Fruit. Veg. You’ve got to get your five* a day. But how do we get ripe fruit from across the world to consumers in the UK, without it going mouldy on the way?

(* Or maybe seven. Or nine, depending on who you listen to.)

Doing a project on this topic can open your eyes to just what’s going on around you – and could be the start of a career tackling the issue.

Making sure that food reaches the consumer in top condition is both big business and an environmental issue.

“Every piece of food has an environmental impact, and the fertilisers and energy used to produce it are wasted if it is thrown away uneaten.”

Scientists and food producers have been researching how to cut back on food losses due to ripening and over-ripening for years, and have made major advances. We’re don’t even notice it when we walk into a supermarket or market and see fruit from around the world, all looking ripe and ready to eat.

 

Get inside the science

Ensuring that fruit ripens on time – but not in advance – is a key issue for food producers. Yet we know surprisingly little about the genetic factors influencing ripeness.

The green colour of unripe fruit is due largely to the presence of chlorophylls, and the development of different colours during ripening is due to the disappearance of these pigments and the synthesis of carotenoids – or just revealing carotenoids that were already there, masked by the chlorophyll. Anthocyanins also make a contribution to colours in some ripe fruits and vegetables. It is now known that several of these pigments are valuable items in the human diet.

Domesticated plants have been the subject of intensive selective breeding programmes and, amongst the many features selected for, colour of the fruit certainly must have been one of the features. The skilful greengrocer arranges a display of fruits and vegetables to entice customers to purchase them, and, for many artists and cooks, the aesthetic appeal of fruit and vegetables depends on their appearance as much as their taste and texture.

We can see that an important biological role of these fruit colours is to appeal to animals, and these animals then have a role in the distribution of the seeds within the fruit.

It is important that the fruit is eaten only when the seeds are mature, and presumably ready to face the jaws and digestive systems of the dispersal animals. It seems logical that most fruits have an unappetising flavour and insignificant colour until the time is ripe for them to be eaten.

In a more modern context, the colour of a fruit is often used as a means of determining their shelf life.

Find out more

• John Innes Centre, Norwick Prof Cathie Martin of the John Innes Centre is an expert in the relationship between diet and health, and in how plant breeding can increase the nation’s health.
• Botanists in the Kitcehn The science duo behind Botanists in the Kitchen tackle the cell biology behind ripeness.
• Genetics Introduces Visual Cue For Palm Oil Ripeness News report on the discovery of a gene that will allow palm oil fruits to change colour when they are ripe.
• MADS-Box Genes Reach Maturity (Science, 12 April 2002), Research article about the genetic regulation of ripening, and the role of MADS-Box transcription factors.

Practical Investigations – step-by-step protocols

• We’ve put together step-by-step protocols for you to use for a practical investigation on this topic.