Fascinating facts behind favourite festive food. Matt Tebbutt is in Portugal, wondering how long an unfinished bottle of port stays drinkable for. Jimmy Doherty finds out why red cabbage is associated with Christmas. Briony May Williams travels to Germany to uncover the secret to a perfect stollen, and uncovers an ingenious invention that might just help with any national shortage of pigs in blankets. Kate Quilton tries out some inventive glazes for seasonal ham.