Imaginative Teaching Resources & Inspirational Career Ideas from the Chilled Food Industry

For more than a decade UK chilled food producers have not sent any food waste to landfill. Instead they redistribute it or send it to anaerobic digestion to generate energy (as biogas) and digestate (e.g. organic fertiliser).

We can all do our bit to minimise food waste at home. Take a look at our ideas and try our experiment exploring what happens when waste food goes to landfill.

But first a bit about landfill…..

When food waste is sent to landfill in (normal household waste collections), it breaks down very slowly in the oxygen-lacking (anaerobic) environment by bacteria that do not require oxygen to survive. As bacteria decompose the food, they create two greenhouse gases – carbon dioxide (CO2)  and methane (CH4).  Both are very good at trapping heat, methane even more so, due to its chemical structure and its lifespan in the atmosphere.

When food waste is composted (either at home or through kerbside food waste recycling collections), it is broken down in an oxygenated (aerobic) environment by bacteria that require oxygen to survive. As these bacteria decompose food they still create carbon dioxide but they do not produce methane. Instead, they create water.

The Science bit

We can watch the chemical breakdown of different food sources and the relative amount of gas it produces.  By filling a bottle completely with water, we create anaerobic (oxygen-lacking) environments that simulate the conditions found when food is sent to landfill instead of being composted.

How to do it

You’ll need four  narrow necked glass or plastic bottles, four balloons and some crushed/mashed  fruit or vegetable food scraps. We used apple, plum and lettuce and mini plastic/glass drinking bottles.

Put some of the mashed fruit or vegetable in three bottles – one fruit or veg in each one. Then top up each bottle with water. Label what is in each bottle.

In the fourth glass jar just fill with water.

Cover all the bottles jars at the top with a balloon and ensure a tight seal.  Place in warm place or on a windowsill and see what happens.

Watch the bottles closely as some of the balloons should begin to inflate as the food scraps decompose and produce methane.  The bottle  with water only should not change as there is no methane production and no gas to fill the balloon.



Waste reduction charity WRAP has some more information for us to digest (!)

In total, a staggering 6.6 million tonnes of food waste comes from our homes each year in the UK, at a cost of £14 billion. Of that, 4.5 million tonnes is food that could have been eaten, which works out to around eight meals per household each week. This ‘edible’ element of household food waste is responsible for 14 million tonnes of CO2-eq* alone – as much greenhouse gas produced as flying from London to Perth more than 4.5 million times.

Globally, around a third of all food produced is lost or wasted, which contributes between 8 and 10 per cent of total greenhouse gas emissions.


*CO2 equivalent (CO2-eq) emission

The amount of carbon dioxide (CO2) emission that would cause the same integrated radiative forcing or temperature change, over a given time horizon, as an emitted amount of a greenhouse gas (GHG) or a mixture of GHGs.

Glossary – Global Warming of 1.5 ºC – IPCC










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