Just use a full package.
Yeast costs next to nothing.
Most packages are meant to start a 5 gallon batch or so (look at
the packaging), so you could use half.
The half you want to save can best be saved in a zip-lock bag
or an air-tight container in the fridge.
Let it contact as less as possible with air.
Air is humid and humidity will dehydrate the yeast.
So when taking out of the packaging and saving likely a bunch of
the yeast is not going to survive.
So why bother.
will often have a good quality wine yeast that is refrigerated. Ask them if they do. My experience with foil sealed yeasts has been variable.
I buy a small package in a resealable bag and rush it home to my own fridge. I use about a third of a teaspoon to a wine must. I can usually get 6 x 1 gallon wines started with this amount.. 8 if I remember to start the yeast a day before the must, am a bit tight with the yeast initially.. And really yeast just multiplies til it dies. I know I can keep the yeast in my fridge for at least a month, because I have done and not had it fail on me..So yeast nutrient and a good yeast plus starting the yeast a day before you need it means you need less yeast. Added bonus?.. you know your yeast is viable.
St Allie When you start your yeast the day before you add it to the must, what is your procedure for mixing the stater do you mix it with the juice in a small container? and what else is mixed with it?
I use a clean quart jar for it. add about a 1/2 cup of warm water and the yeast and leave for quarter of an hour covered ( use a chux cloth), if the yeast is viable you can see it start to work by then. Add about pinch of nutrient and a tablespoon of sugar to another cup of warm water and dissolve, then add to the yeast. I leave it til about lunchtime in a warm place, then add a 1/3 of a cup approx of must.. leave til dinner time and add the same amount of must again, leave in warm place overnight. Next morning, allow the yeast mix to come close to the same temperature with the must and add the whole starter to the must..
I have mostly been making apple wine this month, ( who was the idiot that planted 6 apple trees you ask? .. guilty as charged!) My recipe calls for the must to sit for 24 hours before adding the yeast, so this system works perfectly for that recipe particularly..
Depends on the recipe as to what to add in on top of the starter.. if a recipe says citric acid in it .. then I add a small amount of it to the starter as well.
Have used orange juice and nutrient to start a yeast but don't always have orange juice to hand.