FERMAID™, trademarked commercial product produced by Lallemand and used as a nutrient for yeast. It contains various compounds including amino acids, sterols, yeast hulls, and vitamins. It also contains a limited concentration of fermentable nitrogen (25g/HL = 25 mg/L fermentable N). Samuel Viljoen of Tukulu told me Fermaid is added after alcoholic fermentation has started at between 20-15 Balling (It is ineffective below 15 Balling). If the vineyards have high free amino acids there is no need to add this.

Lallemand describe their product Fermaid K yeast nutrient thus:

Fermaid is a blended yeast nutrient adapted to the fermentation of grape musts, juice from concentrate, fruit musts, corn syrup and honey. Proper use of Fermaid reduces the risk of sluggish or stuck fermentations.

In fermentations, yeast growth must take place before the anaerobic (alcohol) fermentation can begin. In most wine applications, the common active dried yeast inoculation (when yeast is poured into the must) rate is 5 grams (0.2 ounces) per 20 liters (5 gallons) which results in an initial cell concentration of three to four million viable yeast cells per milliliter of must. Under normal conditions, the cell population will increase to 100 to 150 million viable yeast cells per milliliter before growth stops and alcohol fermentation takes over (stationary phase).

Because of this significant increase in biomass, adding Fermaid to the juice or must ensures that a proper balance of nutrients is available to the yeast during this critical growth phase. Without proper nutrition, the risk of sluggish or stuck fermentations increases. These sluggish fermentations are microbiologically unstable and can lead to the growth of undesirable organisms that can result in unwanted by-products, such as acetic acid, acetaldehyde and diacetyl. The most common reasons for stuck or sluggish fermentations are:

a) Improper rehydration, inoculation or fermentation temperature management Nutrient deficiencies
b) Excessively clarified musts
c) Yeast-inhibiting substances such as fungicides, fatty acids or high volatile acidity

To foster the rapid and efficient growth of the inoculated yeast in the fermentation medium, Lalvin Fermaid provides important nutrients and biological factors such as:

a) Usable nitrogen
b) Thiamin, folic acid, niacin and calcium pantothenates
c) Yeast hulls (lipids)

For normal winemaking applications, the recommended addition rate of Fermaid K is 5 grams per 20 liters. For optimal results, 2.5 grams of the Fermaid K should be suspended in the 20 liters of must just after adding your yeast culture to the must, then add the balance of 2.5 grams of Fermaid K anytime between 1/3 and 1/2 way through the fermentation.

NOTE: DO NOT combine the Fermaid K with the rehydrated yeast slurry before inoculation.