Author Topic: Ischia yeast culture  (Read 4479 times)

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Offline theppgcowboy

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Ischia yeast culture
« on: May 18, 2011, 07:45:24 PM »
Generally speaking, what bakers percentage of Ischia yeast culture are people using to inoculate their dough?  Are you doing a preferment, or are you putting it into the whole dough mixture and going from there?
« Last Edit: May 18, 2011, 07:51:46 PM by theppgcowboy »


Offline Bill/SFNM

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Re: Ischia yeast culture
« Reply #1 on: May 18, 2011, 07:57:45 PM »
Generally speaking, what bakers percentage of Ischia yeast culture are people using to inoculate their dough?  

My last batch was at 7% of fully active starter. One needs to be precise about how this is measured since starter includes flour (and water).  Since you asked for baker's %, the 7% ignores the amount of flour in the starter. I actually prefer to include the amount of water and flour in the starter in my calculations, so I calculate starter amount as a percentage of the final dough mass. Same results, but I prefer the latter method, especially in helping me know the hydration level.  

The amount of starter I use is closely tied to other factors such as fermentation temps and time. That batch was a 24 hour dough @ 65F.

 
« Last Edit: May 19, 2011, 07:25:45 AM by Bill/SFNM »

Offline theppgcowboy

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Re: Ischia yeast culture
« Reply #2 on: May 18, 2011, 08:07:50 PM »
Thanks for the reply.  Will give it a whirl.  I like cold to ferment and will make a batch and see how the balls mature of a couple of day.

Offline Bill/SFNM

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Re: Ischia yeast culture
« Reply #3 on: May 18, 2011, 08:21:53 PM »
Thanks for the reply.  Will give it a whirl.  I like cold to ferment and will make a batch and see how the balls mature of a couple of day.

Not sure I understand the allure of cold ferment. Different strokes and all that, but IMO Ischia shines between 65F and 75F. 

Offline theppgcowboy

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Re: Ischia yeast culture
« Reply #4 on: May 18, 2011, 08:32:11 PM »
I can't always say I am going to have pizza tomorrow and do it.  Sometimes I have to wait a couple of day s and want to know the dough is going to be good during the long lag time.  If tomorrow comes and we will indeed do pizza, I get the dough out and  let it temper for the evening.  Otherwise it may have to wait a day or two or three.  But I do like to compare the doughs as they age.  Like my wines after they have breathed and after a day or two or three they sure open up and Mmmmmmm!

Offline kiwipete

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Re: Ischia yeast culture
« Reply #5 on: May 18, 2011, 09:04:16 PM »
I understand your comments about not always knowing went you want pizza, but Bill makes a good point.

Unlike "regular" yeast, a wild yeast like the Ischia culture has yeast and lactobacilli in a symbiotic relationship. But the growth rate of the lactobacilli and the yeast is different depending on temperature. Yeast will thrive at 28C-30C but will decrease its activity as temperatures go down. The lactobacilli continue to multiply better at lower temperatures.

So my guess would be that a cold ferment will produce a much "sourer" pizza, compared to what Bill is suggesting.

I personally ferment my dough at about 27C but with a lower inoculation percentage, to give me an 18-20hr bulk fermentation.

Peter.

Offline theppgcowboy

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Re: Ischia yeast culture
« Reply #6 on: May 18, 2011, 09:18:51 PM »
I am new to eschia yeast, but is there a balancing point with the cold and the warm fermentation?  kind of like enzyme rests in mashing beer?  When brewing you make a rest to create the fermentable sugars and another rest to create the non-fermentable sugars.  Not trying to reinvent the wheel but I was reading the Jeff Varsano recipe and his doughs held for up to 5 days.  My reach in is 40 degrees, are the lactobacilli still being created a lot at that temp?

Offline pizzablogger

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Re: Ischia yeast culture
« Reply #7 on: May 19, 2011, 06:45:12 AM »
@theppgcowboy sounds like a fellow all-grain brewer if you are talking about step-mashing! Good stuff :)

Quote
My reach in is 40 degrees, are the lactobacilli still being created a lot at that temp?

Retardation slows down everything...yeasts, lactobacilli, etc. However, while at a cold enough temperature the yeast goes mostly dormant, the lactobacilli are still able to grow.

