The prominence or depression of the seed, determined by the strawberry variety, is not good or bad, and has nothing to do with whether or not to use pesticides.
95% of strawberry seeds are concave, and only a few varieties of strawberry seeds stand out, with top hair, such as the Korean variety Christmas red (aka sherry incense); some varieties of seeds may also stand out when the temperature is higher, such as Kaono.
These seeds, like sesame seeds, are actually the fruits of strawberries, which is what we usually call "seeds". The red strawberries are made of flower butts and have a high water content, which we call berries.
No.2
Is the size of a strawberry related to medication?
Strawberry size is not related to medication and hormones, but to variety and management. From the first stubble to the sixth and seventh stubble, the fruit will become smaller and smaller.
In addition, how many fruits are left in a plant also affects the size of the fruit, such as the Japanese variety of red face, the first stubble top fruit 6 to 7, if left 2 to 3, the weight of a single fruit can grow to two or two (100 grams) or more.
No.3
What is the cause of irregular shape?
There are two reasons for fruit irregularity: one is that the temperature is low when the flower buds differentiate, resulting in poor differentiation and fruit deformation; the other is that when flowering and pollinating, the temperature is too high or too low, and the bees pollinate poorly or in a timely manner, resulting in irregular fruit. Neither affects normal consumption.
No.4
How do I wash strawberries?
Strawberries are not as dirty as people think, and they do not need to be cleaned by all means, generally strawberries picked directly in the greenhouse can be eaten by washing the dust with running water.
Strawberries purchased from the supermarket can be soaked in water with a little salt for 2 to 3 minutes, and then rinsed with clean water to eat.
Strawberries are fruits with low glycemic index, suitable for all seasons, suitable for all ages, especially after eating some strawberries after meals, which can break down food fats and help digestion. Because the elderly have weak gastrointestinal function, they can eat strawberries after a little soak in hot water. ▲
Editor of this issue: Liu Yunxuan
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