The first place of "the dirtiest fruit", be careful if you take one bite! Many people like to eat it in summer

With the arrival of hot summer, street fruit cutting has gradually become popular. Merchants "thoughtfully" peel and cut the fruits and put them into small boxes, which is very convenient to eat. Moreover, the prices are generally not high, which is really cheap and delicious.

But many people overlook the fact that this seemingly beautiful street fruit cut may very well become a "diarrhea artifact".

Safety risk 1: Moldy fruit is used as substitute

If the fruit is a little rotten, it cannot be sold if it is not thrown away, but it is a pity to throw it away. It is possible that some "smart" merchants will cut off the rotten part of the fruit and leave the good-looking part as fruit slices, passing off inferior products as good ones, which are difficult to distinguish with the naked eye.

There are two common situations in which rotten fruit occurs. One is local tissue damage caused by frostbite or bumps . In this case, you can cut off the bad part and continue eating, but it should be eaten as soon as possible, as it is easy to breed bacteria over time. The other is rot due to poor fruit storage . Although this type of fruit may appear to be only a small part rotten, the entire fruit may have been contaminated. It is not recommended to continue eating it even after cutting off the spoiled part.

An organization collected some slightly rotten fruit samples in the market for microbial and mycotoxin testing and analysis, including the peaches, apples, and grapes we often eat. The results showed that when the fruit was partially rotten or moldy, the whole fruit had a high degree of microbial contamination, such as Escherichia coli, Staphylococcus aureus, and mold. Many slightly rotten fruits have excessive colony counts even in intact parts, and the degree of contamination is not low, but we cannot see it with the naked eye.

Figure: Reference [1]

Gansu Agricultural University has conducted a more detailed study on patulin in rotten apples. The results show that the larger the area of ​​rotten apples, the higher the content of patulin. Patulin will also diffuse into the surrounding tissues of the apples. The farther away from the rotten part, the lower the content of patulin, and the closer the distance, the higher the content. The content will increase with the increase of the diameter of the rotten part. Patulin in the rotten apple will almost diffuse to the entire apple.

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Pathogenic E. coli can cause gastroenteritis symptoms such as abdominal pain and diarrhea;

Under appropriate conditions, Staphylococcus aureus can produce enterotoxins that damage the human intestines, causing symptoms such as vomiting and diarrhea;

Molds are also toxic to a certain extent and can cause neurological and endocrine disorders, immunosuppression, carcinogenesis, teratogenesis, liver and kidney damage, reproductive disorders, etc.

Fungal toxins are also very harmful. For example, patulin can cause acute/chronic food poisoning in consumers, and may cause symptoms such as nausea, abdominal pain, diarrhea, and is teratogenic and carcinogenic. Aflatoxin B1 is highly pathogenic and carcinogenic to humans and animals, and its toxicity is 68 times that of arsenic. It is relatively stable to light and heat, and is not easily decomposed by conventional cooking and heating methods. Human primary liver cancer is likely related to aflatoxin.

Therefore, the deterioration of fruit is not only a surface phenomenon, but also quietly penetrates into various parts. The best way to deal with it is to discard it as a whole. It is really difficult to distinguish the processed street fruit cuts.

Safety risk 2: Poor hygiene conditions

We don’t know what the operating environment is like for the cut fruits, including whether the staff washed their hands and disinfected them carefully, whether they wore disposable gloves, whether the fruits were thoroughly washed before peeling, whether the knives and cutting boards were clean, whether they wore masks, etc.

1

Not washing hands carefully

Our hands may look clean, but they are actually very dirty. A study examined the palm surfaces of 51 healthy college student volunteers. A total of 25 major categories of bacteria were detected on the palms of 27 male volunteers and 24 female volunteers, of which three major categories of bacteria (Actinomycetes, Firmicutes, and Proteobacteria) accounted for 94% of the total. For a total of 102 palms, the research team further identified 4,742 types of bacteria, with an average of 150 types of bacteria on each hand, and the number of bacteria on the dominant hand was higher.

If you don't clean your hands thoroughly or wear disposable gloves before cutting fruit, the bacteria on your hands will contaminate the fruit. Some people will also look at their phones while cutting fruit. Pathogenic bacteria such as Staphylococcus epidermidis, Escherichia coli, Enterococcus, Candida, Staphylococcus aureus, and Salmonella are common on the surface of mobile phones, which can easily contaminate food.

2

Unpeeled fruit

Although the skin of some fruits is not eaten, it is necessary to wash it before peeling it. For example, cantaloupe may carry Listeria, which can cause vomiting, diarrhea, fever, muscle aches, and in severe cases, coma, shock, and death.

According to relevant reports, some Hami melons produced by a farm in Australia were contaminated with Listeria, which caused illness and death. The Hong Kong Food Safety Center reminds: Before eating Hami melon, you need to scrub the entire surface of the Hami melon with a clean brush under running water, then cut it and eat it, and it is recommended to eat it as soon as possible.

3

Knives and cutting boards are unhygienic

If knives and cutting boards that have come into contact with the peel are not carefully cleaned, bacteria will breed, and cross-contamination is likely to occur when used to cut the flesh. The larger the contact area, the easier it is to deteriorate. If you just wipe it with a rag and then use it again, it will "bury" more bacteria.

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4

Not wearing a disposable mask

When we breathe and talk, we produce a lot of droplets. Droplets not only increase the risk of respiratory disease transmission, but also contaminate food.

