Jimmy Doherty looks at some of the tricks food manufacturers use to maintain a constant supply of seasonal foods all year round, as he concludes his mission to unravel the scientific secrets behind mass food production.

In a bid to find out how bananas that grow thousands of miles away always arrive in the supermarket perfectly ripe, Jimmy sets up his own banana-ripening experiment. He also turns his mind to mushrooms, which normally only appear in the fields in autumn, but grace the supermarket shelves all year round.

If people relied on nature to supply salmon to supermarkets, they would find empty fridges for much of the year, so Jimmy visits a salmon farm in Scotland, where he discovers a plot to fool the fish into believing it’s summer when, in fact, it’s really winter.

Finally, Jimmy explains how sandwich ham producers make people think the pink slices are cut from a single joint of meat, rather than lots of tiny pieces squashed together.

Jimmy’s Food Factory is simulcast on the BBC HD channel – the BBC’s High Definition channel, available through Freesat, Sky and Virgin Media.