Zero waste banana bread, aka Sourdough Banana Bread

If you ask my dad, apparently I can get a little obsessive about avoiding food waste, admonishing him every single time he makes ice cream (which is quite often) and, yet again, let’s perfectly good egg whites go to waste. In his defence, egg white omelettes as a solution are out of the question taste-wise and most recipes needing egg whites only need a small number, unless you are serving giants (cases in point: marshmallows, meringues, torrone etc.). But what about financiers, I hear you ask? You are of course correct, and that is always my killer argument. Alas, my timing is never quite on point and typically, by the time I remember that all those beautiful whites left over from making the custard base for the ice cream could so easily be transformed into these rich and buttery little French cakes, it is usually too late anyway.

You only need to take one look at the stamps in my passport to know I am far from being any kind of eco warrior. The reason I care about food waste is that I see it as a wasted opportunity for creating something new (and hopefully delicious), with just a little bit of creativity and flexibility. Plus, I get a real kick out of knowing that something tasty was created from ingredients that might otherwise have gone to waste.

I like knowing that the apple peels from making your apple tarte can be turned into a delicious apple-flavoured glaze with some water and sugar, giving your tarte a beautiful shine; or that the whey left over from making labneh can be used instead of water to make beautiful flatbreads, or that the pineapple core and peel (together with water, sugar and some spices) can be transformed into Tepache, a wonderful Mexican fermented drink.

Why zero waste banana bread? Well, this wasn’t some ill-conceived pun about none of this tasty banana bread going to waste. Rather, it’s the fact, that this is a recipe that not only will make use of any bananas past their prime, but will also use up your sourdough discard should you, like so many of us, have jumped on the sourdough bandwagon thanks to Covid-19. And, in case you have any whey leftover from making labneh for this Tiramisu, you can also add the whey to the banana bread batter (and fret not in case you are out of whey, buttermilk or yoghurt will work equally well). And, if you are anything like me, it will also use up all those nuts left over from Christmas that never got shelled because you don’t even own a nutcracker (and, as it turns out, a pestle and mortar isn’t the best substitute for a nutcracker). 

Zero Waste Banana Bread

Note: This is a riff on a recipe in Tartine No 3 for Banana Tea Cake. In adapting the recipe, I ended up changing the original recipe quite a lot. Gone are the dates, and the cinnamon, and the molasses, and also the same day poolish (if I want to bake banana bread I don’t want to have to travel back in time to remind my late night or early morning self to mix ingredients for a poolish!). And because the banana bread was such a hit with everyone (well, thanks to Covid-19, in this case ‘everyone’ was a grand total of 4 individuals – myself, my boyfriend, plus my friends Miki and Gijs who I shared a couple of slices with in a social distancing appropriate way), I also wanted to share the recipe here. Not just because it is quite possibly one of the most delicious banana breads I have ever made, but also because it is one of the best wholegrain flour recipes I can think of and, as a total fringe benefit, also uses up a handful of ingredients that might otherwise go to waste. One short note on the recipe itself – if you think the 3/4 tsp of salt is a typo, it is not, it is a lot of salt for a cake recipe but it really rounds out the flavour of the banana bread.


300g bananas (ca. 2.5 medium-sized bananas – any leftovers can be peeled, frozen and kept for your next banana bread)
100g sourdough discard
120ml whey (alternatively you can use buttermilk or yoghurt)
120g melted butter
3 eggs
200g sugar
100g all purpose wheat flour
100g wholegrain wheat flour
3 tsp baking powder
1 1/3 tsp baking soda
3/4 tsp salt
120g walnuts and/or pecans


Pre-heat the oven to 180 degrees Celsius and grease a loaf tin and line with parchment paper.

In a bowl mash the bananas. I like to mash them until they are almost puree like (if you prefer your banana bread chunkier, then stop sooner). Whisk in your sourdough discard, whey, melted butter and eggs. 

In a separate bowl combine the sugar, the two flours, baking powder and baking soda as well as the salt. Stir into the wet ingredients. Once the batter seems well amalgamated, fold in the nuts.

Pour the batter into the prepared loaf tin and place in the oven. Bake for ca. 75 minutes or until a wooden skewer inserted into the centre of the cake comes out clean.

Leave to cool for 5-10 minutes before carefully removing the cake and placing it on a cooling rack to cool completely. 



8 thoughts on “Zero waste banana bread, aka Sourdough Banana Bread

  1. This was perfect timing, as I’ve been nursing a sourdough and really don’t like discarding anything. I know sourdough pancakes are good to make with the discard, but this sounds amazing. And the recipe sounds Australian, or British.


  2. Wouldn’t it be worth letting the sourdough ferment with the flour and perhaps the whey for a bit before making the loaf? It’s good not to waste the starter but a bit of natural lift from it fermenting for a bit seems worthwhile as well?


    • Hi Richard. Yes, you could of course rely on the sourdough discard as a leavening agent for the banana bread itself (rather than using the baking powder and baking soda to do that). But I like this recipe in that it comes together very quickly (no needing to wait for anything to ferment) and at the same time uses up things that would otherwise go to waste. But I may start playing around with fermented quick breads (or not so quick breads in that case) – there is a bakery in London (Fortitude Bakehouse if I recall correctly) that does these kinds of fermented quick breads and I have always found that intriguing. As for the natural lift, this banana bread is actually really nice and light with quite an open crumb, despite the high wholegrain flour content.


      • Hi Sophia, that’s great and makes complete sense, thank you for the reply. I live not far from London and I’ve not come across Fortitude Bakehouse before so thanks also for the name. I’ll head there next time I’m (allowed!) in London.


  3. Dear Chef Sophia, may i know whether it is possible to substitute this Sourdough Banana bread recipe either with apple or pineapple to utilise the discard starter ? Your kind attention n advice is highly appreciated. Yours faitfully, Rena at


    • Hi Tabg, you could substitute the sourdough starter with yoghurt I reckon (although I haven’t tried this myself). Beyond that, you would have to see, using watery fruit like apples and pineapple could make the batter too wet for it to have the right consistency so you might also have to adjust the amount of flour. Hope that helps!


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