Nathalie Muller and Thomas A. Vilgis
Why do humans have an extended pleasure in umami? Why has nature chosen glutamic acid and several nucleotides for triggering this specific taste? Why can the umami taste be associated with utterly crucial stages of human evolution and why can it be related with the corner marks of social culture since ages? The domestication of fire (temperature) and fermentation (microorganisms) enabled the transformation of perishable raw foods into safely consumable and storable viands. The transition from nature to culture leads to modern food technology. To present, the three fundamental states of food (raw, cooked, and fermented) have not altered, despite the advanced cooking methods, developed techniques, and evolved culture.
The aforementioned considerations imply the function and meaning of the sense of taste. The function of the gustatory apparatus is deeply rooted in the evolutionary development of humans. The initial meaning of food perception in history significantly differed from the present-day doggerel contests of food critics sitting in starred restaurants. In fact, the five taste receptors – sweet, sour, salty, bitter and umami – had originally been designed for food security, surviving purpose, and social power. The primary tastes reflect a profound relationship between the function of the cells comprising all biomaterials and the function of the physiology of biomaterials. Molecular cell function and taste have a common evolutionary denominator. Certainly, early humans did not season their food with sugar, salt or glutamate. Nevertheless, the sense of taste did provide orientation for food consumption. Particularly, the two extreme basic taste qualities bitter (poisonous) and sweet (eatable) permit a quick judgement about the edibility. A simultaneous presence of sweet and poisonous does not exist. Foods with a slightly salty taste indicate benefits for the mineral balance. Rock salt, a mixed crystal of the cations sodium, calcium, magnesium and the corresponding anions is e.g. linked to cell function.
Early cooking techniques consequently lead to the formation of umami. In a raw state, the molecular components of food are present in their native form; proteins, chain molecules of individual amino acids (shown as balls) are “folded”, and retain their original structure in most cases. The alteration from “raw” to “cooked” progressively takes places by raising the temperature. The thermal energy unfolds the proteins, which lose their structural form, and the food texture is changed. When foods are fermented by the agency of micro-organisms that release enzymes, the proteins are gradually broken down into pieces, until individual peptides and amino acids are released, including glutamic acid. This process results in “umami”, whereas some small fragments of two or three amino acids account for “kokumi” (mouth-filling sensation) if they are still carrying a glutamic acid. Fermented sauces yield always to the basic taste umami and the mouth filling sensation kokumi, as the long-time cooking does: after denaturing, proteins split up in fragments and free glutamic acids, and therefore also in umami and kokumi, as seen in gravy, stock, broth and stew. Different approaches, different cultures, one goal: the depth of good taste.