While most of us think of coffee simply as an enjoyable beverage, Aimee Moser has developed a passion for coffee that verges on the evangelical.

She is regional head barista for Pasty Presto, which has a branch in Silver Street, Salisbury, and it is her job to train store staff up to the exacting standards she deems necessary to produce the perfect expresso.

Once upon a time, most of us thought it the height of sophistication if we brought coffee granules instead of powder for our cup of instant.

Now coffee making is turning into an art form all by itself.

The word barista comes from the Italian and literally means barman but in the brave new world of cafe culture it has come to be used as a term for someone serving in a coffee bar who is professionally trained in making different types of expresso coffee.

A decade ago, it would have been virtually unheard of on the streets of London let alone Salisbury, but the explosion of coffee bars like Starbucks and Caffé Nero means that our High Streets are now teeming with baristi at different levels of expertise whose sole aim in life is to encourage us all to wake up and smell the coffee.

There are even barista world championships held each year to test the mettle of those who aspire to produce a world-class americano, latte or mocha.

Aimee's students may not attain these giddy heights but she attacks her task with vigour.

"How can you show passion for coffee?" she asks.

"You'll see - my eyes light up, this is my baby and when I go into the store, I aim to get the staff excited so that they want to produce a very good cup of coffee - you'll feel it."

And feel it I did as Aimee took me through the basics of expresso making.

Getting it exactly right is a cross between art and science - neither of which you necessarily expect to find perfected in a pasty shop.

Pasty Presto is a Cornish company, started originally in Mevagissey in 1994 as a bakery café producing, as the name implies, pasties to a traditional Cornish recipe.

Today it has 21 stores across the south of England and while its pasties continue to be handmade, the variety of stuffings deviated from meat and potato many moons ago and now embraces everything from curried parsnip to chocolate and banana.

Coffee entered the equation some nine years ago.

Rosie Nock Production Development Manager explained: "Although pasties remain the core of the business, as the company grew and took on bigger sites, we decided to introduce pastries and coffee.

"But everything we do - we do the best it can be.

"We started working with coffee producers Union Hand-Roasted who source all their own coffee and know exactly which farms their coffee comes from."

Although the coffee used in Pasty Presto is a blend from Guatemala, East Africa and Indonesia, the bulk of it comes from Finca Santa Ana La Huerta, a family-owned farm in Guatemala owned by Rony Asensio, known throughout the company as Ronnie's farm.

It's produced and purchased very much on fair-trade principles and Pasty Presto is proud of its ethical trading approach, which means better working conditions for the coffee-growers without compromising the quality of the product.

"We've recently changed the blend," says Rosie.

"Previously the coffee we had was exceptional, very appropriate for the time, but as the coffee market has matured, people are expecting more from a good cup of coffee.

"It's a darker roast unleashing a more intense flavour, very chocolatey with a hint of berries in there and it blends perfectly with the milk, giving a very good latte and cappuccino."

Originally, Union trained the company's staff but now Pasty Presto has set up its own barista council, undertaking the training of all staff who have to complete a four stage licensing programme plus exams before being awarded head barista status.

Aimee's job as regional barista is to maintain a consistent standard throughout all the stores, so she travels from store to store teaching bean lore - where it's grown, the ethics behind it, the quality of the bean itself, how to judge the coarseness of the grind and how to produce that crucial intense full-bodied expresso.

The all important coffee-maker - an impressive bit of Italian kit - has something to do with it and staff are expected to know who to keep it in tip-op condition.

It looks easy enough, but to get it exactly right requires a certain amount of concentration mixed with tapping, tamping, applying even pressure, and polishing- and that's before you let the water anywhere near it.

The perfect pour for their coffee blend is 21 seconds - any longer or shorter compromises the taste - and Aimee can tell instantly that something is not quite right with my first attempt.

Not my fault, it turns out the blend is slightly too coarse and a quick adjustment to the grinder corrects that.

All the coffee is freshly ground on the premises and with the emphasis on fresh, no kilo of coffee remains open and unused for longer than a day.

Any coffee unused at the end of the day is thrown away.

However important the expresso is, it's the frothing and steaming that goes into the milk (they use organic whole milk) that looks and sounds the most impressive.

Aimee can pour her steamed milk onto a latte so that the end result looks like a delicate leaf sketched into the top of the milk.

I went for a full-bodied creamy cappuccino froth and managed a commendable "head" on the expresso.

Instant coffee will never be the same again.