For over a century, yogurt has been a beloved (and nutritious) staple for billions worldwide. On average, each person consumes about 12 kg of yogurt per year. Now, scientists have discovered a clever new way to make yogurt even better — by simply turning up the heat.
Yogurt is made through a delicate partnership between milk and two types of bacteria. Researchers at the Technical University of Denmark (DTU) have found that increasing fermentation temperature can streamline this process, reduce spoilage, extend shelf life, and even cut costs — without affecting flavor.
Turning Up the Heat
Traditional yogurt production uses two bacteria: Streptococcus thermophilus and Lactobacillus bulgaricus. Both of these bacteria work to ferment milk. The process takes place at around 42 °C. The two species work in “protocooperation,” helping each other thrive. But that teamwork often comes at a cost: if fermentation continues after packaging, yogurt becomes overly sour and watery, a process known as post-acidification. We don’t want that.
To slow or eliminate this process, manufacturers have tried everything from mutant bacteria to protective additives. But those solutions can be costly or inconsistent. That’s where DTU’s idea stands out. The team found that by raising the fermentation temperature to 51 °C — just above the bacteria’s growth limit but within their metabolic range — they could steer the fermentation without letting the microbes overrun the milk.
“We’ve studied lactic acid bacteria and their energy metabolism for years, but one day it struck us: what if we let the bacteria acidify without allowing them to grow? It was something of a eureka moment,” says Associate Professor Christian Solem. Solem has researched lactic acid bacteria for more than 25 years and is co-author of a new paper in Food Bioscience describing their findings.
A Smarter Ferment
In their method, researchers first make a small batch of yogurt the traditional way. Then, this “starter” yogurt is added to fresh milk pre-warmed to 51 °C. Even though the bacteria aren’t multiplying, they’re still hard at work acidifying the milk.
Using this high-temperature “non-growth” phase, the team could bring the yogurt to the ideal pH (4.6) in as little as two hours. It was “a fivefold reduction in culture expenses,” the researchers report
But the real bonus is that post-acidification almost vanished. With the bacteria largely dormant after fermentation, the yogurt stayed stable in flavor and texture for far longer than standard products. According to the researchers, this opens the door to “long shelf-life yogurt at a lower cost to the benefit of dairies and consumers.”
There was another bonus: the hotter temperature also kept yeast and molds at bay. Spoilage from yeasts and molds is a perennial headache for yogurt producers, especially in fruit-flavored varieties. But the high-temperature phase turned out to have antimicrobial perks. When the researchers introduced common spoilage microbes — including Aspergillus niger, Penicillium crustosum, and Debaryomyces hansenii— into the process, their numbers plummeted. The warm environment weakened or killed many of the invaders, helping preserve the yogurt without added preservatives.
We could start doing this ASAP
Normally, when there’s an innovation in the food industry, it takes years of testing and confirmation to be sure it can be safely consumed. But in this case, this innovation stands out for its simplicity and the fact that it only introduces a clever temperature tweak.
“In principle, dairies could adopt the method as early as tomorrow. We have not observed any drawbacks, apart from the process taking an hour or two longer — and you will have a more stable and sustainable product,” says Christian Solem.
The method may be especially attractive for yogurt producers in low-resource settings, where cold storage is limited and reducing costs is critical. A version of the process could also be scaled down for home or artisanal production. Of course, large producers could also introduce it, reducing the cost of their operation.
What’s clear is that this study could open a new chapter in one of the world’s oldest fermented foods. For now, yogurt has a hot new future — literally.
