Yogurt Waste Inspires Western Researcher To Innovate – With Sourdough Bread

Latifeh Ahmadi discovers how Greek yogurt by-product could make for less waste, better taste

If you were one of the many amateur bakers who learned to bake sourdough bread during lockdown, you’ll know how complex a single loaf can be. The rise of the bread, moisture, firmness and even crumb structure can make or break your baker’s creation. 

It’s why Latifeh Ahmadi, professor in the Brescia School of Food and Nutritional Sciences, studied each of those factors – and more – in an attempt to perfect the science of sourdough bread. But unlike your homemade loaf, Ahmadi was using a special ingredient of her own: acid whey. 

While the term may sound resigned to the lab, acid whey is a natural ingredient in dairy products like yogurt and cheese, responsible for their slightly sour taste. If you leave a glass of milk out on the counter for a few days, you’ll see the ingredient yourself: a yellow-green liquid that separates, settling at the bottom.  

But when it comes to Greek yogurt, which has a different taste and consistency, acid whey is filtered out in the production process. Rather than go to waste, Ahmadi has found a second life for this by-product, in sourdough bread. Containing the same elements found in regular sourdough starter, known as lactic acid bacteria, acid whey is the perfect substitute. 

“It’s the same type of culture that’s used in bread baking. Instead of combining water with yeast, we’re replacing half of the water with our acid whey,” Ahmadi said.

Using acid whey offers taste and waste benefits
Not only does it produce the same texture, aroma and crumb structure, but it also tastes better than regular sourdough. When participants were given regular sourdough bread and acid whey sourdough during a blind taste test, over 75 per cent agreed they would buy the latter. 

“The result was incredible: the physical properties of the bread were compatible, and in our sensory evaluation most participants preferred our bread over the commercial one.” – Latifeh Ahmadi, professor in the Brescia School of Food and Nutritional Sciences

It’s also healthier. Because acid whey is a component of dairy products, it remains a nutrient-dense liquid containing lactose, and vitamins and minerals like calcium, potassium and zinc. 

The natural acidity of Ahmadi’s bread also gives it a longer shelf life than a supermarket loaf.

“I once counted over 16 ingredients on a package of bread, many of which are preservatives and additives,” she said in disbelief. “Because the acidity in our bread is higher, mold won’t show up as quickly, giving us the chance for a cleaner label.”  

 A sustainable solution 
While the health benefits are an incredible bonus, Ahmadi’s inspiration for the research project arose from the sustainability benefits of her sourdough’s special ingredient, acid whey. 

This unwanted by-product of Greek yogurt is filtered out during production. And it’s no small afterthought – this sticky substance creates a large amount of waste in factories, especially given the ballooning Greek yogurt industry, which shot up to the $9B mark in 2025, taking up more than half of the American yogurt market. Worldwide, it’s forecast to exceed $13B by 2028.

“The problem with all this acid whey is that it can’t be dumped – it would destroy the surrounding environment,” Ahmadi warned. “Because it’s full of nutrients, it would feed a lot of hungry microorganisms in the environment, sparking rapid growth that consumes oxygen and pollutes waterways.”   

It’s why acid whey has been a large focus of study in food science. While solutions have been found using the substance in alcohol production and buttermilk formulation, Ahmadi is the first to prove its success in bread.  

Discovering the environmentally harmful product could have a more sustainable future in sourdough was an exciting discovery for the research team at the Faculty of Health Sciences. What’s more, Ahmadi has hope that it could become a go-to source for a wide variety of fermented foods. 

“We can easily use acid whey not only for bread, but any other fermentation process in the food industry. Now, it’s just about figuring out how to make it readily available for purchase.” 

Getting this fresh acid whey from dairy factories to market is no easy task. First, manufacturers would need to package the liquid by-product for purchase. Ahmadi has found it’s possible, through freeze drying, but the bigger challenge would be convincing dairy producers to adopt this innovative approach. 

“My dream is that one day this sustainable solution will be used throughout industry. When it comes to food waste, we often talk about the use of energy, land, water and fertilizer – but we should consider the food industry just the same. Coming at the problem from new angles like this is key for our future.” 

Learn more about how Western is future-proofing our planet. (https://allin.westernu.ca/future-proofing-our-planet).