Page 5 - C:\Users\garyh\Documents\Flip PDF\BitsandBlobsAS_Issue021_UFOs\

FIGURE 2
STRUCTURE of a MICELLE of whiskey providing there is no contamination during filtration.

Development of deposits and the rate of deposition also depend upon the
Hydrophobic hydrocarbon chains are buried in the interior and
the hydroxyl hydrophilic head groups are exposed to water; think of pH and temperature. Moreover, pH changes with metal ion addition or
as a sphere. While only one hydrocarbon chain is seen attached to the depletion. A critical pH value for a blending of Scotch whiskies was noted
head groups, in biological membranes they are usually exist with two at 4.5 above which deposits occur in a few days (see the note on pH 4.9
hydrocarbon chains per head group. above). A tannin-based factor was suggested as being extracted from
wood during maturation and deposited when a sufficient concentration
of certain metals was present and the pH was above a critical value. The
corrosive effect of alcoholic spirits has been noted in relation to acidity
and can dissolve metals such as copper, aluminum, zinc, cast-iron and
brass. Thus, the contact of brown spirits, at any part of the process, with
respect to pickup of tannins, fatty acids and minerals also needs to be
considered when dealing with the topic of haze prevention. To gain a full
understanding of this topic in relation to different spirits, the reader is
encouraged to review these extensive research papers by Warwicker in
their entirety (Warwicker, 1960; 1963 a, b). In the meantime see also
below.

General Notes Concerning Instabilities
in Spirits Other than the Whiskies

RUM AND BRANDY
Instability in rum and brandy was featured in the second article by
Now these micelles are very small but when masses of them form Warwicker (1963a). Here again his discussion included the issue of
they scatter light, which results in a cloudy suspension. It is such a bad filtration. Deposition of metallic ions or metal complexes along with
suspension of solid particles in a liquid that we referred to above a shift in pH to critical values was found important to haze formation
as a colloid (see SIDEBAR 1: on COLLOIDAL STABILITY and
HAZES). Colloids are not easily filtered out. However, such particu- (pH 4.8 and below bad, pH above 4.9 good). Warwicker also stated: A
late matter can be removed by chill filtration. Furthermore, different “chilling process appears to be the best method of stabilizing rums and
lipids have different length hydrocarbon tails – the length determining brandies.” Chilling must, however, be done at final strength for sufficient
solubility and flavor impact (Discher, 2016). Choice of fermentation removal of water-insoluble matter to avoid deposition (Warwicker, 1963a).
and distillation conditions will impact the types and concentrations of Significantly, a chill proofing process was again noted as not being
fatty acid esters produced and the decisions to be made on filtration
steps implemented post-aging/pre-bottling. The longer hydrocarbon sufficient to ensure product stability though if metal ion contamination
chains make the lipids less soluble and these form micelles just below occurred afterwards. Deposits in such spirits were also found to contain
46 % ABV. Other lipids will only form micelles with a further drop protein matter (see Warwicker 1963a for the physical and chemical
in ethanol content. In lipid chemistry, this is also dependent upon the rationale and evidence for this.)
amount of the lipid present and is known as the critical micelle con- During the 1960’s it seems many manufacturers of beverages started
centration. Different whiskies, based on raw materials and processing,
will harbor different compositions and concentrations of lipids and to use stainless steel tanks for aging or resting or storage of product
so a one size filtration operation may not fit all situations. Some and if these were not free of mineral deposits were a likely source of
non-chill filtered whisky batches will be troubled with haze issues haze promoting metal ions. Furthermore, corrosion of metals by alcohol
while others won’t. And sometimes hazes could be developed for other solutions depends on the acid content, the type of metal and the
reasons. The hazes will be dependent upon not only lipid content time of contact and temperature. Alcohol at 40-50% by volume was
and composition but also on the ethanol concentration, temperature,
possibly on mineral content, and sometime just time itself allowing for demonstrated to attack iron more easily than zinc, copper aluminium,
the aggregation of molecules. tin and bronze (Warwicker, 1963a). Brandy was also shown to “throw
A final point to make concerns the presence in mature whiskies a deposit” if sufficient magnesium had been extracted from filter pads
(and including bourbon whiskies) of sterols which may also precip- (Warwicker, 1960). Thus, some common themes as for whiskies are
itate upon chilling and, as we have seen recently with many calls, clearly apparent here.
possibly even as stored at room temperature (20-25 °C). Several
steroid-based lipids (see schematic in FIGURE 1 and FIGURE 3) GIN AND VODKA
which are related to the better-known cholesterol have been identified Calcium and other mineral/metal deposition is not pH dependent (no
in Bourbon; campesterol, stigmasterol and beta-sitosterol included
in the list and even sugar derivatives such as sitosterol-D-glucoside critical pH determined) as for other brown or aged spirits. While calcium
(Braus, et al; 1957). The glucoside behaves as an organophilic (phil- oxalates are an issue in whiskies, rums and brandies, calcium carbonates
ic = loving) colloid, swells and disperses on heating in organic liquids, are suggested as more of an issue in gins and vodkas. “Gin and vodka
and forms gels on cooling of such dispersions (Braus, et al, 1957 – See should, as for other spirits, not be allowed to come into contact with
also SIDEBAR 1). FIGURE 3 summarizes some details on fatty acids
and sterols.
96 WWW.ARTISANSPIRITMAG.COM