Refresh your Starter
Success depends on your sourdough starter. I cannot emphasise this enough. Your starter needs to be good and lively, containing a healthy population of active microbes. It’s these microbes that produce the gases that fill the dough during fermentation. One of my best friends says that sourdough bakers are like farmers, they are farming microbes. I think this is a really good way to look at what you’re doing as a baker. Get to know your starter – the rhythm of microbial activity after you have refreshed it, how it reacts to different temperatures and different flours. The better you know your starter, the easier it is to predict how long it needs to reach its peak after refreshing.
A less active starter could be the result of many things. It could be that you’re not refreshing it often enough, or because you’re keeping too much starter in the refreshment process. Frequency of refreshment is really important. On the whole, the more frequently you refresh the starter, the more active and more dense the population of microbes will be. In bakeries we’re baking every day. This is one of the reasons bakeries don’t have problems getting their bread to rise, because they’re refreshing continually. Domestic bakers may be leaving their starter for a week at a time between bakes, and then expect it to perform as though it’s still a spring chicken. If your starter has been resting in the fridge for a few days, you have to refresh it a number of times to build the microbial population up before it will be ready to use. If I know that my starter is going to be left for a few days between refreshments, I tend to make it a little wetter than usual. This allows a protective hooch (the liquid that forms on top of the starter when it is left for a while), to develop.
Timing is Everything
For a good loaf we’re looking to use the starter at peak activity, after this the microbial activity begins to decline and you may struggle to get the rise you want. The time it takes for your starter to reach peak activity can be affected by the flour you are using, the hydration and the ambient temperature. Whole wheat and rye flours contain more nutrients and will ferment faster, resulting in a starter which reaches microbial peak sooner. It’s a case of getting to know the flour you use when refreshing your starter. In terms of hydration, a wetter starter will have higher enzymatic activity and reach the microbial peak faster. You also need to keep an eye on temperature, especially if your starter is stored at ambient temperature. There can be a big difference between room temperature on a cold winter day and a warm day in midsummer, and this needs to be taken into account.
A second issue that can arise if you are not refreshing your starter frequently is acidification. The activity of the lactic acid bacteria leads to a build-up of acids in the starter. Some yeasts prefer a less acidic environment than others so, depending on which yeasts are present in your starter, the more acidic environment can result in less yeast activity.
Get the Timings Right for your Leaven
Like the starter, the age of the leaven will dictate the rise of your bread. On a longer, slower fermentation (a retarded method) you’re looking for a younger leaven about 2 – 4 hours old. You don’t want any acidity at all in the leaven, because the dough is going to acidify over 24 hours in the fridge. In an ambient loaf however, a little bit of acidity can help to tighten the gluten.
The amount of leaven you include in the dough is another variable. Too much leaven and you can easily over ferment your bread, but too little and it will be under fermented. There are some processes where I use as little as 2% leaven as an inoculation but, in general, for the formulas we use here at the school we tend to stick to round about 20% – just for ease of continuity really.
