Eternal bread
This is part of our series on upcycling bread and its by-products.
Table of Contents
i. Meals with mythos
Certain recipes have a special mystique about them.
The mole madre, a signature recipe of chef Enrique Olvera at Pujol in Mexico City, is a new take on a traditional mole negro—the famously rich and complex Mexican sauce of herbs, spices, chillies, nuts, chocolate and aromatics. The difference with Olvera’s is that the same original batch is used and reheated every day. As it is depleted, new ingredients that meld together into a celebration of Mesoamerican agrobiodiversity are added; exactly what depends on the season. That original matriarch is now over 10 years old, and she has evolved countless times during her lifetime.
Similar ideas—perpetual stews, master stocks and the like—exist around the world, sometimes simmering away for decades.
Some of our partners in fermentation, like sourdough starters and kombucha SCOBYs, are imbued with similar mythos. Handed down perhaps from a beloved friend, a previous generation of your family, or a benevolent stranger from a local Facebook group, these starters (and the microbial communities within them) evolve over weeks and months and years.¹ Every bread made with the same sourdough starter has some sort of connection, however small, to that same lineage.
What if you could take that idea one step further?
ii. What is you could turn stale old bread back into fresh bread?
What if a restaurant or a bakery made sourdough bread, saved any leftovers that had gone stale, and then incorporated those leftovers into tomorrow's bread? What if they did that again the next day? And again, every day, in perpetuity? Years later, you could be eating bread that contains a little of the essence of every one of those days, a rich edible history of the establishment imbued with a kind of micro-terroir.²
Below, we present a recipe for sourdough bread that uses stale bread soaked in water as a partial substitute for flour and water—reducing wasted bread and flour usage at the same time. In Scotland and Ireland (and no doubt other places) there is a long tradition of making ‘porridge bread’ by using yesterday’s leftover soaked grains (typically oats) as a partial substitute for flour and water.³ At first we thought we’d discovered something new by adapting that porridge bread recipe to use stale bread soaked in water, rather than oats.
We later found out that this isn’t anything we’ve invented at all, and people far more resourceful than ourselves had been practising this for centuries! No wonder, given how much sense it makes to do so, in hindsight. The practice of adding scraps of stale bread to make new bread is centuries old in Germany and Denmark and possibly elsewhere, though it is no longer widely practised today.⁴
We’re puzzled why these two related, likely ancient, and at some point widespread ideas aren’t more common practice. Perhaps it’s part of the larger story of the loss of traditional knowledge still relevant and useful today, and symptomatic of the contemporary culture of consumption and wastefulness. If the resulting bread were some hair-shirted attempt to turn old bread into something virtuous but less palatable, we could understand it. But we’ve achieved delicious results that, in the best possible way, are virtually indistinguishable from a good sourdough loaf made ‘only’ with new flour. The following recipe we arrived at we simply find downright delicious. The glimpse of eternity it offers only adds to the magic.
iii. Recipe
Duration: 2 days. Makes one loaf.
We present this as a base recipe, rather than a perfected iteration, substituting 20% of the flour (and 40% of the water) in a standard sourdough recipe with bread porridge.
Ingredients
(A) Levain
35g Flour
35g Water
35g Sourdough starter
(B) Bread ‘porridge’
125g Stale bread
125g Hot water
(C) Dough
500g Bread flour
375g Bread porridge (B)
375g Water
75g Levain (A)
12.5g Salt
Method
Day 1
Make a levain (A) by combining all ingredients (flour, water, starter). Leave at 30℃ for 1 hour.⁵
Make breadcrumbs from stale bread, then make a bread ‘porridge’ (B) by combining the breadcrumbs with hot water in a pot and mixing. The breadcrumbs don’t have to be ultra-fine, but the finer they are, the less water you’ll need to turn this mixture into a thick porridge.
Combine the flour, water and levain and mix well into a rough dough. Cover and leave for 1 hour at 30℃. Transfer this mixture into a bread mixer bowl, combine with the ‘bread porridge’ (B) and salt, then mix with a dough hook for 5 minutes, or by hand as long as needed, until a smooth well-incorporated dough forms.
Transfer the dough to a wide plastic container, with room for it to expand vertically. Let it sit for 1 hour in a container at 30°C. Then stretch and fold the dough, before refrigerating.⁶ Remove from the fridge and repeat this 2-3 times every half hour, returning to the fridge each time in between folds, before refrigerating overnight.
Day 2
Remove the dough from the fridge. Pour it onto a floured surface, and form it by placing it into a floured rising basket or oiled bowl. Leave to rest for an hour at 30°C.
Tip each onto a tray lined with baking paper.
Bake the bread. We used a commercial oven (Rational Self-Cooking Centre), baking the bread for 30 minutes using the pre-set bread program, with humidity set to maximum. If doing this at home, we suggest that you bake according to your preferred recipe’s method.⁷
Remove from the oven and allow to cool before slicing.
