MATTHEW Algie may have been setting trends for more than a century but all over Glasgow coffee shops are leading the way in the latest fad - micro-roasting.

The city has around 10 shops where experts, known as master roasters, transform raw coffee beans into unique flavours.

At Gordon Street Coffee, in Central Station, John Gartley comes in once a week to roast the shop's signature Glasgow Blend.

Having worked with coffee for the past 18 years, John is an expert and devised the popular blend, made with Brazil, Guatemala, Indian Cherry and Kenyan beans.

John buys green coffee beans, which have been shipped in from around the world, from merchants in London.

The beans all exhibit different flavour characteristics developed by their growing environments, altitude and soil type, and whether they have been processed using the wet or dry method.

John knows the flavour profile of each bean and he knows exactly how he wants it to taste at the end of the roasting process.

First, he prepares the roasting machine, which costs around £25,000, to make sure it's the perfect temperature.

Once the beans are inside and being turned in a large drum, John uses his eyes, ears and sense of smell to make sure they are changing colour correctly.

He said: "Some master roasters will use thermometers and equipment to make sure the beans are at the right temperature, but I prefer to use my own senses.

"Roasting is a series of chemical processes that caramelise the sugar in the beans and change them from green to tan to brown and dark brown.

"When the beans reach 400F the water and CO2 in the beans begins to fracture and they make a popping noise very much like popcorn: that's the first crack.

"At the first crack we start seeing more colour in the beans and I will be constantly checking on them - I am able to correct a roast just from sight and sound.

"The second crack occurs at 440F and this sounds more like paper rustling."

When the beans are the correct colour - John insists they should not be too dark - they are poured onto a cooling tray to bring the temperature down as quickly as possibly and stop them roasting further.

The beans look and smell fantastic - but what do they taste like? At this point barista Christopher Kane steps in to do a 'cupping', which involves filling a cup with finely ground beans and pouring hot water on top.

Once the coffee has infused a fine film appears across the surface, signalling it's ready to be sampled.

Experts - or, in this case, me - break the crust with a spoon to allow the aroma out before scooping a little liquid up to taste.

Christopher prepares three for me to try: Glasgow Roast, Sumatra Wahana and French Roast.

I'm worried, with Christopher and John looking at me expectantly, that I won't be able to tell the difference.

But it turns out nine years of working in a coffee shop while a student were not wasted.

The Glasgow Roast - designed to be "in your face and complex, like Glasgow," according to Christopher - is definitely a dark roast.

It's smoky, slightly like cigars, and very chocolately. Sumatra Wahana, on the other hand, is light and summery with real fruit flavours.

French Roast, on the other, nearly knocks my head off - it has a thick crema on top, a full body and tastes like a proper grown-up's cup of coffee.

With this kind of quality, I wonder what John drinks when he's out and about?

"I'm very fussy," he says. "I will go into a shop and look at a hopper and if the beans don't look exactly right then I'll leave."