Umami in Dried Shiitake Mushrooms
Dried Shiitake Mushrooms
Mushrooms are renowned for their distinct and rich flavors, making them a prized ingredient in various cuisines. Among the numerous mushroom varieties, shiitake mushrooms stand out as one of the most appreciated options. With their robust and earthy taste, shiitake mushrooms bring a delightful depth to dishes. They are particularly esteemed for their umami flavor, which adds a savory and satisfying note to food.
Dried shiitake mushrooms, in particular, are widely embraced in culinary practices to enhance the taste of various dishes. Drying shiitake mushrooms not only extends their shelf life but also preserves their quality, while simultaneously providing a concentrated burst of flavors. By subjecting shiitake mushrooms to the drying process, their moisture content is reduced, allowing them to be stored for longer periods without compromising their taste and texture. As the mushrooms dry, their flavors become more concentrated, resulting in an intensified and robust profile that can enhance the culinary experience. The practice of drying shiitake mushrooms thus serves the dual purpose of prolonging their shelf life and unlocking their concentrated flavors.
When rehydrated, dried shiitake mushrooms release their distinct umami essence, infusing the dish with a unique depth and complexity. Their versatility allows them to be incorporated into soups, stews, stir-fries, sauces, and even vegetarian and vegan dishes, providing a hearty and satisfying flavor experience.
Due to their ability to enhance the taste of food, especially in terms of umami, dried shiitake mushrooms have gained popularity among chefs and home cooks alike. Their umami-boosting properties make them a valuable ingredient for creating delicious and flavorful meals that leave a lasting impression on the palate.
Impact of Dehydration on Umami
Dehydration not only concentrates umami substances but also alters the quantity of these flavor compounds by modifying the structure of proteins and other organic components. When shiitake mushrooms undergo the dehydration process, the removal of water causes a reduction in volume, resulting in a higher concentration of umami compounds. Additionally, the dehydration process induces changes in the molecular structure of proteins and other organic substances, which can impact the overall amount of umami present in shiitake mushrooms. These transformations brought about by dehydration play a significant role in intensifying the umami taste and altering the overall flavor profile of the dehydrated food product.
Different conditions of dehydration have been studied, and the following table is the result of the study, Yang et al, comparing different temperatures for hot-air drying (HD) and freeze drying (FD.) On the righthand side of the table, amounts of umami substances are shown in terms of dry weight (DW,) and those amounts are translated into fresh weight to compare with the original fresh shiitake mushrooms (as “Fresh.”) “EUC” in the bottom of the table stands for Equivalent umami concentrations; EUC is the concentration of MSG (g/100 g) equivalent to the umami intensity given by the mixture of umami amino acids (glutamic acid and aspartic acid) and 5ʹ-nucleotides. It is calculated to measure both the direct contributions from each substance and synergetic effects between different substances.
Obviously the content of umami substances in dried shiitake mushrooms in terms of dry weight is much higher than that of fresh shiitake mushroom, as the dehydration process removes moisture and concentrates the umami substances. It was found that, however, content of umami substances in terms of fresh weight differed in dehydrated samples from the fresh shiitake mushroom; that indicates some mechanisms altering substances during the processes.
Serine (Ser) and Lysine (Lys,) for example, decreased as shiitake mushrooms were dried, and samples with hot-air dried at a higher temperature indicated a sharper decline; it was suggested to be the result of the Maillard reaction during heating.
Glutamic acid (Glu) in hot-air dried samples at 50–60 °C in terms of fresh weight is smaller than that of fresh shiitake mushroom, while when the sample was hot-air dried at 70 °C, Glu was higher than fresh sample. We can argue that there are reduction and production of Glu during the drying process, and higher temperature either weaken the former or strengthen the latter.
Among the organic acids, lactic and succinic acids contribute to umami, and both decreased as shiitake mushrooms were dehydrated. Among hot-air dried samples, the content of those two organic acids was highest in samples dried at 60 °C, indicating a non-linear (convex) relationship between the amount of organic acids and temperature.
Nucleotides suggested a similar picture with organic acids, and the dried samples contained less nucleotides than the fresh sample. Total nucleotides content was lowest in freeze dried samples. Among samples hot-air dried, the one dried at 60 °C kept the smallest amount of nucleotides, suggesting a non-linear (convex) relationship between the amount of nucleotides and temperature.
It is notable that hot-air dried shiitake mushrooms indicate higher EUC than freeze dried ones, and among those hot-air dried, the higher temperature is the more umami content is. The highest content of EUC in the samples hot-air dried at 70 °C was largely attributed to the highest amount of Glu.
Yang, X., Zhang, Y., Kong, Y., Zhao, J., Sun, Y., & Huang, M. (2019). Comparative analysis of taste compounds in shiitake mushrooms processed by hot-air drying and freeze drying. International Journal of Food Properties, 22(1), 1100–1111.
Implication
The quantity of umami substance is influenced by various factors, and the effects of certain conditions can exhibit non-linear relationships. Managing the transformation of umami substances is a complex and challenging task. The amount of umami present in food can be influenced by small details in cooking methods or processing techniques. The impact of these factors is not always straightforward, and their relationship with umami content may follow intricate patterns. Consequently, ensuring optimal levels of umami and effectively controlling its transformation in culinary preparations requires numerous try-and-error experiments, careful attention and expertise due to the multifaceted nature of these processes.