I guess it is important to ask you what type of flavor profile are you looking for in your pizza dough? Are you looking for more of a noticeable, sharp sour note ("bite" or "tang") or for the mellower, some would say almost sweeter, notes which allow the wheat flavor of the crust to come forward more?

Wild yeast cultures can be tricky because you are not only dealing with trying to maintain a healthy balance between the wild yeasts (leavening portion) and the lactobacilli, but a culture is capable of producing both acetic acids (more sharp/sour in character) and lactic acids (more "mellow" in character).

There are a lot of tools to help get you to whatever flavor profile you are looking for:

1. Amount of levain/starter added to the formula
2. Maturity, or "age", of the starter when added to the formula
3. The hydration of the starter
4. Fermentation temperatures
5. Length of fermentation

I personally have found that both ambient (room) and cold fermentations can produce pleasing results.

That being said, I agree with Bill with regards to the 65° to 75° range. I typically use about 3.15% of Ischia starter and ferment between 68° and 72° for a total (bulk and proof) all-in time of 26 to 30 hours and I think the flavor of the Ischia really is in the pocket at that point.

As an aside, that length of fermentation at room temperature (26-30hrs) is not only a good range for me because of amount of levain added to the formula and temperatures, but because of the type of flour I use. The fermentation window between malted and unmalted flours can be very different --K
« Last Edit: May 19, 2011, 06:48:24 AM by pizzablogger »
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foolishpoolish

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Re: Ischia yeast culture
« Reply #8 on: May 19, 2011, 07:23:17 AM »
Quote from: kiwipete
Unlike "regular" yeast, a wild yeast like the Ischia culture has yeast and lactobacilli in a symbiotic relationship. But the growth rate of the lactobacilli and the yeast is different depending on temperature. Yeast will thrive at 28C-30C but will decrease its activity as temperatures go down. The lactobacilli continue to multiply better at lower temperatures
However, while at a cold enough temperature the yeast goes mostly dormant, the lactobacilli are still able to grow.

While all microbial activity drops as the temperature is lowered, the cooler temp actually tend to favour yeast growth (over Lb.). The corresponding enzymatic action of yeast liberates fructose which is co-metabolised by lactobacilli, producing acetic acid. Hence at lower temperatures you have a higher proportion of acetic acid being produced and thus often a perceived "sourer" result.
« Last Edit: May 19, 2011, 10:05:22 AM by foolishpoolish »

Offline Bill/SFNM

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Re: Ischia yeast culture
« Reply #9 on: May 19, 2011, 07:24:42 AM »

2. Maturity, or "age", of the starter when added to the formula


Perhaps we are talking about the same thing, but one of the biggest factors for the flavor contributed by Ischia is the frequency of feeding. Ischia that has been fed 1 -2 times per week produces a very different flavor than one that has been fed 1 per month. I will often double activate a starter if it has been a while since it has been used.


Offline theppgcowboy

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Re: Ischia yeast culture
« Reply #10 on: May 19, 2011, 08:42:39 AM »
Sounds like Ischia is going to be a fun science project.  Thanks guys.  Having had some success in the NY Side of dough, I should not think of from that perspective, it is a whole different animal.  This shall be fun.

Online TXCraig1

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Re: Ischia yeast culture
« Reply #11 on: May 19, 2011, 09:45:55 AM »
I use 0.75% - 1.00% fully active Ischia starter and generally ferment a total of ~26-30 hours at 77F (20-24 hours bulk and another 6-8 hours in balls).

I make my starter about the consistency of pancake batter. I don't see any need to measure the flour or water going into the starter or include them in the total dough calculations at this small of a percentage of the final dough.

I not a fan of cold fermentation - particularly with natural cultures. If things are progressing too fast, I'll put the balls into a big cooler with a half gallon juice bottle of ice and bring the temp down to ~65F, but never less than that.

Craig
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Offline pizzablogger

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Re: Ischia yeast culture
« Reply #12 on: May 19, 2011, 10:05:08 AM »
Perhaps we are talking about the same thing, but one of the biggest factors for the flavor contributed by Ischia is the frequency of feeding. Ischia that has been fed 1 -2 times per week produces a very different flavor than one that has been fed 1 per month. I will often double activate a starter if it has been a while since it has been used.

I agree with you 100%. I feed my Ischia (indeed any culture) at least once per week, regardless of whether I am baking or not.

