A new taste sensation known as kokumi

From sweet to sour and salty, bitter to umami, taste perception greatly influences our sensory enjoyment of food. Many of us are familiar with these five primary tastes. However, researchers have highlighted an additional taste sensation known as ‘kokumi’ that may be important in enhancing these other perceptions.  

Kokumi has been part of the Japanese culinary tradition for centuries. It is associated with foods that exhibit a fullness, succulence and craveability. It is derived from ‘koku’ meaning rich and ‘mi’ meaning taste. The kokumi taste sensation can be found in cheese, yeast extracts as well as wine. Garlic has also been mentioned in early kokumi focused research as Ueda et al. reported that water extracts from garlic enhance umami taste intensity (1). Flavour scientists have had increased interest in this area of research, and they are continuing to discover the characteristics of this new taste sensation. 

Information on Kokumi is in demand

How a food tastes is one of the most important aspects when it comes to consumer food choices and preferences (2). This may be a contributing factor to the increased fascination with taste sensation such as kokumi in recent years. Many people are unaware of kokumi, however, foods having a rich texture and comfortable mouthfeel is something we can all relate to. The deep enhancement of flavour encourages consumption, enjoyment and interest in certain foods. This could indicate why information surrounding kokumi is on the rise. 

How is kokumi different to umami? 

Unlike umami, kokumi compounds do not present a flavour attribute in isolation. Umami is a distinct taste perception by itself, and more can be found about it from the Kerry white paper here. Kokumi peptides are known to enhance the umami taste by promoting a roundness and full mouthfeel (3). This means that the two sensations work in tandem to give us both a savoury flavour with lasting richness (4). 

Kokumi is also associated with the ageing and maturation process. It can be found in foods that have a longer preparation time such as slow-cooked stews and fermented foods. Have you noticed that when we let a stew simmer or allow cheese to mature, it takes on a deeper and richer taste (5)? The balance of salt, sweet, sour and umami in these foods is overlayed by kokumi, which gives them a deep taste (6). 

As mentioned before, slowly cooked foods have distinct flavour profiles associated with kokumi. This is caused by the degeneration of proteins that are present. Proteins are made up of amino acids and peptides. Amino acids are the building blocks of protein and these join to make peptide chains (7). 

Like umami, kokumi substances have peptides and amino acids that are associated with it – for instance, glutathione and gamma-glutamyl peptides. These can be found in aged foods such as gouda cheese and fermented foods such as nattō. These foods deliver a round and rich flavour which is characteristic of kokumi (6)(9)(10). During cooking and ageing, kokumi substances are released from these products, providing depth of flavour(8)(9).  

Science of kokumi – how does taste perception work? 

Researchers have noticed that kokumi substance such as GSH (Glutathione) activates the CaSR (Calcium Sensing Receptor). These CaSR belong to the G-protein receptor family and have been found in the lingual tissue of mice. When mixed with other taste stimuli such as umami, sweet and salty, kokumi enhances thickness and continuity(4). 

These kokumi peptides activate the calcium receptors and create a domino effect of sensation. Essentially, the receptors have a high affinity for the peptides responsible for creating a kokumi sensation. Studies have shown that there is a correlation between the amount of calcium-sensing receptor activity and the intensity of richness that we associate with kokumi. However, this remains a new area of neurogastronomy and requires further, in-depth research (11). 

Why kokumi may be important in the future of food: 

As mentioned before, kokumi is known to heighten the savoury and deliciousness associated with umami. Corporations hoping to transform the flavour profile of various foods have harnessed umami and kokumi as flavour solutions to deliver new and exciting tastes to the market. As we shift towards more sustainable food products and clean label solutions, the use of umami and kokumi could be more important.  

Further development into plant-based meal alternatives has grown in recent years, and researchers have discovered that soybean extracts have the potential to be kokumi enhancers in food products. In addition, different flavourings can deliver a savoury sensation comparable to meat products.  This is the case with products such as yeast extract, as it can replicate meaty flavours in plant-based foods. This is a result of key kokumi peptides that are present within yeast extract (8)(9)(12-14). 

The use of yeast extract application in plant proteins is increasing as it solves the challenge of delivering a clean-label solution with rich, juicy meaty taste, based on its natural composition of umami and kokumi.    

With an ageing population, flavourful foods are important to aid with consumption and prevent the adverse health effects of malnutrition. Older persons have a reduced taste perception and often add salt to savoury foods to enhance the flavour, see the KHNI article The Retiring Nature of Taste Perception. This can contribute to high blood pressure and other cardiac issues. There has been increased research into the potential of umami and kokumi flavours to reduce the salt content of foods (15). However, this concept requires further investigation, but could be of interest to those wishing to reduce their salt consumption. 

