Why control the variables during tea infusion?
To attain the optimum flavour and tactile balance from the infusion it is critical to control the water temperature, the amount of tea and the steep (duration of infusion). This is because during the infusion process, different compounds contained within the tea (e.g. flavonoids, melanoids, catechins*) are released into the water at different stages of the infusion. Towards the end of the infusion there is a greater rate of catechins (which are the bitter elements) being released into the water.
The optimum steep will differ for each tea. This is the optimum point where the full flavour of the tea is released without imparting tannic or bitter flavours into the water. Each tea has its own unique recipe for infusion, determined largely by the rate at which the cells expand. E.g. With green tea, the cells expand at a faster rate than black tea. For that reason the tea imparts it’s flavour at a faster rate, hence the catechins and bitter elements will also be released at a faster rate.
If tea is over-infused, it can become ‘tannic’. Tannic is a term used to describe the undesirable consequence when a lot of the tannin from the tea has been released during the infusion and the bitterness of the tannins dominate the flavour of the tea. This can also result when the steep is too long, and potentially when the water is too hot. As we taste bitterness 10 times more than we taste sweetness, when this occurs bitterness will dominate the sweetness and overall flavour of the tea and the complexity of flavour is diminished.
To consistently achieve the optimum infusion you will need to control the brewing variables.