Author Topic: What actually Causes Leapording?  (Read 3939 times)

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Offline f.montoya

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Re: What actually Causes Leapording?
« Reply #20 on: February 10, 2013, 08:34:20 AM »
<a href="http://www.youtube.com/watch?v=pwf8kwOvcS8" target="_blank" class="aeva_link bbc_link new_win">http://www.youtube.com/watch?v=pwf8kwOvcS8</a>


I agree that colder dough is a big part of it. In the above video, these were the last of 20 pies on a somewhat cold and snowy night. The earlier pies had good leoparding but the pies at the end looked identical to the picture on the front of my bag of Caputo 00 flour. Other factors may have helped. I did a 72 hour cold fermentation with very little yeast(3 grams per 6 pies), but those last 5 or 6 doughballs were definitely cold to the touch by the time I got to them.
« Last Edit: February 10, 2013, 10:45:24 AM by f.montoya »


Online TXCraig1

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Re: What actually Causes Leapording?
« Reply #21 on: February 10, 2013, 09:22:27 AM »
Beautiful pies in the video.
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Offline f.montoya

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Re: What actually Causes Leapording?
« Reply #22 on: February 10, 2013, 09:34:09 AM »
Beautiful pies in the video.

Thanks! I think the pizza gods were smiling on me that night! Hopefully I have similar results this weekend. I'll be doing 6 pies just for my family. :)

Offline sub

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Re: What actually Causes Leapording?
« Reply #23 on: February 10, 2013, 10:48:02 AM »
Hi,

With my little electric oven I can only achieve leoparding with hot air and stone (around 750°f) and the dough must be well fermented (dots on the balls, a good sign ? ) for a lot of them to appears.


Offline Serpentelli

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Re: What actually Causes Leapording?
« Reply #24 on: February 10, 2013, 04:39:42 PM »
From my own experience, extreme heat (over 800 degrees) and long, slow fermentation are the two key areas where you can almost guarantee leoparding. I do not know what the exact science is behind it though.

John

John,

In addition to the nice leoparding in that SWEET lookin pie on your avatar pic, what are the three colors (so nicely arranged)?

John
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Online scott123

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Re: What actually Causes Leapording?
« Reply #25 on: February 10, 2013, 04:54:36 PM »
I've been busy shoveling myself out this weekend, so I didn't get a chance to reply, but I wanted to throw my two cents into this discussion.

Leoparding is, as some people have alluded to, not that complicated.  At it's simplest, it's just uneven browning. It's flash baking providing the coloration with the most contrast. The intenser the heat, the more uneven the browning.  Move the heat source further away, baking slows down, more even golden browning is achieved.  Move the heat source closer, baking speeds up, less even browning/leoparding occurs.

A dough ball might look pretty homogenous on the outside, but moisture and air are not perfectly evenly distributed throughout it. The surface of dough will have some areas that are slightly drier than others.  When the heat is intense, these dry areas brown first, and then, because darker colors absorb heat more efficiently, browning is accelerated and these slightly brown areas will get very dark, very quickly. This is leoparding.  When the heat is less intense, moisture has a chance to flow through the surface of the dough and boil away much more evenly- everything dries out at a much slower/more even pace, and you get golden brown/lack of browning contrast.

Longer fermentation times are residual sugar generators and sugar accelerates browning. The more sugar you have, the faster browning occurs, the more likelihood of leoparding.  The only possible wild card in the leoparding equation is sourdough.  A starter might produce varying quantities of lactic and acetic acid. Acids are browning decelerators, although acetic acid is volatile, while lactic is relatively nonvolatile.  A starter won't necessarily impact leoparding, as seen by Craig's consistently leoparded pies, but, it might impact leoparding if an excess of acids are present.

Leoparding is not mentioned in the VPN/EU guidelines, but 60-90 second bakes are.  With a VPN dough (8 hour minimum fermentation) and an oven that can produce a 60-90 fully browned bake, leoparding will be a foregone conclusion, making leoparding a de facto part of the authentic Neapolitan pizza definition- assuming one adheres to the belief that 60-90 second bake times define authentic NP pizza, as I do.
« Last Edit: February 10, 2013, 04:56:12 PM by scott123 »

Offline f.montoya

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Re: What actually Causes Leapording?
« Reply #26 on: February 10, 2013, 08:38:52 PM »
I've been busy shoveling myself out this weekend, so I didn't get a chance to reply, but I wanted to throw my two cents into this discussion.

Leoparding is, as some people have alluded to, not that complicated.  At it's simplest, it's just uneven browning. It's flash baking providing the coloration with the most contrast. The intenser the heat, the more uneven the browning.  Move the heat source further away, baking slows down, more even golden browning is achieved.  Move the heat source closer, baking speeds up, less even browning/leoparding occurs.

