Ohmic Heating of Liquid Whole Egg: Rheological Behaviour and Fluid Dynamics

Rheological and Flow Behaviour of Yolk, Albumen and Liquid Whole Egg from Eggs of Six Different Poultry Species

Liquid egg products are one of the basic raw materials for the food industry. Knowledge of their rheological and flow behaviour in real technical elements is absolutely necessary for the selection of suitable technological equipment for their processing. In this article, the rheological properties of liquid egg products were determined. Eggs from six different species of poultry are used: domestic hen (Gallus gallus domesticus) hybrid Hisex Brown; Japanese quail (Coturnix japonica); German carrier goose (Anser anser f. domestica); domestic ducks (Anas platyrhynchos f. domestica); domestic guinea fowl (Numida meleagris f. domestica); and domestic turkeys (Meleagris gallopavo f. domestica). Liquid egg products showed pseudoplastic behaviour in range of shear strain rates from 0.2 up to 200 s⁻¹ and at the temperature of 18 °C. Thus, the flow curves were constructed using the Ostwald-de Waele rheological model, with respect to the pseudoplastic behaviour of liquid egg products. According to the values of the coefficients of determination (R²), the sum of squared estimate of errors (SSE) and the root mean square error (RMSE), this model was appropriately chosen. Using the consistency coefficient K, the flow index n and the adjusted equations for the flow rate of technical and biological fluids in standard pipelines, the 3D velocity profiles of liquid egg products were successfully modelled. The values of the Reynolds number of the individual liquid egg products were calculated, and the type of flow was also determined. A turbulent flow has been detected for some liquid egg products.

Ohmic cooking of instant rice cake soup: energy efficiency and textural qualities

The potential of ohmic heating was investigated to cook instant rice cakes according to electric field strengths (9, 12, 15, 18 V/cm) and cooking times (60, 80, 100, 120 s). Customized ohmic heating system was equipped with ohmic cell, electrodes, thermocouple, proportional-integral-differential controller and data acquisition system. Heating rate significantly increased when electric field strengths increased. Heating rate was 12.1 °C/min at 9 V/cm, and was increased to 38.8 °C/min at 18 V/cm. The energy efficiency was evaluated in terms of system performance coefficient (SPC) energy efficiency. The best SPC energy efficiency was 0.65 at an electrical field strength of 18 V/cm. An electric field strength of 15 V/cm and an 80 s cooking time resulted in the most preferable hardness (7.73 N). Ohmic heating would be applicable to cook instant rice cakes, resulting in good energy efficiency and textural qualities.

Evaluating the Feasibility of Ohmic Cooking for Home Meal Replacement Curry: Analysis of Energy Efficacy and Textural Qualities

The feasibility of ohmic heating was tested for cooking instant home meal replacement (HMR) curry mixture. A curry mixture (curry powder, spam, carrot, potato, and water) was ohmically heated to 100 °C using different electric fields (9, 12, 15, and 18 V/cm). Temperature come-up time to 100 °C of curry soup were 5.27 ± 0.63, 3.15 ± 0.39, 2.28 ± 0.19, and 1.67 ± 0.24 min at the electric fields of 9, 12, 15, and 18 V/cm, respectively. The come-up time was decreased as a function of enhanced electric fields (P < 0.05). In terms of energy efficacy, the highest electric field (18 V/cm) resulted in the most efficient system performance coefficient (SPC), with a score of 0.62. In terms of textural qualities, cooking at 15 V/cm of carrot and potato the hardness was 3.41 ± 0.69 N and 1.04 ± 0.18 N, respectively, that resulted in the ideal level of hardness. Our study proposed the positive feasibility of ohmic heating to cook HMR curry soup.