Iain McPherson: The big freezes

24 August, 2023

For most bartenders, coming up with a new bar technique would be a lifetime achievement – something to tell the grandkids about. But for Iain McPherson of Edinburgh’s Panda & Sons, it’s a regular occurrence. 

The Class bar magazine Bar Innovator of the Year already has four techniques to his name which bartenders are now implementing in their entries to major bartending competitions. McPherson explains the techniques on his Transcend menu.

The Transcend cocktail menu at Panda & Sons brings with it an innovative concept. Each chapter shines a spotlight on a different freezing technique, either invented or evolved to enrich flavour. So let me take you through our four processes, showcasing one of our cocktails from each chapter.

Sous pression

What is sous pression? Imagine if sous vide was created in an alternative reality. By containing and harnessing the force generated during the freezing process of a liquid in stainless steel kegs, this makes the alcohol force out the flavour in fruits and herbs etc, just like a chamber vacuum would do. During the freezing process the molecules separate and combine again once defrosted, thus marrying the flavour molecules together. The freezing also softens the alcohol. So you can see this second part has a similar goal to how a water bath impacts flavour.

For our cocktail Sability (Bombay Sapphire Premier Cru gin, fino sherry, Lustau blanco vermouth, Sable grape, Maraschino liqueur) we use the sous pression technique to achieve a very elegant flavour profile from the Sable grape. It marries beautifully with the fino and vermouth and brings that level of sweetness the cocktail was missing initially. We also get a beautiful colour from the grape skin during the process. You could also use this technique to add flavour from any fresh produce.

You don’t need to batch complete cocktails if you don’t want too. If you want to just do a straightforward infusion with a vermouth, for example, this technique works very well for this approach too. Pre-diluting the cocktail is also fine and will enable you to use conventional freezers for pretty much all cocktails that you want to use this technique with.

Freeze drying

Back in the day, freeze drying was limited to astronauts. Now Panda & Sons is the first bar to use a freeze dryer within its drinks programme. Using lyophilisation, a process in which water is removed from a product after it is frozen and placed under a vacuum, allows the ice to change directly from solid to vapour without passing through a liquid phase. You can extract 99% of the water from products, which allows you to store anything for up to 30 years. You also keep the cell structure intact as it’s not been cooked, which means you can rehydrate freeze-dried products. Freeze drying in our eyes is the more sophisticated cousin to the dehydrator. It also helps us minimise waste and break down the limited availability of seasonal products.

Our initial use of our freeze dryer was primarily for garnishes, but for the Seville Negroni (Height of Arrows Heavy gin, Campari, bitter orange, sweet vermouth) we showcase how freeze-dried goods can be used for infusions. We freeze dry the mandarins and vacuum blend them with the gin. By using freeze-dried produce we can still infuse its fresh flavour, but without the dilution a fresh mandarin would bring to the drink.

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