Definition - What does Bloom mean?
Bloom is the powdery or waxy substance which is found on the skin of grapes. However, it is also found on most fruits and some vegetables. It is a natural occurrence also known as oleanolic acid. It works as a natural preservative extending the life of the grapes and also has antiviral properties.
WineFrog explains Bloom
As grapes begin to develop in the vineyard, white and red alike, a white film can be seen coating each berry. This is known as bloom.
It is a natural phenomena which can also be found on other fruits such as plums, cherries, nectarines, etc. This bloom is a sticky, waxy substance that allows certain microbes to attach themselves to the grape. One of these microbes is wild yeast. These are yeasts which are suspended in the air and vary depending on the climate and geography of a region. However, these yeasts may be used to ferment the grapes naturally once crushed.