Droplet outbursts from onion cutting.

Area of Science:

• Biophysics
• Food Science
• Materials Science

Background:

• Onion cutting commonly causes eye irritation due to aerosolized irritants.
• The precise physical mechanisms driving this aerosol release are not well understood.

Purpose of the Study:

• To elucidate the mechanics of tear-inducing aerosol formation during onion cutting.
• To investigate the influence of cutting parameters on droplet ejection.
• To develop a model explaining onion rupture and droplet release.

Main Methods:

• High-speed imaging and characterization of droplet formation.
• Systematic variation of blade sharpness and cutting speed.
• Strain mapping of onion tissue during cutting.
• Development and validation of a bilayer fracture model using experimental and numerical methods, including Instron testing.

Main Results:

• Droplet formation follows a two-stage process: initial outburst and subsequent ligament fragmentation.
• Faster or blunter blades increase the number and energy of ejected droplets.
• The onion's epidermis acts as a fracture barrier, allowing significant mesophyll compression before rupture.
• The bilayer model accurately captures the rupture mechanism, with model predictions aligning with experimental fracture force data.

Conclusions:

• Blade sharpness and cutting speed critically influence aerosol release during onion preparation.
• Understanding these mechanics can inform practices to reduce airborne irritants and potential pathogen spread in kitchens.
• The study provides a foundational model for vegetable tissue rupture relevant to food preparation and processing.