Unique Starter Cultures Affect Bread Quality

There is some evidence, albeit limited, that those with celiac disease can eat sourdough bread without any adverse health effects.

Charlene Van Buiten, assistant professor at Colorado State University’s Department of Food Science and Human Nutrition, has a background in gluten chemistry, and she was curious about the relationship between different sourdough starter culture microbiomes on gluten and its immunostimulatory properties.

“I was really interested in seeing how we could possibly change the structure of gluten protein to make it less immunostimulatory for individuals with celiac disease,” she says.

Much of the previous research on sourdough, she points out, compares yeast and sourdough breads without distinguishing the sourdough starters’ bacteria and their differences.

Van Buiten was the lead researcher on a study recently published in the Journal of Food Science that analyzed the impact of different sourdough starters’ microbes on the characteristics and quality of bread. The work was funded with the support of a $594,000 grant from the U.S. Department of Agriculture’s Novel Foods and Innovative Manufacturing Technologies program.

“We know that there is a lot of diversity in the microbiomes of these starter cultures. But until our study, we didn’t really have anything that characterized how these differences actually translated to differences in bread,” Van Buiten says. “We didn’t know really if they did at all.”

The researchers made 20 loaves of bread using 20 different sourdough starters. The starters were obtained from The Global Sourdough Project, a collection of over 500 starter cultures sourced from around the world. Paper co-author Benjamin Wolfe, an associate professor of biology at Tufts University, is part of the Sourdough Project team.

The scientists also made a control dough using regular yeast. Some of the dough was kept for analysis. The researchers examined the acidity, which contributes to protein breakdown, and the amount of free amino acids, which are a product of protein breakdown. The crumb firmness, loaf volume, and crust color of the baked bread were also analyzed.

Quality Differences

Most of the sourdough breads had higher crumb firmness, lower loaf volume, and lighter crust color than the yeast control, although there was a variation of crust colors among the different sourdoughs. The researchers also found marked variations in pH, acidity, free amino acids, and organic acid levels compared with the control loaf.

There does seem to be a link between the diversity of sourdough starter culture microbiomes and the quality of the resulting bread, says Van Buiten. “I like to make this connection to people diversity—how diversity can make a community stronger because everybody’s bringing something different to the table,” she says. “We kind of see that with bread as well, with our more diverse populations contributing to these quality parameters.”

This could be useful for food producers, who could fine-tune a starter culture to get the specific results and health benefits they’re after, Van Buiten points out. “Our main takeaway from this is that things like your starter cultures should really be considered ingredients,” she says.

This work is part of a larger project. The researchers have already resequenced their cultures to see how—if at all—the starters’ fungi and bacteria change during storage, freezing, and thawing.

They’re also investigating how starters impact shelf stability of bread—if they offer resistance to molding and staling, for example. “We know that these organisms that are in these starters can produce different antioxidant compounds, antifungal compounds, and even exopolysaccharides, and carbohydrates that can prevent or slow the rate of staling in bread,” says Van Buiten.

The ultimate goal, she continues, is to pinpoint the effects of sourdough starters on gluten degradation. While it’s already been shown that isolated bacteria in a lab can break down the gluten in flour enough that it doesn’t trigger an inflammatory response, she wants to see if the same thing happens in actual sourdough bread.

“We don’t really have a real-life application of that, and that’s what we’re interested in pursuing,” says Van Buiten.ft