Can you see if dry yeast is "alive" when re hydrating?

[gobuchul]

I have a few packets of dry yeast that has been left lying around in a drawer for 12 months.

I haven't bothered to brew for ages.

Now with the current situation I would like to start getting my stocks of beer back up.

I have ordered some fresh yeast I it should be here next week but i would like to do a brew ASAP.

Normally I just pitch the yeast straight on top of the wort with no problem so have never bothered re hydrating.

The question is, if I test one of the packets by re hydrating it, is there anything visible that will tell me the yeast is healthy?

Don't want to risk brewing and spoiling a batch of wort.

[CestrIan]

If you rehydrate the yeast properly and it is viable it should go milky. This is from Chris White’s book “Yeast”:

1. Warm the dry yeast to room temperature
2. Cool boiled water to 41C. Use 10x the weight of the yeast 10ml/g dry yeast
3. Sprinkle dry yeast on top. Wait 15 minutes then stir gently
4. Wait 5 minutes and stir again. Should form a cream
5. Adjust temperature to within 8C of the wort temperature
6Pitch the cream into the wort

[Northern Brewer]

I have a few packets of dry yeast that has been left lying around in a drawer for 12 months.

It will be fine - it's not even past its best-before date. Dry yeast goes off at a rate of well under 5%/year in the fridge, a bit more at room temperature but it will be fine.

Last night I put on a starter of some dry bread yeast that's been at room temperature since 2002 (SWMBO started getting ideas after she saw Jamie Oliver making bread and I found it in the cupboard) and it's bubbling away this morning - it's tough stuff.

As an aside - brewing is the perfect way to grow up yeast for bread-making at a time when supermarket supplies of bread yeast are non-existent.

[Bad 'Ed]

I think it's the milky thing that indicates it's ok. I rehydrated old yeast once and it just sat on top of the water not mixing in. So I tried a newer packet and it rehydrated fine (went milky and fermented the beer properly).