Gregg Wallace explores Ribena's Gloucestershire factory. It turns 90 per cent of Britain's blackcurrants into soft drinks, producing three million bottles a week. Gregg takes delivery of 500 tonnes of blackcurrants at a cider mill in Somerset. The harvest comes in during July and August, when there are no apples to process for cider, so they press blackcurrants instead. Gregg discovers how the aroma of the blackcurrants is captured separately and later added back into the drink. Next, the concentrate and aromas are transported to the drinks factory, where they are mixed with 11 other ingredients before being bottled. Gregg watches a machine that can create a plastic bottle in 0.1 of a second and learns why nitrogen is the secret to creating a bottle that won't get stuck in vending machines.

Cherry Healey is harvesting the berries on a farm in Kent - one of 40 that supply the factory. She also heads to the Netherlands to a plant that recycles plastics. It processes two and a half million used PET bottles a day, transforming them into 4mm pellets that can be turned back into drinks bottles. And Cherry is in the lab figuring out why fizzy drinks are so appealing. She learns that bubbles play sensory tricks on us, making fizzy drinks taste colder, less sweet and more flavourful than their still equivalents.

Ruth Goodman is investigating the origins of fizzy drinks. Carbonated water was first sold by Mr Schweppe in 1783, but it was a British husband-and-wife team - Robert and Mary White - who were to popularise fizzy pop. In 1890, R White's styled itself as the world's biggest drinks company and they sold 46 million bottles a year. Ruth looks at why we associate barley water with the great British summertime. Show less