In search of the secret to the bubbles in bubble tea, Kate Quilton visits a cassava farm in Kenya to get to the root of it. Jimmy Doherty is in Somerset exploring why sour milk is sneered at, though soured cream is revered. Plus, Helen Lawal reports from Portugal on canned fish.

Kate Quilton heads to Kenya to see how cold-brew coffee differs from iced coffee. Helen Lawal tries frozen pastries in Portugal to see how well they perform well against fresh, while Briony May Williams heads to Staffordshire to learn how parsnips are cultivated to taste so sweet.