Kombu (Saccharina japonica) is a brown seaweed extensively cultivated and consumed in Japan, Korea and China. Despite its nutritional value, its strong fishy and grassy odour can deter some consumers. Additionally, many of kombu’s nutrients are locked inside rigid cell walls and dense networks that the human digestive system cannot easily break down. As a result, much of this treasure trove of nutrients passes through the body without being absorbed.
A team of food scientists at NUS has found a way to unlock the trapped nutrients in kombu and replace the unpleasant odours with more appealing scents, directly overcoming the 2 major challenges – limited nutrient bioaccessibility and poor sensory experience.
Enzymes and lactic acid bacteria (LAB) fermentation have been commonly used to improve kombu’s nutritional value by breaking down large proteins and carbohydrates into smaller, more digestible components. However, these approaches cannot effectively remove the compounds that give kombu its characteristic fishy and grassy odour.
Building on the knowledge that yeast fermentation can naturally produce pleasant fruity and floral aromas, the NUS scientists took the process a step further by co-fermenting enzyme-treated kombu with LAB and an aroma-producing yeast. The result is a novel probiotic kombu-based blend that is both healthier and more flavourful.
The team’s work was published in the scientific journal International Journal of Food Microbiology on 2 December 2025.
Banana and pear-flavoured kombu, anyone?
In their earlier work published in October 2025, the NUS team demonstrated that fermenting enzyme-treated kombu with LAB effectively releases trapped nutrients. In their latest work, enzyme-treated kombu was fermented using LAB together with an aroma-producing yeast. Analysis of the fermented kombu blend revealed that the LAB-yeast co-fermentation promotes the growth and survival of probiotics compared to LAB-only fermentation. One particular co-fermentation mixture (using the LAB, L. plantarum and the yeast, P. kluyveri) yielded more γ-aminobutyric acid (GABA), a well-known bioactive compound commonly linked to calming effects, stress reduction, and potential benefits for mental health. Importantly, the co-fermentation greatly reduced unpleasant off-flavour compounds while introducing compounds associated with the aromas of bananas and pears.
“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 Shao Quan from the Department of Food Science and Technology in NUS Faculty of Science. “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.”
Fermented kombu as a functional food
Following LAB-yeast co-fermentation, the fermented kombu product becomes exceptionally nutritious and is fortified with probiotics and GABA, which positively influences gut and mental health respectively. Subsequently, the fermented kombu blend could be used to develop fermented kombu-based functional foods – foods that provide health benefits beyond their basic nutritional value – and beverages that are healthy and tasty.
“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,” said Dr Lu Yuyun, Senior Research Fellow and co-corresponding author of the research paper. “This approach may also be adapted to other seaweed species to broaden the range of appealing seaweed-derived products.”
Currently, few if any commercial kombu products are made using LAB-yeast fermentation, underscoring the innovative nature of this research.
“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,” said Ms Geng Chenhan, third-year PhD student and first author of the research paper. “In future, we will also conduct sensory evaluation to better understand consumer preferences for seaweed-based foods.”