NUS team turns Kombu into banana- and pear-scented probiotic superfood

Food scientists at the National University of Singapore have developed a co-fermentation method that improves both the nutritional profile and flavor of kombu, potentially opening new pathways for seaweed-based functional foods and beverages.

• NUS researchers have developed a LAB-yeast co-fermentation method that increases nutrient bioaccessibility and reduces off-odors in kombu.

• The process has boosted probiotic survival and increased levels of γ-aminobutyric acid in specific fermentation combinations.

• The resulting fermented kombu blend has exhibited banana and pear aroma notes while reducing fishy and grassy compounds.

Kombu, or Saccharina japonica, is a brown seaweed widely cultivated and consumed in Japan, Korea and China. Although valued for its nutritional properties, its strong fishy and grassy odor has limited broader consumer appeal. At the same time, many of its nutrients are trapped within rigid cell walls and dense structural networks that the human digestive system struggles to break down, reducing bioaccessibility.

A research team from the Department of Food Science and Technology at NUS has addressed both issues through a two-stage fermentation strategy. The team, led by Associate Professor Liu Shao Quan and including Senior Research Fellow Dr Lu Yuyun and PhD student Ms Geng Chenhan, published its findings in the International Journal of Food Microbiology on December 2, 2025.

Enzymatic treatment and lactic acid bacteria fermentation have previously been used to break down large proteins and carbohydrates in kombu into smaller, more digestible components. However, these approaches have not effectively removed compounds responsible for undesirable odors.

Building on earlier work published in October 2025, the NUS team first treated kombu with enzymes to release trapped nutrients. In their latest study, they co-fermented the enzyme-treated kombu with lactic acid bacteria and an aroma-producing yeast.

The addition of yeast proved significant. Analysis showed that co-fermentation with LAB and yeast promoted stronger probiotic growth and survival compared to LAB-only fermentation. One combination in particular, using the LAB L. plantarum and the yeast P. kluyveri, generated higher levels of γ-aminobutyric acid, commonly known as GABA, a bioactive compound associated with calming effects, stress reduction and potential mental health benefits.

At the same time, the co-fermentation process reduced off-flavor compounds linked to fishy and grassy notes and introduced compounds associated with banana and pear aromas.

“Kombu has a tremendous amount of untapped potential to be a superfood, but for its health benefits to reach a wider population, kombu has to be more palatable and its nutrients more accessible,” said Associate Professor Liu. “While enzymatic treatment followed by lactic acid bacteria fermentation liberates beneficial nutrients, the combination with yeast fermentation further produces fruity aroma compounds, improving the flavour profile of the fermented kombu.”

Following co-fermentation, the resulting product contained probiotics and elevated GABA levels, positioning it as a candidate ingredient for functional foods. Functional foods are defined as foods that provide health benefits beyond basic nutrition.

Dr Lu said the team viewed the co-fermentation protocol as a platform technology for broader product development. “Our unique co-fermentation method of processing kombu is the gateway to creating new health products. With our tastier fermented kombu, we could create fermented seaweed drinks, probiotic seaweed-based supplements or even use it as ingredients in plant-based foods,” she said. “This approach may also be adapted to other seaweed species to broaden the range of appealing seaweed-derived products.”

Commercial kombu products using combined LAB-yeast fermentation remain limited, underscoring the novelty of the approach.

Ms Geng, first author of the paper, said the team’s next focus would be refining the process. “Elevating the flavour profile of kombu makes it more enticing to a broader range of consumers. Our next goal is to optimise fermentation conditions, such as fermentation sequence, time and temperature, to further improve process efficiency and product quality,” she said. “In future, we will also conduct sensory evaluation to better understand consumer preferences for seaweed-based foods.”

The researchers believe that improving both bioaccessibility and flavor simultaneously is critical if seaweed is to move beyond niche culinary uses and into mainstream functional food categories. By combining enzymatic treatment with targeted microbial fermentation, the NUS team has demonstrated a method that addresses the two longstanding barriers of nutrient availability and sensory acceptance in one integrated process.

With further optimization and validation, fermented kombu blends could support the development of probiotic seaweed beverages, supplements and plant-based formulations designed to deliver both nutritional and sensory appeal.

(Main photo: The NUS researchers used a combination of LAB and aroma-producing yeast to co-ferment enzyme-treated kombu. The resulting fermented kombu blend is not only highly nutritious but also has pleasant banana and pear notes)