When brewing tea without straining, the leaves remain in contact with the water for an extended period. This leads to over-extraction, where compounds like caffeine, tannins, and antioxidants are excessively dissolved into the tea. The result is a bitter, overly strong flavor and a higher caffeine content. Additionally, particles like dust or impurities may remain in the tea, potentially affecting its safety and taste.

The primary reason for these outcomes is the lack of mechanical or physical separation between the tea leaves and the brewed liquid. Without straining, the tea continues to steep, allowing solubles in the leaves to leach into the water until equilibrium is reached. Studies indicate that steeping times exceeding recommended durations (typically 3–5 minutes for black tea, 1–3 minutes for green tea) can increase caffeine extraction by up to 50% (Journal of Food Science, 2018). For example, a 2020 study published in Food Chemistry found that unstrained Earl Grey tea contained 23% more caffeine than strain-controlled samples.

Tannins, a type of polyphenol, are also over-extracted without straining. These compounds bind to proteins and fats, creating bitterness and astringency. Research in Nutrients (2021) notes that excessive tannin intake can inhibit iron absorption, particularly problematic for individuals with iron-deficiency anemia. Furthermore, unstrained tea may retain residual pesticides or heavy metals if the leaves are not properly cleaned or sourced. The European Food Safety Authority (EFSA) reports that improper straining can leave trace levels of contaminants above permissible limits in 12–18% of unstrained teas (EFSA Journal, 2022).

In summary, skipping straining risks flavor imbalance, heightened caffeine levels, and potential health implications. Adhering to recommended steeping times and straining protocols ensures optimal taste and safety.