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Why does milk curdle when tea is made with jaggery, but stay smooth with sugar? Is jaggery to blame, or something inside it? The answer lies in simple kitchen science
When jaggery is added to hot milk tea, its acids react with the milk proteins, leading to curdling.
It has happened in countless kitchens. Someone adds jaggery to boiling milk tea and instantly, the tea curdles. Even when jaggery is added before or after boiling, the result is often the same. But when sugar is used, the tea turns out perfectly fine. Why does this happen? This isn’t kitchen magic gone wrong; it’s pure chemistry.
The main reason milk curdles when jaggery is added is acidity. Jaggery is a natural, minimally processed sweetener that contains malic acid and other organic acids. Milk, on the other hand, contains a protein called casein. When jaggery is added to hot milk tea, its acids react with the milk proteins. Combined with heat, this reaction causes the casein proteins to clump together, leading to curdling.
Sugar doesn’t cause this problem because it is highly refined and contains no acids, so it doesn’t disturb the milk’s structure.
How To Add Jaggery Without Curdling Your Tea
If you prefer jaggery tea, a few careful steps can help:
- Prepare the tea fully and add the milk first
- Turn off the flame before adding jaggery
- Grate or powder the jaggery so it dissolves quickly
- Avoid boiling the tea after adding jaggery
- Use older or dry jaggery, as fresh jaggery has higher acidity
- Prolonged boiling increases the chances of curdling.
Other Common Reasons Milk Tea Curds Suddenly
Jaggery isn’t the only culprit. Several everyday ingredients can also spoil milk tea if used incorrectly.
- Ginger: Ginger contains proteolytic enzymes that break down milk proteins. If ginger is added after milk and boiled for too long, the milk can curdle. Always boil ginger well in water before adding milk.
- Basil (Tulsi): Excessive boiling of basil can curdle milk due to its mild acidity.
- Cardamom and Cinnamon: Old, damp, or stale cardamom and cinnamon can affect the milk’s texture and cause curdling.
- Milk Quality: Milk that appears normal may already contain bacteria producing lactic acid, lowering its pH. When this milk meets hot tea, curdling happens instantly.
Milk Tea Around The World
Milk tea is enjoyed in 40 to 50 countries, though preparation styles vary widely.
- India & Pakistan: Masala chai is world-famous, and tea usually means milk tea
- Bangladesh & Nepal: Strong milk tea similar to India
- Taiwan: Birthplace of bubble tea
- Hong Kong: Famous for ‘Hong Kong-style milk tea’
- Thailand: Known for orange-coloured Thai milk tea with condensed milk
- Malaysia & Singapore: ‘Teh tarik’, poured theatrically to create froth
- Mongolia: ‘Suute tsai’ made with milk, salt, and sometimes butter
- Britain: Milk added to black tea is the norm
- Ireland: Highest per-capita tea consumption, prefers milk tea
- Yemen: ‘Adeni tea’ made with milk and spices
- Turkey: One of the largest tea-drinking nations, but tea is consumed without milk
India’s Most Unique Milk Tea: Kashmir’s Noon Chai
Kashmir stands out with its royal and unusual Noon chai, also called pink tea. Unlike regular brown tea, this tea is pink in colour and salty, not sweet.
- Known as pink tea in Kashmir and desi tea in Jammu
- Made by boiling dried green tea leaves until water reduces by half
- Milk, sugar, and salt are then added
- Some add a pinch of baking soda
- Often stored and consumed like kahwa
- Locals say it keeps the body warm and doesn’t cause gas
- Sometimes topped with crushed dry fruits
Hyderabadi Irani Tea: A Class Apart
Hyderabadi Irani tea is prepared differently. Tea and milk are cooked separately. The milk is boiled until thick, almost like rabri, and then mixed with the tea decoction, giving it a rich, creamy texture.
From jaggery chemistry to global tea traditions, that one curdled cup of chai has a lot more science and culture behind it than we realise.
February 10, 2026, 08:10 IST