Sorting technology combats toxic weeds in vegetables

Toxic weeds pose a serious challenge for processors, making vegetable crop protection technology essential to safeguard food quality. Poisonous weeds such at Datura stramonium (thorn apple, jimsonweed, stinkweed, angel’s trumpet) and Solanum dulcamara (nightshade) are particularly problematic when mixed with green beans and baby leaf spinach, where their color makes detection difficult. Once blanched or cut, these weeds become even harder to identify.

Though rare, food contamination incidents have occurred. In December 2022, more than 130 Australians experienced hallucinations and delirium after eating baby spinach suspected of containing toxic weeds. In Slovakia in 2011, deep frozen spinach puree contaminated with jimsonweed was linked to a food-borne outbreak.

Why toxic weeds are difficult to detect

Nightshade fruit appears as a small green ball that eventually turns black, resembling a blueberry. In early stages, it closely matches spinach or green beans, making it hard for traditional sorters to detect. When cut or blanched alongside vegetables, shape-based detection also fails. Datura fruit, small and spiked, loses its spikes during blanching, further complicating sorting.

Because of these similarities, processors must sort by biological characteristics, not just shape and color. TOMRA Food has developed advanced solutions for detecting and removing toxic weeds across IQF, canned, fresh pack and fresh-cut products.

Vegetable crop protection technology solutions

The TOMRA 5B and TOMRA 5C machines are designed to identify and reject toxic weeds. Many processors run both units on the same line: the 5B before slicing or blanching, and the 5C after processing with Biometric Signature Identification (BSI and BSI+) technology for final checks.

The TOMRA 5B uses 360-degree camera technology, lasers and shape algorithms to sort by color, shape and structure, achieving up to 99% detection of foreign material. The touchscreen interface provides real-time data and alerts operators when cleaning is needed. Beyond beans and spinach, it can also sort peas, carrots, corn, bell peppers, lettuce, potatoes, French fries, chips and specialty potato products.

McCall Farms in South Carolina increased its annual green bean production from 18 million to 204 million cans after adopting the TOMRA 5B.

“The performance superiority of TOMRA’s sorters is staggering,” said Amanda Salisbury, maintenance superintendent. “It’s a delight to watch them perform. We got results above expectations — a 99% removal rate for all defects. Our product quality has risen substantially.”

AI and big data enhance protection

The TOMRA 5C uses high-resolution lasers and sensors combined with BSI technology to detect weeds even after slicing or blanching. By analyzing spectral imaging, the sorter can identify internal biological signatures, distinguishing toxic weeds from good produce.

Artificial intelligence continually improves detection accuracy. Operators can also create new sorting programs, while TOMRA Insight, a cloud-based data platform, enables live monitoring and retrospective analysis to improve efficiency and assess raw material quality.

Virto Group, a multinational vegetable producer, recently installed 11 sorters equipped with BSI+ in its main Spanish plant.

“Our main objective was to take a quantum leap in new technologies for foreign material sorting,” said José Antonio Baldero, technical manager.

Sorting manager Franciso Casas added, “Our new TOMRA units can do things that were complicated before we had them.”

Protecting consumers and meeting demand

With organic production and pesticide restrictions increasing globally, processors face greater weed-related risks. By adopting advanced vegetable crop protection technology, companies can address retailer expectations, reduce contamination risk, and protect consumer health.

As consumer demand for organic vegetables grows at a project rate of 10% – 13% annually through 2030, investing in high-performance sorting systems ensures both food safety and operational efficiency.

– By Jacob Hobbel. Hobbel is the global category director for vegetables and fruit for TOMRA Food.