What is the deposit that forms in the bottles over time?

The colour, aromas and taste sensations of Traditional Balsamic Vinegar of Modena P.D.O. are the result of a myriad of natural chemical components that form over the extremely long ageing period. These are often molecules of considerable volume and weight that continue to form, increasing the viscosity of the product. As they tend to gradually settle over time, they create the typical deposit in the bottom of the bottle, which can vary in thickness