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Cooking

Playing with fire

Liquid smoke adds depth to a variety of recipes – from the usual yummy suspects to the very, very surprising.

Cooking with liquid fire (Globe photo / Jim Scherer)
By Jeff Potter
October 3, 2010

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The smoky smells that we associate with barbecue goodness result from the chemical reactions that occur during pyrolyzation (burning) of wood. And the flavor that we think of as “smoky” does not come from a chemical interaction between the food and the smoke, either. This quirk means that the chemicals in smoke can be isolated, and generating smoke flavor can be separated from the step of applying that flavor to food.

Most cooks will buy their liquid smoke at the grocery store. But if you’re ambitious, you can make your own for about $20 worth of supplies and a few hours of your time. It’s rewarding to see how straight-forward it is to make, and the process touches on some elementary chemistry techniques as well. (For more on making liquid smoke, see Kitchen Aide.) My favorite store brand is Wright’s Liquid Smoke, which I have found at Johnnie’s Foodmaster and Shaw’s supermarkets in Boston. It’s good policy to look for a product that only lists water and smoke concentrate in the ingredients. And be conservative with the flavoring – you can always add more. Here are three very different recipes from my new book, Cooking for Geeks, that make use of liquid smoke.

S’mores Ice Cream Serves 4 to 6

This recipe uses liquid smoke to impart the toasted flavor of campfire-roasted marshmallows. Serve with hot fudge or more chocolate syrup. Whipped cream, nuts, and cherries are optional.

2 cups whole milk

1 cup heavy cream

1/3 cup sugar

¼ cup chocolate syrup

¾ cup miniature marshmallows

15 drops liquid smoke

1 cup graham crackers, toasted and chopped into pieces

In a mixing bowl, combine the milk, cream, sugar, chocolate syrup, marshmallows, and liquid smoke. Proceed with the directions for your ice cream maker. Once the ice cream has set, stir in the graham cracker pieces.

Smoky Salmon Gravlax ServesS 4 to 6

Salt curing – as is done in gravlax – is the first step in making lox. After curing, lox is also cold-smoked, which is the process of exposing a food to smoke vapors that have been cooled. You can approximate the flavor of lox by adding liquid smoke to the rub. (Since liquid-smoke formulas vary, and since too much liquid smoke can create off-flavors, use 10 drops – less than ¼ teaspoon – the first time you make this recipe, and take note if you think the amount should be adjusted up or down for future batches.) Curing inhibits most common bacterial growth but does not prevent all types of bacteria from growing.

This recipe is a bit heavy on the salt to err on the side of safety, but you should still avoid serving it to anyone in an at-risk group, including pregnant women, young children, older adults, and persons whose immune systems are compromised. You can reduce the saltiness by rinsing the finished product in water, then re-coating it with more dill and crushed peppercorns.

5 teaspoons kosher salt

1 tablespoon sugar

3 tablespoons finely chopped fresh dill

1 teaspoon vodka

1 teaspoon peppercorns, crushed with a mortar and pestle

10 drops liquid smoke

1 pound salmon fillet, preferably a center cut for easier slicing, washed and bones removed

In a bowl, mix together the salt, sugar, dill, vodka, peppercorns, and liquid smoke. Place salmon on a large piece of plastic wrap, then sprinkle salt mixture over fillet and massage into flesh. Wrap the fish in the plastic and refrigerate for 1 or 2 days, flipping and massaging twice a day through the wrap. Unwrap, remove skin, slice as much as you’re going to eat right away, and serve. (The remaining gravlax can be stored in the refrigerator for up to a week.)

Oven-Cooked Barbecue Ribs Serves 4 to 6

2 pounds baby back ribs, trimmed of excess fat

1 tablespoon salt

2 tablespoons brown sugar

1 tablespoon cumin seed

1 tablespoon mustard seed

20 drops liquid smoke

4 tablespoons ketchup

1 tablespoon soy sauce

1 teaspoon Worcestershire sauce

Heat oven to 300 degrees, with a rack set in the middle position. Place the ribs in a 9-by-13-inch baking pan. In a small bowl, mix salt, 1 tablespoon brown sugar, cumin seed, mustard seed, and liquid smoke. Rub ribs all over with spice mix, cover with foil, and bake for 45 minutes.

Meanwhile, in another small bowl, combine the ketchup, soy sauce, remaining brown sugar, and Worcestershire sauce. After the ribs have cooked for 45 minutes, remove foil. Use a pastry brush to coat ribs on both sides with sauce. Return ribs to oven and cook, uncovered, until tender, about 45 more minutes. Serve warm.

Excerpted from Cooking for Geeks: Real Science, Great Hacks, and Good Food by Jeff Potter. Published by O’Reilly Media (2010). Send comments to cooking@globe.com.

  • October 3, 2010 cover
  • Globe Magazine

KITCHEN AIDE
Distill-your-own

Wood is primarily made of cellulose, hemicellulose, and lignin; during burning, they convert to several hundred different chemical compounds. The aromatic molecules that provide smoke flavoring are generated by the lignin, which breaks down at around 752 degrees Fahrenheit. Cellulose and hemicellulose break down at lower temperatures (480 to 570 degrees), but they generate compounds that detract from the flavor. When grilling, you should make sure you have a hot fire, which will guarantee that the lignins, and not just the celluloses, break down.

Liquid smoke is made by heating wood chips to a temperature high enough for the lignins in wood to burn, condensing the resulting smoke, and then dissolving it in water. The water-soluble components of smoke remain dissolved in the water, while the non-water-soluble components either precipitate out or form an oil layer that is then discarded. The resulting product is an amber-tinted liquid that you can brush onto meats or mix into your ingredients.

Making your own liquid smoke can be a little tricky because of the high heat required and the difficulty in capturing the resulting compounds correctly, not to mention the need for proper chemistry-lab equipment for creating a closed system and heating it safely. If you do make your own liquid smoke – it’s a fun experiment, and there are how-to tips in my book – you’ll probably find that it’s a lot of work. Still, understanding that liquid smoke is nothing more than smoke particles captured in water removes most of the mystery.