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Knox™ keeps Crunchy Caesar Salads extra fresh

Nowadays, every fast-food chain and company canteen has a choice of salads on the menu, often with tempting names such as Veggie Delight, Thai Chicken Salad or Crunchy Caesar Salad. One indispensable ingredient is cos lettuce or iceberg lettuce. A unique innovation that ensures fresh-cut lettuce stays fresh for longer has recently opened up new opportunities for the foodservice market.

Although there are some clear differences per country, the foodservice market is growing worldwide according to Rabobank’s ‘Global Outlook – Foodservice 2019’ report. In the USA, for example, the concept of ‘casual dining’ – a cross between a restaurant and a fast-food chain – is becoming increasingly popular. Meanwhile there is a growing focus on ‘healthy’ and ‘fresh’ across the globe. Bauke van Lenteren, Manager Convenience at vegetable breeding company Rijk Zwaan, confirms this trend: “We’re seeing healthy food, fresh ingredients and minimal waste becoming ever-more important in the out-of-home market.” 

Less waste

Salads are a good fit with that trend and they are increasingly taking centre stage, whether on people’s plates or ‘on the go’. But how can an out-of-home chain ensure its Crunchy Caesar Salads stay fresh and appealing? Rijk Zwaan, the market leader in lettuce, has the answer to that question in the shape of its award-winning innovation, KnoxTM. Van Lenteren: “KnoxTM is a natural trait that delays pinking in lettuce, which extends the shelf life by at least two days and reduces waste. It was launched in 2015 and we now offer a complete range of KnoxTM lettuce varieties enabling year-round production. The range includes iceberg and cos, which are both widely used lettuce types in the out-of-home market. We have a suitable variety for every application.”

Seeing and tasting

She has noticed rising interest in KnoxTM varieties: “I took several convenience and foodservice companies on a guided tour of our demo field in Fijnaart during the Demo Days in early June. We will also be promoting our KnoxTM lettuce varieties at PMA in Monterey, USA, in late July, Hort Connections in Melbourne, Australia and again in the demo field in the Netherlands in September. Anyone who is interested is welcome to come and see, taste and compare our lettuce varieties for themselves.” That’s how we share a healthy future.

Foodservice facts and figures*

  • Foodservice will continue to grow worldwide in 2019
  • Casual dining is the biggest growth area in the USA
  • Spain is the ‘sweet spot’ in Europe
  • Healthy and fresh fast food is showing strong growth across Europe
  • In China, the key growth accelerators are ‘digital’ and ‘delivery’

*Source: Rabobank – ‘Foodservice 2019 – Global Outlook’ report

Rijk Zwaan is exhibiting at PMA Food Service in Monterey, California, USA, on 26 and 27 July 2019. For more information about Knox™, go to

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Innovation transforms the lettuce landscape

Knox extends the shelf life of lettuce by 2 days.

Nothing beats the freshness of fresh lettuce, and fresh-cut bagged lettuce has gained considerable ground in recent years. However, the pinking on the edges poses a problem. In response to this, the breeders at Rijk Zwaan – who are continually working on innovations and improvements to existing products – set out in search of a nature-based solution. They developed a research method and tested the extent of discolouration in hundreds of lettuce heads. And then they had a breakthrough: the researchers found a plant with no discolouration even after three days. Extensive laboratory and practical tests have confirmed this unique trait.

Crossing into varieties

It appeared to be a recessive trait and breeders set to work to investigate its inheritance pattern. Once techniques such as genetic markers had provided certainty, it was time for the next step and the breeders initiated back-crossing into various lettuce types as quickly as possible. Finally, after a decade of continuous research and development, the breeders presented six varieties with the KNOX gene: Cos, Batavia, Iceberg, butterhead, Salanova® Crispy and Salanova® Butter.

A bright future for lettuce

KNOX was officially launched onto the market in September 2015 during the Rijk Zwaan Leafy Event, and the KNOX varieties were on display in the demo field in Fijnaart immediately afterwards. Visitors were very interested in the concept. All the enquiries from growers and processing companies are currently being evaluated so that widespread trials can start in 2016. Thanks to KNOX, the future of lettuce looks even brighter. Needless to say, the assortment of varieties will gradually be extended over the coming years to eventually make a KNOX version available for every favourite.

“KNOX extends the shelf life of lettuce by 2 days”

According to Bauke van Lenteren, Convenience Manager at Rijk Zwaan, KNOX responds to an important need among processors. “Thanks to KNOX, fresh-cut lettuce does not always need low-oxygen packaging. This reduces costs and gives processors more options when blending . Furthermore, it eliminates the unpleasant smell associated with opening low-oxygen packaging.” Combining the benefits for the processing industry with the advantages for retailers – better inventory management and less waste – reveals the true scope of KNOX: a more sustainable chain in which this groundbreaking innovation will hopefully stimulate consumers to purchase and hence eat lettuce more often. “After all, the KNOX benefits ultimately create a better consumer experience too.”

“Result of thorough research”

Rijk Zwaan researchers Johan Schut and Kees van Dun were closely involved in the development of KNOX. “It was a severe test of our patience sometimes. When we conducted a screening using wet filtration paper, we noticed that the exposed edges of the lettuce produced a pinkish colour upon contact. But unfortunately none of the leaf discs from our genetic material showed any deviations. We then hit on the idea that the plant might need to be a little older so we decided to use a batch of 10,000 plants grown to maturity.”

“In the test, one of the discs showed significantly less discolouration. The plant was retrieved and thankfully it produced seeds quite easily so breeding work could start soon afterwards. And the results of the first ‘bag trials’ were positive, too. The fact that it was a recessive trait made it a bit more difficult to cross it into commercial material. In order to be able to demonstrate the trait when heterozygous there was an immediate need for a genetic marker, which was a considerable challenge in view of lettuce’s large genome. Genomic breeding and bioinformatics were just starting to gain ground at that time so, supported by these disciplines, molecular biology was able to develop the marker entirely in-house.”