A chilling tale?

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apples_stacked
Ever wondered how apples stay on supermarket shelves all year round? The magic of refrigeration.
If you shop on the VegVan you will have noticed that stocks of UK apples are dwindling, and by the time you read this they will probably have finished altogether. But you might not have stopped to consider that having UK apples until late April means that the apples you were eating last week were probably around 6 months old! Harvested in autumn last year, they have been sitting in chilled warehousing waiting to be delivered into your hands long after the apple ‘season’ has finished. Apples are often stored in atmosphere-controlled refrigerated environments with high CO2 and low oxygen content to slow down their respiration, meaning they last longer. Non-organic apple stores may also be suffused with a biodegradable chemical vapour that blocks the apples’ ethylene receptors and slows the ripening process even more. This is all very modern technology – consider that in 1970, 40% of the UK population still didn’t have a fridge – but refrigeration is now an essential feature of our fruit and veg industry.

Storage doesn’t only extend the season for local produce, but it’s also vital for moving food around the world. The apples from Argentina and New Zealand (where autumn harvest runs from February to early May) that are now filling supermarket shelves will probably have been kept in chilled warehouse storage in their country of origin before being loaded aboard refrigerated cargo ships to get to you. Back before refrigeration was commonplace, huge quantities of ice was chipped out of frozen lakes, rivers and ponds to keep food cool in shipment – ice was big business. By the 1860s, beef was being shipped in small amounts from the US to London, in heavily insulated cargo holds packed with ice and salt. Refrigeration systems had become established by the turn of the century, and by 1935 one million tonnes of meat, 500,000 tonnes of butter and 430,000 tonnes of apples and pears were being imported into the UK each year on refrigerated ‘reefer’ ships. These days, a relatively small proportion of the world’s cargo ships are true reefers, and it is increasingly common for cargoes of fruit and veg to be carried in individual refrigerated containers on standard container ships, meaning temperature can be controlled all the way from pack-house to wholesale or retail distribution centre.

stalkonapples
Apple storage how it used to be done: covered with maize stalks for insulation from temperature fluctuations
So back to our fruit, if we want to eat apples out of season what’s better from an environmental point of view? Months of chilled storage for UK apples, or refrigerated shipping from the southern hemisphere? A Defra funded study in 2008 found the answer was unequivocal – the total global warming potential from the lifecycle of imported New Zealand apples was 2.5-3 times greater than UK apples, even after UK apples had been kept in chilled storage for 5 months. So the message, for apples at least, remains… eat local, and eat seasonal(ish)! Working out the environmental footprints for the many possible combinations of production type, origin, storage, transport and so on for each different item of fruit and veg is a tricky business (the famous example, from the same Defra study, is that Spanish tomatoes generally have less GHG impact than supermarket UK tomatoes, despite transport), and there are no straightforward answers – but it seems that eating a variety of local, regional and UK-produced produce as close as possible to its natural seasonal rhythm is a good rule of thumb for fresh, tasty, low-impact food.

Further Reading:

Modern Farmer: The Science of Cold Apple Storage
Defra (2008) Comparative Life Cycle Analysis study
FCRN Working Paper: Food Refrigeration