appraisal of NGS, but most if not all focus on the absence of negative flavors. One exception here is the positive flavor differences between neutral spirits from different commodities. Certainly in the Scotch whisky industry, where around 60% of the spirit produced is from grain, there is a consensus that NGS from maize is sweeter than its wheat counterpart. Any NGS that does not rate too highly in terms of quality can potentially still be employed, although it is perhaps wise to put it under total reflux in the presence of copper in the still prior to the production of a gin or vodka. Unlike NGS, white spirits are final products that, once approved, will go to the consumer. The major categories here are vodka and gin, although other products such as aquavits and absinthes can reasonably be included here too. As for NGS, dilution to around 2023% ABV is recommended, but here the distiller is looking for the presence of those positive attributes that define the brand, as well as ensuring the absence of flavor negatives. So both training and familiarity with the brand are essential prerequisites for reliable product assessment. Various approaches can be used here. For botanical spirits it is likely that the distiller would look for botanicalspecific attributes, not least as these can help distinguish the brand from its competition. Brown spirits have the additional complexity of non-volatile wood components being present, including sugars, tannins and Maillard reaction products. Earlier we mentioned astringency, which is a drying of the palate caused by the precipitation of salivary proteins out of saliva (think of a heavy red wine). This is induced by tannins
and is responsible for astringency in some brown spirits. So for brown spirits, there is more of a case for moving beyond nosing to taste evaluation, given the presence of a range of non-volatile species. Again, dilution to reduce the impact of ethanol burn is highly desirable, even though it may induce haze formation in nonchill filtered products, typically due to the precipitation of longchain fatty acids. There is a relatively new category of “brown spirits” derived from the exposure of white spirits such as gin to wood. Generally, these are aged for shorter periods of time than traditional brown spirits, but nonetheless are likely to become increasingly popular in the future. (Arguably the tequila and aged genever industries have been the most successful in marrying delicate spirits with wood maturation.) We need to develop our understanding of the flavor interactions in these novel category extensions. Despite advances in our understanding of the physiology of taste perception, we are still a long way from developing instrumental mimics of human perception. So, for the foreseeable future, as an industry we need to rely on sensory evaluation tools as an essential component of process and product management. Rigorous training and appropriate sample preparation are critical features for reliable sensory monitoring systems to improve the quality of sensory data.
Paul Hughes, Ph.D. is assistant professor of food science and technology at Oregon State University in Corvallis, OR. For more info visit www. oregonstate.edu or call (541) 737-4595.
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Published on Sep 19, 2017