Equivalent Umami Concentration
Equivalent Umami Concentration (EUC) is a formula to quantify umami concentration from different umami amino acids (Asp and Glu) and 5-nucleotides (IMP, AMP, and GMP) as the umami intensity in terms of monosodium glutamate (MSG). It was developed from Yamaguchi et al (1971) and a few precedent studies and has been widely used as an inclusive measure of umami.
Yamaguchi, S., Yoshikawa, T., Ikeda, S., & Ninomiya, T. (1971). Measurement of the relative taste intensity of some l‐α‐amino acids and 5′‐nucleotides. Journal of food science, 36(6), 846–849.
Formula
In the formula, Y (EUC) equals the estimated equivalent concentration of sodium glutamate (mg MSG/g). The value of 1218 is the coefficient of synergy; ai refers to the concentration of Asp and Glu (mg/g); bi refers to the relative coefficient of the Asp and Glu equivalent to MSG (Asp: 0.077, Glu: 1.000); aj refers to the GMP, AMP, and IMP concentration (mg/g); and bj refers to the GMP, AMP, and IMP relative to the improvement of the relative coefficient of IMP (AMP: 0.180, IMP: 1.000, GMP: 2.300).
The first term ∑aibi measures the direct contribution to EUC from amino acids (i.e. Asp and Glu) with different weight for two amino acids. The second term 12.18(∑aibi)(∑ajbj) captures the contribution of synergetic effects of having both amino acids and 5-nucleotides for each combination; there are 2 x 3 = 6 pairs and each pair is assigned different weight.
Usage of EUC
Measuring Umami Evolution while Cooking
As mentioned in a previous Medium article, cooking methods have an impact on the presence of umami compounds in ingredients. The EUC is a useful quantitative measure that captures the changes in the overall umami score during cooking processes. For example, a study examined the transformation of umami taste in beef when cooked using a low-temperature technique like sous vide. The researchers discovered that the umami flavor, as measured by the EUC, increased when the beef was cooked at 70 °C (158 °F) for 12 hours compared to being cooked at the same temperature for just 30 minutes. Such approach is helpful to seek for optimal cooking methods with umami in consideration.
Measuring Umami in Ingredient Paring
Quantifying the synergistic effect in EUC is beneficial when considering ingredient pairings, emphasizing the importance of combining ingredients rich in amino acids and those rich in 5-nucleotides. To illustrate this, let’s consider the umami content of Katsuo-dashi soup stock (abundant in IMP), Tamari sauce (abundant in amino acids), and a mixture of the two at a ratio of 98:2. The EUC values for Katsuo-dashi and Tamari are 12.698 and 16.913, respectively. However, when these ingredients are combined, the EUC significantly increases to 29.254, primarily due to the synergetic effect.
Here’s an additional example involving the addition of tomato paste to pork. Pork, being a type of meat, naturally contains a good amount of nucleotides, and when combined with tomato paste, which is rich in amino acids, the overall umami profile is significantly enhanced. These two ingredients complement each other, resulting in a product with a high umami concentration. In particular, when pork and tomato paste are combined at a ratio of 8:2, the EUC value reaches 42.621, with approximately 96.2% of this umami intensity attributed to the synergetic effect between the two ingredients.
In this example, beef is used instead of pork and is found to have higher levels of amino acids but lower levels of 5-nucleotides compared to the previous sample. When beef is combined with tomato paste, the resulting total umami concentration is lower, indicating that these two ingredients are less complementary to each other, resulting in a diminished synergetic effect. Specifically, when beef and tomato paste are combined at a ratio of 8:2, the EUC value is estimated at 16.040. Approximately 89.8% of this umami intensity is attributed to the synergetic effect between the two ingredients.
Summary
The umami taste is derived from various substances, particularly amino acids, nucleic acids, and organic acids. The synergetic effect between these components plays a crucial role in enhancing umami perception, making it challenging to quantify accurately. However, the Equivalent Umami Concentration (EUC) provides a straightforward method to estimate the overall umami intensity, expressed in terms of monosodium glutamate (MSG) equivalence. The EUC serves as a convenient tool for measuring umami levels in ingredients both before and after cooking processes. It also aids in the exploration of complementary ingredient pairings to enhance umami flavors.
