FIGURE 2 Experimental set-up to assess impact of entrainment vs maceration (B vs MB) and additional reflux (M vs MB). HUGHES & HARTZOG
chemical activity of copper metal can induce some changes at a molecular level to the oil components themselves. These are some of the problems we are currently investigating in our laboratory. Our initial work has focused on how still configuration affects oil delivery into the distillate. Using a copper benchtop still (capacity around six liters) we defined three experiments, utilizing the ginzero recipe (Fig. 2):
Macerate 1: distilled with the gin basket absent (M)
Macerate 2: distilled with the gin basket present (MB)
Entrained: botanicals suspended on gin basket (B)
This gave us two meaningful comparisons. Firstly, M vs MB was designed to provide insight into whether additional reflux surface (in this case provided by the gin basket in the MB set-up) materially affected the oil yield in the final spirit.
MACERATE no basket (M)
MACERATE with basket (MB)
Secondly, by comparing the spirits from MB and B, we were seeking insight into how maceration and entrainment affected the final oil profile in the spirit. Using sophisticated analytical methodology (SPME-GC-MS) we were able to detect and roughly quantify a range of botanical oil components, including monoterpenes, sesquiterpenes and a range of esters (Fig. 1). Comparing a selection of botanical oil components (Table 1) clearly indicates that
FIGURE 3 A sensory comparison of the gins produced by maceration (with and without basket, M and MB) and the gin produced by entrainment (B). As reflected by the instrumental analyses, the entrained sample, B, was the least intensely flavored, whilst the high aniseed rating for the MB sample at least partly reflects the presence of elevated levels of anethole. HUGHES & HARTZOG Cool Mouthfeel
M MB B
Dried/Ripe Fruit Nutty
MACERATE with entrainment (B)
the entrained sample, B, was the lightest overall in flavor components, whereas the additional reflux provided by the basket in the MB vs M comparison generally had only a minor effect, with the exception of anethole, which we presume comes from the cinnamon used. A comparison of sensory profile data for the three distilled samples reflected the analytical observations. Specifically the MB sample scored highly on aniseed, which was in keeping with the higher levels of anethole in that sample. Additionally, the entrained sample, B, generally showed the lowest scores for the various sensory attributes tested. Overall, though, it is important to recognize that the balance of flavors also impacts on perception and product preference. For instance, floral, aniseed and astringent/drying varied widely across the three samples even though the botanical recipe was unchanged. To further understand the role of copper in botanical flavor expression for gin, we constructed two glass still configurations (Fig. 4). Copper mesh was used to introduce a defined surface area of copper in the still and, as a control, a stainless steel mesh of identical mesh size to the copper was used, to ensure equivalent levels of reflux. Our aim here was to understand whether there was any chemical interaction between copper and the oils from the botanicals, perhaps in turn leading us to discover novel chemistry
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