In physics, different properties of each item are used in order to distinguish the items from each other. These properties are generally referred to as distinguishing properties, and density or specific weight is a distinguishing feature.

The determination of viscosity in terms of liquid products is one of the important characteristics at various stages of food production. The viscosity of many liquid products varies in cooling, heating or concentrating processes. The difference in the density of foods is particularly important in mixing and size reduction processes. The density and viscosity at various stages of production should be measured at regular intervals. Modern devices for density and consistency measurements are used in these facilities.

Physically, the weight in grams of a cubic centimeter of a substance is called density or specific gravity. Of the objects with the same volume, the weight of the densities is higher. The densities of pure substances, ie their extracts, are constant. The densities of the mixtures are variable. The volume and thus the density of the material change with temperature.

A pycnometer is a laboratory device made of special glass which is usually used to determine the specific gravity (density) of liquids. They can be with or without thermometers. The density (specific gravity) of all liquids, which are approximately 25 degrees fluid, can be determined with a pycnometer.

The specific gravity of various liquid foods is determined by the pycnometer within the scope of physical analysis in authorized laboratories. Food safety and human health laboratories, advanced technological devices and experienced employees serve. At the same time, the standards, generally accepted test methods and test criteria published by local and foreign organizations are complied with in these laboratories. In this way, reliable and unbiased results are obtained.

A few standards considered in density determination studies are:

• TS EN 1131 Fruit and vegetable juices - Determination of relative density
• TS ISO 279 Determination of density and relative densities of essential oils