Fermentation is one of our oldest methods for preserving food. All around the world people have been transforming food with the help of microbes for thousands of years. The problem is, this simple method has had an identity crisis. We tend either see it as a fashionable fad, or a strange science. But there are people who want things to change. So in this programme Sheila Dillon meets 'The fermenters'. Ukranian food writer and chef Olia Hercules, who grew up with fermented foods; Roopa Gulati, using fermentation to explore her Indian heritage; entrepreneur Deborah Carr, whose fermentation business is going from strength to strength; and seasonal chef Tom Hunt who is putting seasonal ferments back on his restaurant menu. In 2016, It's time to rethink fermentation.