Page 32 - Craft of Whiskey Distilling

19 | AmErICAn DIstIllInG InstItutE
mashtunthermalmassThisisafancytermforheatthatislostthroughamashtun. If you pre-heat the mash tun with hot water to above the temperature of that which you intend to mash prior to doughing in, the thermal mass is 0. In the interest of simplicity, I am using the assumption that you are following this common practice. If you are not, then some more elaborate calculations are required to determine this loss because every mash tun varies in it’s ability to hold heat. To determine thermal mass of a cold vessel requires empirical data specific to the subject vessel from which you can then derive the factor to use in calculations. This topic is beyond the scope of this chapter.
sparge To introduce hot water beyond that of the water used to complete the mash- ing process with the purpose of rinsing as much sugar as possible from the mash. The use of this technique reduces the size of the vessel required to complete the mashing process which is a cost and space saver.
tincture of Iodine used to test for the presence of starch in a mash runoff. Place filtered runoff on a white plate in a thin layer, put a small drop of iodine in the layer. If the color changes little, there is no starch left in solution. If the color changes to blue or black, you need to rest the mash further.
Wash This term denotes a fermented solution which may or may not include solids that is placed in the still for distillation.
Before continuing into the technical details of mashing it must be noted that there are two schools of thought in the artisan segment regarding how a whiskey wash should be distilled. There are some that believe a greater character can be derived by charging the still with the whole wash without separating the grains from it. One positive attribute of this is that if fermentation is undertaken on the whole mash, the resultant wash will yield slightly more alcohol due to continuing conversion during fermentation. The nega- tive impact of this practice is that by not separating the wort from the grains, your still charge will be significantly reduced versus just filling it with the wort. It is interesting to also note that all Scotch distilleries lauter their wort. This is not mandated by law like many of their practices so it is either a historical practice or they feel that there are benefits to separating the grain from the wort. So, this is a subjective choice rather than a objective technical mandate.