The supermarkets know that shoppers don't show much allegiance to them any more, so what techniques are they coming up with to keep us coming back?

This time, in an age when we expect everything delivered in an instant, how the supermarkets are working to bring us our food on demand. Gregg sees how Ocado are using robots to revolutionize online delivery and visits a state-of-the art lettuce farm in Norfolk where they supply 300 million lettuces per year exactly when we want them. Meanwhile, Nikki tests out the Co-op's new pay-in-the-aisle technology as we move towards a checkout-free future.

Supermarket Secrets is going behind the scenes again to reveal how the supermarkets are using the latest technology and science to bring us our food. In this series, Gregg Wallace and consumer journalist Nikki Fox discover how much the Internet is transforming the way we shop and the food in our trolleys.

Tonight , the supermarkets fight to be the first with the latest food fashions. Gregg joins Tesco's Head of Plant Innovation as he invents new vegan meals that he claims will taste like meat, and sees how Asda are using ingenious growing techniques to make tomatoes sweeter than strawberries. Meanwhile, Nikki looks at the latest craze for sensory shopping.