Fruit for the fridge or the bowl?

Fruit for the fridge or the bowl?

New-season apples will stay crisp and flavoursome in a refrigerator, but the best place for tomatoes is in the fruit bowl.

This is because less ripe tomatoes, like avocadoes and pineapples, are sensitive to chilling and will soften and lose flavour in the fridge, says Associate Professor John Mawson.

Director of the University’s Centre for Postharvest and Refrigeration Research in Palmerston North, Dr Mawson says tomatoes have an optimum storage temperature of about 10 degrees, making the fridge too cold. The fruit bowl (at room temperatures of between 15 and 25 degrees) is close to the ideal ripening temperature but too warm for long-term storage.

“Cold sensitive fruit such as tomatoes undergo a change in metabolism in the fridge, which leads to a loss of texture and flavour, so the best approach is to buy them close to their peak of ripeness and eat them soon, or ripen a little further in a bowl or paper bag”

Dr Mawson says some early varieties of apples like Royal Gala will soften in the fruit bowl comparatively rapidly, and if a crisp texture is preferred, are best kept in the fridge until a day or so before eating. Keeping them in a plastic bag will minimise water loss and prevent them from shrivelling.

Beyond New Zealand’s consumer market, finding the optimum conditions for storage of fruit and vegetables has huge implications for the export market, and Dr Mawson is leading a research project into “active packaging” for fruit and vegetables. Active packaging aims to create conditions to optimise storage life by altering gas composition, as well as protecting the fruit against changes in temperature and humidity.

“It’s about working with the product’s natural processes to slow down its metabolism and protect against disorders. For example, we are looking at using the natural anti-microbial activity of certain compounds in fruit and vegetables to minimise rot. These compounds are released as gases into the active packaging which works to fight rot and prolong the life of the product.”

Dr Mawson is currently focusing on optimising feijoa storage for an increasingly interested export market. Native to South America, feijoas grow well in New Zealand but have a limited season despite a lengthy flowering period. This leads to trees full of fruit at differing stages of ripening, and, coupled with the tendency of feijoas to rot quickly, limits export opportunities. Research into the grading and storage of feijoas aims to reduce costs and increase opportunity for New Zealand growers.

ENDS

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