Though each ingredient will contribute different amounts of flavor, we begin any new syrup with some basic starting points.
Temperature Ranges for Sous Vide Fruit Syrups
- Delicate Fruits (raspberries, blackberries, citrus juice): 125 – 135F for 2 hours
- Moderate Fruits (apples, pears, stone fruits): 135 – 140F for 2 hours
- Dried Ingredients (Barks, spices, dried fruits): 145F – 155F for 2 hours
- Decide on your base syrup or sweetener. When using fresh fruits for use in sour-style cocktails, we favor a neutral Simple Syrup base: equal parts sugar and filtered water. Denser syrups, for use in Old Fashioneds and such, are best with a more robust Demerara syrup: two parts demerara sugar to one part filtered water.
- Fire up the immersion circulator and set the temperature.
- As the water bath warms up, weigh out your desired amount of syrup. Depending on the flavoring ingredient, we often begin our experiments by equal weights of both syrup and ingredient. In later refinement, often enough we dial this back a bit.
- If you don’t have access to a vacuum packing machine (which sucks out air and seals the syrup in a bag — and also costs big chunk of dough), don’t stress. Fill the syrup in sealable mason jars. It’s best not to have too much air inside the jars, so for small experiments, get some small jars. For large production, grab some liter sized ones.
- Once the circulator reaches temperature, place the sealed syrup into the bath.
- At desired time (we start at 1 hour), set up a container with water and ice. Remove syrup and place into ice bath.
- When it reaches room temperature, strain out solids
- If you have a centrifuge, spin the syrup for 10 minutes at 10,000 rpm to clarify.
Sous Vide: Fruit Syrups
Heat is a great tool for extracting flavor, and when it comes to syrups, a tried and true way of quickly infusing a solution of sugar and water with vibrant flavor and aroma. The only problem is when dealing with fragile ingredients, heat can sometimes do more harm than good. With fresh fruits in particular – especially delicate ones like berries – we’ve often been haunted by the sad reality that heat can sometimes battle vibrancy and freshness, and in their place can be a sad and artificial interpretation of the original ingredient.
Recently, we’ve been experimenting with low and measured heat applications with fruit syrups. We call this “sous vide” even though most of the time vacuum isn’t a huge part of the process; what we’re really doing is using heat in very precise ways to speed up the process of flavor extraction, but not apply too much to manipulate the freshness of the fruit.
Raspberries, for example are an important component in classic cocktails – the Clover Club is a requirement for any bartender’s repertoire – but we’ve always been bothered by the inconsistency that comes with muddling fresh raspberries into the drink. The size of each berry can be different (even if minutely) and so we can never be sure the drink will be the same each time. The same sentiment is true of almost all muddled fresh ingredients, and though it’s our goal to preserve the identity of our natural ingredients as much as possible, as bartenders, we need the convenience, consistency, and stability that a syrup brings to service.
Making a raspberry syrup by either blending raspberries with simple syrup or allowing raspberries to soak in simple syrup overnight was OK, but the mixture is exceptionally unstable. By placing this mix on a stove and cranking up the heat, we gained stability but quickly lost the raspberry’s inherent freshness, turning what was once a clear and focused flavor into something that was candy-ish. It was tasty, sure, but it was something different than the raw ingredient. Closer to jam, less like chewing on a raspberry. No dice.
Our first ah-ha! moment came thanks to a good friend and crazy talented chef, Phillip Kirschen-Clark. In collaborating with him on a project a couple years back, we were talking about this same problem – that cooked fruit syrups lose their luster quickly – and he opened our eyes to indirect heat extraction. By boiling a small amount of water in a pot, setting a stainless bowl above with the syrup and ingredients inside, covering it in plastic wrap, and allowing the steam heat to cook the syrup gently and evenly from below. What came out the other side was a breakthrough in flavor clarity, an elegant and intensely flavored syrup that tastes closer to raw raspberries than anything we’d been able to pin down.
Getting our hands on a Polyscience Immersion Circulator changed the game again, allowing us to dial in very specific temperatures for syrup preparation and offset the labor intensiveness of indirect heat extraction. An immersion circulator is essentially a high quality heating coil controlled by a little computer. When immersed into a water bath, the computer accurately controls the temperature of the water, keeping it consistent for extended time – like cruise control for heat. By placing our syrup in a sealed bag (or sealed jar) and keeping it immersed in the heated water, the syrup cooks consistently from all sides without any spikes or troughs in temperature – just nice, even, continual heat. This method, known widely as sous vide cooking, is all the hot-shit rage in cooking these days, and it’s quickly becoming the only way we make syrups using fresh ingredients. Raspberry Syrup, Pineapple Gum, Demerara Gum, house made Tonic, there’s just no two ways about it, the technique is here to stay for our crew.
Different ingredients require different temperatures, and that’s another great asset of sous vide syrups: the ability to be laser-focused and precise for extended periods of time. This is even more important when considering fragile ingredients – citrus, being a prime example. The moment even a little bit of heat is applied to citrus juice (lemon or lime, for example), their flavor rapidly changes. It’s why pasteurized juice is bullshit and will never match freshly pressed juice. In the case of some of our citrus-based syrups, we use very low heat for long periods of time to make sure that the syrup never tips towards that artificial flavor. Our Meyer Lemon Cordial (recipe coming soon), for example, uses the juice of meyer lemon as the water component in a syrup, along with zest of the fruit and cane sugar, cooked at 125F for two hours. The result is a delicate but pungent syrup, encompassing both the aromatics of the zest and the juicy acidity of the juice.
In the case of raspberry syrup, we’ve found that keeping the berries whole and cooking in a simple syrup inside the sealed bag (see photos to the left) produces a beautifully clear syrup, vibrantly red and transparent. The first interaction we have with a drink is its appearance – it’s an important consideration – and so sous vide presents another asset in the visual identity of a cocktail.