Can Microorganisms Contaminate Organic Fruits And Vegetables?

By Froots

Everyone prefers to consume fruits and vegetables of good quality. That’s how the demand for organic fruits and vegetables has increased in the last few decades compared to the conventionally grown ones. Unlike conventional ones, the organic produce is more nutritional with good health benefits due to the absence of synthetic pesticides or chemical fertilizers, growth hormones, antibiotics, genetically modified organisms, and heavy metals. But there are very few research studies regarding the microbes in organic foods. Is there any microorganism in organic fruits and vegetables? Are they all harmful? If so, how? Is there any preventive measure?

Microbiology of fruits and vegetables
Remember that microorganisms are omnipresent. Similarly, they are also present in organic foods. There are two types of microbes present in the plants:

  • Endophytes, otherwise called as beneficial microbes, help enhance the nutritional value of the plant by improving its growth and protecting it from pathogens.
  • Pathogens, otherwise called as harmful microbes, affect the plant’s growth. They cause diseases and affect the health condition if consumed.

A recent comparative study of conventional and organically grown produce revealed that the organic produce, unlike conventionally grown produce, was free from pathogens. The reason is organic farming enhances the growth of beneficial microbes so that they can protect the crops from harmful pathogens. Hence, organically farmed produce will remain safe. Even the chance of having fecal contamination due to the use of manure as fertilizers can be reduced by following varied preventive measures, thereby bringing foodborne diseases under control.

What are the common foodborne pathogens found in organic fruits and vegetables?

Foodborne pathogensFoodborne diseases
Escherichia coli O157:H7Food poisoning
Salmonella typhiTyphoid
Escherichia coliDiarrhea
Campylobacter jejuniCampylobacteriosis
Listeria monocytogenesListeriosis
Toxoplasma gondiiToxoplasmosis
MoldsMold toxins

The common symptoms of all these foodborne diseases include fever, abdominal cramps, stomach pain, diarrhea, dehydration, headache, nausea, and vomiting.

Sources of contamination of fruits and vegetables

Manure
Foodborne pathogens breeding inside the gastrointestinal tracts of livestock come out as waste (dung), which in turn is used as manure for organic farming . Hence, there is a chance of fruits and vegetables grown out of this manure to get contaminated followed by developing illness if consumed by humans.

Apart from manure, there are other routes of contamination such as water for irrigation, direct contamination by birds, insects, livestock, and wild animals, as well as post-harvest issues like worker hygiene that includes improper handling, harvesting equipment, washing or cleaning with sewage water, poor packaging with gunny bags, storage places, methods of transportation, etc. At last after buying them from the market, if these fruits and vegetables are consumed in raw uncooked form, the chance of developing illnesses is higher.

How to reduce microbial contamination in organic fruits and vegetables?

  1. During farming
    To decrease fecal contamination, the manure should either be composted at 55-77 °C. Or the non-composted manure should be allowed to age at least 90 days before harvest. In the case of the crops in close contact with soil, allow the manure to age at least 120 days before harvest.

2. Post-harvest cleaning with electrolyzed water during storage and packaging
Electrolyzed water is prepared by the electrolysis of ordinary tap water containing saline (salt), which is an effective disinfectant. Before proceeding for sales, the crops after harvest are immersed in electrolyzed water. The pathogen, if any, gets killed due to oxidative stress within a few seconds.

The electrolyzed water from the generators has an Oxidation Reduction Potential (ORP) of between 1100 – 1200mV which helps in employing oxidative stress on pathogens effectively. This level allows the disinfection effect to take place in the millisecond range rather than seconds.

Pathogen/Indicator Survival in seconds (s) or hours (h) at ORP (mV)
<485
Survival in seconds (s) or hours (h) at ORP (mV)
550 < X < 620
Survival in seconds (s) or hours (h) at ORP (mV)
>665
 Escherichia coli O157:H7>300s<60s<10s
Salmonella spp.>300s>300s<20s
Listeria monocytogenes>300s>300s<30s
Temperature tolerant food-borne pathogens>48h>48h<30s
Source: http://www.water-research.net/pdf/orpdisinfection.pdf

3. During supply chain
As mentioned above, there is a chance of contamination during the supply chain due to the workers hygiene issues.

4. Before consumption 
Since the quantity of pathogens is minimal in organic fruits and vegetables, the common household practices are enough to get rid of pathogens.

  • Washing – Washing with tap water could potentially reduce microbes by 0.5 to 2 log CFU/g according to the extent of surface attachment. 
  • Chlorine dioxide gas treatment – In the case of an injured organic vegetable surface, the pathogen might have penetrated deeply. Hence, just a tap water wash is not enough. A gaseous treatment with chlorine dioxide gas may work out. 
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  • Peeling – Peeling is the standard physical method used to ward off the spoilt fruits and vegetables, as well as reduce microbial contamination.
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  • Blanching – Blanching is a process where the raw fruit or vegetable is subjected to mild heating followed by cooling. This process results in the inactivation of enzymes, followed by the elimination of microbes from the surface of fruits and vegetables owing to the thermal effect. Finally, the shelf life of these raw items will get prolonged. 

Does organically farmed produce have more pathogens compared to the conventionally farmed ones?

A research study published in the Journal of Food Protection revealed the potential association between the certification of organic farming and the reduced prevalence of foodborne pathogens. According to this experiment, the prevalence of foodborne pathogens in the non certified organic farms was significantly higher than in conventional produce. However, when it comes to certified organic farms, the prevalence of foodborne pathogens was not significantly higher. Hence the author of this research article says, “Based on the absence of E coli O157:H7 and the very low Salmonella prevalence, the assertion that organic produce has greater pathogen contamination does not seem to be supported.”Many studies have revealed that the prevalence of foodborne pathogens is too less in organic fruits and vegetables, which can be reduced by following proper washing methods. On analyzing around 179 samples of organically grown lettuce, the scientists found that the microbial contamination was very occasional.

Key Takeaways

Compared to the conventional produce, it is evident that organic fruits and vegetables are comparatively fresh with no chemical preservatives, harmful pesticides or fertilizers, as well as heavy metals. They are rich in nutritional value and antioxidant levels with less impact on the environment. Moreover, organic farming increases the yield of beneficial microbes. Hence, the prevalence of microbial contamination is very rare at every stage including sowing, post-harvesting, and before consumption. Even if there occurs any microbial contamination, steps such as manure composting, electrolysis, washing, peeling, and blanching can eliminate the microbes effectively. Hence, it is proved that organic fruits and vegetables are more effective than conventional ones considering the health of the consumers. 

Better late than never! Don’t let conventional foods harm your health; opt for natural and pure organic foods! 

References:

https://www.cidrap.umn.edu/news-perspective/2004/05/study-yields-mixed-findings-about-microbes-organic-produce

https://www.omicsonline.org/open-access/organic-food-and-health-a-systematic-review-2161-0711-1000532.php?aid=90187#13

http://www.water-research.net/pdf/orpdisinfection.pdf

Photo by Sven Scheuermeier on Unsplash

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