Definition - What does Suspended Solids mean?
Suspended solids are pieces of matter left in the wine juice after pressing in the fermentation process and during aging. There are many different types of suspended solids, like grape solids leftover from pressing that include the skins, seeds, pulp, and stems as well as physical components from the vineyard, like dirt, molds, chemical agent residue, and insects. There are also solids added during the winemaking process like yeast and tannins and solids that break down into solid chemical compounds.
WineFrog explains Suspended Solids
Solids in wine have both positive and negative functions, wine cannot be absent of solids as it would make the wine unbalanced and take away structure and flavors. Wine also should not contain too many solids, as it would taint the clarity and quality of the juice. There is a fine balance that must be achieved to produce wine with the correct amount of suspended solids.
Naturally, suspended solids migrate when allowed to settle, landing at the bottom of the settling tank, making filtration relatively simple, and some winemakers can measure the remaining amount by looking at the clarity. There are other ways to measure suspended solids in the wine that include, using a calibrated cylinder (testing a small amount), a centrifuge machine which spins the juice to measure solids, a turbidity meter, and inline monitoring (using light). To remove suspended solids many just wait for gravity to move the solids to the bottom of the bulk tank after several months. However, some winemakers use a process called fining which adds chemicals that bind to the solid particles or absorbs them.