Studies have found that normal talking, coughing and sneezing will release droplets. Larger droplets can fall to the ground before moving a horizontal distance of 2.5 meters, while smaller droplets will completely evaporate into droplet nuclei before falling to the ground, remain in the air for a long time and move with the airflow.

Wearing a mask properly can effectively prevent droplets from contaminating food.

Safety risk three: unknown production and storage time

We don’t know the production and storage time of the cut fruits that have been placed on the stalls. The degree of fruit deterioration will increase with the storage time, and the safety risk of eating it will also increase. Moreover, under the same environment, cut fruits are more likely to breed bacteria and deteriorate than intact fruits. After all, the fruit is surrounded by bacteria the moment it is cut.

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It is summer now, and the temperature in many places may have reached above 30℃. 4℃~60℃ is the dangerous temperature zone for food. At this temperature, various bacteria will multiply very quickly, which is simply a "happy paradise for bacteria" .

A 2017 study published in Foodborne Pathogens and Disease compared the growth of Salmonella and E. coli in fresh-cut cantaloupe, honeydew, mango, watermelon, dragon fruit, papaya and pineapple at different storage temperatures.

The results showed that the Salmonella and Escherichia coli in fresh-cut fruits did not change significantly within 6 days when stored at 5°C; however, when stored at 25°C, the number of these two bacteria increased by 4 times within one day at most. The longer the storage time, the greater the number of bacteria.

In recent years, some people have analyzed the microbial contamination of some fresh-cut fruits sold in Beijing, and found that the pathogenic bacteria contamination of fresh-cut fruits sold in Beijing is not optimistic, and the detection rate of Staphylococcus aureus is high. The National Food Safety Risk Assessment Center and the School of Life Sciences of Anqing Normal University have also analyzed the contamination of important foodborne pathogens in retail fresh-cut fruits in the five urban districts of Beijing. Among the 218 fresh-cut fruit samples, the number of samples contaminated by Staphylococcus aureus, Listeria monocytogenes and Escherichia coli was 36, 4 and 17 respectively, and Salmonella was not detected.

It can be seen from this that the probability of street-side cut fruits being contaminated by bacteria is not low. The longer the storage time and the higher the temperature, the higher the risk of food poisoning.

Summarize:

Although it is convenient to buy fruit slices on the street, it is best not to buy from untrustworthy shops, as it may cause diarrhea, especially for children, the elderly, pregnant women and other people with low immunity. If you really want to eat it, you can find a shop with qualified hygiene conditions and can buy and cut it on the spot, which is relatively safer.

References

[1] Liang Ke, Wang Yi, Li Bin, Huang Ziyin, Shi Song. Analysis of microbial and fungal toxin contamination in moldy fruits[J]. Food Safety Guide, 2021(31):103-105

[2] Liu Huafeng, Han Shunyu, Sheng Wenjun, Zhu Xia, Jiang Yumei. Study on the distribution of patulin in rotten apples[J]. Food Science, 2010, 31(07): 51-53.

[3]Fierer N, Hamady M, Lauber CL, et al. The influence of sex, handedness, and washing on the diversity of hand surface bacteria[J]. Proceedings of the National Academy of Sciences, 2008, 105(46): 17994-17999.

[4] Ma Jianrong, Mo Wanying, Yu Yonghong, Shen Xiaomeng. Current status and prevention of mobile phone bacterial contamination[J]. Science and Technology Horizon, 2020, 0(2): 146-148

[5] Centre for Food Safety, Government of the Hong Kong Special Administrative Region https://www.cfs.gov.hk/english/multimedia/multimedia_pub/multimedia_pub_fsf_141_03.html?continueFlag=a62df2743e84be762c56e10f74ddc812

[6] Dai Hui, Zhao Bin. Movement and propagation patterns of human exhaled droplets and droplet nuclei[J]. Chinese Science Bulletin, 2021, 66(4): 493-500

[7] Feng, K., Hu, W., Jiang, A., Saren, G., Xu, Y., Ji, Y., & Shao, W. (2017). Growth of Salmonella spp. and Escherichia coli O157:H7 on Fresh-Cut Fruits Stored at Different Temperatures. Foodborne pathogens and disease, 14(9), 510–517. https://doi.org/10.1089/fpd.2016.2255

[8] Liu Yuzhu, Zhang Xiaoai, Cui Xia, Wang Di, Lu Zheng, Zhang Yi, Wang Lili, Zhang Penghang, Zhang Xun, Niu Yanlin, Chen Qian, Ma Xiaochen. Study on the microbial community structure and drug resistance gene characteristics of some commercially available fresh-cut fruits and freshly prepared fruit juice drinks[J]. Capital Public Health, 2024, 18(1): 50-54

[9] Bai Yao, Ma Jinjing, Huang Minyi, Peng Zixin, Wang Wei, Hu Yujie, Yan Shaofei, Li Hui, Li Nan, Xu Jin, Li Fengqin. Study on contamination and drug resistance of important foodborne pathogens in retail fresh-cut fruits and vegetables in five districts of Beijing[J]. Chinese Journal of Food Hygiene, 2021, 33(6): 692-697

Planning and production

Review丨Zhang Yu, researcher/PhD, Chinese Center for Disease Control and Prevention, national health science expert

Planning丨Yinuo

Editor: Yinuo

Proofread by Xu Lai and Lin Lin