Milk Curdling in Bubble Tea
We wanted to write an article on milk curdling after Hanye and I each ordered a taro milk tea, one cold and one hot. After four hours of walking around, I became thirsty and finally decided to pop the seal with my fat straw and took a massive gulp. My eyes lit up and I immediately spat it right out. Hanye was laughing away whilst drinking her cold bubble tea with no problem.
What’s in Milk?
Milk is made up of many different components including proteins, fat, sugar and water. The amount of each varies depending on individual animals, breed, stage of lactation, age and health. The average composition of cow milk from is: 87% Water, 4% fat, 3.4% protein, 4.8% lactose and 0.8% others including minerals.
What is curd?
The process of curdling is when the proteins in milk, specifically casein, binds together forming larger molecules (coagulate) and falls out of solution. In milk, casein quite happily floats around freely in its negatively charged state, repelling each other. When the pH falls, the charge on casein becomes neutral and binds together, which we can see. This occurs at acidic conditions of less than pH4.6. That is why when clumps are formed when adding lemon juice to milk. This is actually how cheese is made!
What about non-dairy creamer?
Non-dairy creamer is similar to milk, except it does not contain lactose (sugar), hence why it is safe for those who are lactose intolerance without any nasty surprises.
In cold and room temperature, the curdling process is slowed down, however it is speeded up by heat, hence why I wasn’t able to drink my hot taro milk tea after 4 hours.
So! If you decide to order or make a hot milk tea, make sure you don’t leave it out too long otherwise you won’t get the same experience as a fresh hot milk tea.