Double Lemon-Lime Soda - Cook's Science

Ingredients

450 g	water
225 g	sugar
160 g	(4 stalks) lemon grass, trimmed to bottom 6 inches, quartered lengthwise and sliced thin
28 g	makrut (kaffir) lime leaves, sliced thin
8 g	grated lemon zest (from 3 lemons)
8 g	grated lime zest (from 4 limes)
1 g	kosher salt
6 g	citric acid
	club soda

2 cups water

1 cup plus 3 tablespoons (8 ounces) sugar

4 stalks lemon grass, trimmed to bottom 6 inches, quartered lengthwise and sliced thin

1 ounce makrut (kaffir) lime leaves, sliced thin

¼ ounce grated lemon zest (from 3 lemons)

¼ ounce grated lime zest (from 4 limes)

¼ teaspoon kosher salt

1 ⅛ teaspoons citric acid

club soda

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makrut (kaffir) lime leaves,: Makrut (also known as kaffir) lime leaves are the highly aromatic leaves of the makrut lime tree. They are used extensively in southeast Asian cuisines, where they add heady lime aroma to curries, soups, and stews. Look for them in Asian markets, or you can buy them by clicking here.

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grated lemon zest (from 3 lemons): It is hard to accurately measure grated zest by volume. If you don’t have a scale, just use the zest from 3 whole lemons.

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grated lime zest (from 4 limes): It is hard to accurately measure grated zest by volume. If you don’t have a scale, just use the zest from 4 whole limes.

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citric acid: Citric acid is the primary acid found in lemons and limes. Fresh lemon and lime juice flavor deteriorates rapidly, greatly decreasing the syrup’s shelf life. Adding dry citric acid gives the syrup bright acidity that makes the lemon and lime taste more like themselves, and extends its shelf life by lowering pH, which inhibits bacterial growth. You can buy it by clicking here.

Essential Equipment

Fine-Mesh Strainer
Cheesecloth
Digital Kitchen Scale
Cream Whipper with CO₂ Cartridges (Optional)

Instructions

- 450 g water
- 225 g sugar
- 160 g lemon grass (4 stalks), trimmed to bottom 6 inches, quartered lengthwise and sliced thin
- 28 g makrut (kaffir) lime leaves, sliced thin
- 8 g grated lemon zest (from 3 lemons)
- 8 g grated lime zest (from 4 limes)
- 1 g kosher salt
Combine water, sugar, lemon grass, lime leaves, lemon zest, lime zest, and salt in small saucepan and bring to gentle simmer over medium-high heat, stirring occasionally. Turn off heat, cover, and let steep at least 1 hour or up to 4 hours.
- 6 g citric acid
Line fine-mesh strainer with 4 layers of cheesecloth and set strainer over liquid measuring cup or bowl. Strain syrup through cheesecloth into bowl. Gather edges of cheesecloth and join in middle to form ball; using your hands, squeeze ball to extract as much liquid as possible. Discard solids in cheesecloth. Whisk citric acid into syrup until dissolved. (Syrup can be transferred to airtight container and refrigerated for up to 2 weeks.)
- club soda
To make 1 glass of soda, pour cold club soda (and ice, if desired) into glass and add chilled syrup to taste.

Alternatively, you can carbonate this soda in a cream whipper. Transfer cream whipper base to freezer and chill until very cold, at least 15 minutes. Pour 227 g (1 cup) cold water and 60 grams cold syrup into cream whipper and add 30 grams (about 3 cubes) ice. Stir until ice is dissolved. Screw cap on cream whipper and charge with 1 CO₂ cartridge. Shake cream whipper for 20 seconds. With nozzle facing up, cover nozzle with paper towel (to catch any small amount of spray), and very slowly vent the cream whipper completely. Charge with 1 more CO₂ cartridge and shake cream whipper for 20 seconds. Let cream whipper sit for 5 minutes. With nozzle facing up, cover nozzle with paper towel (to catch any small amount of spray), and very slowly vent cream whipper completely. Unscrew cap, pour soda gently down side of serving glass, and serve (with ice, if desired).

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very cold,: Carbon dioxide solubility (how well it dissolves into water) increases as water temperature goes down. So, for the bubbliest results, you want your soda to be as cold as possible.