Learning from failure
In our first attempt with this recipe, we ripped the bread into large chunks by hand, including some very hard crusts, rather than grinding them into breadcrumbs. To compensate for this obvious-in-hindsight mistake, we added lots of additional water (400ml extra, for a total of 900ml water) to the ‘porridge’ but didn’t adjust the water otherwise, which ultimately resulted in a very overhydrated end product. Whilst it was far from unpleasant (almost like an oil-free focaccia in texture), it didn’t develop a satisfactory crust and wasn’t quite the loaf we were looking for. As such, we’d strongly recommend not exceeding the overall amount of water recommended given in the recipe. If the porridge looks dry, don’t worry, it’ll combine with a good kneading, especially if using a mixer with dough hook to combine.
iv. Further experimentation
Like all bread recipes, this should be taken as a guide for navigating the specificities of one’s own ingredients, and we would encourage you to try to adapt your go-to sourdough bread recipe based on the one we shared here. We used a low-maintenance method, but you might decide to leave the levain to rise for longer, autolyse the dough before adding the starter, let the dough rest for longer at various stages, or stretch and fold it more. You could also use not completely dry bread if desired, but you would need to adjust the water.
This 20% substitution of flour with breadcrumbs is much higher than other similar published recipes we’ve seen, which tend to be about 10%. Ever keen to experiment, we tried different ratios but found that 20-25% was the sweet spot, as anything higher didn’t reliably rise, resulting in inedibly dense bread.
Some variables we think would be worth exploring further:
What is the ‘optimal’ percentage of old bread to new flour? How does changing that percentage affect the end product and how might that vary between different bread styles and flour types?
How would different combinations of stale bread and ‘fresh’ flour contribute to the flavour profile of the bread?
How fermentable is the old bread? How does its presence affect the microbial ecology compared to using only flour?
How would years of daily usage of the previous day's bread change the (next) end product, iteratively and cumulatively?
What about different porridge breads? What if you made porridge bread with leftover congee, grits, polenta or ugali? How could they impact the microbial ecology, flavour, or nutritional profile of sourdough bread? How might the base recipe need to be adapted to include more diverse grain porridges? The possible combinations are tantalising.
We’d love to hear from you if you make any headway on these or other eternal-bread-related questions.
Contributions & acknowledgements
Kim and Eliot developed the bread recipe. Eliot wrote the article in discussion with Kim, and Josh provided contributions and editorial feedback.
Thanks to the team from the Rob Dunn Lab at North Carolina State University for thoughtful discussion surrounding this topic.
Eliot photographed the bread in our food lab.
Related posts
Endnotes
[1] The actual extent to which the age of a well cared for sourdough starter influences the characteristics of the bread it is used to make remains an open question. Whether a decades old starter makes ‘better’ bread than a month old one hasn’t really been settled in the literature, especially as flavour is very personal and cultural and ‘better’ in this sense is hard to measure. Some interesting recent research investigating these types of questions includes the Global Sourdough study led by the team at Rob Dunn’s lab which included starters up to 100 years old, with publications contributing to the discourse including: Elizabeth Landis et al. (2021), ‘The diversity and function of sourdough starter microbiomes’, eLife; Martha Calvert et al. (2021), ‘A review of sourdough starters: ecology, practices, and sensory quality with applications for baking and recommendations for future research’, PeerJ; Erin McKenney et al. (2023), ‘Sourdough starters exhibit similar succession patterns but develop flour-specific climax communities’, PeerJ.
[2] Much like a several-year-old sourdough starter will contain little—if any—of that original blend of flour, water and microbes (some variant on the ‘Ship of Theseus’ or ‘Trigger’s Broom’ thought experiments), but will nonetheless gain a particular identity through the continuity of that cumulative evolution.
[3] We can’t help but marvel at all the possible types of porridge bread, since porridges of one form or another are almost as widespread a human food as bread is. Indeed a kind of porridge was probably the prototype from which both bread and beer eventually were elaborated. Robert Braidwood et al. (1953), ‘Did Man Once Live by Beer Alone?’, American Anthropologist.
[4] We stumbled upon Jeffrey Hamelman’s writing in ‘Bread: A Baker’s Book of Techniques and Recipes’ and his recipes that use an ‘old bread soaker’, via a 2010 article by Susan Tenney of the Wild Yeast Blog. We also recommend these articles by Rezka El Baz, who has developed recipes for both porridge bread and (as they call it) recycled bread.
[5] We used an old plate warmer wherever we call for resting 30℃. You can also use a fermentation chamber, or simply leave it by a radiator, or even just at room temperature for a bit longer, and achieve perfectly fine results.
[6] See The Perfect Loaf’s guide here.
[7] See The Perfect Loaf’s base recipe here.