If your customers have become blasé about passion fruit juice, perhaps it's time to offer them a taste of lulo.

It is one of four chilled fruit juice flavours offered by start-up business Juna, a German-Colombian outfit that is donating 5p from each bottle sold to fruit growers in Colombia.

The mandarin-sized fruit, which has a citrus flavour described as a combination of rhubarb and lime, isn't the only unusual fruit in the line-up. The guanábana, which has a dark green skin and is filled with white pulp containing black seeds, and mora andina, which has an intense and slightly bitter berry taste, also feature.

The juices, which retail at £2 to £2.20 for a 250ml bottle, were launched by German-Colombian couple Christian Kaufholz and Angela Arévalo in Berlin two months ago.

They are available in Taj Natural Foods in Brighton and the company is seeking further listings.