Inside the Factory - Season 8

Gregg Wallace is following production of a seasonal favourite, the Yorkshire pudding. Inside the factory in Hull, they produce five hundred million frozen Yorkies every year. Although the factory makes them by the tonne, the ingredients are as simple as when you make them at home – flour, eggs, milk and salt. But the processes are entirely industrial, with high tech mixers, a 53 metre-long conveyor oven and huge freezers.

Gregg learns that the key to getting the perfect Yorkshire pudding shape is to trap air in the batter while mixing, and to make sure the oil added to the cooking pan forms a ‘halo'. 

Elsewhere in the episode, Cherry Healey visits one of the country's largest wheat testing and storage depots where each silo contains enough wheat to make flour for 416 million Yorkshire puddings. And if you prefer beef to your Christmas turkey, she teams up with food scientist, Barbara Bray to learn how to cook the perfect gravy for a Sunday roast. 

And historian Ruth Goodman bites into the history of the roast dinner; and helps a chef master the art of washing up Tudor-style.

Gregg Wallace explores the Jelly Bean Factory in Dublin to reveal the incredible processes it employs to make ten million colourful little sweets every day.

Cherry Healey visits the University of Birmingham to learn about the important role glucose plays in our bodies, and she visits a lipstick factory to discover how one of the ingredients in jelly beans plays a key role in the production of her lippy.

Historian Ruth Goodman is serving up the history of jelly and delves into the story of post-war pick‘n'mix.

Gregg Wallace visits two factories in Italy and Wales to explore the fascinating secrets behind how Welsh jeans brand Hiut make their trousers, learning how denim cloth is made and then transformed into one of the world's most popular items of clothing.

Meanwhile, Cherry Healey visits a zip factory to learn how the ubiquitous fastener is made, and she heads to the research and development facility of a denim manufacturer to witness environmentally friendly ways of distressing denim to make a new pair of jeans look old.

Historian Ruth Goodman discovers an unknown name in the history of jeans who helped to shape their design forever, and uncovers the fascinating history of indigo dye.

Gregg Wallace explores the Dell Ugo factory in Hertfordshire to reveal how it makes 500 million stuffed pasta parcels every year.

He's following production of one of their best sellers, crab and crayfish raviolo, and where better place to start than at the intake bay with a delivery of frozen crayfish tails. Factory manager Cesra Da Rocha explains that they receive around half a tonne a week of the freshwater crustacean, enough to make over two hundred thousand individual raviolo, the slightly bigger cousin of ravioli.

The delivery is wheeled over to the factory's kitchen area, where Gregg meets one of the owners, Charlie Ugo. Charlie tells Gregg that, along with crayfish, the other key ingredient is crab. They use a mixture of both white and brown crab meat to balance out the flavours. Before the crab goes into the mixer, Gregg helps to add parsley and coriander, mayonnaise, salt and the crayfish. Then in goes the crab, followed by blue whiting, which is a fish from the same family as cod and haddock, adding a fish stock flavour and texture. Then it's lobster stick and lemon juice, followed by some very specific mixer timings: 32 seconds in one direction, then 32 in the other. Breadcrumbs are added, and it's all precisely mixed again.

With the filling made, it's time for the pasta, made from special flour milled from durum wheat, which is higher in protein than traditional flour. When the flour is mixed with water, the proteins within the flour combine to form strands of gluten which turns it into dough. The more protein, the more strands are formed and the stronger the dough will be. The factory needs a strong dough to withstand the rigorous processes used to turn it into raviolo. At this factory, they make fresh pasta dough, which requires egg. The ingredients are combined with water, but the mix is nothing like a finished dough yet; it's too dense, so it's sent through a specialist machine which folds and kneads it to make it stretchier, before a set of rollers creates two separate continuous sheets of pasta. After passing through two more sets of rollers, the pasta is eventually taken down to the perfect thickness for making into parcels.

