As beer styles go, India Pale Ale is a bit of a head-scratcher. It's not from India and it's not always pale. It can be strong but it can also be session-strength. It can be English, American, Belgian - or any number of different nationalities, for that matter. It's the most modern beer style of all but it has an Australian history that goes back almost 200 years.
One thing is clear: IPA, as it's generally known, is hugely popular. Indeed, it can be fairly described as the beer that has driven the craft-beer boom.
Wander into any beer-savvy bar around the globe - from Melbourne to London via San Diego - and you'll find IPAs. The new breed of beer drinker can't get enough of this hop-heavy, bitter, extravagantly fragrant style.
That's true of many brewers, too. "I love it," says Andrew Gow, the head brewer at Mornington Peninsula Brewery. "I was looking yesterday at our records: about 20 per cent of the specialities that we've done have been based around IPAs. I enjoy the big hop flavours and aromas, plus a good whack of bitterness."
For Gow, an IPA is a "big, bitter pale ale", but there are plenty of beers labelled IPA that don't fit that description, such as Black IPAs - with the colour and some of the flavour of a stout but the aroma of an IPA - or session IPAs that, to the uninitiated, might seem to bear a striking resemblance to pale ales due to their relatively low alcohol content.
"IPA has come to convey an expectation of a lot of hop character in the beer, whether the beer is pale, red, amber, whatever," says Mitch Steele, the brewmaster at the Stone Brewing Company in San Diego and the author of IPA: Brewing Techniques, Recipes and the Evolution of India Pale Ale, perhaps the definitive book on the style. "It doesn't necessarily mean 'pale' any more; it has taken on a larger context of being a family of very hoppy beer styles."
Australian drinkers have a long history with IPA. The earliest-known mention of India Pale Ale - so named because it was originally brewed to be exported from Great Britain to India - came in an advertisement in an 1829 edition of The Sydney Gazette and New South Wales Advertiser.
Australian IPAs these days tend towards the American model, with more hop aroma than those original IPAs. It's also from America that two more versions of IPA - Belgian and White IPA - have come, even if the influence for them derives from the home of moules frites.
Gow was one of the first Australian brewers to make a white IPA, which combines the virtues of a witbier - with its orange-peel and coriander character - with an IPA. "I was reading an American magazine called Draft and they had a graph of IPAs, of all the different styles," he says. "[The American brewers] Deschutes and Boulevard had done a white IPA; I thought the citrus-hop aspect thrown at a witbier, with its fruity aromas, would really work.
"We brew it every summer now. The first year was a bit rough and too bitter; it needed tightening up. It's got those lovely citrus notes and also the more earthy tones of coriander."
Such is IPA's current popularity that you might assume the style is headed for a fall. Not so, according to Steele. "Since the beginning of craft brewing in the 1970s and 1980s, there have been beer styles that have been centre stage that have now receded into the background: fruit beers, amber ales, pale ale have all gone through this cycle," he says.
"It will be interesting to see what happens with IPA. Part of me believes that with all the new hop varieties coming out from breeding programs all over the world, IPA will be a mainstay for a long time."
That is Gow's view, too. He's working on his own take on IPA. "I'm looking at doing - without sounding too wanky - a Triple IPA, which will be 12, 13 per cent," he says. "It's almost overloaded with hops … I don't know, with the blending of styles now, you can throw hops at anything and call it IPA, can't you? There's no boundaries now, which I think is a good thing. Strict style guidelines have been thrown out of the window."
KNOW YOUR IPAS
English IPA - Marmalade bitterness married to plenty of biscuity, sweet malt character. Try: Meantime IPA (London, UK).
American IPA - Huge citrus-tropical fruit aroma and lots of bitterness balanced by a toffee sweetness. Try: Feral Hop Hog (Swan Valley, WA).
Black IPA - A touch of coffee roastiness laid over the classic American IPA character. Try: Kooinda Black IPA (Heidelberg, Vic).
White IPA - A marriage of citrussy IPA and spicy, moreish witbier. Try: Mornington Peninsula White IPA (Mornington, Vic).
Session IPA - A lower-strength IPA - what some might call a hoppy pale ale. Try: Founders All Day IPA (Michigan, US).