A dough ball might look pretty homogenous on the outside, but moisture and air are not perfectly evenly distributed throughout it. The surface of dough will have some areas that are slightly drier than others.  When the heat is intense, these dry areas brown first, and then, because darker colors absorb heat more efficiently, browning is accelerated and these slightly brown areas will get very dark, very quickly. This is leoparding.  When the heat is less intense, moisture has a chance to flow through the surface of the dough and boil away much more evenly- everything dries out at a much slower/more even pace, and you get golden brown/lack of browning contrast.

Longer fermentation times are residual sugar generators and sugar accelerates browning. The more sugar you have, the faster browning occurs, the more likelihood of leoparding.  The only possible wild card in the leoparding equation is sourdough.  A starter might produce varying quantities of lactic and acetic acid. Acids are browning decelerators, although acetic acid is volatile, while lactic is relatively nonvolatile.  A starter won't necessarily impact leoparding, as seen by Craig's consistently leoparded pies, but, it might impact leoparding if an excess of acids are present.

Leoparding is not mentioned in the VPN/EU guidelines, but 60-90 second bakes are.  With a VPN dough (8 hour minimum fermentation) and an oven that can produce a 60-90 fully browned bake, leoparding will be a foregone conclusion, making leoparding a de facto part of the authentic Neapolitan pizza definition- assuming one adheres to the belief that 60-90 second bake times define authentic NP pizza, as I do.

This makes perfect sense. ^^

Question, Scott...Would the temperature of the dough at the time of the bake have any impact on the moisture/dryness of the dough's surface? More specifically, if we expose the doughballs to cold air for an hour or so before the bake, will it dry the surface of the doughballs and might this cause more even leoparding? The reason I say "even leoparding" is I see the finer spots distribute nicely on the edges on certain pies, as opposed to others that will develop larger black spots instead of the fine, evenly distributed ones, even though the dough is the same dough and the oven is the same temp. The only two things that could be different would be that the dough had cooled(I kept my doughballs in plastic containers outdoors in cold weather), and the coal bed was larger toward the end of the night in the WFO.

Online TXCraig1

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Re: What actually Causes Leapording?
« Reply #27 on: February 10, 2013, 09:22:37 PM »
I think there is definitely more going on than surface dryness. While “uneven browning” might be an accurate description of the visual appearance, I don’t think it adequately describes the phenomenon of leoparding. One can achieve uneven browning by any number of means that don’t constitute leoparding. Further, I think some of what we see described as leoparding might be more accurately described as “uneven browning,” and this is where I would be inclined to believe factors such as differential surface moisture play a role.

I’m not ruling out surface moisture as a contributing factor, but believe that leoparding likely has more to do with 1) the proper distribution of bubbles in the dough, 2) the strength of the dough and its ability to contain the gas in small bubbles near the surface long enough for a bubble to expand past the surface and char, and 3) sufficient heat to push out the bubble before the surface becomes too hard for it to happen.

My guess is that there is some critical size and location that causes certain bubbles to become leopard spots when certain other conditions are met. We know that fermentation time affects the crumb structure with rapid rise times often resulting in tighter crumbs. It would not surprise me if one of the reasons longer fermentation favors leoparding is because it produces the necessary bubble structure. After a longer fermentation (I don’t know what this time is exactly, but it’s more than a couple hours), bubbles of different sizes are fairly evenly distributed throughout the dough.  You can see this looking at the bottom of a dough ball in a clear plastic container. It can’t be that every bubble near the surface can become a spot, or the entire surface would erupt. Which particular bubbles become spots must be the result of multiple factors such as size, location, dough strength, and temperature such that only certain bubbles of a similar type become spots. My experience with my own pies and my recollection from pictures of other pies seem to support this - the spots are generally similar in size on a given pie. Pies with the micro spots don’t tend to also have a lot of large spots and vice versa.

I think the second factor is that the dough needs to be developed enough that there is sufficient strength to maintain the bubble past the surface of the dough.However, as dough continues to age, at some point it starts to weaken.  I think we tend to see the larger, more pronounced spots in some longer fermented dough because the dough surface weakens and it is easier for the bubbles to expand.  5Stagioni is a stronger flour than Caputo, and I can tell you in no uncertain terms it is more difficult to get larger spots out of it AOTBE. If the dough becomes too weak, I believe it also negatively impacts the texture of the crumb – perhaps this is the correlation that lead Marco to believe large spots is an indicator of a “defective” dough?

Lastly, I think you only get the spots with very high temperatures because you need to get these key bubbles expanding fast enough that they can push past the dough surface before the surface hardens to a point that they can no longer push out. I’m guessing that at temperatures below 750F or so, the surface of the dough hardens before enough pressure is generated inside the critical bubbles.

