Temperature Increase Research of Particles Formed by Ultrasonic Grinding of Spinach Leaves

Abstract

The researchers chose spinach leaves as the research object for obtaining a natural dye based on chlorophyll because the vegetable is a food raw material rich in this pigment, and biologically active substances source with variety of its functional properties. To solve the problem of more complete chlorophyll extraction from crushed spinach leaves, they are to subject to a preliminary short-term soaking in a water/organic reagent emulsion under ultrasonic influence. Given that the water-based spinach suspension is thermolabile, a man must observe temperature restrictions, since when a certain critical temperature value is exceeded, the chlorophyll decomposition probability with its consumer properties loss is high. As it is practically impossible to determine the temperature inside a fine particle suspended in an aqueous emulsion experimentally, the authors considered to model internal and external heat transfer by solving the differential equation of heat energy transfer under appropriate boundary conditions using the numerical method of finite differences. The research determined structural-mechanical and thermophysical characteristics of crushed spinach leaves experimentally using the complex calculation method of thermophysical parameters based on the thermal inertia properties of a thermocouple. A man verified the solution adequacy by empirically determined suspension temperature after completion of the technological procedure. According to the developed algorithm, the authors compiled a program for the temperature fields evolution in the object of study considering the incident ultrasonic flow and an internal heat source with the new surface formation when grinding spinach particles in order to comply with thermal restrictions and maximize the quality parameters preservation. The article considers the rational duration of the ultrasonic grinding process without exceeding the recommended threshold temperatures.