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A sequel of sorts to my slightly long-winded look at the science of sourdough, boiling it all down to a few practical pointers for creating, maintaining and baking with your sourdough starter at home. Does the Internet really need another one of these? Possibly not. Also, the idea was to keep this short and sweet. Oops…

PART ONE: Create your starter

  1. Mix together flour and water. Any flour is suitable, but the higher the ash content the better, so you’re best off with rye, followed by wholewheat, and then whites such as strong bread flours. Place in a covered container – you want it to breathe, but don’t want flies and the like getting in. A ‘Le Parfait’ jar is perfect.
  2. Find somewhere warm – you want an ambient temperature of 25-30 degrees centigrade. This may be in a low oven (or with only the pilot light on), in an airing cupboard, or – if you’re a real fancypants –   in (or on the lid of) a temperature controlled water bath.
  3. Leave it for a couple of days in your chosen warm environment, giving it a stir occasionally to aerate. It should start to bubble slightly. It’s alive!
  4. Feed the starter every day – add equal quantities of flour and water (around 50g each should be fine) per day. Again rye or wholewheat are best. Aerate each time. If possible, split the feed into 2 or 3 feeds per day. Once per day, discard most of the mix before you replenish it. This gets rid of the exhausted flour and encourages quicker yeast growth.
  5. After around 7 days you should have a fairly sweet and mildly sour smelling, nicely bubbling starter. There is, however, always an element of unpredictability when creating a sourdough starter. If it hasn’t worked (see PART TWO first), then throw it away, sterilise your storage jar and try again.

NOTE: Creating your very own starter can be fun, but for guaranteed results and a better chance of longer term starter stability you’re better off nabbing a healthy bit of sourdough from elsewhere – a baker, a friend or the Internet. All it takes is a spoonful or even a piece of starter that’s been frozen or dried out, added at step one above to get things going in the right direction.

PART TWO: Dealing with a faulty sourdough starter

  1. So your sourdough has gone belly up or your attempt at creating a starter from scratch doesn’t seem to have worked? Don’t throw it away just yet. First, sniff it and look at its colour. If it smells awful or there’s yellow, green, or obvious signs of mould then chuck it, otherwise…
  2.  If it looks muddy then that just means it’s separated and that it probably needs a good feed. Check your storage temperature (lower is better for yeast), make sure you feed the little guy three times a day for a while, and try adjusting the flour to water ratio to form a wetter starter for a while.
  3. If your starter smells too vinegary, then either make it wetter, try raising the storage temp (but not beyond 35 degrees C) or do both. Feed and see how it is after another 3 or 4 days.
  4. If your starter smells like nail varnish remover, then lower the storage temperature and, again, feed for a few days more.
  5. Your starter is yeasty but doesn’t seem particularly sour? Time to raise the storage temp a little. Also consider making the starter a little more fluid for a few days.

PART THREE: Long-term sourdough care

  1. If you’re going to make bread every 4-7 days then keep your sourdough in that warm storage spot. Try to feed it three times a day for 2-3 days before each use, otherwise once a day should keep it happy. Remember to check the smell and adjust the heat and fluidity as required (see PART TWO).
  2. If you don’t need the starter for a while then you can put it in the fridge. Yeast and lactic acid bacteria activity will slow right down and eventually halt. When you need to use it again, bring it back out a few days in advance, and either stir all the gunk back together or discard the dirty liquid at the top. Go back into intense 3 times a day feeding mode just to get it nice and bubbly/sour again.
  3. For ultra long storage you can try freezing or dehydrating your starter. All you need is a couple of spoonfuls. To dehydrate it, simply spread it thin onto a plate and place in the fridge for a few days until dry. To bring it back to life go back to step 1 in PART ONE, and add it as you would a sample of somebody else’s starter.

NOTE: It’s worth freezing or dehydrating a portion of a healthy sourdough, just to give yourself a backup plan in case your lovely starter take  a turn for the worse somewhere down the line.