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very slowly vent the cream whipper completely.: This step removes air from the cream whipper, which is important for two reasons. First, getting the air out means we have more space to add carbon dioxide, which is what will make our drink nice and bubbly. Second, small pockets of air trapped in the soda act as unwanted nucleation sites, causing the dissolved CO₂ to turn into bubbles in the chamber instead of in our glass.

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gently down side of serving glass,: All carbonated beverages benefit from being poured like a beer: gently down the side of the glass.

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carbonate this soda in a cream whipper.

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add chilled syrup to taste.: I like this soda best with 4 parts club soda to 1 part syrup (227 grams (1 cup) club soda to 60 grams (¼ cup) syrup), but feel free to adjust to your preference.

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pour cold club soda (and ice, if desired) into glass: Always pour the club soda into the glass first and then add the syrup. Since the syrup is denser than club soda, it will naturally flow to the bottom of the glass, gently mixing the drink for you. Gentle mixing means that more carbonation stays in the drink until you drink it.

Instructions

- 2 cups water
- 1 cup plus 3 tablespoons (8 ounces) sugar
- 4 lemon grass stalks, trimmed to bottom 6 inches, quartered lengthwise and sliced thin
- 1 ounce makrut (kaffir) lime leaves, sliced thin
- ¼ ounce grated lemon zest (from 3 lemons)
- ¼ ounce grated lime zest (from 4 limes)
- ¼ teaspoon kosher salt
Combine water, sugar, lemon grass, lime leaves, lemon zest, lime zest, and salt in small saucepan and bring to gentle simmer over medium-high heat, stirring occasionally. Turn off heat, cover, and let steep at least 1 hour or up to 4 hours.
- 1 ⅛ teaspoons citric acid
Line fine-mesh strainer with 4 layers of cheesecloth and set strainer over liquid measuring cup or bowl. Strain syrup through cheesecloth into bowl. Gather edges of cheesecloth and join in middle to form ball; using your hands, squeeze ball to extract as much liquid as possible. Discard solids in cheesecloth. Whisk citric acid into syrup until dissolved. (Syrup can be transferred to airtight container and refrigerated for up to 2 weeks.)
- club soda
To make 1 glass of soda, pour cold club soda (and ice, if desired) into glass and add chilled syrup to taste.

Alternatively, you can carbonate this soda in a cream whipper. Transfer cream whipper base to freezer and chill until very cold, at least 15 minutes. Pour 1 cup ice-cold water and ¼ cup chilled syrup into cream whipper and add 1 ounce (about 3 cubes) ice. Stir until ice is dissolved. Screw cap on cream whipper and charge with 1 CO₂ cartridge. Shake cream whipper for 20 seconds. With nozzle facing up, cover nozzle with paper towel (to catch any small amount of spray), and very slowly vent the cream whipper completely. Charge with 1 more CO₂ cartridge and shake cream whipper for 20 seconds. Let cream whipper sit for 5 minutes. With nozzle facing up, cover nozzle with paper towel (to catch any small amount of spray), and very slowly vent cream whipper completely. Unscrew cap, pour soda gently down side of serving glass, and serve (with ice, if desired).

Hide Annotation

very cold,: Carbon dioxide solubility (how well it dissolves into water) increases as water temperature goes down. So, for the bubbliest results, you want your soda to be as cold as possible.

Hide Annotation

very slowly vent the cream whipper completely.: This step removes air from the cream whipper, which is important for two reasons. First, getting the air out means we have more space to add carbon dioxide, which is what will make our drink nice and bubbly. Second, small pockets of air trapped in the soda act as unwanted nucleation sites, causing the dissolved CO₂ to turn into bubbles in the chamber instead of in our glass.

Hide Annotation

gently down side of serving glass,: All carbonated beverages benefit from being poured like a beer: gently down the side of the glass.

Hide Annotation



carbonate this soda in a cream whipper.

Hide Annotation

add chilled syrup to taste.: I like this soda best with 4 parts club soda to 1 part syrup (227 grams (1 cup) club soda to 60 grams (¼ cup) syrup), but feel free to adjust to your preference.

Hide Annotation

pour cold club soda (and ice, if desired) into glass: Always pour the club soda into the glass first and then add the syrup. Since the syrup is denser than club soda, it will naturally flow to the bottom of the glass, gently mixing the drink for you. Gentle mixing means that more carbonation stays in the drink until you drink it.

Ingredients

Essential Equipment

Instructions

Instructions

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