The white wine making is singular because of the absence of maceration. The fruits are traded and crushed immediately in order to avoid any contact between musts and grape skins. Free from its solid parts, the must is going to ferment.
A white wine is often defined by its freshness due to a good acidity level. That’s why the malolactic fermentation is usually avoided.
It is necessary then to avoid any contact of the must with the environmental air. White juices and wines are indeed sensitive to oxidation which modifies the colour and the aromas.