PART FOUR: Using your soudough

  1. If you’ve been changing the fluidity of your starter to tweak its properties then you want to adjust the mix just before usage to get a 1:1 ratio. This will then work with any sourdough recipe you choose, or at least make it easier to calculate the correct amount.
  2. Been feeding your starter rye or wholewheat but want to create a pristine white sourdough loaf or baguette? Just make sure you switch to white flour for the last three days before usage, remembering to discard most of the old mix each time.
  3. Don’t forget that sourdough takes much longer to rise. Adjust the first and final rise times accordingly if adapting a recipe with baker’s yeast, and also remember that you’ll need to cook at higher temperatures to get the same level of browned crust.
  4. Remember the bit about throwing away most of your starter every day? You don’t have to chuck it in the bin. It can be added to a basic bread recipe alongside a (reduced amount of) baker’s yeast to make a sort of hybrid loaf. Even better it can be use as the basis for a superb batter for fish and pretty much anything else you want to deep fry.
  5. You can check to make sure your starter is healthy enough to bake with by mixing a tablespoon with 100g of flour, 70g of water and 2g of salt, and checking to make sure it rises by 50% after around five hours.
  6. The ideal ratio of sourdough starter to fresh ingredients is 20 percent. Most recipes stick roughly around this area. Here’s an example recipe…

BASIC SOURDOUGH BREAD (technique shamelessly adapted from Dan Lepard)

Ingredients: 200g of sourdough, 500g of flour, 320-340g of water, 10g of salt.

Roughly mix together by hand or with a mixer. Leave for a few minutes and then form into a ball on a floured or oiled surface Push the dough, fold it back over, turn again and repeat a few more times. Leave it for 10 minutes more and then do it all again. Do this 3-5 times in total and leave until expanded by 50% from original size. Shape your loaf (watch this youtube video for some techniques), leave until risen by 50% again. Place in an oven pre-heated to 220-240 degrees centigrade for at least an hour, placing a pan with freshly boiled water underneath in the oven. If possible don’t use fan-assisted heating, at least not for the first 10-15 minutes. Turn down the heat to 200-200 degrees at this point. Cook for a further 20 to 35 minutes, depending on whims of your oven and final desired crust, consistency and moistness.

AND FINALLY: Go buy yourself some good bread books. Dan Lepard’s The Handmade Loaf or Short & Sweet (bread and much, much more), Peter Reinhart’s The Bread Baker’s Apprentice, plus Dough and Crust by Richard Bertinet are all worth your time and money.

Much has been written about how to make bread using your very own sourdough culture.  Much of it is at best confusing, and at worst just plain wrong. Advice to throw in all manner of extra ingredients – raisins, grapes, kefir, even yoghurt – only serve to confuse matters, when what’s really required is water, flour, air, the right temperature, a little care and attention, and – if creating a starter from scratch – a touch of luck. Frankly, though, it’s far easier to beg, borrow or buy some sourdough from a friend, bakery or online source and take it from there.

But it’s the long term relationship with a sourdough where real problems often arise.  People slavishly follow superstitious rituals, fearful that it will expire without them. Or they forget about the starter for a while, discover an unappetising jar with one layer of sludge and another of grey water some weeks later, and chuck the lot down the sink in the belief that’s it’s ruined. Big mistake. The truth is that sourdoughs don’t die easily. They do, however, easily go a little off the rails if left to their own devices. Which is why, in order to keep the dream alive, it pays to understand a little about what’s going on in there.

Unlike baker’s yeast, which contains exactly what it says on the tin, sourdough is a little more complex. As with kefir, it involves a symbiotic mix of bacteria and yeasts. In very simple terms, one provides the sour notes, the other the gases that raise and aerate the bread. Both contribute to the final flavour, the behaviour and the general health of the ever-evolving starter. The challenge involves achieving and then maintaining the right amount and type of acidity while also encouraging good acid-tolerant yeast growth.

Acid House

The thing that really separates sourdough from regular bread dough is Lactic Acid Bacteria (LAB). Lactic acid bacteria are classified according to a whole range of properties, including cell structure, their growth at different temperatures, salt and acid tolerance, and sugar fermentation. The main class relevant to breadmaking is the lactobacillus.

Lactobaccilus is then further divided into three different types of lactic acid bacteria: Obligately Homofermantative, Facultatively Heterofermentative and Obligately Heterofermentative. The first reacts with fructose and ferments mainly to lactic acid. The second ferments mainly to lactic acid, with pentose sugars also producing lactic and acetic acids. And the third type of LAB ferments to both lactic and acetic acid.

