Smoothness of alcoholic beverages is a general descriptor correlated with age (maturity) and associated with higher consumer preference or flavor quality. Product smoothness is often associated with decreases in attributes such as trigeminal burn, sourness, astringency and overall mouthfeel. A common strategy to improve the overall flavor profile and smoothness is to age alcoholic spirits after distillation. For example, bourbons and scotches are typically aged at least 3 years, and rums, tequilas and brandies are aged anywhere from 2 to 10 years or more. Though effective in improving the palatability of spirits, distillation and aging techniques have changed little over the last several hundred years and the costs associated with distillation, filtration and aging are extremely high, often accounting for half to two-thirds of the total product cost.
Historically, research on the flavor quality of alcoholic products has focused on the aroma attributes as they relate to changes of the volatile markers during production (fermentation, distillation, clarification, filtration and other clean up steps depending on the final product) as well as during maturation-storage. Little is known regarding the chemistry changes in distilled spirits during maturation that affect taste, tactile and trigeminal sensations, which undoubtedly impart smoothness.
In alcoholic beverages, trigeminal burn has been almost exclusively attributed to ethanol content by activating the neural receptors on the tongue and palate responsible for temperature and tactile sensations. Trigeminal burn intensity has been shown to decrease during maturation or after the application of multiple distillations and filtration steps while the ethanol content remains constant. This reduction is associated with improved smoothness perception suggesting that trigeminal burn is influenced by other molecular species that likely activate or act synergistically (with ethanol) to activate causative neural receptors.
A holy grail of the alcoholic beverage industry has been to control the trigeminal burn perception of alcoholic products. Dr. Smaro Kokkinidou and Prof Devin Peterson examined the chemical species of alcoholic products and have identified novel molecular drivers of trigeminal burn. Their findings indicated that carbonyl species in alcoholic products modulate the perception of trigeminal burn, thus providing novel chemical markers for smoothness. These new findings, in addition to advancing our understanding of flavor development in alcoholic products, provide additional tools to optimize the selection of raw materials and processing technologies and accelerate aging (years to days). Ultimately, this will improve the palatability of a wide range of alcoholic products, including alcoholic beverages such as fermented and distilled spirits as well as pharmaceutical and personal hygiene products.
To read more about this research:
Kokkinidou, S. Peterson, D.G. 2016. Identification of compounds that contribute to trigeminal burn in aqueous ethanol solutions. Food Chem. 211: 757-762 http://www.sciencedirect.com/science/article/pii/S0308814616308068