On Scalds and Scalding

Rye flour and red rye malt scald for Moscow Rye
Rye flour and red rye malt scald for Moscow Rye

Not long ago I was surprised and pleased to find myself, my new book (The Rye Baker) and this blog mentioned in a Washington Post food article titled “Why are some rye breads scalded?” By way of defining a scald, the author posted a link to the British blog Virtuous Bread that describes the how-tos of scalding and concludes – rightly so – that the technique produces a “gorgeous bread” with a crumb that’s “soft and chewy as if there was a lot of fat in it.”

From my point of view, the article was a very good start, but only part of a more complex and nuanced story.

As a physical process, scalding is nothing more than soaking milled grain in near-boiling water and letting it stand for a period of time in either a heated or unheated environment. Time and temperature bring about a series of physical and chemical changes that depend on whether the flour is refined or wholegrain and which influence the taste and/or texture of the finished loaf.

Scalding milled whole grains – the method I use most frequently – influences the chemistry of dough fermentation and the flavor profile of my breads. In a nutshell, three elements influence dough chemistry: the amylase enzymes that convert starches to sugars, the yeast that convert those sugars into alcohol and CO2 and the lactobacilli (LAB) that convert sugars into the lactic and acetic acids that give sourdough breads their characteristic tang.

Each of those three elements has a different temperature/activity curve. Yeast is most active at around 82°F/28°C and LAB at about 90°F/32°C. Both yeast and LAB are living organisms that can’t survive at temperatures above 140°F/60°C. Amylase enzyme activity, on the other hand, peaks in the range of 140-170°F/60-77°C and grinds to a halt above 175°F/80°C. Many of the scalded breads I bake call for keeping the scald at a “sweet spot” of 160°F/70°C for anywhere from three to 18 hours; others allow the scald to return gradually to room temperature.

What this means in practical terms is that scalding milled whole grain, which is rich in natural amylase, effectively kills both the yeast and LAB present in the grain and creates an ideal environment for the conversion of starches to sugars. The sugar-rich scald both provides a nutritional boost to both the yeast and LAB that ferment the final dough and also produce the subtle play of sweet and sour typical of Russian and Baltic rye breads.

I’ve already written about several rye breads that use scalds to control enzyme and fermentation activity, specifically Deconstructed Saison Rye, Black Rye Bread and Moscow Rye, and over time will almost certainly post lots more.

The second type of scald the one that Virtuous Bread describes – is tangzhong (湯種) — which translates as “boiled roux” — a Chinese technique for scalding refined flours that has become common throughout Asia, most notably as a major component  of Hokkaido Milk Bread, and is now being widely adopted by Western bakers.

Simply stated, making a tangzhong entails combining about a third of a bread’s total flour with five times its weight in liquid, typically water or milk, and heating the mixture to a temperature of 150°F/65°C. The tangzhong is then allowed to cool to room temperature before being incorporated into the final dough. Note that even though the hydration of a tangzhong dough using the above proportions is about 160%, the flour absorbs a large amount of the liquid — far more, in fact, than it would absorb in a standard, non-scalded dough.

Tangzhong is less a chemical than a physical process. Heating the dough-water slurry pre-cooks the starches in the flour, transforming them into a wet gel. It also hardens the proteins, making them incapable of forming the gluten that gives bread both its structure and chewiness. With increased moisture and diminished gluten-forming capacity, doughs made with tangzhong bake into the tender, close-crumbed, almost cake-like loaves of Hokkaido Milk Bread that line the bakery shelves of the Asian markets that have proliferated throughout Southern California (where I live) and elsewhere.

That said, scalding is a highly flexible technique that I think more bakers ought to explore and incorporate into their breads. The combination of milled grain and hot water enhances the ability to control the fermentation behavior of my doughs and widens the range of flavors and textures I can coax out of my finished loaves.


21 Comments

  • Yael Levi

    June 23, 2016

    Stanley –
    Thank you for your clear & concise explanation. It definitely makes it less daunting for me to now venture into the realm of scalding.

    Reply
    • Henrik

      June 26, 2016

      Being from southern Swedish, I’ve been using scalds for many years, but almost always by simply mixing in boiling water into sifted or wholemeal rye flour. From your explanation, this means the yeast and bacteria are (all?) killed and amylase gets to work producing sugars. But, am I right to assume that this enzymatic activity only continues for as long as the scalded mixture is at 60-70ºC or does it go on regardless, but just at a slower rate? If wanting a sweeter loaf with this method, should I try to keep the scalded mixture at the optimum temps for longer, say 5-6 hours or even longer? Is the method equivalent to what Peter Reinhart calls a mash?
      Thanks again for a great post!

      Reply
      • Stanley Ginsberg

        June 27, 2016

        The enzyme activity will continue, as you note, but more slowly. When I want to accelerate the process, I keep my scalds covered in an oven set at 160F/70C for 5-12 hours. I’ve also found that the combination of rye flour and red rye malt produces a sweet and fragrant scald that reminds me of fresh apples.

        Reply
        • Stuart Borken

          March 22, 2017

          Doesn’t the use of diastatic malt powder also produce more sugar for the yeast to work on by digesting starch into usable sugar for the yeast?

          Reply
          • Stanley Ginsberg

            March 23, 2017

            Yes it does. Scalding has the added benefit of killing the microorganisms that consume those sugars.

  • Henrik

    June 27, 2016

    Unfortunately, my wood fired oven never goes below 100C because we bake in it twice a week and our domestic oven can’t be set to less than 100C. But maybe it doesn’t matter if we keep the scald at 40-50C for 24 hrs or longer. I’ve been wanting to try red rye malt for a long time, but we can’t get it where we live (NE Vic, Australia) and information is hard to find, so I’ve used malted brewers’ rye and toasted it as follows: 100C for an hour and then 170C for an additional half hour. The rye comes out reddish once ground and smells a little like roasted coffee or heavily toasted rye bread. Is that close or have I over-cooked it, or is there another method? Also, how much red rye malt should one use or what’s the typical range to use in a loaf? I’ve tried 1% (bakers %) and it does affect flavour, but it’s very subtle.

