ENTHUSIASTIC television personality and ex-greengrocer Gregg Wallace was left "really impressed" by a Somerset company while filming an episode of Inside the Factory. 

He visited Yeo Valley Organic's Blagdon farm and factory with the BBC show to see the production process for the company's Fruity Favourites yoghurt four-pack.

The episode was first broadcast in January and featured presenter Cherry Healey and historian Ruth Goodman alongside the MasterChef co-host.

"Every self-respecting packed lunch has one of these – a yoghurt," said Gregg at the start of the episode.

"And we Brits love them, eating a whopping 500,000 tonnes of the stuff every year.

"This is the Yeo Valley yoghurt factory in rural Somerset. Every year, they churn out 125 thousand tonnes of yoghurt. That’s enough to fill 60 Olympic-size swimming pools.” 

One million pots of yoghurt leave Yeo Valley's factory every 24 hours and the company produces almost 2,500 tonnes of it per week - and it gets through around 11 tonnes of fruit per day. 

Gregg visited the farm and production line with Inside the Factory to reveal exactly how they do it, while Cherry helped out at a south Herefordshire blackcurrant farm.

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Gregg's first step was the visit the farm's organic cows, looked after by Gabby Coles. 

When yoghurt production started on the farm in the mid-1970s, there were just 35 cows.

Now, the herd is 240-strong, and it produces 6,000 litres of milk every day – but that is still less than 2% of the yoghurt factory’s daily intake, with the rest coming from a local co-op of organic farms. 

Gregg was responsible for cleaning the cow’s teats with antiseptic wipes while Gabby milked the cows using a sophisticated vacuum milking machine.

He confessed that was a little nervous as an "inner-city boy" around large animals. 

From there, the milk is filtered and cooled from the cow’s body temperature of 38.5°C down to 3°C before being transported in a refrigerated truck to the factory 10 minutes away.

Wearing a hairnet, Gregg then visited the factory's milk intake area to visit supply manager Adam Fry, who explained the vast quantities of milk needed to produce so much yoghurt.

He said: "On site, we hold around 350,000 litres of milk. That’s a day’s worth of production."

The factory's milk is stored in six giant silos, which each contain around 600 bathtubs of milk – enough for 154,000 pots of yoghurt.

Gregg saw a sample of the product be tested for the first of three times in a laboratory to ensure its quality before it was sent to the raw milk blend area, where it is mixed with cream, skimmed milk powder and organic sugar.

The milk blend is then treated and pasteurised at 98°C for around three minutes, creating a food-safe mix that is ready to be turned into yoghurt.

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The factory’s technical scientist, Chris Coggins, then adds 'good bacteria' to the milk blend.

The bacteria break the milk's lactose down into lactic acid, which makes the yoghurt acidic and thickens it. 

"My bacteria may be the microscopic magicians that turn my milk mixture to yoghurt," said Gregg.

"But if you want to make yoghurt on a massive scale, you need some serious hardware."

After it is warmed to 42°C in 12 stainless-steel tanks with a combined capacity of a quarter of a million litres to encourage the bacteria to multiply, the yoghurt is cooled and ready to be flavoured. 

The strawberries, raspberries, apricots and peaches used by Yeo Valley come from Europe, but the blackcurrants are harvested in the UK – as Cherry discovered in Herefordshire.

At the blackcurrant farm, Cherry said: "In a very short window of about six weeks, an entire year’s supply of these little juicy currants needs to be picked and stored.

"To maintain freshness, the blackcurrants must get from field to freezer in less than an hour."

Almost 10% of the 650,000 tonnes of blackcurrants collected at the Herefordshire site were sent for yoghurt production at Yeo Valley, where they are turned into conserves at a processing plant in Crewkerne. 

Once the fruit conserves were added and mixed into the yoghurt, Gregg saw pots be filled at a rate of 28,800 per hour before they were packaged in cardboard. 

"It's a pretty sight. A bit like me," said Gregg as he watched the coloured pots being manoeuvred into boxes by machines. 

After being cooled once more to achieve the perfect consistency, Gregg's yoghurts were dispatched - just  23 hours after the production process started.

"I am really impressed," he said. 

"Honestly, I can’t believe how much work goes into making a pot of yoghurt and getting it on the shelf.

"I’ve loved the lot. The messy mixing and the clever chemistry. But do you know what really impressed me, what I really honestly loved? It’s where it all started – those cows."

Away from the factory, viewers saw Cherry test different types of plant-based milk, including soy, oat, rice, coconut and almond, in coffee and as an ingredient in Yorkshire puddings. 

The 10 Years Younger host also saw how yoghurt pots can be made from 100% recycled plastic.

Historian Ruth investigated the ground-breaking technology of milk deliveries using electric floats from the early 1920s and followed in her grandfather’s footsteps by driving a working model.

After that, she navigated her way through the complex and controversial history of the scone.