THE MUSTARD BULLETS AND THE DELIGHTFUL CULINARY ADVENTURE IN AN INDIAN KITCHEN: HIGH-SPEED VISUALIZATIONS, FLOW PHYSICS, AND MECHANISMS

Abstract

Mustard seeds play a crucial role in Indian culinary practices and culture, not to mention the adventurous ordeal of dodging the so-called "mustard bullets" when they pop in hot oil, a familiar experience for those who cook with them. The popping of mustard seeds, while seemingly straightforward, is actually a complex phenomenon not extensively studied. It is believed to be caused by the water content within the seeds turning into steam under high heat, leading to the seeds popping. This study focuses on analyzing the movement of mustard seeds to delve into the flow dynamics and mechanisms behind this popping process. The research aims to define the motion of the seeds, quantify the force imparted upon human skin during impact, and elucidate the reason for the associated painful sensation. Experiments were carried out using high speed imaging and microscopic study of the mustard seeds to study its morphology and drag characteristics. The findings reveal that the rupture of the seed, due to the interaction between the superheated steam within and the hot oil, generates a force that propels the seeds. Upon ejection, the oil surrounding the seed displays two different outflow patterns. This study concludes that the painful sensation from "mustard bullets" is not directly due to the impact pressure but rather the interaction between the hot oil, carried by the seed, and human skin, with the seed's role being to transport the hot oil and sustain its temperature during the flight.