Dried yeast not always sterile and viable.

I think a starter is essential, to prove the yeast is OK. I always use Safale 04 and about 1 in 12 sachets fails to "start", so I throw it away and make a new starter. I don't fancy a failed yeast in my wort. My tests of a yeast are 1) musn't sink too fast after carefully scattering on the surface in a starter of water at 24 deg C and 2) In less than 1 hour must start to form a head and 3) after I add 1 teaspoon of brewing sugar to 200 ml of liquid starter, there must be a head of at least 2 inches depth within a further hour that resembles meringue.....in looks only!

I am very consistent with my starters and cleanliness so I conclude the problem is in the yeast packet. Any thoughts?

Danstar for one says no to dry yeast starters:

The factory builds into each yeast cell an abundance of the stress factor; trehalose. Our recommendations is to rehydrate the yeast in warm water and pitch into the wort (or must) within 30 minutes, because the yeast will begin to metabolize its carbohydrate reserve including trehalose immediately upon reactivation and weaken the yeast if it is not in the presence of a new supply of energy. It will have also used up the stress factor that would have assisted it in adapting to the new osmotic environment. I am sure that there is more to the explanation than I have given.

PITCHING TEMPERATURE AND NUTRIENTS - Danstar Premium Beer Yeasts

Proofing before pitching is one thing...starters a whole nother ball game.

I wait an hour, then add brewing sugar, then wait for a 2 inch head, should I add a little wort instead of brewing sugar, say 1:1 with starter volume giving OG of starter around 1.020 ?

BOBTHEukBREWER said:

I wait an hour, then add brewing sugar, then wait for a 2 inch head, should I add a little wort instead of brewing sugar, say 1:1 with starter volume giving OG of starter around 1.020 ?

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Basically what they are saying is that they prepare the yeast so that as soon as they are activated/hydrated, the buggers are ready to go to work and ferment your 5 gallons of wort. If you want to proof the yeast w/ something containing maltose just to see if they are live, fine...as soon as you see the yeast foaming, pitch.

Honestly though I don't see the point. I've used a number of dry yeast packets from Fermentis and Danstar over the past few years and never encountered a single dud. Now if you're brewing with questionable old yeast that's been sitting in who knows what condition for who knows how long, then proofing makes sense.

Any idea why are you having so many problems with dry yeast?

BOBTHEukBREWER said:

2) In less than 1 hour must start to form a head and 3) after I add 1 teaspoon of brewing sugar to 200 ml of liquid starter, there must be a head of at least 2 inches depth within a further hour that resembles meringue.....in looks only!

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I for one have maybe only once seen a "head" or krausen formed in a starter. I wouldn't take the lack of one as evidence the yeast is no good. I also don't use starters for dry and have never had an issue with them taking off in less than 12 hours.

I only buy my yeast sachets 10 at a time, and Safale 04 has a 2 year best before date. I store them cool, but not in a fridge. I will post a photo of my next starter which is tomorrow , actually my last brew before Xmas.

I do something similar and buy several packets at a time to keep in my fridge for when needed or as backup/emergency/just-in-case-yeast.

I have been using Dry Yeast for well over 2 years now. I have never made a dry yeast starter but have always rehydrated. And I have never had a dud.

I store my sachets in a 35 degree refridgerator.

GilaMinumBeer said:

I have been using Dry Yeast for well over 2 years now. I have never made a dry yeast starter but have always rehydrated. And I have never had a dud.

I store my sachets in a 35 degree refridgerator.

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+1

In fact, we've had this discussion lately that Fermentis is one of the few dry yeast makers that don't even say to rehydrate it, let alone make a starter for it.

Now I won't even rehydrate unless the packet specifically says to OR I have doubt about the age of it, but since I tend to shop from high turnover shops who store their yeast in fridges, that's rarely an issue.

Safale is rapidly becoming my yeast of choice because it tends to take off really fast, dry and straight from the packet..

I've used dry yeasts for years, and never had a dud.

I think all of you failed to read what Bob has posted. He said his starter consisted of water at 24c. So what he is doing is rehydrating and not really making a starter as we know it.

One point in rehydrating is to do it correctly. In addition to having the correct temperture is to not have it in the medium too long before pitching, so to avoid stressing the yeast out by depleating the built in reserves of glycogen. I think most yeast maunfacturers recomend 15 minutes of rehydration.