Why Are Leafy Greens Prone to Contamination?

Leafy greens are a versatile and incredibly healthy food source. They are rich in essential minerals and vitamins, including vitamin A, vitamin C, calcium, iron, magnesium and potassium. They are also high in antioxidants.

Unfortunately, they are also vulnerable to contamination that can cause foodborne illnesses. Leafy greens are particularly prone to carrying E. coli, so growing and storing them correctly requires insight and the right tools to stop contamination and help greens flourish.

Leafy greens — including romaine and green-leaf lettuces, spinach, kale and collards — are prone to contamination primarily due to their delicate leaves and how they are grown, harvested and processed. Through preventive measures, including contamination testing and safe handling techniques, you can reduce the spread of contaminates on leafy greens to ensure greater regulatory compliance and consumer safety.

Bacterial Growth and Leafy Greens

Two of the most common leafy green contaminants are E. coli and salmonella. The risks of leafy greens contamination with these bacteria include a host of health issues — some quite severe. Harmful strains of E. coli can cause diarrhea, blood in the stools, vomiting and abdominal pain. In rare cases, they may also cause kidney failure and death. Likewise, salmonella can cause fever and stomach cramps.

Humid conditions, warm temperatures and unhygienic conditions can all cause these pathogens to thrive on leafy greens.

How Do Leafy Greens Get Contaminated?

Leafy greens can become contaminated with bacteria like E. coli and salmonella in several ways:

• Soil contamination: Soil can be a breeding ground for contaminates like bacteria and even toxins like lead. Leafy greens can become contaminated by affected soil by absorbing toxins through their roots.
• Water contamination: In improper conditions, water systems can become contaminated with pathogens from sewage or animal runoff. These pathogens can spread if the contaminated water irrigates the soil in which the leafy greens grow or is used to wash the leafy greens. Beyond irrigation, water also plays a vital role in post-harvest washing, spraying and chilling leafy greens during transportation and storage. Using clean, quality water throughout is, therefore, imperative.
• Exposure to animals: If the leafy greens are grown where livestock or domestic animals may roam, they can become contaminated directly from animal droppings. Insects like flies can also carry and spread bacteria.
• Improper harvesting techniques: Improper handling practices during harvesting, processing and packaging can easily contaminate leafy greens. Some examples include staff not following proper hygiene protocol, washing hands, wearing gloves or sanitizing tools and equipment.
• Incorrect transport and storage conditions: All produce needs to be kept at the right temperature and humidity levels during transportation and storage to prevent contamination. If these conditions are not met, bacteria may thrive. As with any part of the supply chain, transportation and storage conditions must be clean and hygienic to stop bacteria from multiplying.
• Improper eatery or consumer handling: Agricultural sectors can take all precautionary measures to ensure delivery of clean leafy greens that are safe to eat, but they can become contaminated at the very last stage — when the greens are prepared for a meal. Cross contamination can occur from non-sanitized surfaces, using unclean knives and other utensils, and not following basic practices like thoroughly washing the greens or hands before preparation.

Preventive Measures and Safety Protocols

Preventive measures, such as the right handling of greens and testing for bacteria, are key to preventing and reducing the risk of contamination. Implementing safety measures ensures regulatory compliance across the agricultural and food industries, as it leads to greater food safety and consumer trust.

The Food and Drug Administration (FDA) has also long recognized the need to break the cycle of recurring E. coli outbreaks in leafy greens. It has developed and implemented the Leafy Greens STEC Action Plan (LGAP) to address and combat the issue. The plan involves prioritizing inspections, investigating the root cause of contaminations, advancing technology that can assist with bacterial detection, and data sharing.

Managers and staff across all sectors can also implement the following techniques and protocols to combat leafy green contaminations:

Pre- and Post-Harvest Handling of Leafy Greens

Careful pre- and post-harvesting of leafy greens should involve the following safety measures:

• Using reliable compost and fertilizers to reduce pathogenic microorganisms
• Using clean, quality water for irrigation and post-harvest cleaning and chilling
• Using water quality testers for contamination control
• Disinfecting all vehicles for transportation
• Humidity and temperature monitoring for fresh produce during transportation
• Regularly sanitizing utensils and food preparation surfaces to prevent cross contamination
• Ensuring workers across the supply chain incorporate practices that meet standard hygiene procedures for food handling
• Using modified atmosphere packaging (MAP) to extend the shelf life of greens and regulate the growth of microorganisms
• Educating consumers on how to reduce the risk of food poisoning from leafy greens

Using state-of-the-art testing equipment throughout growing, harvesting and post-harvesting also helps reduce outbreaks. Quality inspection tools, animal and fly or insect controls, and tools for water, soil and food analysis are essential. They all help those in the agricultural and food sectors protect and regulate their produce to ensure compliance with food safety laws.

Testing Methods for Contamination Detection

In the food industry, testing for E. coli and other contaminants on leafy greens is an important part of quality assurance. The process is highly involved, but crucial to ensure that the food industries are delivering products safe for consumption. Testing leafy greens generally involves the following basic steps:

• Samples from various batches of leafy greens are collected using sterile equipment.
• The sample is prepared in the lab and transferred to an enrichment broth such as tryptic soy broth (TSB) for easier E. colidetection.
• The sample is also incubated to increase the likelihood of detecting contamination.
• Confirmation tests are conducted to confirm the presence and strain of E. coli.
• Results are analyzed and reported.

If contamination is confirmed, an appropriate plan is executed. This may involve product recalls and extensive investigations of what caused the outbreak.

QA Supplies CO2 Testing Products

Testing produce is essential for consumer safety and trust. Following hygiene and safety standards and regular water, soil and food testing is vital for protecting your leafy greens. It helps prevent the outbreak and spread of bacteria like E. coli and salmonella.

At QA Supplies, we provide quality testing products and environmental controls to suit your commercial needs for delivering quality produce and other perishables. We have testing instruments for water, soil and food analysis, produce quality tool kits and pest control equipment. We also offer a wide range of equipment for production, including harvesting tools. Contact us today to discuss our testing solutions or request a catalog of all our products.