This is my theory anyway.
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Offline arspistorica

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Re: What actually Causes Leapording?
« Reply #28 on: November 21, 2013, 02:35:37 PM »
Been meaning to contribute my thoughts to this subject for some time, but wasn't sure there was an appropriate thread on which to post.  After reading everybody's thoughts on the matter, I think every comment on this thread has relevance to this unique phenomena, and I thought I'd chime in as well.  My comments will be limited to those changes that take place within dough systems (internal factors) versus those from external influences (such as air temperature or moisture content during baking, etc.).

Browning in dough-related products comes either from direct caramelisation of residual sugars or from non-enzymatic Maillard reactions produced under thermal degradation, as Omid has rightly pointed out.  Even more astutely, scott123 writes leoparding is, "[a]t it's simplest . . . just uneven browning.  Longer fermentation times are residual sugar generators and sugar accelerates browning. The more sugar you have, the faster browning occurs, the more likelihood of leoparding."

To add further to the above, longer fermentation times, although an indirect agent of leoparding, are not the direct cause, and not because they generate residual sugars, per se, as yeast can easily remove 95% of glucides in a dough system, which are among the most prevalent reducing sugars for pyrolytic-based browning (caramelisation), along with maltose (which is also substantially removed from doughs during elongated fermentations).  This removal of the most prevalent sugars in a dough leads to a nice pale canvas on which the leopard spots can appear.

The uneven browning scott123 refers to has to do with selected increased browning, due to abundant amino acids left in a dough system; hence, the selected unevenness of the browning.  Longer fermentations increase Maillard reactions because they lead to a larger window for wheat's native proteases to release abundant amino acids.  A similar effect could be achieved through prolonged autolysis (10 - 16 hours) and without the need for longer fermentations, though there may be more residual reducing sugars that contribute to the overall browning of the dough if the inoculant is not increased.  This is not to say reducing sugars do not play a role, as the  sugars resultant from longer fermentations and/or of doughs with a high amount of prefermented flour lead to the characteristic dark spots as well.  In fact, many of these sugars (like arabinose, ribose or xylose) generate darker spots than do glucose or maltose when combined with amino acids, although they occur in much smaller amounts.

The second major component has to do with the dehydration of a dough ball's exterior, alluded to by f.montoya.   bakeshack writes, "A cold fermented dough baked in a very hot WFO will form blistering much easier although they tend to be larger blisters compared to the micro blistering you get from RT fermentation," going on to say it "is very similar to the surface blistering you get from a retarded Tartine loaf . . . During baking, this allows the CO2 gasses to escape up to the surface of the crust and form blisters."  Though, he incorrectly states the reason these blisters form ("gluten degradation"), TXCraig1 hits the nail on the head:  "I think the second factor is that the dough needs to be developed enough that there is sufficient strength to maintain the bubble past the surface of the dough."

This "sufficient strength" is the result of long fermentations especially when the dough proofs in its final shape, thus allowing for increased surface exposure and a higher degree of moisture loss to the outside environment (especially pronounced under refrigerated conditions).  The reason the Tartine (or any long-proved loaves) have blisters is the same reason they have significantly thicker crusts than similar loaves with shorter proofing times:  lower water-activity on the surface of the dough at the time of baking.  Outwardly migrating moisture is hence trapped by the dough's having developed a thicker skin, with the characteristic blisters forming, protruding like goosebumps that, in a very hot environment, will selectively brown more than an even, lower surface.

In short, less reducing sugars (general dough caramelisation), more amino acids (Maillard browning) and a thicker dough skin (greater rate of blisters formed) are the primary reasons for leoparding from a dough's perspective.
« Last Edit: November 21, 2013, 04:29:21 PM by arspistorica »
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Offline TonyK

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Re: What actually Causes Leapording?
« Reply #29 on: November 21, 2013, 06:31:38 PM »
@sub,

Those spots  are usually minerals that have darkened during maturation of the dough. It's normal. I'm not sure about the leoparding though, it's kind of an American fetish and not something paid much attention to in Naples - those fellas are primarily going for a golden colour. My thought was that it's more obvious when the dough has been allowed to acidify for longer periods. You can always tell because the dough gets a pale as opposed to golden hue when baked, this usually goes hand in hand with prominent leoparding - so I assumed it was related.


Offline PizzaDiFiore

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Re: What actually Causes Leapording?
« Reply #30 on: December 09, 2013, 12:36:51 PM »
I was going to say sugars in a Maillard reaction!

Offline Tscarborough

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Re: What actually Causes Leapording?
« Reply #31 on: December 10, 2013, 11:34:08 AM »
What causes leoparding is clear:  Tiny bubbles extend beyond the surface of the crust and the thinner skin on the bubbles bakes faster than the surrounding area.

The question is what causes those bubbles to form in the right size and placement to create leoparding.

The advantage is clear to me (other than it looks cool):  It provides small amounts of char distributed across the crust. Goldy-locks style, not too little, not too much.