"The glucosinolates in brassicas convert to nitriles when the plant is damaged, so when they're chopped and prepared they won't have as good a flavour," he told fellow growers and suppliers. "It's part of the plant's defence mechanism."
He added: "Brussels sprouts left on the stalk will taste better. I have done taste tests at Booth's supermarkets comparing freshly cut leaves to those cut the day before. There is a clear difference."
Molyneux was demonstrating the effect a range of green cover crops on his fields near Ormskirk, which he said improve soil health and so crop quality.
- Full report on the day in next week's Horticulture Week magazine.