Innovative Two-Step Fermentation Method Revolutionizes Yogurt Production

Researchers at the Technical University of Denmark (DTU) have introduced a groundbreaking two-step fermentation method that promises to transform the yogurt manufacturing process. This innovative technique significantly reduces costs associated with starter cultures while extending the product's shelf life. The development comes amid rising global yogurt consumption, which is projected to average nearly 12 kilograms per person annually.

Traditional yogurt production typically requires a substantial amount of starter culture, which is added to milk and fermented at a temperature of approximately 42°C for 4 to 6 hours. This method faces several challenges, including high costs of starter cultures, limited shelf life, and post-acidification, a process where the yogurt continues to acidify even after production, adversely affecting quality and longevity.

According to Associate Professor Christian Solem, a leading researcher in lactic acid bacteria and co-author of the study published in the journal *Food Bioscience* in June 2025, the new method allows for a remarkable reduction in the quantity of bacterial cultures used. "By only using 20% of the standard starter culture, we can achieve a similar level of acidification without the drawbacks associated with traditional methods," Solem stated.

The innovative process involves an initial fermentation at 42°C, followed by a temperature increase to 51°C. At this elevated temperature, the bacteria stop dividing but continue their lactic acid production. This method not only achieves a more stable product but also acts as a mild pasteurization phase, eliminating up to 99.9% of yeast cells and mold spores that could shorten the yogurt's shelf life.

Postdoctoral researcher Shuangqing Zhao, the corresponding author of the study, further elaborated, "We tested this method on three different starter cultures, including those prone to post-acidification, and found that the issue was effectively resolved in all cases. While the exact extension of shelf life is yet to be determined, we anticipate it will exceed the current norm of 3 to 4 weeks."

The financial implications of this new technique are significant. Current production methods require dairies to use up to 0.18 grams of starter culture per liter of milk, leading to considerable costs. Solem emphasized the importance of this reduction, noting, "Lowering the starter culture requirements by a factor of five can lead to substantial savings, especially in an industry where profit margins are tight."

In addition to cost savings, the extended shelf life facilitates improved planning and logistics in yogurt production. With longer-lasting products, dairies can potentially produce larger batches and streamline their operations, minimizing downtime associated with equipment cleaning and reconfiguration between production runs.

This pioneering method could be adopted by dairies almost immediately, as it requires no new technology—only a modification of temperature controls during production. "In principle, dairies could adopt the method as early as tomorrow," stated Solem, who also noted that the process may take an additional hour or two but results in a more stable and sustainable product.

As the yogurt market continues to expand, innovations like this two-step fermentation method highlight the intersection of sustainability and economic viability within the food industry. Dairies and consumers alike may benefit from the ability to produce higher-quality yogurt with reduced costs and longer shelf life, paving the way for a more resilient dairy sector in the future.

In conclusion, the development of this cost-effective yogurt manufacturing technique represents a significant advancement in food technology, offering potential benefits that extend beyond the immediate financial implications to encompass broader sustainability goals within the dairy industry.