The quick answer to how Ian makes Sacred Spirits is that he macerates botanicals in wheat grain neutral spirit before diluting that spirit with distilled water, then uses reduced pressure distillation to produce highly concentrated botanical flavoured spirits. These are blended and hydrated to make products such as Sacred Gin, and/or sold as ‘varietal’ botanical spirits. All quite straightforward? Perhaps. That is, apart from what ‘reduced pressure distillation’ is and that fact that this operation takes place in his dining room.
So what is reduced pressure distillation? Separating ethanol alcohol from water and other chemicals is possible due to their differing boiling points. At normal atmospheric pressure alcohol boils at around 78.5°C and water boils at 100°C, thus alcohol is more volatile than water and will escape from the body of the boiling liquid more readily than water. Hence, ethanol vapours can be separated and condensed to produce liquid ethanol alcohol.
Often referred to as ‘vacuum distillation’, reduced pressure distillation works on the principle that the lower the pressure the lower the boiling point of liquids, including water and ethanol alcohol. Thus the use of a vacuum pump allows you to reduce the pressure and so distil at temperatures barely warmer than a hot summer’s day. Ian distils each botanical separately under a vacuum ranging from 1/12th atmosphere to 1/6th atmosphere. He says reduced pressure distillation “results in distillates that taste fresher when compared to the result of traditional distillation where delicate botanical aromatics have been damaged by heat”.
There is also a ‘negative activated carbon effect’ from distilling botanicals separately. When botanicals are distilled together, as in traditional gin distillation, the presence of just one single absorbing element will affect the entire gin as it will absorb flavours from its neighbouring botanicals.
Thus reduced pressure and reduced temperature of Ian’s distillation method also means three dimensional terpenes such a limonene, geraniol, pinene, eucalyptol and terpenoids such as citral, menthol etc. do not have the opportunity to stereoisomerise into their more ‘stewed’ versions, which would be recognised as ‘marmalady’ and bitter flavours, often prevalent in gins distilled at higher temperatures.
Ian’s set up starts with a two-stage rotary vain vacuum pump of the type usually used to prime refrigeration systems. When it runs this throws out an oily mist which covers its immediate environment, so it has been consigned to what used to be his children’s wendyhouse in the garden. A pipe into and out of this vacuum pump runs into his family’s dining room through the window, then into and out of the distilling equipment spread out on the dining room table.
Ian distils at 25˚C to 50˚C depending on the botanical being distilled. He has found that 40˚C is the maximum temperature that botanicals which are sensitive to heat can be distilled at without denigration of flavour. Above this, the proteins and molecules in the botanicals essential oils are liable to be damaged by the heat. The same is true of human beings: if you have a fever over 43˚C then your protein molecules would be fatally bent out of shape.
Ian’s system is basically a series or laboratory glass chambers connected by plastic piping. Within this there are three different boiling points, each a glass chamber still in water baths of distilled water heated using laboratory style controllable electric heaters. A magnetic stirrer in each vessel ensures the heat is evenly distributed to avoid what Ian calls ‘pumping’ in the still.
Each of the three still chambers is connected to a condenser cooled by a cooling system powered by a domestic central heating water pump and water tank. Blocks of ice made in the family’s chest freezer are placed in the water tank and the cold water is then pumped around the system. The distilled spirit condenses and fills glass collecting chambers linked to each condenser. Ian used to also use CO2 refraction in the system but no longer uses dry ice as he found it to be of little extra benefit.
Around the system Ian has isolator valves so he can close off any of the three still chambers, and what he calls indicator chambers after each of the still chambers. If one of these fogs up then it means not all the spirit vapour is being caught by that condenser and he needs to turn down the heat on that still to slow distillation, otherwise vapour could travel round the system and damage the vacuum pump. A liquid nitrogen cold finger at the end of the system also helps protect the vacuum pump by catching any last vapour in the system. This has the benefit of also catching and collecting fascinating volatile elements with low molecular weight, such as hydrocarbons.
Pumping air out of the system minimises oxidation damage, particularly important when distilling fragile botanicals such as tomato stalks. To do this Ian first fills the system with CO2 and then pumps the CO2 out using the vacuum. By this process any possibility of contamination by oxygenation is removed.
This Heath Robinson-style laboratory distilling equipment may sit on the dining room table of a suburban family home in north London but rest assured it is fully licensed. Ian starts with a high quality English wheat neutral spirit distilled in Manchester, which he buys duty paid (rather than under bond). He is not actually making alcohol, just redistilling it with botanicals, so there is no additional excise duty payable. Also as the base spirit is of such high neutrality there is no danger of health threatening methanol in his finished distillates.
Ian stores the results of each distillation separately, blending them together to make his gin. This highly concentrated mix of botanical distillates is sent to the bottlers where it is diluted with wheat neutral alcohol and purified water. The concentrated nature of the botanical distillates Ian produces means that relatively little distillate produces a lot of gin.