    Reply
    • Stanley Ginsberg

      June 28, 2016

      You might consider setting the scald in the oven doorway and leaving the door half-closed or fully open, making sure to monitor the temperature until you’ve figured out the right approach. As for the red rye malt, I do something similar: I roast brewer’s rye malt at 200C for about 20 minutes, until it’s fragrant and takes on a dark brick-red color. As for percentages, I’ve seen formulas with up to 5% of total flour. As a general rule, though, I think 1-2% is more than adequate.

      Reply
  • Henrik

    June 28, 2016

    Excellent suggestions. Thank you! I have to say that you’re blog is wonderful and being a rye fan, the information you provide is of great value (looking forward to your book). Here in Australia, I suspect rye bread is even less appreciated than in the US. My rye loaves are always the last to sell, if at all. People that come up to me at markets, almost always say they don’t like rye bread or that their children will find it too strong or dense, yet as soon as they try a piece, the response is generally “Oh! That’s yummy. Not at all what I expected.” That’s rye bread!

    Reply
    • Phil

      March 27, 2017

      I’m sure there are good ones in Stan’s book, but I’d also recommend in Hamelman’s Bread the recipe for 5 grain sourdough rye. It has only 25% rye, all prefermented 14-16 hours (“rye sourdough”), a scald of mixed grains (he uses cracked rye, rolled oats, flax, and sunflower seeds, but you modify of course). The beauty of Hamelman’s rye sourdough preferment breads is the short bulk and final rise times (90/75 minutes respectively, without folds). The effect is a mild tang and a soft, moist crumb, with a ton of nutrition for a 75% AP bread.

      Reply
  • Marty

    July 1, 2016

    Is scalding desirable when using flour from sprouted grain? What would be the benefit?

    Reply
    • Stanley Ginsberg

      July 5, 2016

      Sprouted grain is essentially malted grain that hasn’t been dried and malt is very common in rye scalds. The immediate benefit would be twofold: first, the sprouted grain is rich in active amylase enzymes, which play a critical role in germination, and second, the grain itself (or the flour) would already be rich in sugars, especially maltose, which is a favored nutrient for lactobacillus, which sours the dough.

      Reply
  • Henrik

    July 5, 2016

    Maybe this question should be asked under another topic, but your point about maltose and lactobacillus raises an important question for me: how do you ‘best’ or most effectively control the sourness of rye loaves? I’ve tried varying the hydration (100% – 200%) and age of the leaven (12-48 hours at 15C), but I just don’t get consistent results. For example, I made your Crusty Country Austrian rye a couple of days ago and it came out looking and tasting great, but as to sourness, there was barely a hint. Any thoughts?

    Reply
    • Stanley Ginsberg

      July 8, 2016

      There are a bunch of factors that affect the acidity of a dough, but the most important are time and temperature. Lactobacillus reaches its peak activity level at about 95F/35C while yeast activity peaks at 81F/27C. Keeping your sponge near that 95F level will promote acid production, and the longer the sponge ferments, the greater its acidity.

      Reply
  • Henrik

    July 26, 2016

    I tried an 18 hr scald yesterday (100% rye, 200% water, 1% each of red and white rye malt, 65 deg C) and this morning the scald was somewhat frothy and smelling a little funky. It also had a very thin slimy layer on top, probably a yeast I think. Other than smelling a little strange, is the scald dangerous or bad to use?

    Reply
    • Stanley Ginsberg

      July 29, 2016

      I think you probably ended up with some fermentation activity, which is surprising, considering the length of the scald and the hold temperature of 65C. I don’t know that I’d scald anything for that long; generally a 3-8 hour scald is more than sufficient to release the sugars in the rye. As for using it, I’d err on the side of caution and discard it.

      Reply
  • Ivan

    January 23, 2017

    Sorry for the late comment, but I was wondering if there is a specific difference between a scald and a mash (as described in Peter Reinhart’s Whole Grain Bread; I think you list it on the book resources in The Rye Baker): keeping the mixture at 66C for a few hours (shorter than a traditional scald). Is a mash just a more controlled type of scald? Would it yield any advantage over a scald? If so, how would you adapt a traditional rye scald to a mash?

    Reply
    • Stanley Ginsberg

      January 24, 2017

      Peter Reinhart’s mash is closer to the type of compound sponge I refer to as an opara, which is the Russian word for “yeasted scald.” In his description of mashing, Peter makes clear that the process involves adding a yeast medium, whether it’s commercial or sourdough, to the enzyme-active or -inactive gelatinized starches that the scalding process produces.

      As far as scald duration is concerned, it can vary, depending on the specific bread and its region. I’ve seen scalds as short as a few hours and as long as 12-15 hours.

      Reply
  • Margaret

    September 25, 2017

    What is in a sponge, does it have the yeast, if so will taking it up to 95 f kill the yeast?

    Margaret

    Reply
    • Stanley Ginsberg

      September 25, 2017

      All sponges consist of flour, water and yeast. Since yeast activity peaks around 80F and comes to a near standstill at around 95F (see the chart on p. 33 of The Rye Baker), I wouldn’t take my sponge much above 85F, if I’m interested in maximizing yeast activity. If you want a more acidic sponge, then by all means ferment it at 95F; just remember to add commercial yeast to your final dough to ensure an adequate rise.

      Reply
      • Margaret

        September 27, 2017

        After the ferment could I add more sourdough instead of commercial yeast and get the same results?

        Reply

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