Sounds complex, but the thing to note is that it’s last two that play the key role in sourdough, with the most dominant strain of LAB, L. Sanfrancisco, falling into the Obligately Heterofermentative category. Microflora will vary in near-infinite numbers of ways between one sourdough starter and the next, but if you’ve got L. Sanfrancisco or some equally sturdy European strain in there then it’s going to give you a good shot at obtaining both the milky lactic and sharp acetic acids, as well good stability and longevity. For this reason, you’re always going to be better off with starter taken from somebody else’s existing, healthy batch than by starting one yourself. It’s not so hard to make a starter from scratch, but you’re always initially at the mercy of whatever flora are present on the flour you begin with or are in the air nearby, and the starter’s longevity is less of a sure thing.

Assuming (for the moment) that you have a sourdough starter up and running, the next question is how to keep the damn thing alive and healthy. There are three things to consider: the growth of the lactic acid bacteria itself, the production of acids by the LAB, and the growth of the yeast…

Hot and Wet

When it comes to LAB, it’s actually water content rather than temperature that plays the dominant role. The lactic acid production isn’t particularly affected, but acetic acid production is. The more fluid the sourdough, the lower the acetic production. In other words, if your starter is getting too vinegary then try tempering this with a more liquid-like consistency for a few days. If it’s not sharp enough, then go for a firmer mix.

Temperature does still play a part when it comes to LAB. Happily the ideal temperature for the growth of the LAB is still same as the one for its production of acid – between 30 and 35 degrees centigrade. These higher temperatures will increase the speed of acidifation. (Some types of LAB will thrive at low temperatures and others at much higher, however.) That said, it’s the lactic acid production that is increased by higher temperatures, not acetic. So, another way to tweak the balance between the lactic and acetic notes is to raise or lower the holding temperature.

Which brings us to the yeast. The best temperature for the yeasts in a sourdough isn’t necessarily the same as for the LAB and acid production. Yeasts will generally thrive in the 30 to 35 range, but actually grow best in an acid environment in the 20 to 25 range, and even in this range will grow many times slower than the bacteria in the starter. (Note that yeast growth rapidly tails off above 35 degrees centigrade.) Yeast activity can also affect the behaviour of any homofermentative LAB present in the dough, with higher temperatures resulting in the more production of more volatile compounds, including ethyl acetate. If your sourdough smells a bit too much like nail varnish remover, this is why.

According to Harole McGee’s On Food And Cooking, sourdough yeasts grow best in more fluid environments. The Handbook Of Food Science, Technology & Engineering, however, states that the development of sourdough yeast is poorer in fluid sourdoughs – making it necessary for professional baker’s using a thinner final dough to augment their sourdough with baker’s yeast to get the necessary rise. Certainly yeast activity is more readily observed in a more fluid starter – just remember to either thicken it up a day or two before use or else adjust the final bread recipe if it’s based on a sourdough with a standard 1:1 flour to water refreshment ratio. Note that there’s no harm in adding baker’s yeast to a dough mix for baking, especially if you need a quick rise but want some of that unmistakeable tang (though this approach does mean that the sourdough yeasts and baker’s yeasts will compete for available food). But it’s never a good idea to add it to your sourdough starter. It won’t help the balance of your starter at all, and baker’s yeasts will soon die off in an acid environment anyway.

Vitamins and Minerals

The final piece of the puzzle is the extraction rate. Often overlooked, it’s nevertheless another important aspect of sourdough maintenance. Put simply, higher extraction flours provide more available vitamins and minerals for the starter. This in turn increases LAB activity and acid production. Note that rye flours have higher extraction rates than standard wheat flours. Higher extraction rates also mean higher ash levels. Don’t be thrown by the reference to ash – it’s just a fancy way of saying ‘mineral content’. The ash content in turn results in higher available acidity in the sourdough, measured as total titratable acidity (TTA). Higher ash flours – wholemeal has around 1.5% ash, compared to many whites with around 0.5% (French T55 has, surprise, surprise, 0.55%) – therefore will acidify more quickly.

That’s probably more than enough to digest for one blog entry. More next time on the practical aspects of creating, feeding, and refreshing sourdough starters next time, along with some pointers on sourdough baking, and a few good reasons why sourdough bread really is best.

Scribbling, ponderings, and maybe a little food porn…

by Mark Ramshaw

owner at feast for the senses
food design, private catering, consultancy

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