Authors: Rita Vilaça and Susana Soares
LAQV-REQUIMTE, Porto, Portugal
Microbial Communities Taste Axis: A Journey Through Flavour
When we think about what makes food taste good, we often focus on the ingredients, cooking methods, or recipes. However, microbial communities play a significant role behind the scenes. From the soil that nourishes our crops to the fermentation processes that change raw ingredients into flavourful foods, and even the microbes in our mouth that help us perceive and modify those flavours, microorganisms are closely involved in every step of the flavour experience. In cereal-based foods, particularly fermented ones like wheat, the impact of microbes on taste is especially strong. Microbes in the soil and plant influence the nutritional and sensory qualities of the grain. During fermentation, specialized bacteria and yeasts unlock aromas, tastes, and health-boosting compounds in these foods. As we eat, the microbes in our mouths interact with the food and metabolize food compounds, releasing flavour-active metabolites, subtly changing our perception of flavour. In fact, there is bidirectional interplay: what we eat alters the oral and gut microbiomes, and the oral microbiome, in turn, affects how we perceive flavour.
The unique taste of fermented cereal-based foods strongly influences consumer choices, sparking considerable scientific interest in how these flavours develop. The microbial journey from soil to fermentation to mouth perception is changing our understanding of how to create food that meets consumer demands for nutritional, healthier, and safe alternatives.
From Farm to Fork: Soil Microbes and Cereal Flavour
Surprisingly, the microbial communities in our soil, mainly bacteria and fungi, are crucial for the taste and nutritional value of grains like cereals (e.g., wheat). Cereals provide essential vitamins, minerals, fibre, protein, polysaccharides and bioactive compounds. The soil and plant microbiomes affect how plants absorb nutrients and control key biochemical pathways that shape the flavour and nutritional qualities of cereals.
Some microbes, for instance, can increase the levels of natural compounds like phenolics, vitamins, and proteins in the mature grains used for food processing. It’s not just about producing resilient crops; it’s also about growing flavourful and nutrient-rich ones engineered from the soil upward across the entire food production chain. Research has been examining how to use soil and plant microbiomes to adjust plant metabolism, similar to how we use starter cultures in food, to enhance both flavour and nutritional value right at the source.
Microbial Fermentation as a Flavour Alchemy
For wheat-based fermented foods, like sourdough bread, fermented wheat germ, or traditional steamed buns, fermentation provides a simple and cost-effective way to improve the off-flavours of grains, reduce the presence of anti-nutrients, and enhance the digestibility of cereal-based foods. For example, lactic acid bacteria (LAB) and yeasts break down the starches and proteins in flour, producing a range of flavourful and aromatic compounds like acids, esters, and aldehydes. These contribute to the tangy taste, subtle sweetness, and deep umami of sourdough bread. Taste isn’t the only benefit. The right microbial strains can also boost the health advantages of the final product. Some LAB release bioactive compounds like antioxidants or lower anti-nutrients like phytic acid. Others help make gluten proteins easier to digest. Using local microbial strains from the soil or cereal plants with desirable traits can lead to more reliable improvements in the quality of fermented cereals. Choosing the right starter culture is not just about fermentation; it’s about shaping the entire sensory and nutritional profile of a fermented food product.
The Oral Microbiome and Taste Perception
Even after food is prepared, microbes continue to play a vital role in your mouth. The oral microbiome, particularly bacteria like Streptococcus and Prevotella, chemically interact with what you eat. They can release hidden aroma compounds while you chew, affect how sweet or sour something tastes, and influence how your taste buds respond.
For example, these bacteria can break down complex molecules in fermented wheat foods, releasing aromatic volatiles that travel from your mouth to your nose and enhance the overall flavour experience. They can also change the environment on your tongue, subtly influencing how you perceive saltiness, bitterness, or richness. In other words, your unique oral microbiome may explain why you prefer or not certain fermented foods.
From the soil where wheat grows to the microbes that ferment it and the ones in your mouth, microbial communities continuously shape our food intake experiences and flavour perception. They are recognized as flavour-makers, nutrition enhancers, and sensory modifiers.
The WHEATBIOME project is exploring the science of flavour and nutrition by studying the wheat microbiome throughout its life cycle, from soil and plants to human consumption. The consortium is investigating how factors like farming practices (organic vs. conventional), irrigation methods, wheat genotypes, and soil composition affect the soil and plant microbiomes in two climate zones: Mediterranean Spain and Atlantic Netherlands. Simultaneously, lab-scale experiments are examining how native lactic acid bacteria and fungi from wheat grains drive fermentation processes that enhance flavour, reduce gluten immunogenicity, and release beneficial bioactive compounds. These insights will help design wheat-specific microbial fermentation processes aimed at increasing both nutritional value and sensory appeal.
Uniquely, WHEATBIOME is also exploring the role of the human oral microbiome in flavour perception by exploring how interactions between oral microbes and fermentation-derived compounds affect taste experiences of fermented wheat-based foods. In parallel, the project will evaluate how enzymatic processing during digestion influences the release and transformation of bioactive peptides and compounds. Using a novel in vitro microbiome model of colonic fermentation integrated with the standardized INFOGEST human gastrointestinal digestion protocol, wheat-based fermented foods will undergo simulated oral, gastric, and intestinal digestion in the presence of both oral and colonic microbiome models. By analysing the soluble digestion fractions and assessing protein digestibility, alongside the evaluation of microbial metabolism in fecal samples, WHEATBIOME aims to reveal how enzymatic digestion, and microbial interactions together shape the bioaccessibility, structure, and sensory potential of peptides as they progress through the digestive system. Together, this innovative research presents a comprehensive view of how microbiomes from soil to humans can be used to create healthier, tastier, and more sustainable cereal-based foods. The journey of flavour is truly microbial from start to finish.
