Don’t be fooled by those TV commercials showing rivers of plump blackcurrants migrating across hill and dale towards the Ribena factory. They’re not as juicy as they look — or at least as they used to be.

The makers of the deep purple drink that has been with us for more than 70 years have been forced to develop a new super-strain of blackcurrant that can cope with Britain’s increasingly mild winters.

Two of Britain’s main varieties of the fruit — Baldwin and Ben Lomond — are expected to die out from key growing areas within ten years because of climate change.

A heavy frost is needed to ensure that their buds break properly to produce fruit. Warmer weather in recent years has led to a steep decline in harvests and fruit quality.

Now Ribena’s manufacturer, GlaxoSmithKline, has bred a new variety, named after the Scottish mountain Ben Vane, that can survive the change in weather patterns. The species was created via conventional breeding methods in partnership with the Scottish Crop Research Institute and has just completed a three-year trial.

The first commercial crop has just been harvested from a farm in Newent, Gloucestershire, and will be used to make Ribena this year.

“We need to secure the long-term supply of blackcurrants for Ribena,” said GlaxoSmithKline’s procurement director Michael Dunsire. “We hope to multiply the programme next year and have the variety in several more farms.”

Mr Dunsire said that the company, which buys 95 per cent of Britain’s 12,000 to 13,000-tonne blackcurrant crop — including some from the Queen’s farm at Sandringham — started to notice about five years ago that the buds on several of the older varieties were breaking unevenly, leading to uneven ripeness of the fruit. “When it was picked, some of the fruit was still green while some was black, which led to poor juice quality,” he said.

The problem has led to a significant fall in juice yields from an average of 1,000 litres per tonne of fruit.

“The older varieties really do need a period of proper dormancy during the winter,” he said. “If we don’t adapt, in a few years time Scotland will probably become the only place in the UK where it will be possible to grow blackcurrants on a commercial scale.”

He said that the introduction of Ben Vane would take several years because new plants did not start to bear fruit for at least two years and the new variety was still being perfected.

Britain is the world’s only commercial producer of blackcurrants and the industry is worth about £8 million a year. Mr Dunshire said that the wholesale prices paid per tonne of fruit could vary from £150 to £900 depending on the juice content. He said that the main difficulty in developing the new variety was balancing the need for a berry that had a lower chilling requirement than conventional blackcurrants with the need for good flavour and a high juice content.

Britain’s climate is warmer now than it has been at any time since measurements began in the 17th century. Winters have warmed by 1C or more since the beginning of the 19th century and the past 20 years have experienced an unusual run of warm summers.

Blackcurrants have been grown for hundreds of years but their popularity soared during the Second World War when it became difficult to import oranges and other fruits from overseas and the Government encouraged the crop as a rich source of vitamin C.

The berries were once a popular crop in the US but were banned in the early 1900s after they became associated with a tree disease called white pine blister rust, which threatened the country’s powerful lumber trade.

In the past, GlaxoSmithKline has been criticised for adding too much sugar to Ribena, which critics claim damages children’s teeth.

Ribena, which is worth about £192 million per year to GlaxoSmithKline, has run into problems in recent months because of a scandal over vitamin C levels, which were lower than advertised in samples of the drink in New Zealand and Australia.The company was forced to issue an apology and was fined by a court in Auckland.

There are 41 growers in the UK across Kent, East Anglia, Somerset, Herefordshire, Scotland and Northern Ireland. Several of them have been producing the crop for decades.

Glaxo has also developed another variety of blackcurrant called Ben Klibreck, which is designed to have a slightly higher chilling requirement but has better overall juice quality. Three acres have been cropped this year at Bradenham Hall Farm in Thetford, Norfolk.

It’s good news for Ribena drinkers. But will the stuff still turn your teeth purple?

Fast-forward farming

— Blackcurrant farmers are not alone in having to adjust to the changing climate

— By 2050 summer temperatures in the South East are expected to be 1.5C (2.7F) to 3C warmer than they are now

— This spells trouble for growers of hops, pears and plums

— Some farmers could start experimenting with new crops such as maize

— Last year Sainsbury’s started selling British-grown apricots for the first time. Apricot trees flower in February, making them extremely vulnerable to frost

— Other crops that are to be grown commercially soon include walnuts, sunflowers and even olives

Source: Times database

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