Demand for sourdough bread is increasing, even in countries where yeast bread has been the standard for ages. This encourages the development of efficient sourdough baking processes on an industrial scale. “Reliable solutions for baking sourdough bread on an industrial scale are already available,” says Christian Degraeuwe of Spiromatic.
It looks like the increased demand for sourdough bread is not just hype. Artisan bakeries specializing in sourdough bread are springing up everywhere. Even so, they have difficulty in meeting rocketing demand. That’s because consumers increasingly appreciate the advantages of sourdough: it has more taste, it’s healthier and it’s easier to digest. And it has that great-looking crust. What’s more, it has longer shelf-life; even after several days it’s still yummy and wholesome. However, only an artisan baker can make a genuine sourdough loaf. At least that’s what artisan bakers say.
Three main challenges
Their claims should be put into sharper focus, says Christian Degraeuwe, food technologist at Spiromatic. “While I certainly appreciate the attraction of artisan baking, I’m pretty sure that industry can also produce high-quality sourdough bread. Technically speaking, you need to address three main challenges. Firstly, there’s the need to make and maintain good sourdough or ‘levain’ pre-ferment, which is a time-consuming and complex process. Secondly, sourdough needs to rise up for a much longer time than yeast dough, which is inconvenient in an industrial context. And thirdly, opinions on how to make good sourdough bread vary a lot, even among artisan bakers. This further complicates the development of an industrial response. However, good solutions are already available.”
Making and maintaining pre-ferment
The pre-ferment challenge is probably the most straightforward. “At home, it would take seven or eight days to make a sourdough pre-ferment,” says Degraeuwe. “In an industrial context, this is typically accelerated to hours rather than days by using a ‘mother starter’, a biological culture of lactic acid bacteria that is commercially available. This starter speeds up the pre-fermenting process without affecting sourdough quality. Then, part of the pre-ferment is tapped into mix and knead tanks to make sourdough, while the remainder is maintained within the pre-ferment tank using a fed-batch procedure. This process typically goes on for a full week.”
Machine suppliers should be able to flexibly adjust to the wide range of opinions on sourdough bread baking
Tuning the entire process
The longer rising time is a slightly more difficult challenge, which is why some industrial bakeries add up to 7% yeast to the sourdough. “That could be an option, but some will find this practice deceptive,” says Degraeuwe. “You might mix in 1 or 2% yeast without losing much of the quality of sourdough, but mixing in 7% yeast would essentially make a yeast bread with just a sourdough flavor, lacking any of the other advantages. A genuine sourdough approach would be to adjust the timetable to allow for the longer rising times. Of course, this could have a significant impact on the bakery’s internal organization and may also increase costs. The entire process must be carefully fine-tuned and automated to make it economically viable and profitable.”
Meeting industry preferences
The need for customization also results from the third challenge: that no two bakers agree on how a good sourdough bread should be made. “Opinions vary a lot among bread bakers and specialists,” says Degraeuwe. “They all have their particular preferences with respect to taste, texture or appearance. As a result, ingredients may vary. Some allow the use of a percentage of yeast, others denounce it completely. Some insist on using rye, others prefer wheat. Preferences for rising and baking times and temperatures may also vary greatly. In addition, efficiency considerations are at play in optimizing the use of ingredients, accelerating the process flow and keeping energy costs down. This sets new standards for installation suppliers. Extensive process expertise and food technology knowledge are required as well as the ability to adapt and finetune the system according to customer preferences. These aspects are of crucial importance when selecting a supplier.”