"Hey guys,
Please bear with me. I need to paraphrase that which I have read with regard to the importance of making a yeast starter. I need my understanding corroborated by the multitude. This writing is intentionally condensed, i.e., I have disregarded finite detail and summarized for the sake of brevity.
Two Major Active Yeast Phases:
There are two major phases with which we must be concerned when dealing with yeast:
1) aerobic
2) anaerobic
Aerobic phase:
When yeast is first pitched, oxygen that's dissolved in the liquid portion of wort, is used by yeast to propagate. Stated differently, no alcohol is made during the aerobic phase. The aerobic phase is used strictly for reproduction. Reproduction continues until all available oxygen is used. Quickly increasing yeast-count is very important because this leads to quicker oxygen depletion. The sooner oxygen is depleted, the quicker ETOH production begins. The longer it takes yeast to convert the ""system"" from aerobic to anaerobic, the greater the chance that old yeast become sick and produce off-flavored products. Also as the time interval increases between the aerobic and anaerobic phase, the opportunity for wort to become infected with wild yeast or bacteria heightens. Stated differently, rapidly converting from aerobic to anaerobic phase is desirable because this decreases the chance of wort infection and off-flavored products. Rapidly evolving young healthy yeast adds to the overall health (taste) of fresh wort. Vast numbers of healthy young yeast are needed to quickly deplete dissolved oxygen so the anaerobic phase can be initiated.
Anaerobic:
A very basic review of the aerobic phase has been presented. Discussion of the anaerobic phase will be far shallower.
It is the anaerobic phase that produces ETOH. The faster we convert to anaerobic phase, the faster we will produce ETOH. The faster our conversion occurs, the less chance we have of incurring an infection. The only way I know of accelerating conversion is to use up oxygen. The only way I know to quickly deplete oxygen is to vastly increase the number of yeast. The only way I know to vastly increase the number of yeast is to make a Yeast Starter.
Yeast Starter:
This is the section where I become somewhat confused regarding the process of making a Yeast Starter ,, as well as ingredients used. According to instructions, it takes about 16 to 18 hours, after hydrating a couple packs of dried yeast, to successfully make about 1 quart of Yeast Starter.
When deciphering instructions from various authorities, most authorities clash over one thing or another regarding the making of a Yeast Starter. All agree that you begin with a yeast count that is scant by comparison and in 18 hours healthy yeast have multiplied to an untold number. Naturally, this is desirable.
It would seem that nearly all authorities allude to or outright state that the temperature of the Yeast Starter should be maintained at the temperature of the wort. If not, when the starter is pitched, yeast well be "shocked" causing death or sickness to the healthy yeast, or an overall "unhappy feeling" which may lead to a "stuck fermentation", a "retarded fermentation", a bad taste, or all three. Ok, I can blindly follow that reasoning.
Regarding ingredients, all seemingly agree that one should never stray from the composition of wort being used. Again it is cited that yeast may become "sick" and this could result in unwanted, distasteful products. At least one authority states that the starter should be made from the wort being used. Even so, the authority shortly contradicts himself when highly recommending the addition of DME (dried malt extract), which is never added to my wort. The authority goes on to state, "If a starter is made from strictly sucrose and water, and this mix added to a wort, made in part from grain, yeast will "hit a brick wall" when faced with the proposition of utilizing such sugars as maltose (and various other sugars from grain) thus fermentation may stall". Still, another authority makes no mention of DME but highly touts the use of DAP (diammonium phosphate), citric acid, CaSO4~2H2O (gypsum), and Epsom Salt as additives to make all Yeast Starters. I can clearly see the importance of adding plant food, e.g., DAP and Epson Salt, to the fray as sugar may not be enough to feed yeast. I can also see the importance of maintaining an acceptable pH and SG when making the starter.
All having been said, deviation from the working wort will have occurred when additives are incorporated into the starter. This is confounding and counter to recommendations that a starter be practically identical to the wort being used.
1. In your experience with making starters, have you experienced a total stall, retarded fermentation, or off taste if, when making a starter, deviating from the wort ingredients using additives?
2. I would like to make a wash using a simple mixture of sugar and water, with a SG between 1065 & 1080, and pitch a hefty starter to accelerate the process from aerobic to anaerobic. What are your recommendations for a starter that is to be used with a simple sugar/water wash?
KGB"
