Molecular size distribution in long-aged food beverages and alcoholic drinks: a preliminary inquiry towards understanding physical and sensory realted properties.

The present study supports the idea that physical- and sensory-related properties of long-aged beverages and alcoholic drinks containing reducing sugars would be described not by an unique value rather as a distribution of values due to the time-dependent increase of molecular heterogeneity in molecular sizes and structure. A wide range of beverages and alcoholic drinks obtained after different ageing periods were fractioned by Size-Exclusion Chromatography (SEC), then the elution profiles were analyzed by using a chemical-groups sensitive detector, i.e. an ultraviolet-visible (UV-VIS), coupled to a mass-sensitive detector. i.e. a differential refractive device (DRI). The analysis of the probability density function as well as of the cumulative density function allowed to compare distribution properties among the investigated samples. This is because, unlike small molecules, such liquid matrices undergo accumulation of biopolymers (melanoidins) throughout the ageing period at room temperature. In general, results proved that all the investigated matrices would be defined as heterogeneous mixtures of chromophore-labeled copolymers, uncolored and brown, highly polydispersed with respect to their molecular size (ranging between 0.2kDa to over 2000kDa) and their chemical structure. In particular, the molecular size distribution of the end-products was attributed to the raw materials used for their production; while, the final content of the biopolymers is strictly related to the extent of the thermal treatment applied along to the making process and to the storage time at room temperature.