Influence of geometric and dynamic parameters of a water-polymer jet on characteristics of food products hydro-cutting process

Abstract

Introduction. The process of water-polymer jet cutting of food products in order to increase the efficiency of the method of hydro-jet cutting by modifying the working fluid is investigated. Materials and methods. The process of cutting chicken fillet, hake fish, beef and pork meat is researched. The experiments were carried out at temperatures of -7 °C and -25 °C, pressure changes from 50 MPa to 150 MPa, nozzle diameter 0.35.10-3, 0.6.10-3 m and velocity of the water-polymer jet movement relative to the sample of food product of 0.015, 0.025, 0.050 and 0.100 m/s. The PEO concentration with molecular mass of 6.106, 4.106 and 3.106 varied from 0 till 0.05%. Results and discussions. The depth of the cut in a frozen food product increases quite rapidly with the increasing of concentration and PEO molecular mass and reaches its maximum at some optimal concentrations (Сopt.). For PEO with a molecular mass of 3∙106, the Сopt equal to 0.015-0.020%, and for molecular mass of 4∙106 and 6∙106 – 0.007-0.010% and 0.0015-0.0020%, respectively. Increasing the diameter of the nozzle hole under the constant pressure of PEO water solution leads to increasing of the cutting depth in a food product. Noted character of influence of nozzle hole diameter of hydro-cutting jetshaping head on the cutting depth is due to the fact that the nozzles usage with a relatively big nozzle outlet diameter under the constant velocity of water-polymer jet movement in relation to the food sample and pressure of PEO water solution in front of the nozzle should lead to increasing of energy per unit of the cutting food product surface. To achieve the same cutting depth of frozen food products (in the range of -7 and -25 °C) it’s enough to have water-polymer jet pressure of only 45-65% from the water jet, and vice versa, under the same initial pressure, 1.5–2.5 times increase in the depth and cutting velocity with water-polymer jet is observed, what tells about the special mechanism of its interaction with a food product. The dependence of the dimensionless cutting depth by water-polymer jet in frozen food products from the dimensionless distance to the nozzle section is obtained. The usage of high-velocity jet of PЕO water solution for cutting frozen food products considerably increases the efficiency of the cutting process and the quality of the cutting surface. Conclusions. In order to significantly improve the efficiency of food products water-cutting process, it is advisable to use jet of PEO water solution as the working fluid.