In any modern account of the history of India Pale Ale, you’ll generally find a declaration that the casks of well-hopped beer sent out to India by ship via the Cape of Good Hope in the late 18th century matured and developed quickly in a way that the same beer kept at home in Britain did not. It was this accelerated maturation in a short time (three to four months or so) caused by travelling through the warm waters and hot climate of the central Atlantic and the Indian Ocean as the sailing ships twice crossed the equator that gave IPA the character that was so much appreciated by expatriate Britons in Bombay, Madras and Calcutta, supposedly. But is this actually true?
You’ll be pushed to find contemporary (that is, 18th and 19th century) confirmation of the “hot maturation” theory for IPA’s popularity in India. Contemporary writers talked about the enthusiasm with which IPA was consumed in the Indian heat, but never seemed to mention whether it was altered to the good on its way east.
Certainly “hot maturation” can’t be the cause for any popularity for IPA back in Britain, since if the beer did go through any accelerated changes on the voyage to the sub-continent, this couldn’t be happening to the beer stored in chilly cellars back home. Are current writers on beer guilty of assumptionism (otherwise known as “you’re making this up”), the crime of assuming without evidence that situation A must surely have brought about result B – that beer on board a sailing ship travelling through the tropics must surely have matured quickly?
For the defence, there is irrefutable evidence that wine certainly undergoes accelerated maturation when heated over months: this is precisely what happens in the making of Madeira. And how did the style of wine known as Madeira originate? Why, by casks of wine being bought on the island of Madeira, in the Atlantic, by the officers of sailing ships on their way to India from Europe. When it arrived in India, having been heated to temperatures of 40C (104F) or more for months in the holds of the wooden ships as they travelled under the baking sun, the Madeiran wine had acquired a new, fuller, deeper, rounder flavour.
After the wine makers back on Madeira discovered what had happened to their product on its journey east, and how it was more popular (and could be sold for a higher price) because of the changes brought about by hot maturation, they artificially recreated at home the conditions on board the India-bound ships. By heating their wines in tanks surrounded by pipes full of steam, keeping the contents of the tanks at 40C for months, the Madeiran wine makers were able to produce vintages that had undergone the same changes as the wine that had been at sea for 12 or 16 weeks under the sun.
Subsequent scientific studies have shown that for every 10C (18°F) increase in temperature, the ageing rate of wine doubles in the case of “low energy barrier” reactions and leaps an amazing eight times in the case of “high energy barrier” reactions. In other words, at 43C, compared to a cellar temperature of 13C (55F), some ageing reactions are happening eight times faster, and others a staggering 448 times faster. A wine spending three months at 43C, therefore, will have some of the characteristics of a wine that has spent two years in a cellar, and some of the characteristics of a wine that has spent 112 years in a cellar. Not all of those reactions will produce good results of course: the Madeirans were lucky that their wine evolved very well under hot maturation conditions.
But does the same thing actually happen with beer? Pete Brown wrote a best-selling book, published last year, in which he took a cask of Burton-brewed IPA to India by ship. He decided that, yes, the ship-borne beer had aged better and matured more than the same brew kept at home. But while I’m not knocking his huge achievement in organising the trip (and getting an excellent, highly readable book out of it), Pete himself never actually drank ship-borne IPA alongside stay-at-home IPA.
Earlier this year I decided I had the opportunity to conduct an experiment myself to test the “hot maturation” theory. Take two 75cl bottles of Meantime Brewery’s fine naturally conditioned IPA, 7.5 per cent abv, made in Greenwich, with East Kent Golding hops like the original IPAs. Leave one sitting in a cool cupboard in West London. Take the other by aircraft to the Middle East and place it, wrapped in a thick black plastic bag, outside on a shaded Abu Dhabi balcony for three months. Turn the bottle over occasionally to stir up the yeast inside and try to reproduce the sometimes violent rocking that casks of ship-borne IPA must have suffered on their journey from Britain to the sub-continent. In Abu Dhabi the beer would undergo temperatures that rose as high as 45C (113F), and seldom, if at all, dropped below 26C (79F) even at night. Fly the bottle back to London, open it alongside its non-traveller companion and contrast and compare.
I was lucky to have a professional brewer to help me do the contrasting and comparing: Steve Wright, top man in the mashing and pitching department at Hopback Brewery in Salisbury. He’s an old friend of a couple of very old friends of mine, and Steve and I were both invited to a barbecue our mutual pals were holding. I took along the two bottles of Meantime IPA so that he could give his expert take on the experiment.
The result was a relief, because I’ve been repeating the “hot maturation” meme myself when writing about IPA, with the growing fear that it might not actually have any reality. But the two bottles, stay-at-home IPA and three months in the Gulf heat IPA, were unmistakably different, the beer that had made a 7,000-mile round trip instantly recognisable. The bottle that had been in the heat certainly wasn’t noticeably oxidised, skunked or suffering from any other fault, Steve and I agreed, and it was very drinkable. More than this, the IPA that had stood on the Tropic of Cancer being gently baked was deeper, rounder than the same beer that had been kept in conditions no hotter than a chilly English Spring. With the hot-matured IPA the Goldings “Seville orange” was even more marmalade-y, the malt more rotund, more caramelly. The stay-at-home IPA was silver trumpets, with everything higher, brighter; the well-travelled, “maderised” version was golden trombones, a baritone to its brother’s tenor.
Which one was better? I liked them both very much, and I wished I had taken more bottles with me, and kept more at home, to make more side-by-side comparisons. If the stay-at-home beer just had a fetlock ahead of the “hot matured” beer, this was probably, I think, because we were drinking something that had not been designed to undergo a “maderisation” process: I’m sure a beer could be made to thrive even more when subject to hot maturation than Meantime’s IPA did.
Surprisingly, this is an experiment that seems not to have been done very much: Dr John Harrison of the Durden Park Beer Club, the British home-brew group that specialises in recreating old beer recipes, kept a well-hopped IPA in a cask in his shed over an English summer at least once, and we tasted the results at the seminar the British Guild of Beer Writers held on IPA at the old Whitbread brewery in London in 1994. But an English summer won’t reach the temperatures even a Gulf spring will, and the changes to the beer will be nothing like as pronounced. I suggest that if you want to try this one at home, you’ll have to be able to keep your beer at or above 40C for extended periods, and not let it drop below 26C at any time. That means, for professional brewers, a brewery somewhere in or near the tropics where casks can be stored in hot shade, or a heated storeroom, or a set of Madeira-style tanks warmed up by steam pipes or their equivalent.
For any brewer wanting to supply a particularly “authentic” form of IPA, however, I’d suggest “hot maturation” for three months is just the gimmick to put you ahead of your rivals. Your customers will certainly be able to taste the difference.