This article was first published in The Montreal Gazette.
Cavemen in the Stone Age didn’t have many luxuries. They had, however, learned to make fire by banging together flintstones or rubbing two sticks together, and that at least made their cold and dingy dwellings more comfortable.
And fire did something else. Once the caveman had clubbed his prey, which of course wasn’t a dinosaur, fire allowed the meat to be cooked. If the meat wasn’t eaten right away it would be hung to dry because experience had shown that dried meat keeps longer, especially if exposed to smoke.
Much later, science would demonstrate that bacteria require moisture to proliferate, hence the preservative action of drying, and that smoke contributes to the effect due to the antibacterial compounds it contains.
There was another benefit. The meat tasted better! And we have been enjoying smoked meat ever since. At least until studies revealed that where there is smoke, there may be more than one kind of fire.
That fire is in the form of some nasty compounds in smoke, with the term “carcinogen” rearing its ugly head. Smoke contains literally hundreds of compounds, a number of which, particularly polycyclic aromatic hydrocarbons (PAHs) and heterocyclic amines (HCAs) are of concern. In cell culture and animal studies, these have been shown to cause changes in DNA that can lead to cancer.
Cells and animals aren’t people, but some epidemiological studies have also linked the consumption of smoked meats to intestinal cancer. For example, in one region of Hungary where home-smoked foods are a major part of the diet, the incidence of stomach cancer is twice that in the rest of the country. Analysis of meats there was found to contain an average of 4.16 micrograms per kg of benzopyrene, one of the polycyclic aromatic hydrocarbons. This is roughly six times the average of 0.7 micrograms per kg detected in commercially produced smoked foods in the rest of the country. The European Union sets a safety limit of 2 micrograms per kg of benzopyrene in meat.
Besides the carcinogens already present in smoke, the heat associated with smoking can also result in chemical reactions in the meat that form yet more carcinogens such as acrylamide, acrolein and nitrosamines. The latter are the result of nitrogen and oxygen in the air forming nitric oxide that then reacts with naturally occurring amines in the meat to form nitrosamines. Unfortunately, these concerns also come into play with barbecued foods that owe at least some of their delightful taste to smoke.
It turns out that food does not actually have to be smoked in a smokehouse or grilled on a barbecue to have the flavour of smoke. That’s thanks to an accidental discovery in 1895 by Missouri pharmacist Ernest Wright. As the story goes, Wright had noted a drop of liquid trickling down a stove pipe and surmised that it was the result of smoke condensing on the cooler surface. Could this be liquefied smoke, he wondered? A taste confirmed that it was indeed “liquid smoke.” Maybe food could be smoked, he thought, without the need for a smokehouse.
Wright designed an apparatus, essentially a still, in which smoke from burning hickory wood ran through a cooling column where it condenses into a liquid. He made a fortune by selling his liquid smoke not as a flavouring, but as a preservative. Competitors, seeking another angle, entered the business and promoted liquid smoke as a flavouring agent. The marketplace was soon flooded with smoked cheese, oysters, potato chips, soups, hotdogs and even bacon that never saw a smokehouse.
The European Food Safety Authority (EFSA) threw a wrench into the works in 2013 by questioning the safety of liquid smoke. No regulations were introduced at the time, but it was recommended that liquid smoke be used in reduced quantities. Ten years later, EFSA changed its tune and concluded that liquid smoke flavouring cannot be considered safe for human health. What changed? Technology!
More sensitive tests had been developed for genotoxicity, the property of a chemical to damage a cell’s genetic information. Also, analytical techniques to identify the various components of liquid smoke had improved. For example, 2-furanone and pyrocatechol now joined the other genotoxic compounds found in smoke. Not only were these present, but their amounts exceeded the “threshold of toxicological concern (TTC).” For chemicals that can damage DNA, the TTC is defined as a daily intake of 0.0025 micrograms per kg of body weight, roughly 1.5 micrograms for an adult. The EFSA now concluded that “no safe concentrations can be defined for such substances.”
However, the European authority is not a regulatory agency, so EU countries will have to decide whether the use and sale of liquid smoke should be curbed.
Canadian and U.S. regulatory agencies so far do not see any risk with liquid smoke as it is used. Actually, there are fewer carcinogens in liquid smoke than in traditionally smoked meat. That’s because when smoke condenses, it forms an aqueous layer and a heavier oily layer. The oily layer contains the fat-soluble compounds like the polycyclic aromatic hydrocarbons, while most of the flavourful compounds are in the water layer, which is the one used for “liquid smoke.” Furthermore, compounds such as 2-furanone are found in other foods that have been heat treated as well. For example, one study detected higher-than-TTC levels of 2-furanone in chocolate sampled from chocolate cakes and crêpes.
To sum up, liquid smoke, which is always used in small amounts, is hardly a health concern. In smoked potato chips or smoked cheese, for example, the fat content is a bigger issue than the trace carcinogens in the smoke flavouring.
By contrast, foods that are exposed to real smoke will contain far more carcinogens. A serving of smoked herring, smoked salmon or — I wish I wouldn’t have to say this — Montreal-style smoked meat will all deliver far more than the daily threshold of 0.15 micrograms of genotoxic chemicals. Moral of the story? Don’t eat these foods every day!
As for asking if Montreal-style smoked meat could be made with liquid smoke instead of a smoker: Don’t even let that question roll off your tongue!
@JoeSchwarcz
