It’s the chemistry of the meat, the chemistry of the smoking and the chemistry of the cooking that combine to make bacon smell and taste irresistible, as Veronique Greenwood discovers.

There are few foods as sensual and appealing as bacon. The mere smell of it can take you by the nose and lead you across the house to the kitchen. It vaults anything from eggs to chocolate to Brussels sprouts to new levels of deliciousness. (If you haven't seen the Portlandia sketch “The Celery Incident”, suggesting nefarious roots for the current add-bacon frenzy, I suggest you take a gander.) Bacon is vivid and specific and entirely unlike anything else. It even supposedly acts as a “gateway meat” to tempt vegetarians. So what makes bacon taste like it does? And could chemists make non-meat products with the same taste?

Sometimes in flavour chemistry you find a single molecule that's enough to evoke a specific taste. Almond flavour centres on benzaldehyde, and banana on isoamyl acetate, though of course the real deal involves a mixture of many compounds in addition to those. Likewise, there isn't just one molecule that screams bacon. But the flavour begins with the meat itself – the pork belly that's cured, smoked, and sliced thin.

Some of the major flavour players are the result of the pork belly's fat breaking down, says Guy Crosby, food scientist and science editor at America's Test Kitchen. It's not just the white marbling that's in play. The cell membranes of the muscle tissue contain fatty acids that disintegrate during cooking to yield a bouquet of flavourful compounds like aldehydes, furans, and ketones. By themselves, some of these molecules have distinct tastes or smells – furans have a sweet, nutty, caramel-like note, aldehydes a green, grassy note, and ketones tend to be buttery – but whatever they are doing together seems to be key. If any of these classes of molecules were missing from the overall bacon flavour, you would notice it.

The diet and breed of the pig affect just which specific fatty acids are present in the meat, and hence which molecules will result when they break down. In fact, a lot of what makes it possible to tell one species' meat from another, according to Chris Kerth, a professor of meat science at Texas A&M, is traceable to the fats in membranes of muscle cells. That gamey lamb flavour, for instance, is partly down to the particular array of membrane lipids and their breakdown products.

When the cured pork bellies are smoked, they take on another set of flavour compounds

The curing salts that are applied to the pork belly affect flavour too, in part by changing the course of the chemical reactions the fats can take. They arrest progress down certain routes and shunt the bulk of the molecules down others.

When the cured pork bellies are smoked, they take on another set of flavour compounds. The smouldering wood releases acrid-smelling phenols as well as sweeter-smelling compounds, including the evocatively named maple lactone. “It's the combination of those two – the acrid and the sweet – that creates the real flavour of smoke,” Crosby says. “You really don't have the flavour of smoke without both of those.”

Fake bacons

The last major contributor to bacon's goodness is the Maillard Reaction, which occurs when sugars and amino acids combine under high heat and which you induce whenever you toast bread or sear meat. Crosby says the molecules generated at this phase include more furans, as well as pyrazines and thiazoles, which have nutty, caramelised tastes and aromas. As it happens, chocolate also owes some of its flavour to the Maillard Reaction, thanks to the browning of the cocoa beans. But it's not clear if this shared chemistry has anything in particular to do with why bacon chocolate bars are so delicious – the science of flavour pairings is thorny and controversial.

There are many meat-free bacons – “fakeons” – on the market, although opinions vary on how well they mimic the real thing. So if you had to create a bacon flavour from scratch – no bacon allowed – what would be in it? The Jelly Belly Company, which creates exquisitely specific flavours for its confections, does not yet have a bacon bean and would not speculate on the subject. “You never know what may or may not be in development,” their spokesperson wrote. But Kerth was willing to muse. “It's overly complex, but you could come very close,” he reflects. “It all depends on the food product, but it would be a combination of the furans from the Maillard Reaction, the phenols from the smoke, and some salt.” Three ingredients – sounds simple enough. But that’s probably only the start. “And then you gotta have some aldehydes...”

In the end, it seems that a real bacon flavour, using no bacon, would be quite an undertaking.

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