With the pasta made and the filling ready, it's time to make the raviolo with the help of another clever machine. Gregg watches on as the two pasta sheets enter a stuffed pasta-forming machine. As they pass through, 15 grams of the fishy filling are deposited at precisely spaced intervals, before the pasta is pressed together and cut out by a roller at a rate of 280 a minute. Then the stuffed pasta parcels are sent through a tunnel, where they're blasted with steam, pasteurising them. The pasteurisation process not only kills microbial activity to extend shelf life, it also sets the gluten stands within the pasta dough, holding them in place and stabilising the shape. Then it's a quick journey through a drier and into a giant chiller, which brings their core temperature to below four degrees Celsius.

Finally, ten raviolos are portioned into individual packs, and they head to the dispatch area, where they're loaded into waiting lorries before being sent the length and breadth of the UK.

Elsewhere, Cherry Healey visits Cromer on the Norfolk coast to discover the traditional fishing techniques still used to catch the crab for Gregg's stuffed pasta; and she conducts an intriguing experiment to find out if the music we listen to can affect how we taste food.

Historian Ruth Goodman learns how Italian immigrants in Bedford helped to build Britain, and she tucks into the extraordinary origins of gluten free food

Gregg Wallace explores the secrets of the Guinness brewery in Dublin to reveal how it makes two million litres of Irish stout every single day.

Cherry Healey visits a water treatment centre to learn how reservoir water is treated to provide clean drinking water to the people of Dublin, as well as to the stout brewery. And she visits a farm in Worcestershire to help with the hop harvest.

Historian Ruth Goodman delves into the history of Irish pubs and explores the extraordinary story of how pub games helped the Allies in the Second World War.

Gregg Wallace visits the colourful and fragrant Lush factory in Dorset to learn how an astonishing 14 million bath bombs are produced every year.

Cherry Healey visits Loughborough University to learn how taking a hot bath can provide some of the benefits of exercise, and she visits a cutting-edge lab which grows human skin for cosmetic testing.

Historian Ruth Goodman explores a time when complex perfumes were thought to ward off the plague and learns how the living conditions of coal miners and their families were transformed with the introduction of communal showers.

Gregg Wallace explores the Axminster factory in Devon to reveal how 46,000 square metres of carpet are produced every year. He follows the production of one of their best sellers, the Havana Diamond Steel wool carpet.

Meanwhile, Cherry Healey visits the Good Housekeeping Institute to learn the science behind the best ways to remove stubborn stains from carpets, pitching her home remedies against the expert's methods to tackle stains from butter, milk and red wine.

And historian Ruth Goodman learns how the groundbreaking methods of a Devon-based carpet maker in the 18th century revolutionised intricate carpet making and explores the rise and fall of the hard-wearing flooring linoleum.

Gregg Wallace is in the UK's city of chocolate, York, exploring how the Nestle factory makes more than 8 million bars of chocolate every day. The bar he's following is the one packed full of bubbles - the peppermint-flavoured Aero.

Meanwhile, Cherry Healey is in the Berkshire countryside, learning how a cocoa plant quarantine facility is preventing a worldwide chocolate shortage. And historian Ruth Goodman is serving up the bitter history of drinking chocolate.

Gregg Wallace explores the HSL factory in West Yorkshire to find out how they make more than 5,000 sofas every year. The huge site has 250 staff dedicated to furniture making. Gregg is following the production of one of their best-selling sofas, the Burros Classic in indigo.

Cherry Healey learns about the science of light bulbs to create the perfect environment to snuggle up on the sofa and visits a foam factory to see how comfy padding is produced in just a few minutes.

Historian Ruth Goodman takes a front row seat to discover the history of the sofa and stitches together the fascinating story of one of the world's most famous sewing machines.

Gregg Wallace explores the Farrow & Ball factory in Dorset to learn how they produce up to 200,000 litres of paint and 10,000 metres of wallpaper a week. They make 270 different coloured paints, but Gregg is learning how they make ‘sulking room pink'.

Meanwhile, Cherry Healey discovers how a key ingredient in the paint-making process is mined at a huge china clay mine in Devon and learns the art of hanging wallpaper at a DIY school.

And Ruth Goodman is in the Lake District, exploring the history of wallpaper, and visits Portsmouth to uncover the extraordinary story of how ships in the First World War were painted with dazzling patterns to evade German submarines.