As many of us gear up for the annual Christmas feast, some of you may be wondering how to eat everything before it goes off. It’s a great question, as the UN puts global food waste at a whopping 1.3 billion tonnes a year – that’s one third of all edible produce being thrown in the bin.

So this week the team investigates listener Peter’s query about what makes some fruit and vegetables rot faster than others. Preserving food used to be about ensuring nomadic populations could keep moving without going hungry, but these days some things seem to have an almost indefinite shelf-life. Is it about better packaging or can clever chemistry help products stay better for longer? A Master Food Preserver explains how heat and cold help keep microbes at bay, and how fermentation encourages the growth of healthy bacteria which crowd out the ones that make us ill.

Presenter Datshiane Navanayagam learns how to make a sauerkraut that could keep for weeks, and investigates the gases that food giants use to keep fruit and veg field-fresh. But as the industry searches for new techniques to stretch shelf-life even further could preservatives in food be affecting our microbiome? Research shows sulphites may be killing off ‘friendly’ gut bacteria linked to preventing conditions including cancer and Crohn’s disease.

Produced by Marijke Peters for BBC World Service.

Featuring:

Christina Ward, Master Food Preserver