Explosion cavity that forms when a drop of water hits the hot oil. Credit: Tadd T. Truscott
Experienced cooks can determine when cooking oil has reached the right temperature for frying by introducing moist chopsticks into the hot oil. Bubbles form on the sticks and the sound they make can tell the cook when it is time to add food to the pan.
In Fluid physics, researchers from the United States, Canada, and Saudi Arabia carefully studied the bubbles that form when water droplets come in contact with heated cooking oil. When the researchers inserted wet chopsticks into hot oil, they found that the type and number of bubbles formed depended on the amount of water absorbed by the chopsticks, as well as the material of the chopsticks.
They experimented with drops of water and drops of dough suspended on the tip of a toothpick. The drop of water exploded when it hit the hot oil, where the drop of paste developed bubbles on its surface.
To further investigate what happens when food is placed in hot oil, the researchers used a small piece of damp paper with water as a model. They found that the amount and type of bubbles in this case depended on both the amount of water and the temperature. They observed that different types of steam cavities formed in hot oil when the water was in it.
These initial experiments led to a series of more controlled studies using a configuration that allowed drops of water to be added to the hot oil from an overhead cable in a mobile setting. A high-speed camera and a sensitive microphone were used to collect detailed data about the shape of the bubbles that form when the water drop hits the hot oil and the sound they make when they explode.
“We found three types of bubble events in our experiments: an explosion cavity, an elongated cavity, and an oscillating cavity,” said author Tadd Truscott.
The blast cavity forms when a drop of water enters the hot oil and undergoes a micro-explosion due to the sudden rise in temperature, forming a vapor bubble that can break the surface. The elongated cavity involves a drop of water that explodes without breaking the surface.
Video of the blast cavity that forms when a drop of water hits the hot oil. Credit: Tadd T. Truscott
The oscillating cavity occurs when the drop slips from the cable and is quickly submerged. It undergoes a multi-step explosion process and begins to oscillate before breaking into numerous small bubbles.
The audio signals from the microphone revealed that the three types of cavities produced different acoustic or sound characteristics.
“We can distinguish different characteristics of the acoustic signal for each type of cavity,” Truscott said. “Deciphering sound signals could lead to future applications, such as acoustic detection of aerosol generation.”
The article is entitled “Morphology of bubble dynamics and sound in heated oil”.
The Matryoshka effect: researchers describe the underwater phenomenon More information: Morphology of bubble dynamics and sound in heated oil, Fluid physics (2022). DOI: 10.1063 / 5.0088065 Provided by the American Institute of Physics
Quote: The crackling sound of frying reveals a complex physics (2022, June 7) recovered on June 7, 2022 from
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