Which infusion of tea contains the most nutrients?
Some people claim the first brew should be discarded, arguing that all the beneficial essences emerge in subsequent infusions. Others hold that the first steep is the richest, with all nutrients concentrated in the initial tea liquor. There are countless conflicting claims, each backed by personal experience.
Recently, a research team from the Shanghai Academy of Agricultural Sciences published a paper titled From Fresh Tea Leaves to Tea Liquor: Variations in 32 Bioactive Compounds During Processing and Brewing of Eight Tea Types in the journal LWT. The study provided data-supported conclusions for green tea, black tea and white tea.
1.The first brew is essence
Researchers selected representative tea samples from 8 provinces in China, including 5 green teas, 2 white teas, and 1 black tea, all processed according to local traditional techniques.
Table 1 Processing steps of 8 types of tea
According to the ratio of 1 gram of tea to 50 milliliters of water, brew at a fixed temperature of 90 ℃ for 5 minutes each time for three consecutive infusions. Measure the content of three core substances in each tea soup: catechins, free amino acids, and phenolic compounds.
These three types of substances are not only the main sources of tea's antioxidant and other health benefits, but also determine the core flavors of tea soup such as freshness, bitterness, etc.
The results of the experiment are very clear: regardless of the type of tea or the type of active substance, the nutritional concentration of the three tea soups shows a consistent pattern - the first brew has the highest concentration, the second brew significantly decreases, and the third brew continues to decrease. There is no situation where the nutrition of the second or third bubble exceeds that of the first bubble.
Figure 1 Changes in Nutrients in Longjing and Maofeng 3 brews
Taking Longjing, which is well-known to everyone, as an example, the amount of catechins dissolved in the first brew is 1.32 times that of the second brew and 2.23 times that of the third brew;
The difference in amino acids is more pronounced, with the first brew being 2.23 times that of the second brew and 3.63 times that of the third brew;
The amount of phenolic compounds in the first brew is 2.3 times that of the second brew, and by the third brew, it is less than a quarter of the amount in the first brew.
Figure 2 Changes in Nutrients of Three Bubbles of Meizhan Black Tea
The trend of black tea and white tea is completely the same. For example, in Meizhan black tea, the amount of catechins in the first brew is 1.48 times that of the second brew and 2.72 times that of the third brew;
The attenuation amplitude of white tea is greater, with the catechin content in the first brew being 1.54 times that of the second brew, and by the third brew, it is only about one tenth of that of the first brew.
Figure 3 Changes in Nutrients of Three Brews of Hunan and Guizhou White Tea
If we look at the specific functional ingredients, the pattern becomes more intuitive.
EGCG is the most active catechin and the core source of tea's antioxidant capacity.
The data shows that Longjing's first foam can dissolve about 51% of EGCG, which is 1.87 times that of the second foam and 2.39 times that of the third foam;
The proportion of EGCG in the first brew of Meizhan black tea reaches 56%; 61% of EGCG in white tea is dissolved in the first brew.
The later the soaking, the faster the content of these core functional ingredients decreases.
2.The influence of raw materials and processes on dissolution rate
Why is there such a pattern? In fact, it is essentially the diffusion principle of soluble substances.
Figure 4 Differences in catechins between fresh and dried tea leaves of 8 types of tea
The nutrients in tea are mostly water-soluble. When dry tea comes into contact with water, substances will diffuse from the high concentration inside the tea to the low concentration water. The larger the concentration difference, the faster the diffusion rate.
When brewing tea for the first time, the concentration of substances in the tea leaves is the highest, and the concentration difference between the tea leaves and water is the largest, so the dissolution rate is the fastest and the amount dissolved is the highest.
In this liquid, soluble substances on the surface and intercellular spaces of the tea leaves will be rapidly released.
By the second infusion, the concentration of the remaining substances inside the tea has decreased, and the difference in concentration with the tea soup has become smaller. It still needs to pass through structures such as cell walls to be released, and the speed naturally slows down.
By the third brew, there were not many easily soluble substances left, and most of the remaining components were firmly bound and difficult to diffuse, resulting in a lower amount of dissolution.
Figure 5 Differences in amino acids between fresh and dried tea leaves of 8 types of tea
Of course, the dissolution rate of different types of tea varies.
Green tea undergoes high-temperature withering and mechanical rolling, which fully destroys the cell structure of the leaves and exposes nutrients more fully, resulting in a faster overall dissolution rate. The first two brews can release most of the active ingredients.
The processing of white tea is relatively gentle, without a withering process, and some even do not have a rolling process. The leaf cells are preserved more intact, and the resistance to material diffusion is greater, so the overall dissolution rate is slower.
Table 2 Nutrient dissolution curves of 8 types of tea
Not only multiple infusions, but even extending the brewing time for a single infusion follows the same pattern.
This study also simulated the dissolution kinetics and found that catechins dissolve the fastest in the first few minutes of brewing. After reaching equilibrium, even if the soaking time is further extended, the concentration will not increase significantly.
For example, some green teas can dissolve most of the catechins within 4 to 8 minutes, and the added nutrients are very limited even after soaking for a longer period of time.
Essentially, they all follow the same principle: the release of soluble substances is always fast first and then slow, and more then less.
Overall, this systematic study covering three major tea categories, eight varieties, and tracking 32 active substances confirms a simple rule with solid quantitative data: the nutritional components of tea are highly concentrated in the first two tea soups, with the highest concentration and total amount in the first brew. The decay rate of different tea types and components varies, but the overall trend of "the first brew being the most enriched and decreasing with each brew" is consistent.
