Healthy eaters looking for the fruity content of their five-a-day can have a real problem when winter refuses to end.

They can eat home-grown apples and pears that have been stored after autumn picking.

Frozen soft fruit is available but the freezing process takes its toll in flavour, texture and nutrients.

Supermarkets are bursting with imported fruit but there is a price to pay both in cash terms and in food miles.

That's why I go to Yorkshire to discover a tasty and nutritional fruit that is harvested in the depths of winter.

I'm in the Yorkshire Rhubarb Triangle, nine square miles of West Yorkshire between Wakefield, Morley and Rothwell.

Rhubarb is a native of Siberia and thrives well in the cold, wet winters of Yorkshire.

The Yorkshire cultivation method for forced rhubarb was developed in the early 1800s.

Rhubarb fields were fertilised with large quantities of horse manure and night soil from the nearby colliery villages as well as with wool waste from the county's many textile mills.

The rhubarb plants spend two years out in open fields without being harvested. While in the fields the plants build their strength with energy from the sun.

After the first frosts plants are moved into the sheds in November where they are kept in complete darkness.

The plants begin to grow in the warmth and the stored carbohydrate in the roots is transformed into glucose, resulting in forced rhubarb's delicious sweet and sour flavour.

The sheds are long, low buildings which were originally heated with coal - local, plentiful and cheap.

Today they use imported oil or gas.

Forced rhubarb grown in the sheds is soft and tender and up to two feet long. Leaves are a pale greeny-yellow, stalks smooth and crimson.

Traditionally the pickers pull the stalks in candlelight from just before Christmas and then throughout January and February. They use candles because strong light will stop the growth.

By March the harvest is over and the root stock is totally exhausted and used for compost.

West Yorkshire once produced almost all of the world's winter forced rhubarb from its many forcing sheds. They shared the landscape with another major industry, coal.

Before Maggie Thatcher murdered the mining industry this was one of the most productive coalfields of Britain.

Indeed while we were here we called in at the former mining village of Lofthouse to pay tribute to the victims of one of Britain's saddest and most unnecessary mining disasters.

We found a seven-sided stone obelisk listing the names of seven dead miners at the point where they were trapped below ground in 1973.

The memorial is on the south side of Batley Road, opposite the junction with Wrenthorpe Lane.

The Lofthouse Colliery disaster occurred when a new coalface was excavated too close to an abandoned, flooded 19th-century mineshaft.

The sudden inrush of water trapped and drowned seven miners 750 feet below ground.

A six-day rescue operation was carried out but only one body was found.

Disgracefully the location of the flooded shaft was known to National Coal Board (NCB) before the new shaft was sunk.

Records indicated that a flooded shaft ran near the new diggings but these records had not been checked properly by the NCB.

The Lofthouse deaths led to important new legislation.

The Mines (Precautions Against Inrushes) Regulations 1978 required examination of records from the Natural Environment Research Council as well as from geological memoirs, archives, libraries and persons with knowledge of the area and its history.

The pit closed in 1981 and today Lofthouse is one of the villages famed for the production of forced winter rhubarb.

Others include Kirkhamgate, East Ardsley, Stanley, and Carlton.

In 2010, Yorkshire forced rhubarb was awarded Protected Designation of Origin (PDO) status by the European Commission's Protected Food Name scheme just like Champagne, Parma Ham and Melton Mowbray Pork Pies.