As fermentation proceeds, yeast continue to propagate. Similar to reproduction in any species, certain attributes and amounts of cellular material are transferred to descents. Active dry wine yeast that is not properly rehydrated will show a gradual reduction in cell membrane thickness from generation to generation, coupled with decreasing amounts of nutrient reserves required for successful fermentation.

Several companies now offer proprietary yeast rehydration nutrients to help ensure healthy yeast during the rehydration process. These include products such as Dynastart, GoFerm, and PreFerm. These products are created primarily from autolyzed yeast cells. They contain many essential micro-nutrients, such as membrane lipids and sterols, and vitamins including biotin, niacin, and thiamine, that are readily absorbed by active yeast cells.

Providing such nutrients helps activate the yeast's internal metabolism quicker prior to inoculation. This leads to a substantial increase in cell volume as the original structures of the yeast's plasmatic membrane are modified. The benefits can make a significant difference to the yeast.

• Better viability and membrane fluidity promotes healthier yeast population.
• Steadier metabolic rate throughout fermentation.
• Increased resistance to osmotic shock due to high sugar concentration, important at inoculation.
• Increased resistance to ethanol, important towards the end of fermentation and essential when creating a yeast culture for re-starting a stuck ferment.
• Increased aroma production.
• Increase resistance to stress from nutrient deficiencies. 
• Decreased production of volatile acidity.