Conclusion 

There may be potential for kokumi to be a staple taste sensation in future taste solutions. It supports the savoury, delicious and juicy flavours of umami to deliver a balanced, rich, and deep sensation. It could be one of the unsung heroes in taste perception and there is scope for further research and development into its uses. As taste is a key determinant of food enjoyment, scientists continue to uncover novel applications of kokumi and hope to further use its properties. Taste and texture go hand in hand to enhance the culinary experience of food and there is potential for kokumi to contribute further to our enjoyment of delicious taste.

• Hilary McCahill, BSc, RD

  Hilary McCahill is a qualified dietitian in both Ireland and the UK and is a graduate of the human nutrition and dietetics programme jointly shared by Trinity College Dublin and Technological University Dublin. She is currently a quality graduate within Kerry Group’s graduate programme. She is passionate about all things food, health and nutrition having spent time working in both food industry and within clinical settings.

• References
  1. Ueda, Y.; Sakaguchi, M.; Hirayama, K.; Miyajima, R.; Kimizuka, A. Characteristic Flavor Constituents in Water Extract of Garlic. Agric. Biol. Chem. 1990; 54, 163–169.
  2. Stok, F. M., Renner, B., Clarys, P., Lien, N., Lakerveld, J., Deliens, T. Understanding Eating Behavior during the Transition from Adolescence to Young Adulthood: A Literature Review and Perspective on Future Research Directions. Nutrients, 2018; 10(6), 667.
  3. Tang, CS. ,Tan VWK., Teo PS., Forde CG.. Savoury and kokumi enhancement increases perceived calories and expectations of fullness in equicaloric beef broths. Food Quality and Preference, 2020; 83 103897 
  4. Keast, R., Costanzo, A., & Hartley, I. (2021). Macronutrient Sensing in the Oral Cavity and Gastrointestinal Tract: Alimentary Tastes. Nutrients, 13(2), 667. https://doi.org/10.3390/nu13020667
  5. Toelstede S, Dunkel A, Hofmann T. A series of kokumi peptides impart the long-lasting mouthfulness of matured Gouda cheese. J Agric Food Chem. 2009;57(4):1440-8. doi: 10.1021/jf803376d
  6. Finger TE, Barlow LA. Cellular Diversity and Regeneration in Taste Buds. Curr Opin Physiol. 2021; (20)146-153. doi: 10.1016/j.cophys.2021.01.003. 
  7. Lopez MJ, Mohiuddin SS. Biochemistry, Essential Amino Acids. [Updated 2021 Mar 26]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK557845/ 
  8. Charve, J.; Manganiello, S.; Glabasnia, A. Analysis of Umami Taste Compounds in a Fermented Corn Sauce by Means of Sensory-Guided Fractionation. J. Agric. Food Chem., 2018; 66, 1863–1871
  9. Kaczmarska, K., Taylor M., Piyasiri U., Frank, D. Flavor and Metabolite Profiles of Meat, Meat Substitutes, and Traditional Plant-Based High-Protein Food Products Available in Australia 2021; Foods 10, (4) 801. https://doi.org/10.3390/foods10040801
  10. Lee, Y.-C.; Chi, M.-C.; Lin, M.-G.; Chen, Y.-Y.; Lin, L.-L.; Wang, T.-F. Biocatalytic Synthesis of γ-glutamyl-L-leucine, a Kokumi-Imparting Dipeptide, by Bacillus licheniformis γ-Glutamyltranspeptidase. Food Biotechnol. 2018; 32, 130–147
  11. Maruyama Y, Yasuda R, Kuroda M, Eto Y. Kokumi Substances, Enhancers of Basic Tastes, Induce Responses in Calcium-Sensing Receptor Expressing Taste Cells. PLOS ONE, 2012; 7(4): e34489. 
  12. Shibata M., Hirotsuka, Mizutani Y,Takahashi H.,Kawada T., Matsumiya K., Hayashi Y.,Matsumura Y., Isolation and characterization of key contributors to the ‘kokumi’ taste in soybean seeds, Bioscience, Biotechnology, and Biochemistry 2017;81, (11): 2168–2177.
  13. Liu, J., Song, H., Liu, Y., Li, P., Yao, J. and Xiong, J. Discovery of kokumi peptide from yeast extract by LC-Q-TOF-MS/MS and sensomics J. Sci. Food Agric., 2015;95: 3183-3194. 
  14. Žugčić, T., Abdelkebir, R., Barba, F. J., Rezek-Jambrak, A., Gálvez, F., Zamuz, S., Granato, D., & Lorenzo, J. M. Effects of pulses and microalgal proteins on quality traits of beef patties.   Journal of food science and technology, 2018; 55(11), 4544–4553.
  15. Rhyu, M. R., Song, A. Y., Kim, E. Y., Son, H. J., Kim, Y., Mummalaneni, S., Qian, J., Grider, J. R., & Lyall, V. Kokumi Taste Active Peptides Modulate Salt and Umami Taste.  Nutrients, 2020; 12(4), 1198.