I believe that many people have encountered such a situation: the apples at home have been left for a long time to produce brown spots or the oranges have been moldy for a few days! I feel a pity to throw it away, but can I still eat the undamaged part? In fact, once signs of decay appear on the surface of the fruit, it indicates that the microorganisms inside have begun to multiply. The secondary metabolites (mycotoxins) produced in the process multiply faster and diffuse from the rotten part to the non-rotten part. At this time, it shows that it looks good. Part of it has actually been contaminated by these mycotoxins! After eating, it will cause health risks to the human body.
Fruits are an important part of the human diet. They are rich in vitamins and minerals. They have anti-aging properties, enhance immunity, and prevent cardiovascular diseases. However, the problem of pathogen infection in fruits has not been widely recognized by the public.
Fruits are susceptible to contamination by pathogenic bacteria during growth, harvesting, transportation, storage, and sales. Especially during storage, various mycotoxins are produced, which endanger human health. Among them, the mycotoxins that contaminate fruits mainly include Alternaria toxin, patulin and ochratoxin. Almost all common fruits in life are at risk of contamination, such as apples, pears, peaches, kiwis, tomatoes, and grapes. According to incomplete statistics, due to the limitation of storage technology and fresh-keeping technology in my country, the corruption rate of fruits after picking is as high as 30%. This not only causes hundreds of billions of economic losses, but also directly affects the healthy development of my country's food safety.
Mycotoxins in fruits
Alternaria mycotoxin
Alternaria alternata mycotoxins are a series of metabolites produced by Alternaria alternata, and are one of the most common fungi that contaminate fruits and vegetables. Commonly found in all kinds of fruits and their products, grains and their products, etc. According to incomplete statistics of researchers, the contamination rate of Alternaria mycotoxin in tomato sauce in a certain place can be as high as 25% to 75%. Due to the lack of sufficient toxicological data in my country, relevant standards have not been established. Most of the fungi have low acute toxicity. Only two toxins have been confirmed to be carcinogenic and have a certain degree of correlation with esophageal cancer.
Patulin
Patulin is a secondary metabolite produced by fungi such as Aspergillus and Penicillium. It is produced by infection of pathogenic bacteria after the peel is damaged. At the same time, it is very easy to infect the surrounding pulp tissue. Patulin is a small molecule compound with a polyketolactone structure and has high thermal stability. Its activity can reach 10 seconds without being destroyed under the action of 90°C. It is commonly found in spoiled apples, hawthorns, grapes, pears and other fruits and their products. Apples and their products are considered to be the most susceptible to patulin contamination. According to my country's "National Food Safety Standards Limits of Mycotoxins in Foods" (GB2761-2017), the limit standard for patulin in fruits and their products (except fruit peel), fruit and vegetable juices and beverages is 50μg/kg. Patulin is acutely toxic, toxic to the human lungs, liver, kidneys, and immune system, as well as chronic toxicity, such as cytotoxicity. Because children prefer to drink fruit juice, the intake is larger and the tolerance is poor, and it is easy to exceed the maximum tolerable amount.
Ochratoxin A
Ochratoxin A is a toxic metabolite produced by fungi such as Aspergillus ochra and Aspergillus charcoal. Ochratoxin A is commonly found in grapes and their products, such as wine or raisins. In 2017, the limit of ochratoxin A was added to the limit of mycotoxins in food: the limit in wine is 2.0μg/kg. Researchers once tested 84 wines from Ningbo and other places for ochratoxin A, and found that the detection rate was as high as 100%. Not only that, the content of this toxin in raisins is much higher than that in wine. There are three types of ochratoxins: A, B, and C. Among them, ochratoxin A is the most common and the most toxic. It has been identified as a type IIB carcinogen by the International Agency for Research on Cancer. It can destroy the immune system. The liver and kidneys cause damage, cause fetal malformations, miscarriage and death, and are highly carcinogenic.
Teach you how to pick fruits
It is best not to eat rotten fruits! Pay attention to the following points when choosing fruits:
1. It is best to choose fresh fruits with bright color, and try not to choose fruits with dull color, brown spots or mechanical damage. If this mechanical damage causes an open wound to the fruit, that is, the fruit is broken, it may cause fungi and bacteria, and then rot.
2. Be wary of the cut boxed fruits on the market. Because it is possible that the merchant will continue to sell the intact part of the fruit after cutting off the rotten part of the fruit.
3. For perishable fruits, such as strawberries, peaches, etc., it is best to choose independent packaging, with good appearance and bright color, and eat as soon as possible. Strawberries are easily damaged by collisions and are easily contaminated by pathogenic bacteria, thereby producing mycotoxins. Because of its soft tissue structure, peaches spread faster than other fruits. Therefore, special attention must be paid when selecting such fruits.
4. Not edible sugarcane with reddish center. This is because sugarcane is infected by Arthrobium spp. which produces a toxin that is harmful to the human nervous system-3-nitropropionic acid. The substance stimulates the mucosa of the gastrointestinal tract, damages the cranial nerves, and is acutely toxic. If consumed too much, it can cause respiratory failure and even death. It is better to choose sugarcane with uniform thickness, shiny skin, white frost, straight shape and delicate smell.
