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| FREQUENTLY
ASKED
QUESTIONS |
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Frequently Asked Questions
1/ Why do some strains produce more neutral alcohol in colour and flavour?
The compound responsible for yeast flavour are almost wholly derived from yeast metabolism. Some strains can produce up to three times as much fusel alcohols as others. It has been identified that Safdistil B-28 produces high amount of ethanol and carbon dioxide but limited amount of other compounds such as esters, higher alcohol and acids.
2/ Which other parameters can affect alcohol flavour?
Parameters such as fermentation temperature and wort composition can highly affect alcohol composition at the end of fermentation. For example, stimulation of growth by oxygenation causes less ester to be formed. Furthermore, various physical factors can effect the esters synthesis. This increases with high temperature and decreases with agitation and pressure.
3/ Can we propagate dry yeast?
When you try to propagate active dry yeast for a long time you reduce the efficiency of the yeast. The combination of temperature and ethanol concentrations (above 5%v/v) do increase the alcohol intolerance, resulting in cell mortality. Increasing the concentration of ethanol during propagation will initially be inhibitory and latterly lethal to the yeast.
However, the major risk in propagation is to propagate contaminants. When you try to propagate active dry yeast you can easily increase the levels of contamination because bacteria and wild yeast often grow quicker than Saccharomyces yeast.
We therefore recommend reducing the propagation time of dry yeast to a minimum (6 to 8 hours maximum).
4/ Can we recycle dry yeast?
The risks and the stress applied on yeast during recycling are similar to the one described in the propagation stage. In addition, there is the risk of development or unsuitable metabolites (such as lactic acid and acetic acid which strongly reduce the yeast efficiency) and the risk of genetic mutation and cellular ageing.
To maintain the best yeast efficiency we recommend that you avoid recycling.
5/ What is the shelf life of dry yeast?
Dry yeast has a two years shelf life and can therefore be stored for some months without an extensive loss of viability if temperature and packaging are controlled. Dry yeast is therefore immediately available from the shelf and can be used as and when required by the distillery.
6/ Is dry alcohol yeast similar to baking yeast?
No, Alcohol yeast has been specially selected in our R&D departments to provide the best fermentation performance in an anaerobic condition. It has been proven that these strains have a poor performance in bread production.
7/ Why are bacterial specifications so important?
Lactic and acetic bacteria can strongly affect the yeast performance and alcohol taste. This can be explained by nutrient competition or direct killing. It has been also identified that bacteria produce more higher alcohol, acetic acid, lactic acid than Saccharomyces yeast that can strongly affect ethanol purity.
8/ What substrate can be fermented by Safdistil B-28?
Safdistil B-28 is able to ferment a wide range of different substrates including cane and beet molasses, and various hydrolysed cereals (corn, rye, wheat).
9/ Should the wort be supplemented with additional nutrients?
Nutrients such as Nitrogen, Phosphor, minerals or vitamins are often present in limited quantity in the wort. This can strongly affect the yeast performances. Some substrate such as molasses should be systematically supplemented with nitrogen, others should required supplementation of phosphate, minerals and vitamins.
10/ How much ethanol is it possible to produce with Fermentis yeast?
The concentration of ethanol produced depends on the initial sugar concentration, the availability of the required nutrients and the ability of the yeast to resist to high alcohol concentration. Safdistil B-28 has proved that it is able to ferment various substrate up to 14% v/v ethanol.
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