Does yeast go bad?

Hello,

This might be a trivial question, but does yeast go bad if the packet is opened and kept around for some weeks?

thanks, tarak

Reply to
Tarak Parekh
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Yeast can go bad. I assume that you are talking about dry yeast rather than compressed fresh yeast which has a very limited shelf life. There is a "use by" date stamped on the package. That date is for unopened packages. Once opened it will go bad rather fast. That said, if you buy bulk yeast and store it properly it should be good for at least a year, possibly much longer. I buy yeast in one and two pound packages at the warehouse clubs and GFS food service. Around the holidays even my Meijers store carries the large vacuum sealed bricks of yeast. I store mine in a glass jar or plastic container with a tight lid. I keep it in the refrigerator. Some people keep it in the freezer. I used to do that but I have read that freezing it isn't as good as refrigerating it. You can usually find yeast selling for about $2/lb. It is so much more economical to buy in bulk that you could throw out the excess every 12 to 18 months and buy a new package. The last I looked, a strip of three small packets of yeast cost nearly as much as a pound. Since I used about 2 pounds of yeast a year this is a no brainer for me.

For a comprehensive discussion of yeast, see:

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Reply to
Vox Humana

Just wrap it tightly and refrigerate it. Yeast does die of old age, so when you have some that is past the date on the package you will need to use more of it than otherwise. Of course, if its more than 6 months or so out of date, pitch it.

Reply to
Mary

Dry yeast once being released from its vacuum packing and or nitrogen packaging in cans or in sachets start to decompose as the atmospheric moisture and oxgyen gets absorbed by the (bone dry) yeast which faciliate microbial reaction that tends to its gradual self destruction. Once you opened a sachet of dry yeast of even instant yeast it is best to be used immediately.This is most important if your atmospheric conditions is high humidity and temperature. This spontaneous degradation of exposed dry yeast can be slowed under very cold storage but not for very long as the dry and frigid freezer conditions will gradually dessicate the residual moisture(especially if the container is already permeable) in the dry yeast cells contributing to its deterioration of activity. This is the same result in using freeze drying in the drying of yeast where viability is affected as well as the fermentation performance. There is a limit of moisture so that the cells can be truly dormant(inactive?) and not dead(completely inactivated). Common dry yeast have a moisture content of up to 8% and instant yeast can have moisture of 5% . There are some yeast that are protected such as the newer types of instant yeast where during the processing of the crude yeast cake prior to the drying processs it is treated with carboxymethylcellulose,methylcellulose or emulsifiers such as lecithin , sorbitan esters,etc.The main reason for these addtiives is the reduction of the yeast solids leached during yeast rehydration. Another way if improving the storage stability is the addition of antioxidants(BHT-butylated hydroxyanisole). Then that is considered a really a ' protected yeast' ; and have an increased stability to exposure to atmospheric conditions. But still these treatments will only slightly prolong the shelf life.And cannot replace the ideal storage under nitrogen atmosphere at reduced pressure?(vacuum). In terms of storability the instant dry yeast has an edge over the common active dry yeast. Roy

Reply to
Roy Basan

Truly vox,many people claim that they can place the opened yeast container in the freezer and can have a long life like an unopened container. In the past decades when this instant yeast was still new I already noted that the storability of this instant yeast is better than the common active dry yeasts. I still remember I opened a 2 pound can of active dry yeast and used a portion and kept the rest frozen. I almost forget it and I remember it a several weeks later.When applied to lean dough recipes I observed that the rising power was impaired. There was also a an instance(in the same period) when I opened a 500 gram pack of instant yeast and after using a portion wrapped the 4/5 full sachet it with plastic and place in the freezer.It was left there for about 4-6 months.When I used it again I noticed a decrease in leavening performance although the bread is still satisfactory. I presume then that was the time when the technology for improving the yeast was not yet perfected. Just a year ago I trained people in a bakery and was observing their undesirable habits of opening yeast and placing it in the cold room and forgetting about it. Out of curiosity I used one sample (of forgotten instant yeast) it in making sweet doughs and the result was still as good ! But technically if you have to measure the gassing power by specialized laboratory apparatus you can see a measurable decrease in gassing power in frozen opened instant yeast sachet versus the fresh sachet of the same yeast. However bakers can never realize it in practice; as long as the bread comes out fine.Even microscopic examination of the yeast cells you will find out that there are more dead yeast cells in the frozen opened sachet than in the freshly opened sachet. Another effect is that the stored opened yeast tends to have develop slightly faster the dough than the freshly opened one. It means that there is already the release of reducing substance glutathione.The indicator of the presence of many dead cells in the yeast substrate. The yeasts (of recent years)are more robust anyway compared to the earlier version of the same yeast and the strain was continously genetically improved for better baking and storage tolerance.This is further enhanced with the additives used in the manufacture of such yeast.That is why if yuo seal the container very well that the moisture cannot seep in then it will have an improved shelf life. Another thing also if you lived and work in a tropical climate I have observed that even frozen yeast does not perform as well during storage studies as in countries with colder climates. I do not mean to discourage people from storing instant yeast for long time but for me, knowing the technical effect of such storage I would not think of opening a yeast and store it in the freezer and use it for making bread during my next birthday... Now regarding your thoughts about Fleischmann yeasts and Saf yeast. I would recommend the later.I had such good experience with SAF yeast for more than a decade. I am not aware if Fleischmann had been able to keep up with yeast technology as I do not have good memorable experience with their yeast since before.For me its just an ordinary yeast . I do not know now as I usually use fresh yeast in my institutional breadmaking and brands do not mean a thing in such item as compressed yeast. Roy

Reply to
Roy Basan

Yes, it can go bad. I keep large packages of yeast in their original mylar wrap, tightly sealed with a heavy rubber band, in the freezer. My last lb pkg lasted 3 years.

Minteeleaf

Reply to
Minteeleaf

I've got half a pound of SAF Instant in a jar in my freezer that expired in 1999, didn't disappoint me when i made a batch of pizza crusts tonight.

- Eric

Reply to
Eric Jorgensen

Interesting question. It will lose its oomph with age, but as far as 'open' -- I buy mine in bulk and keep it in covered jar in the fridge. Seems like you'd do something similar? If that constitutes 'open', it will be fine.

Reply to
Melba's Jammin'

I buy the Red Star yeast in the 2# pkg at GFS. When open, I put it in a snap lid glass jar which stays in my freezer. As I always proof my yeast, I've found out it will easily last for over a year. I also use it right out of the freezer. Buy Bulk! Don't waste your hardearned money on those tiny single use packs.

Reply to
Nortwoods

Amen!

Just do the arithmetic. A strip of three packets costs $2 (?) Two pounds of bulk costs $3. the bulk yeast will last a year or two. Keep it in your freezer. Take out what you need. Put the rest of it back in. End of discussion. It keeps for at least a year. I keep mine in the fridge and it keeps a year.

This isn't rocket science.

Barry

Reply to
barry

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