Re-washing yeast from a starter?

[PiPhilling]

About a week ago I washed the yeast from my first 1gal brew and ended up with three 16(+/-) oz jars of yeast. I've never washed yeast before and am not sure if I got it right. So here's my question, if I make a starter for one of the jars and it goes off well can I re wash the yeast for use at a later date? Or is it going to be "spent"?

 

[Bheher]

If you got three 16 oz jars from a 1 gallon brew then you didn't do it right. So I would just throw the 3 jars out. You should have only had one 16 ounce or two 8 ounce jars from a one gallon batch.

To answer your question, yes you could make a starter then wash it.

 

[CA_Mouse]

I agree that you have a lot more than just yeast. From a recent 5.5 gallon Belgian I got 4 jars with approximately 125ml of yeast in each jar.

Yes you can make a starter with the yeast and then rinse it for a later brew.

 

[PiPhilling]

Thanks for the advice and the answer. I thought I may have done something wrong, I guess I'll try again on the next one. (;,

 

[eastoak]

Thanks for the advice and the answer. I thought I may have done something wrong, I guess I'll try again on the next one. (;,

you can also skip the washing and jar it up for storage.

 

[flars]

Don't throw it out.
Take one of the jars and go through the rinse process again. Boil a quart of water. Cool the water. Pour one of you 16 ounce jars into a quart size sanitized jar. Top off the quart jar with the boiled and cooled water. Swirl it to mix completely.
In 20 to 30 minutes you will see a thin clearer layer forming at the top of the quart jar. At the bottom you will see the trub and break materials beginning to form. The yeast is in the middle.
When about one third of the quart jar has cleared you are ready to pour off the yeast. Have a sanitized pint jar ready. In a single pouring motion, pour off the clear top layer, down the sink, and then fill the pint jar. This will be fairly clean yeast.
What is left in the quart jar can be discarded being mostly trub and other waste.
All the yeast from the one brew can eventually be consolidated in one pint jar.

 

[eastoak]

yeast "washing" does what besides increase the chances of picking up a contaminant in the process described above?. put the yeast cake into jars then store it, skip all of the other steps.

 

[PRE66_6TART]

I'm no expert by any means, but the arguments I've read against yeast rinsing are pretty convincing. The only possible reason to do it I've seen is that it might increase long term viability, but if you're not using it right away I would make a starter anyway, so I don't see the point.

 

[EarlyAmateurZymurgist]

Yeast rinsing is little more than amateur brewer voodoo. Yeast rinsing is not practiced outside of amateur brewing for a good reason; namely, the process is not supported by science. In fact, as I have stated in gory detail before, rinsing yeast with boiled tap water can be harmful to the culture. Yeast is a living organism. Rinsing yeast with boiled tap water is the microbiological equivalent of someone forcefully stripping off one's clothes and throwing one into the Bearing Sea, as it removes the culture's food supply and it's protective barrier.

A little known fact in the amateur brewing community is that yeast can use ethanol as a carbon source via a phenomenon known as diauxic shift. All one needs to do is to oxygenate the culture. In the presence of oxygen, the culture will leave the stationary phase and switch into respirative growth mode using ethanol as its source of energy. Respirative growth is significantly more efficient than fermentative growth.

Most amateur brewers have heard the claim that wort doesn't need to be aerated when pitching dried yeast. Believe it or not, there is a quite a bit of science that supports this claim. Contrary to what is claimed in many older amateur brewing books, brewing yeast strains do not respire at normal wort gravities. Regardless of dissolved oxygen level, brewing yeast strains will choose fermentative growth over respirative growth in the presence of glucose concentrations above 0.3%. This phenomenon is known as the Crabtree effect. While energy is derived primarily via anaerobic fermentation at normal wort gravities, brewing yeast strains have leaky metabolic pathways. Oxygen is taken in via the respirative metabolic pathway and shunted towards the biosynthesis of sterols and unsaturated fatty acids, which are needed for cell wall health. Many amateur brewers have heard about the olive oil as a replacement for aeration study that was conducted by Grady Hull at New Belgium Brewery. The reason why olive oil works as a replacement for aeration is that yeast do not need dissolved oxygen if they have sufficient sterol and unsaturated fatty acid reserves. Olive oil provides these nutrients directly to the yeast culture.

Dried brewer's yeast does not require aeration because it is propagated respiratively in a device known as a bioreactor. The low-gravity highly-oxygenated culturing medium is held at a steady state by continuously adding new nutrient while removing yeast. The glucose level is held below the Crabtree threshold, resulting in explosive yeast biomass growth (as I mentioned above, respirative growth is significantly more efficient than fermentative growth). In fermentative growth mode, the sterols and unsaturated fatty acids that are synthesized by the mother cells at the start of fermentation are shared with all of their offspring, which results in depletion by the end of fermentation. In respirative growth mode, yeast cells directly synthesize their own sterols and unsaturated fatty acids during propagation. Dried yeast cells never go through anaerobic cell division until they are pitched; therefore, they are ready to go to work right out of the package.

