Are Yeast Saprophytes?

Question

In a vineyard, yeast is commonly found on the bloom of the grape berries – Assuming it feeds on the grape how can they be termed as saprophytes as the grape would be a living organism and not dead or decaying organic stuff

Answer 1

Because they are breaking down the sugars and converting them into alcohols, this makes them a saprophyte, at its simplest level.

They are not actively attacking the grapes, but are taking advantage of an, already active, infection and injury, likely. That, or it is growing in the flower nectar.

Unfortunately, some of these byproducts that come from the yeasts will destroy the plant material. Some success has be achieved using Kaolin clay.

https://www.gardeningknowhow.com/edible/fruits/fegen/fixing-sour-fruit-problems.htm