I also rarely use the starter straight out of the fridge...meaning I never take it out, wait for it to wake up and then incorporate it into the formula. Typically take it out, wait for it to wake-up, rise and reach break (or as close to it as time allows) and then dump off and feed again. Once the second feeding has caused another rise and break, that is when I typically incorporate into the formula.

Probably a lot better ways to go about it, but while my pizzas are not always optimal for any number of reasons, I do not have any issues with fermentation or spring and have no need to supplement a small quantity of IDY or ADY to add a boost. --K
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Offline pizzablogger

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Re: Ischia yeast culture
« Reply #13 on: May 19, 2011, 10:06:42 AM »
While all microbial activity drops as the temperature is lowered, the cooler temp actually tend to favour yeast growth (over Lb.). The corresponding enzymatic action of yeast liberates fructose which is co-metabolised by lactobacilli, producing acetic acid. Hence at lower temperatures you have a higher proportion of acetic acid being produced and thus often a perceived "sourer" result.

That's an excellent point, as always Toby and well explained  :)

Cooler temps and/or lower hydrations = more acetic (generally)
Warmer temps and/or higher hydrations = more lactic (generally)
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Online TXCraig1

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Re: Ischia yeast culture
« Reply #14 on: May 19, 2011, 01:32:55 PM »
While all microbial activity drops as the temperature is lowered, the cooler temp actually tend to favour yeast growth (over Lb.). The corresponding enzymatic action of yeast liberates fructose which is co-metabolised by lactobacilli, producing acetic acid. Hence at lower temperatures you have a higher proportion of acetic acid being produced and thus often a perceived "sourer" result.

I don’t think this correct. In a typical sourdough, water causes amylase enzymes to break down the starch in the flour into sucrose and maltose. The lactic acid bacteria (LAB) predominantly feeds on the maltose (and often can't metabolize other sugars), and the strains of yeast often found in sourdough cultures can't metabolize the maltose, so there isn't any competition for food. Also, while consuming the maltose, the bacteria release an enzyme that breaks down maltose into glucose which gives a boost to the yeast.

The LAB primarily produce lactic acid. Acetic acid only represents about 20-30% of the total acids produced. Lactic acid has more sour smell, while acetic acid has more sour taste. Cooler temps and lower hydrations do favor acetic acid formation (rather than ethanol) as a result of a different metabolic pathway used at lower temperatures; this however does not mean that cooler temps result in a more sour dough. While cooler temps may produce a higher proportion of acetic acid, the total acid produced will be less. Warmer temps generally favor the LAB and result in more sour flavor. At cooler temps, activity differences are minimal.

CL
« Last Edit: May 19, 2011, 01:46:24 PM by TXCraig1 »
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foolishpoolish

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Re: Ischia yeast culture
« Reply #15 on: May 19, 2011, 01:52:11 PM »
I don’t think this correct. In a typical sourdough, water causes amylase enzymes to break down the starch in the flour into sucrose and maltose. The lactic acid bacteria (LAB) predominantly feeds on the maltose (and often can't metabolize other sugars), and the strains of yeast often found in sourdough cultures can't metabolize the maltose, so there isn't any competition for food. Also, while consuming the maltose, the bacteria release an enzyme that breaks down maltose into glucose which gives a boost to the yeast.

The LAB primarily produce lactic acid. Acetic acid only represents about 20-30% of the total acids produced. Lactic acid has more sour smell, while acetic acid has more sour taste. Cooler temps and lower hydrations do favor acetic acid formation (in lieu of ethanol) as a result of a different metabolic pathway used at lower temperatures; this however does not mean that cooler temps result in a more sour dough. While cooler temps may produce a higher proportion of acetic acid, the total acid produced will be less. Warmer temps generally favor the LAB and result in more sour flavor. At cooler temps, activity differences are minimal.

CL

Craig, that info is largely correct but does not describe the full picture. The characteristics of lactobacilli and yeast fermentation are only part of the equation. The other, equally important, part is that of available substrate which directly influences metabolic behaviour.

In my original reply, I was explaining that at cooler temperatures acetic acid is produced by lactobacilli in the co-metabolism of maltose and fructose (released as a result of amylolytic yeast enzymes). Since the overall activity is lower, there is less competition for co-substrates allowing the acetic acid production to be proportionally higher than at higher temps. At higher temperatures,  you will see more of the heterofermentative lactobacilli producing ethanol + lactic acid.

