Study and development of a functional fermented drink based on Sobacha: A Japanese infusion of roasted buckwheat seeds

Nowadays, consumer’s demand for the development of functional foods on the market, i.e., satisfying hunger and nutrient intake, but also preventing chronic diseases and improving physical and mental health, is constantly increasing. At the dawn of a food transition encouraging the consumption of healthy and sustainable non-dairy probiotic products, the development of a functional drink based on Sobacha is considered. This cereal matrix is an infusion of roasted buckwheat seeds widely consumed in Asian countries for its health benefits. Resulting from a Japanese expertise of buckwheat roasting, the matrix presents anti-inflammatory and antioxidant properties. Moreover, kombucha has gained immense popularity in recent years due to its many health benefits. As fermentation improve the nutritional and organoleptic status of grain products, the mixed fermentation process involved in the development of Hakko Sobacha is conducted by inoculating a symbiotic culture of bacteria and yeasts into the cereal matrix. Considering the beverage characterization, the kinetics of volatile organic compounds (VOCs) were determined using stir bar sorptive extraction—gas chromatography—mass spectrometry. Odor-active compounds were theoretically calculated to estimate consumer perception. Finally, sensory analyses highlighted the appreciation and preferences of the consumer towards the beverages. The fermentative yield differences observed between the two buckwheat concentration modalities are due to the number of sugars available for fermentation but also to the nutrients available from the complex sugars of the starch matrix. The study of volatile organic compounds shows the analysis of production kinetics of potentially aromatic compounds such as esters, aldehydes, ketones, terpenes, ... from carboxylic acids and alcohols. The synthesis of these aromas evolves during fermentation, reflecting the activity of microorganisms to use multiple fermentative pathways in search of an optimal environment for their development. Consumers appreciate the beverage with the highest buckwheat concentration for its fruity (citrus), green, creamy, and spicy (from esters, ketones, and phenols) aromas, as well as for its acidity, predominant roasted hazelnut aroma (from pyrazines of sobacha). Opposite consumers appreciate the drink less concentrated in buckwheat for its sour, floral, grilled, fruity (melon), green notes (from carboxylic acids, esters, and alcohols mainly) but also for its color, freshness, and sparkle. As this study allowed to characterize Hakko Sobacha, an insight for the development of new drinks by controlling the fermentation process was suggested. Such a methodology should allow a better control and optimization of their sensory profile, which could in turn lead to greater consumer acceptance.