When brewing Astragalus astragalus, water temperature and brewing time do significantly affect the dissolution of its active ingredients. This influence not only impacts the taste of the tea but also directly affects whether the beneficial components of the astragalus root are fully absorbed. Astragalus root, a common food and medicine ingredient, contains core components such as polysaccharides and saponins, which are mostly water-soluble. The dissolution and release of these components require appropriate temperature conditions and sufficient permeation time. If the water temperature is inappropriate or the brewing time is insufficient, even high-quality astragalus root will have difficulty fully integrating these components into the tea, resulting in a reduced tea effect.
From the perspective of water temperature, temperature directly determines the dissolution rate and total amount of active ingredients released. The polysaccharides in astragalus root are highly sensitive to temperature. If brewed with warm or cold water, the slower movement of water molecules makes it difficult to effectively penetrate the cell wall structure of the astragalus root. Even with prolonged steeping, these water-soluble components are only slowly and sparingly released, resulting in a bland tea with a low content of core ingredients. When brewing with boiling or near-boiling water, the high temperature accelerates the penetration of water molecules, allowing water to enter the astragalus root more quickly, promoting the expansion of its cell walls and allowing polysaccharides, saponins, and other ingredients to dissolve more efficiently. Furthermore, astragalus root possesses a unique herbal aroma, which is enhanced by high temperatures, ensuring both flavor and optimal dissolution of its ingredients. This avoids the situation where insufficient water temperature results in "tea flavor without dissolution of the active ingredients."
However, there's no need to worry about boiling water destroying astragalus root's active ingredients. Key ingredients in astragalus root, such as astragaloside IV and astragalus polysaccharides, are more stable in short, high-temperature brewing times and are not easily degraded. Instead, they are more fully released with the help of high temperatures. If the water temperature is too low, the dissolution rate may be too slow, causing some ingredients to remain in the astragalus root. Even with extended brewing times, ideal dissolution will be difficult to achieve, ultimately resulting in waste of raw materials.
In addition to water temperature, brewing time also plays a key role in the dissolution of active ingredients. Even at an appropriate high temperature, if the brewing time is too short, the water and the astragalus root won't have enough contact time, and the active ingredients won't fully dissolve before being discarded. This will result in a significant amount of beneficial ingredients remaining in the astragalus root residue, unavailable for human consumption. For example, if the tea is immediately poured out after adding boiling water, it will often be a pale yellow and bland in flavor, because the ingredients haven't fully dissolved. Prolonging the brewing time, allowing the astragalus root to fully soak and simmer for a while, allows water molecules to more thoroughly penetrate the raw material, gradually extracting the active ingredients. The tea will gradually darken to a light brown color, develop a richer herbal aroma, and have the characteristic mellow taste of astragalus root.
However, longer brewing times aren't necessarily better. If the steeping time is extended beyond a reasonable range, in addition to the active ingredients, small amounts of substances such as tannins contained in the astragalus root may also leach out. These substances can impart a noticeable bitterness to the tea, disrupting its original palatability and potentially worsening the drinking experience. At the same time, prolonged open-water steeping can expose the tea to excessive air, leading to oxidation of some ingredients and compromising overall quality. Therefore, the key to brewing time is "moderation"—ensuring the full dissolution of active ingredients while avoiding the introduction of unnecessary bitterness due to prolonged brewing.
In actual brewing, the coordination of water temperature and brewing time is also crucial. Generally, after brewing with boiling water, covering the cup or pot with a lid while steeping reduces heat loss, maintaining the high temperature longer and further enhancing the dissolution of ingredients. For example, when brewing Astragalus in a thermos, the insulation keeps the water temperature elevated for a longer period, allowing for more complete dissolution of active ingredients even with the same brewing time as in a regular cup. Using a regular glass cup, promptly covering and steeping after adding boiling water can achieve similar results.
Water temperature determines the efficiency of dissolution of the active ingredients, while brewing time determines the full extent of this dissolution. The two work together to optimally release the active ingredients of Astragalus membranaceus into the tea, ensuring both flavor and a more complete exposure to the beneficial ingredients. For daily brewing, simply adhere to the principle of "boiling with boiling water and simmering for a moderate amount" to achieve optimal dissolution with simple operation, avoiding waste due to inappropriate water temperature and duration, while providing a superior drinking experience.
