Why milk gets spoiled when adding ginger during tea preparation?

Milk gets spoiled when adding ginger during tea preparation because of the presence of protease
which basically acts as a curdling agent.
& Zingipain, a protease, is found in ginger. This protease catalyses the denaturation of the milk
protein, converting it from a water-soluble to a water-insoluble form, which results in the
formation of milk curd, when ginger is added to milk.
When milk is added, the protease found in fresh ginger basically acts as a curdling agent.
Therefore, it is best to first bring the milk and water to a boil before adding the ginger a few
seconds later or two to three minutes later.
This will ensure that it won’t cause the milk to curdle when exposed to a temperature of roughly
100°C. This means that adding ginger requires a temperature of at least 100°C.
The trick is to boil the milk and water first, and then add the ginger just as it begins to boil. It
won’t curdle because it will then be exposed to temperatures around 100 degrees. Additionally, if
you have grated your ginger, only add the flesh to the chai rather than the juice.