Sensory significance of aroma carry-over during bottling from aromatized wine-based beverages into regular wine

Abstract

In 2020 one out of  eight wine bottles were filled with a flavoured wine-based beverage.
Installed sealings absorb aroma compounds and release them during subsequent bottling of regular wines. This unintentional carry-over bears the risk to violate the legal ban of any
aromatization of regular wine.  Due to the highly seasonal bottling of aromatized wine-based beverages such as mulled wine, an installation of a second bottling line  reserved for aromatized beverages only is too expensive. Thus we investigated the absorption and desorption process during bottling and cleaning in order to minimize aroma carry-over by improved cleaning efficacy.  If cleaning obeys good manufacturing practice (GMP) and traces of aroma compounds in the subsequently filled wine show no sensory significance, this unintended aroma carry-over will be considered as technically unavoidable and has no legal consequences anymore. Based on a novel direct analysis of aroma compounds within the sealing polymers, which we exposed to aromatized wine and cleaning agents in a model
system, a GMP cleaning sequence removed only 11–62% of the seven absorbed marker
aroma compounds such as γ-decalactone, α-ionon or eugenol.1 Among the cleaning factors, high temperature of 85 °C revealed the largest cleaning efficacy, while chemical additives such as citric acid, caustic soda or ozone exhibited only minor impact. A total removal of absorbed aroma compounds from sealing however was not achieved, making a later release into subsequent wines possible. To study the requested absence of sensory significance, odor detection thresholds of seven aroma compounds commonly used for aromatization were determined in water, model wine and regular white wine. Applying the odor activity concept to traces of aroma compounds detected in the subsequent bottled wines allowed us to determine unequivocally their sensory impact. 

Studying uptake, cleaning and further release in two industry scale bottling lines we could confirm the uptake of marker compounds into built-in sealing during the filling of mulled or aromatized wines for four days. GMP cleaning only reduced small amounts of absorbed aroma compounds from the sealing, which was also the case for the subsequent bottling of regular wines. Sensory evaluation of the wine before and after bottling by a 2-out-of-5 test could not detect the bottled wine. In fact, concentrations of respective aroma compounds remained below the analytical limit of detection or way below their respective sensory
thresholds. In conclusion, despite of migration of aroma compounds into the sealing of a bottling line, execution of GMP cleaning and dilution effects in the subsequently filled wine prevented any aroma carry-over of sensory significance. Thus, a potential analytical determination of aroma traces would not lead to legal prosecution.