Please note that lactic acid will always be produced by the Lb regardless of temperature, homolactic fermentation or either of the heterofermentative pathway(s) which accounts for the difference in overall proportions of acid product.

Regarding smell and taste, you have the right assertion but the wrong order ;)
Acetic acid is a volatile acid and therefore responsible for that "sour smell" (and taste) whereas Lactic acid is non-volatile and therefore "sour taste" only. Esterification with ethanol can then result in additional aromas such as "creamy" or "milky" (as some have described).

Additional note:
Many Lb can and will metabolise glucose. It's not necessarily an "either/or" situation.
As you rightly point out:  some (commonly found in sourdough) yeast strains cannot metabolise maltose.
The unique relationship between Lb Sf and say...Candida Humilis* is that Lb Sf will metabolise maltose which is an isomer consisting essentially of two glucose molecules. It will use one of the glucose molecules for itself and leave one which can then be metabolised by the Candida.

*As I understand it, in the time since Ganzle's '98 paper, Candida Milleri has fallen out of use as a yeast classification.
« Last Edit: May 19, 2011, 02:41:11 PM by foolishpoolish »

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Re: Ischia yeast culture
« Reply #16 on: May 19, 2011, 02:59:28 PM »
Regarding smell and taste, you have the right assertion but the wrong order ;)
Acetic acid is a volatile acid and therefore responsible for that "sour smell" (and taste) whereas Lactic acid is non-volatile and therefore "sour taste" only. Esterification with ethanol can then result in additional aromas such as "creamy" or "milky" (as some have described).

I don’t think we disagree about much here. Perhaps a little on the issue of smell.

Clearly, you’re right that acetic acid is more volatile than lactic acid. So are a lot of other things. That doesn’t mean they smell more sour in the sense of sourdough. If you smell vinegar in your crust, I agree it is the acetic acid. However, I don't think vinegar is the smell generally associated with sourdough - rather the lactic acid smell.

Also, C. Milleri is still commonly used. It is however synonymous with C. humilis http://www.uniprot.org/taxonomy/51915 and http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?lvl=0&id=51915

CL
« Last Edit: May 19, 2011, 03:02:26 PM by TXCraig1 »
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Re: Ischia yeast culture
« Reply #17 on: May 19, 2011, 03:10:32 PM »
I don’t think we disagree about much here. Perhaps a little on the issue of smell.

Clearly, you’re right that acetic acid is more volatile than lactic acid. So are a lot of other things. That doesn’t mean they smell more sour in the sense of sourdough. If you smell vinegar in your crust, I agree it is the acetic acid. However, I don't think vinegar is the smell generally associated with sourdough - rather the lactic acid smell.

Also, C. Milleri is still commonly used. It is however synonymous with C. humilis http://www.uniprot.org/taxonomy/51915 and http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?lvl=0&id=51915

CL


Agreed. As I tried (badly) to explain in my reply to your post, there are a number of aromas that indirectly result from acid production which are not the acids themselves (eg aromatic esters). Ethyl lactate would be one of them. I guess you could call that "lactic acid smell" if you like.

I was not aware Candida Milleri was still commonly used in scientific literature. I had not seen it mentioned in most of the recent papers I have browsed.  Thanks for the update.
« Last Edit: May 19, 2011, 03:20:16 PM by foolishpoolish »

Offline ringkingpin

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Re: Ischia yeast culture
« Reply #18 on: May 19, 2011, 03:12:06 PM »
I agree with you 100%. I feed my Ischia (indeed any culture) at least once per week, regardless of whether I am baking or not.

I also rarely use the starter straight out of the fridge...meaning I never take it out, wait for it to wake up and then incorporate it into the formula. Typically take it out, wait for it to wake-up, rise and reach break (or as close to it as time allows) and then dump off and feed again. Once the second feeding has caused another rise and break, that is when I typically incorporate into the formula.


Funny, I ALWAYS pull my starter straight from the fridge, dump it in the mixer and I'm off to the races.  If I'm doing a cold ferment, I'll use cold water.  If I'm planning on using the dough soon, I'll use a very warm water.
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Re: Ischia yeast culture
« Reply #19 on: May 19, 2011, 05:28:46 PM »
...there are a number of aromas that indirectly result from acid production which are not the acids themselves (eg aromatic esters). Ethyl lactate would be one of them. I guess you could call that "lactic acid smell" if you like.

I think I just did.  :)

I enjoyed the discussion.

CL

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