 

[flars]

Yeast rinsing is little more than amateur brewer voodoo. Yeast rinsing is not practiced outside of amateur brewing for a good reason; namely, the process is not supported by science. In fact, as I have stated in gory detail before, rinsing yeast with boiled tap water can be harmful to the culture. Yeast is a living organism. Rinsing yeast with boiled tap water is the microbiological equivalent of someone forcefully stripping off one's clothes and throwing one into the Bearing Sea, as it removes the culture's food supply and it's protective barrier.

This has been copied from the Lallemand Danstar website;http://www.danstaryeast.com/articles/rescuing-old-yeast

Question and answer when yeast was inadvertently stored for 7 months in the refrigerator.

G'day Drs, About while ago I was bottling a batch of hefeweizen and wanted to reserve some yeast from it. My method was to rinse about 100mL thick yeast slurry in cooled boiled water once or twice, removing as much trub as possible, before leaving it under a 300mL layer of cooled boiled water and storing in the fridge at 1C. The strain was White Labs Hefeweizen (WLP300).

I didn't intend on leaving it so long, but today, about 7 months later, I made up a 250mL batch of ~1.035 SG wort with some Wyeast nutrient and pitched it onto the yeast (I poured off the water first). It's in a small plastic bottle and I am squeezing air in and shaking it to introduce as much O2 as possible. It's now fermented out so something is alive.

If I wanted to use this yeast, which I probably don't, what would be your suggestions as for how to build up a healthy crop of yeast for pitching? I'm not yet at the plating and culturing stage, and I realize that this would be a good method, but what else can I do?

I realize this is probably not anything you'd recommend to the public, but I'd like to know if in desperate times that there's something you can do to save very old yeast.

Thanks,
Stuart

RESPONSE:

Stuart, Under your circumstances you did the right thing. You can store yeast under water for longer period of time. But it is critical, as Dave pointed out, that you wash your yeast thoroughly and remove all residual sugars and that you store the yeast as cold as possible without freezing them.

Once you decide to reuse the yeast again you should build up a starter culture, like you did, because you will find a higher concentration of dead cells after extended storage. But with the remaining viable cells you should be able build a good starter if you pamper your yeast with oxygen and nutrients (FAN, minerals)

Regards,
Tobias & Forbes

 

[EarlyAmateurZymurgist]

The responder is basing his answer on a study that was performed a couple of decades ago. However, that study involved using a centrifuge and autoclaved distilled water to remove all nutrients from the culture, which forced the culture into dormancy. That level of separation is impossible achieve at home. The culture does not go dormant when rinsed with boiled tapped water using the technique that is prescribed on this forum and other amateur brewing sites. It remains in the stationary phase and starts to autolyse unless forced out of the stationary phase via the introduction of a carbon source.

“In the stationary phase, the accumulated yeast biomass remains relatively constant and the specific growth rate (&#956 returns to zero. After a prolonged periods in the stationary phase, yeasts may die or autolyse. This in turn may influence the continued growth and survival of the residual yeast cells.”

Walker, Graeme. Yeast Physiology and Biotechnology. Wiley

Furthermore, boiled water is not sterile, tap water is not nutrient free, and the pH of water is significantly higher than that of green beer, which allows spores to germinate. Water has to be autoclaved at 250F/121C for at least 15 minutes to be considered sterile.

Here's a link to an article about yeast storage that was written by Chris White for BrewPub Magazine:

http://www.probrewer.com/resources/library/bp-healthyyeast.php

"Yeast is a living organism and is most happy and healthy when feeding on wort sugars. When fermentation is complete, yeast cells flocculate to the bottom of the fermenter. They then go into a resting state. Yeast under beer is fairly stable, and most brewers agree that the best place to store yeast is under beer."

"Storing yeast under water, as opposed to under beer, is becoming more popular. Sterile distilled water storage puts yeast in a resting state, and some reports suggest yeast can be stored in this manner for years, with no refrigeration. Storage under water is generally done with small quantities of yeast, which are then propagated in a lab. But it is possible that this can be applied to storage of yeast slurries. Some brewers are now trying this. The key is to use sterile distilled water and wash the yeast slurry several times in the sterile distilled water to remove any traces of beer. This is best done with a centrifuge, but that is impractical for most craft brewers. White Labs has had mixed success with sterile water storage, so time will tell if this procedure will work for craft breweries."

I have searched several major scientific research databases for publications that support storing yeast under boiled tap water. However, I have yet to find a single publication that supports the process. If storage under boiled tap water was a viable solution for the long term storage of yeast, there would be hundreds of publications in which the process was referenced because Saccharomyces cerevisiae is one of the most researched microorganisms on the planet. The groundwork for the field of genetic engineering was basically laid by Øjvind Winge using Saccharomyces cerevisiae at Carlsberg Laboratory.

In closing, I have maintained a yeast bank on agar slants for most of the time that I have been an amateur brewer. If sterile water storage was truly viable in a home brewery, I would not mess with slanting yeast. As it stands, the best way to store yeast at home is on agar slants.