They discovered that compounds called isothiocyanates (ITCs) which fight forms of cancer including prostate and gastrointestinal cancers, were significantly more abundant in rocket one week after processing, but then tailed off.
Remarkably, the ITC sulforaphane increased by up to three times following commercial processing and seven days of shelf life.
University of Reading food chemist Dr Luke Bell said: "The discovery is really surprising, going against the assumption that nutrients found in rocket will dissipate over the period of time following harvest.
"Our study has shown that the processing actually has a potentially beneficial effect to consumers, and that rocket lovers can have confidence in the health boost a bag of rocket will give them."
The researchers also analysed whether the levels of the cancer fighting compounds varied according to the flavour profile of rocket.
"The cancer-fighting compounds are prevalent in each variety, meaning that regardless of whether you like rocket mild or hot and peppery, you will still get the same potential health boost," Bell added.
The study was funded by research council and part-sponsored by Bakkavor and Elsoms Seeds.
Bakkavor's agronomic development technologist Dr Lorraine Shaw said: "As a leading supplier of prepared salads we are keen to support research projects such as this, in order to further understand the role key ingredients can play in the healthy eating habits of consumers."
Elsoms managing director Robin Wood added: "We want to understand how we can improve the taste sensation of rocket for the benefit of the consumer, so we were delighted to support the project which has given us valuable information for our rocket breeding programme."