Knox Rijk Zwaan field

In September 2015 Rijk Zwaan launched ten types of lettuce with a unique characteristic, Knox, a natural trait that extends the shelf life of fresh cut lettuce, and according to the Dutch group things have moved very quickly since then.

Processing companies and retailers all over the world have been eager to start working with these lettuce varieties, according to Rijk Zwaan's convenience specialist Bauke van Lenteren.

“We developed Knox in direct response to what processing companies wished for most,' she explained. 'Sales of fresh cut and bagged lettuce had been growing strongly for years, but the pinking on the edges continued to pose a tricky problem. Knox extends the shelf life, plus it means that fresh cut lettuce doesn’t always need low-oxygen packaging. That not only reduces costs but also opens up more opportunities for blending different types of leaves.”

Less waste Waste reduction is perhaps the most important advantage of all, van Lenteren continued. “Knox also offers significant benefits in the rest of the chain. For retailers, the advantages include improved inventory management and less waste. Extending the shelf life by just one extra day generates a 25 per cent cost saving. And consumers benefit too: bagged salads stay fresher for longer, and the lettuce still has its fresh green colour a day after the bag has been opened. So Knox can raise the purchasing frequency and hence also boost lettuce consumption.

“In September 2015 we introduced ten lettuce varieties with the Knox trait in various types of lettuce, including cos, batavia, iceberg lettuce, butterhead, Salanova Crispy and Salanova butterhead,' she added. 'There was tremendous interest from growers and processing companies all over the world, and the development has rapidly gathered pace ever since. Processing companies in the UK, Switzerland, Poland, Australia and the USA are already working with our Knox lettuce varieties, and they are all very enthusiastic.”