September 26, 2023 - 10:30am
Yeast conversions
We're just trying to do some conversions for recipes and it seems a lot of sites contradict each other. We need a definitive conversion from fresh yeast to both active dry and instant. Fresh is just too hard to maintain at the volumes we use it so we have to rely on packets. (...but while we're on the subject if anyone knows of any way to keep fresh yeast 'fresh' for long we're all ears)
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4yr old Redstar ady - still going. - just kept in the fridge. Enjoy!
I thought we had seen that fresh should be used within days. It was fresh I was asking about at the end, but in any event even dry or instant have acted remarkably less after a year.
But, it's the conversion I'm more interested in right now.
Don't know - is it less effective - don't notice anything - but i could be missing something after almost 5yrs and countless starters. Oops - conversions - only ever used this kind of yeast so don't know. I just read the entire thread and realize that I was mistaken - I haven't used fresh yeast. Enjoy!
Here are a few links -
https://redstaryeast.com/yeast-conversion-chart/
https://www.omnicalculator.com/food/yeast-converter
https://www.kingarthurbaking.com/pro/reference/yeast
The page on King Arthur's says
Yes, I'm aware of all those links and they and several others, as I mentioned in my question, tend to contradict each other.
The yeast manufacturers can tell you about their products, but I don't know about reliable information across different brands.
https://www.fleischmannsyeast.com/baking-basics/yeast-101/
https://redstaryeast.com/yeast-conversion-chart/
Here is an interesting thread wherein someone spoke to Lesaffre about ADY vs IDY vs fresh yeast. Apparently things have changed since many of us learned about the differences years ago.
Hi!
Fresh yeast keeps well for two months refrigerated, at least the new strains of compressed yeasts. It's a very long time! The old strains of compressed yeasts lasted only a week when refrigerated, the next generation of compressed yeasts lasted a month, and now we've got strains of compressed yeasts with two months expiration dates.
The problem of conversion even between two different compressed yeasts let alone compressed and dried has to do with different strains used in compressed yeasts preferred in different countries and by different manufacturers, and trying to match them with different strains of ADY and IADY from different manufacturers.
Some strains are slow gassing with two peaks of their gassing power over a period of 3-6 hours of fermentation followed by a decline, some are fast and superfast, or osmotolerant, or with only one peak in their gassing power, etc.
In automated systems of bread production on rigid schedule, or even in bread machines at home, many substitutions even if numerically correct just won't work. Bread doughs won't mature, or proof on time, or even rise well during baking, because it coincides with a trough between two gassing peaks in their yeast's gassing power over time profile! We' d have to either find yeasts that match our schedule or adapt our bread production schedule to our yeast. Beware of that when you substitute.
Also, even if you find a perfect match between compressed and dry, reality does not match theory. In theory, the most common proportions are 1g of fresh compressed equals 0.33g just opened instant or 0.4g properly reconstituted active dry. In reality, it is either less than that or more, for example closer to 1g compressed = 0.25g instant or 1g compressed = 0.4g instant = 0.5 active dry yeast which must be tempered and rehydrated at 43C for 10 min prior to use. Instant yeast can be bloomed in seconds by stirring it in room temperature water or even in cold water or milk.
The proper pretreatment of yeast procedures according to AACCI are
For CY: 5 min before mixing, weigh compressed yeast, crumble it into a beaker and soak in water at 70°F (21°C) for yeast rehydration.
For ADY: Warm yeast to room temperature for at least 30 min before use. Prepare 3% sugar solution with water for yeast rehydration in a beaker (rehydration water is 4–5 times the weight of yeast). Then, weigh dry yeast and add to sugar solution with initial mild hand stirring. Rehydrate at 110°F (43°C) for 10 min with sufficient stirring to obtain a uniform suspension of yeast.
Not following these guidelines will affect the rate of conversion, because a rather large % of dry yeast cells will be damaged or killed when treated harshly before mixing.
Conversion rates also change depending on hydration and sugar % in your dough.
So, experiment with different strains and different conversion rates to find out what really works for you and your breads and maybe contact yeast manufacturers to assist you with the available options and substitutions.
Hey there Tinpanalley,
Adding on Mariana's comment on "experiment with different strains and different conversion rates to find out what really works for you and your breads"
I use a spreadsheet for yeast conversions, which if desired, can be changed depending on what works best based on what type can be purchased locally.
You may find it useful for creating your own definitive conversions from fresh, active or instant and vice versa.
You can find the Yeast Converter here. There are instructions how to use but its simple enough to work out without them, but let me know if you need any more detail.
Rafe