During the fermentation, yeast need nitrogen, minerals and vitamins in order to function properly. The YAN (Yeast Assimilable Nitrogen) has to be about 250 – 300 ppm. Often it is necessary to add some nutrients to ensure a proper end of fermentation. More detailed information is available on the TDS “DistilaVite”.
To start we recommend maximum dosage and after achieving good results, optimize the dosage by gradual reduction.
In the process of production of dry yeast, we take out the water which was in the cell membrane. Rehydration brings back the molecules of water and wakes up the yeast allowing more efficient and consistent fermentation.
There are a number of factors which affect rum quality. These factors include:
– Sugar source (cane juice, can syrup, or molasses)
– Type of yeast
– Fermentation and distillation methods and practices
– The aging and maturation process
– Quality of water used in spirit dilution.
Some recommendations :
– use yeast strain which is thermo-resistant
– use yeast strain adapted to the substrate
– decrease initial density (gravity) of medium you are fermenting
– use complex nutrients tailored to the substate : some microelements (like manganese) increase yeast resistance to stress factors incl.temperature.
The ideal temperature depends on what you want to get out the fermentation. High temperature results in fast fermentation kinetics but can cause yeast stress and affect the flavour profile (high fusel oils production). Low temperature results in slow fermantation kinetics and also impacts flavour (presence of volatile compounds). Temperature should also depend on the robutness of the yeast being used.
Many rum fermentations are carried out between 32°C – 33°C.
This does require some work and equipment. One method is to distill and take a density reading.
With laboratory glassware designed to give amount of distillate needed add to an exact amount of fermented mash.
Add the same amount of water rinsing out first container.
Distill off the initial volume exactly and measure the density of this sample. Be sure temperature is correct.
Another instrument which simplifies the process and can give good results is to use an ebulliometer.
Several parameters will influence your fermentation times:
- Temperature : cooler temperatures will typically be longer fermentations,
- Substrate / feedstock,
- pH : 3.6 – 5.3
- Agitation during fermentation : a moderate agitation will help,
- Choice of yeast : contact your local LBDS technical representative to get the best Distilamax strain according the parameters and the distilled spirits you want to produce,
- Adequate nutrition : it is a key point to get a healthy yeast working very well and to finish the fermentation properly.
When a brick/bag is open, it is recommended to store it in the fridge and use the yeast in the next 3 days.