Why does paste sometimes cause oil to split during cooking?

Question

Understand how moisture and heat cause paste to release oil early.

Answer 1

Paste can cause oil to split during cooking because of its high water content and the presence of starches or sugars that can burn and destabilize the oil. The water turns to steam, disrupting the oil's emulsion, while the starches and sugars caramelize and burn, leading to oil breakdown.

Detailed Explanation:

When you add a paste to hot oil, several things happen simultaneously. First, the water content in the paste rapidly heats up and turns into steam. This sudden introduction of water disrupts the oil's structure, causing it to splatter and potentially separate. Second, many pastes contain starches (like flour or cornstarch) or sugars. At high temperatures, these carbohydrates can quickly caramelize and burn. These burnt particles contaminate the oil, lowering its smoke point and causing it to break down and 'split,' meaning the oil separates into its component fatty acids and glycerol. This process is accelerated if the oil is already old or has been used multiple times. The presence of impurities further degrades the oil's ability to maintain its integrity. The splitting is visually noticeable as the oil becomes cloudy, darkens in color, and may even produce an acrid smell.

Pro Tip:

To prevent oil splitting when using pastes, temper the paste by gradually adding small amounts of the hot oil to the paste before introducing it to the entire pan. This helps to equalize the temperature and reduce the shock to the oil, minimizing splattering and burning.